Orthodontic Cyber Journal

Correction of Class II division 1 malocclusion using Functional Appliances

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Author: Dr.Sridhar Kannan

Professor,Dept. of Orthodontics and Dentofacial Orthopedics

Sudha Rustagi College of Dental Sciences & Research

Kheri More,Village Bhopani

Faridabad.

Co-Author: Dr.Gaurav Gupta

Senior Lecturer, Dept. of Orthodontics and Dentofacial Orthopedics

Sudha Rustagi College of Dental Sciences & Research

Kheri More,Village Bhopani

Faridabad.

Co-Author: Dr.Abhishek Goyal

Senior Lecturer, Dept. of Orthodontics and Dentofacial Orthopedics

Sudha Rustagi College of Dental Sciences & Research

Kheri More,Village Bhopani

Faridabad

Address for

Correspondence: Dr Sridhar Kannan

B-XI/8193, Vasant Kunj, New delhi-70

Tel: 9818212912

Email: sridharkannan_in@yahoo.com

INTRODUCTION

The term “Orthodontics” and “Dentofacial Orthopedics” are essentially’ distinct in that they represent a fundamental variation in approach to the correction of dentofacial abnormalities.

While Orthodontics implies, by definition, the correction of dental irregularities, dentofacial orthopedics conveys the much broader concept that treatment aims to significantly improve facial appearance and skeletal relationships in addition to correcting irregularities of the teeth.

Functional appliance therapy is that aspect of dentofacial orthopedics that aims to improve the functional relationship of dentofacial structures by eliminating unfavourable developmental factors and improving the muscle environment enveloping the developing dentition¹.

Functional appliances, by altering the position of the teeth and supporting tissues, establishes a new and more optimal functional behavioural pattern which leads to adaptive changes in the bone form and helps the dentofacial complex achieve, its optimal genetic growth potential^2-3.

The occlusal inclined plane is the fundamental functional mechanism of the natural dentition¹.

Twin block appliances are simple bite blocks designed for full time wear that achieve rapid functional correction of malocclusion by the transmission of favourable occlusal forces to occlusal inclined planes that cover the posterior teeth^4-5.

The goal in developing the twin block technique was to maximize the growth response to functional mandibular protrusion by using an appliance that is simple, comfortable and esthetically acceptable to the patient.

The objectives of early orthodontic intervention are to correct obvious problems and to intercept developing problems and prevent them from becoming worse. Class II malocclusion of more than 6mm of overjet can be treated early with functional appliance to^6-7:

1. To eliminate functional problems such as lip sucking habits.

2. Reduce overjet, decreasing the risk of traumatic occlusion on the upper incisors.

3. Improve the esthetic appearance of the patients with convex profiles and

retrusive lower faces

4. Control the skeletal discrepancy between the upper and lower jaws by

stimulating the mandibular growth.

5. Help develop a normal occlusion and facial harmony and promote stability through

out the period of facial growth.

This article will analyze the clinical and cephalometric effects of twin block on patients with severe classII malocclusion in the early permanent dentition and permanent dentition. This section illustrates examples of the treatment of uncrowded ClassII division1 malocclusion in different facial types with twin block appliance to compare the response to treatment.

Case Report

A 12 year old female presented with the chief complaint of unesthetic appearance of her protuding upper incisors. On clinical examination patient had convex soft tissue profile with protruded upper lip, retrognathic mandible. the lower lip was functioning entirely behind the maxillary incisors, which were between the lips at rest.(Fig.1)

Fig.1-Pre-treatment Extraoral Photographs

The patient, who was in the early permanent dentition, had a Class II molar and canine relationship, an overjet of 13mm and an overbite of 5mm. Midline diastema was present in the upper arch with well aligned lower arch.(Fig.2)

Fig.2 Pre-treatment Intraoral photograph.

Cephalometric analysis showed a skeletal Class II malocclusion (ANB = 8°, FMA = 23°) due to mandibular deficiency (SNB = 74°) and maxillary protrusion (SNA = 82°). Both the upper and lower incisors were proclined U1-SN =120°, IMPA = 95°) with interincisal angle of 116⁰ although the maxillary proclination was more pronounced. (Fig.3) & (Table 1).

Fig.3 Lateral Cephalogram tracing

Table 1. Cephalometric Data.

A twin block was advised to stimulate mandibular growth during the development of the dentition. The bite registration was taken with a vertical opening that exceeded the freeway space by 4mm. Contact was maintained between the appliance and the maxillary posterior teeth, but the mandibular posterior teeth were encouraged to erupt by progressively trimming the acrylic on their occlusal and lingual aspect.

After 24 months of treatment with the twin block appliance, a significant improvement in the soft-tissue profile was evident, and labial competence was achieved (Fig. 4). With the overbite and the overjet reduced, the sagittal relationship between the arches improved along with the achievement of bilateral Class I molar relationship.

Fig.4 Post-functional Extraoral Photographs.

The effects of the twin block appliance therapy were evaluated cephalometrically after about two years of treatment (Table1). A reduction of 4° in ANB was achieved, mainly by a forward displacement of the mandible (SNB = 78°) and by controlling the sagittal growth of the maxilla (SNA = 83°). Mandibular base length increased by 6mm, showing substantial growth of the lower jaw (Ar-Pog = 102mm). The vertical skeletal dimension was slightly increased (SN-MP = 29°), with decease in the inclination of the upper incisors (U1- SN = 94°).

As the permanent dentition was completed, a Class I molar and canine relationship was obtained, and the overjet and overbite were corrected (Fig. 5).

Fig.5 Post-funtional Intraoral Photographs.

The twin block was then worn at night only for retention.

Post-treatment cephalometric analysis indicated an improvement in the sagittal jaw relationship (ANB = 4°), due almost entirely to a forward movement of B point (SNB = 78°) and a further increase in mandibular base length (Ar-Pog = 102mm). The vertical dimension, as expressed by FMA, increased by 2°.

Case Report-2.

An 11 year old female reported with forwardly placed upper incisors. After clinical examination and cephalometric evaluation she was diagnosed as Class II Division1 malocclusion with convex facial profile, retrognathic mandible, increased overjet and overbite(Fig.6-7).

Fig.6 Pre-treatment Extraoral Photographs

Fig.7 Pre-treatment Intraoral Photograph

After complete diagnosis and treatment planning, functional appliance therapy was chosen as the first line of treatment. Twin block appliance was delivered to the patient after following the standard procedure of bite registration. Functional appliance therapy continued for two years to achieve desired improvement in the facial profile. Marked post functional changes were seen with improvement in the convex facial profile, reduced overjet and overbite (Fig.8-9). Cephalometrically, there is reduction in ANB angle by 4⁰ indicating the improvement in sagittal jaw relationship predominantly because of forward movement of point B and increase in mandibular base length.

Fig.8 Post-functional Extraoral Photographs

Fig.9 Post functional Intraoral Photograph

Case Report-3

An 11 year old male was diagnosed with Class II Division1 malocclusion on account of retrognathic mandible, convex facial profile, angle’s Class II molar relation, proclined maxillary incisors, increased overjet and overbite (Fig.10-11).

Fig.10Pre-treatment Extraoral Photographs

Fig.11 Pre-treatment Intraoral Photographs

Considering the clinical examination, cephalometric analysis and age of the patient, it was decided to treat the patient by functional growth modification. Twin block functional appliance was given to the patient to be worn for next two years. After 24 months of treatment with the twin block appliance, a significant improvement in the soft-tissue profile was evident with improved lip competence (Fig.12).

Fig.12 Post Functional Extraoral Photographs

With evident reduction in overjet and overbite, the sagittal relationship between the arches improved along with the achievement of bilateral Class I molar relationship (Fig.13). Post-treatment cephalometric analysis indicated an improvement in the sagittal jaw relationship (ANB = 4°), due almost entirely to a forward movement of B point (SNB = 77°) and a further increase in mandibular base length (Ar-Pog = 102mm).

Conclusion

The principal advantage of functional appliances in Class II therapy is that they not only correct the malocclusion, but are also effective in improving the soft-tissue profile and the intermaxillary relationship. Early treatment can eliminate etiologic factors such as sucking habits, restoring normal growth and reducing the severity of skeletal abnormalities. Once the growth period is over, treatment options become more limited. Mixed-dentition therapy can therefore help create a more stable and esthetic occlusion than if treatment is delayed until the permanent dentition.

References

1. Clark WJ. Twin Block functional therapy. Applications in Dentofacial Orthopaedics.Mosby, 2nd edition

2002; 1-10.

2. White, L.: Early Orthodontic intervention, Am. J. Orthod.113:24-28, 1998

3. Bench, R.W.; Gugino, C.F.; and Hilgers, J.J.: Bioprogressive therapy, Part 8, J. Clin. Orthod. 12:279-

298, 1978.

4. Bishara, S.E. and Ziaja, R.R.: Functional appliances: A review, Am. J. Orthod. 95: 250-258, 1989.

5. Arvystas, M.G.: The rationale for early orthodontic treatment, Am. J. Orthod. 113:15-18, 1998

6. Murillo, J.C.: Mixed-dentition treatment with the selective functional appliance, Am. J. Orthod. 63:596-

605, 1973.

7. Cozza P, De Toffol L. Funtional appliance treatment for Severe classII malocclusion in the early mixed

dentition. J. Clin. Orthod.2003; 37(2): 69-74.

Bone sounding: a clinical tip for Microimplant placement

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Mehta S^a, Gupta K^a, Valiathan A^b, Urala A^c, Thomas B^d, Bhat GS^e

a – Postgraduate Student, Manipal College of Dental Sciences, Manipal, India.

b – Professor, Department of Orthodontics and Dentofacial Orthopedics, Manipal College of Dental Sciences, Manipal, India.

c – Reader, Department of Orthodontics and Dentofacial Orthopedics, Manipal College of Dental Sciences, Manipal, India.

d – Professor, Department of Periodontics, Manipal College of Dental Sciences, Manipal, India.

e – Professor, Department of Periodontics, Manipal College of Dental Sciences, Manipal, India.

Postal Address

Professor Ashima Valiathan

BDS (Pb), DDS, MS. (USA), FDSRCPS(Glasgow).

Department of Orthodontics and Dentofacial Orthopedics,

Manipal College of Dental Sciences,

Manipal- 576104.

Karnataka, India.

Tel no: (0820)2922184, Mobile: 09886100125

Email id: avaliathan@yahoo.com

After their introduction by Kanomi¹ in 1997, microimplants have become a sensation enabling diverse clinical applications. Orthodontic miniscrews have been used to provide stable skeletal anchorage for both direct and indirect orthodontic traction. One of the challenges of microimplant placement is planning its correct positioning in the bone to achieve proper stability. The insertion technique should maximize the available bone volume while avoiding adjacent anatomical structures such as dental roots, nasomaxillary cavities, and neurovascular tissues.²

There is no doubt that the radiographic method is more reliable than clinical observation because it is unaffected by tooth movement, but its disadvantage is the difficulty of interpreting and applying the results in clinical practice.³ Three dimentional CT (computed tomography) scans provide detailed information on potential implant sites such as bone depth and density, but they are expensive and associated with radiation exposure. We just recommend a simple clinical maneuver – “Bone Sounding” to acquire an understanding of the bone level and thickness of the soft tissue overlying the bone.

In this technique a periodontal probe (or an endodontic spreader or file with a stopper) is used to measure the probing depth following local anesthesia administration (figure 1). Insertion into attached gingiva is preferable; therefore the probe or the spreader is used to punch the soft tissue in the desired safe area. The deepest point at which the probe meets strong resistance from contact to the bone is recorded as the bone probing depth. A microimplant is then placed in an area where bone probing depth is minimum and thus the soft tissue thickness least (figure 2). This can be especially useful when placing microimplants in the palatal region where greater variations of the soft-tissue thickness have been reported compared to the variations of the cortical bone thickness⁴.

Fig: 1

Fig: 2

The case below shows attempts to place a palatal microimplant (1.3 mm×9mm) in a patient with thick mucosa and high arched palate (figure 3). Since the mucosa was thick it provided an instant dip hence microimplant failed twice. Theoretically, a microimplant should be placed 4 to 8 mm from the gingival crestin the palatal tissuebetween first molar and second premolar⁵. Though placed in the same range, the implant failed. Clinically bone sounding was performed and the probe was moved in the adjacent area to determine the site with the least probing depth. The same miniscrew was then placed at that site which proved to be successful (figure 4). The bone probing depth at failure site was found to be around 5mm and the site of successful placement had probing depth of 3mm.

Fig: 3

Fig: 4

This knowledge allows the clinician to place a microimplant in sound bone and, therefore, increases the success rate.

References

Kanomi R. Mini-implant for orthodontic anchorage. J Clin Orthod 1997;31:763-67.
Park HS, Jeong SH, Kwon OW. Factors affecting the clinical success of screw implants used as orthodontic anchorage. Am J Orthod Dentofacial Orthop 2006;130:18-25.
Bjorn Ludwig, Bettina Glasl, S. Jay Bowman, Benedict Wilmes, Gero S.M. Kinzinger, Jorg A. Lisson. Anatomical Guidelines for Miniscrew Insertion: Palatal Sites. J Clin Orthod 2011;45:433-41.
Kim HJ, Yun HS, Park HD, Kim DH, Park YC. Soft-tissue and cortical-bone thickness at orthodontic implant sites. Am J Orthod Dentofacial Orthop. 2006;130:177-82.
Bong-Kuen Cha, Yeon-Hee Lee, Nam-Ki Lee, Dong-Soon Choi, Seung-Hak Baek. Soft Tissue Thickness for Placement of an Orthodontic Miniscrew Using an Ultrasonic Device. Angle Orthod 2008;78(3):403-8.

Gentle Jumper- A Light Force Fixed Functional Appliance

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TITLE

Gentle-Jumper- A Light Force Fixed Functional Appliance

1. Dr. Amit Prakash

Senior lecturer

Department of Orthodontics and Dentofacial Orthopedics

Darshan dental college and hospital, Loyara, Udaipur

2. Dr. Arundhati P. Tandur

Professor

Senior Private Practitioner in Bangalore

3. Dr. B.C. Karunakara

Professor

Department of Orthodontics and Dentofacial Orthopedics

K.L.E.S Institute of Dental Sciences, Bangalore

4. Dr. Sumita

Professor

Department of Orthodontics and Dentofacial Orthopedics

K.L.E.S Institute of Dental Sciences, Bangalore

5. Dr. Nitin Dungarwal

Senior lecturer

Department of Orthodontics and Dentofacial Orthopedics

Darshan dental college and hospital, Loyara, Udaipur

Corresponding address –

Dr. Amit Prakash

Department of Orthodontics and Dentofacial Orthopedics

Darshan dental college and hospital, Loyara, Udaipur

E-mail address- drprakash24@yahoo.co.in

amitprakash30@gmail.com

Abstract

The present protocol for the correction of Class II malocclusion with mandibular retrognathism is by using the fixed functional appliances. This article includes a case treated with Gentle Jumper – a flexible fixed functional appliance. A pre-pubertal patient with class II malocclusion with 70% deep bite was treated with Gentle Jumper along with fixed appliance (MBT- 0.022” slot). Deep bite has been treated with extrusion of posteriors and proclination of anteriors. It resulted in the favorable skeletal and dentoalveolar changes in the mandible. There was slight proclination of lower incisors. Good soft tissue changes were noted. Gentle Jumper is an efficient class II corrector in pre-pubertal period. It promotes patient compliance with very minimal breakages.

Key words: Gentle Jumper Deep bite, Class II malocclusion

Introduction

Fixed functional appliances are non-compliance Class II corrector. As an adjunct to fixed appliance therapy, the Gentle Jumper ¹presents an opportunity to minimize extractions and to reduce or eliminate headgear. When activated 4 mm, the Jasper Jumper will exert 360 grams of force. By comparison, at the same amount of deflection, the Gentle Jumper exerts just 75 grams of force, which is better suited to mixed dentition cases.

The Gentle Jumper provides the following advantages:

1. They are fixed so patient cooperation is assured.

2. They work along the growth or Y axis, thus they properly advance the mandible rather than retracting the maxilla.

3. Because of the ball joint, the Jumpers swivel allowing normal functions such as eating and tooth brushing.

4. They are safe. No extra-oral traction is involved.

5. They are cosmetic.

6. They can be used for Class II or Class III corrections and can apply different forces on each side of the jaw for cross bites.

7. Forces are adjustable and measurable.

Measuring for correct size:

To get the right length, have patients bite in their retruded or centric bite and measure from the mesial of the headgear tube to the distal of the lower ball stop, then add 12 mm (4 mm for the tube, 4 mm of free play, and 4 mm of built-in activation). Some patients may require different length Jumpers on the left or right side.

Sectional Wire for main arch wire attachment

A sectional wire has been specially designed for Gentle Jumper use. The uniqueness of this wire lies in the anterior loop design and its attachment to the main arch wire. This loop design allows for attachment to the main arch from lingual to buccal as opposed to the conventional wrap around from buccal to lingual. The advantages are lower profile and minimal patient irritation in addition to trouble free action and the virtual impossibility of displacement from the main arch.

The hypothesized mechanism of Class II correction with Gentle jumper include:

Basal restraint of the maxilla.
Dento alveolar retraction of the maxillary dentition.
Dento alveolar protraction of the mandibular dentition.
Increased growth at the mandibular condyle.
Downward/forward glenoid fossa remodeling
Lateral expansion of the maxillary molars.

Case Report

Diagnosis

A 14 year old female reported with the chief complaint of irregularly placed upper and lower front teeth. She had skeletal and dental class II malocclusion with upper and lower anterior crowding. She had a convex profile, decreased lower facial height, deep mentolabial sulcus. (Fig: 1) Model analysis revealed crowding of 2mm in the upper arch and 4mm in the lower arch, an overjet of 6 mm and overbite of 5 mm (70%).lower midline is deviated towards right side by 1mm. 4mm of curve of spee present in the lower arch. (Figs: 2,3)

Figure 1: Pre-treatment extraoral photographs

Figure 2: Pre-treatment intraoral photographs

Figure 3: Pre-treatment intraoral photographs

Treatment Objectives

Correction of skeletal class II
Correction of class II canine bilaterally and class II molar relation on right side
Relieving of upper and lower anterior crowding
To correct the midline discrepancy
To correct the deep curve of spee
To achieve ideal overjet /overbite
Correction of convex profile

Treatment plan

Non-extraction was planned because space requirement was minimal. Fixed functional (Gentle jumper) was planned to correct skeletal and dental class II malocclusion. As the objective was to correct both skeletal and dental relation flexible appliance with light force was selected. Placement of fixed functional bilaterally was planned so that we can achieve Class I canine relation and midline match. (Fig:4)

Fig 4-With fixed functional appliance (Gentle-Jumper) - 0.019x0.025 SS arch wire

Treatment Progress

Initial alignment and leveling was done with 0.016” NiTi followed by0.019”×0.025” NiTi. After initial alignment & leveling, 0.019”×0.025” stainless steel was placed in both arches. Additionally, 10º labial root torque was added in the anterior segment of the lower archwire to counteract the lower incisor proclination. Upper and lower arch consolidation was done. Sectional 0.017”×0.025” stainless steel wire was placed in the auxiliary lower tube. The Gentle jumper was placed and continued for 6 months. (Fig: 5,6) After removal of the fixed functional appliance , Class II elastics were continued for 2 months for retention of the correction. (Fig: 7)

Figure 5: Post-functional extraoral photographs

Figure 6: Post-functional intraoral photographs

Figure 7: Post-functional photographs with Class II elastics for retention

Conclusion

Gentle jumperis an efficient class II corrector in patients with retruded mandible producing favorable skeletal, dentoalveolar and soft tissues changes.
It provides an alternative to other fixed functional class II appliance systems. Together with dental effects, the mandibular displacement achieved leads to an improvement in sagittal discrepancy.

Bibliography

M. Papadopoulos. Orthodontic treatment of the Class II noncompliant patient. Mosby; 2006: p 21-203.

Semi Rapid Maxillary Expansion: A Literature Review

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Dr. S. Fayyaz Ahamed, M.D.S

Consultant Orthodontist,

Coimbatore, India.

Email: drfayyazahamed@gmail.com

ABSTRACT:

Orthopedic and orthodontic forces are used routinely to correct maxillary transverse deficiency (MTD). A new approach, namely, semi rapid maxillary expansion (SRME) was introduced with the hypothesis that SRME may stimulate the adaptation process in the nasomaxillary complex and thus would result in reduction of relapse in the post-retention period.

Current standards for reviews require performing a meta-analysis on the subject. However, an exhaustive search of the literature on SRME, did not unearth enough articles with strong study designs or common denominators to perform a meta-analysis.

The aim of the article is to present a comprehensive review of the literature, including indications, diagnosis, guidelines for case selection, a brief overview of the techniques, complications, risks, and limitations of semi-rapid maxillary expansion (SRME) to better aid the clinician in the management of MTD in contemporary practice.

Key words: Maxillary transverse deficiency, semi rapid maxillary expansion, rapid palatal expansion, slow maxillary expansion, literature review.

INTRODUCTION:

Rapid maxillary expansion (RME) had been proposed since the 19 century by Angell in a case report to correct maxillary constriction.1 An accompanying commentary on the article suggested that the possibility of achieving orthodontic maxillary expansion (OME) was “exceedingly doubtful.” After initially falling to disrepute, it was reintroduced in the middle of the last century by Andrew Haas.2 As early as 1920, Mesnard demonstrated radiographically that the midpalatal suture could be separated using fixed appliance and that the space would be filled with bone around 4-6 weeks.3

The incidence of maxillary transverse deficiency (MTD) in the deciduous and mixed dentitions is estimated at 8% to 18% of patients having orthodontic consultations.4 This entity may occur in the primary dentition and manifest itself as a constriction of the lateral dimension of the upper arch. Different methods have been used to expand constricted maxillary arches. When evaluated on the basis of frequency of the activations, magnitude of the applied force, duration of the treatment, and patient age, different mechanics produce rapid, semi-rapid, or slow expansion.5

Figure 1 - consort diagram.

INDICATIONS FOR SRME

Indications for SRME are similar to RME. RME has been shown to be a valuable aid in the orthodontic treatment of patients exhibiting

1. Transverse maxillary deficiency.

2. Posterior crossbite.

3. Crowding.

4. Pseudo-class III malocclusion.

5. Rhinologic and respiratory ailments.

6. Cleft lip and palate.6,7

It has also been reported that RME has a positive effect on breathing patterns and conductive hearing loss in growing children with maxillary constriction.7

DIAGNOSIS

Unlike discrepancies in the vertical and the antero-posterior dimensions, diagnosis of MTD is difficult. There is much literature on the various methods used to diagnose this condition. Clinical evaluation, model analysis, occlusograms, and radiographic measurements have been recommended for an accurate assessment.8

Clinical evaluation includes assessment of the maxillary arch form and symmetry, shape of the palatal vault, overhanging palatal cusp of maxillary molars, width of the buccal corridors on smiling, occlusion, and predominant mode of breathing (nasal or oral). Excessively wide buccal corridors, paranasal hollowing, or narrow alar bases usually suggest MTD.

The soft-tissue thickness should also be evaluated because it can mask MTD. Another factor that needs assessment is a mandibular shift on closure. This can often be a chin deviation with a unilateral crossbite. With the advent of digital models in routine clinical practice, additional tools can be used to evaluate arch form and tooth inclinations.9

The advent of 3-dimensional imaging techniques is the most recent tool for diagnosis that has enabled an accurate visualization of the craniofacial region. Ghoneima et al.10 stated that Volumetric 3-D CT scanning provides a useful method for assessing skeletal and dental changes after rapid maxillary expansion.

AGE AS CRITERIA

Age has also been discussed as a factor in the prognosis of RME, especially regarding long-term stability. Bishara and Staley11 stated that the optimal age for expansion is before 13 to 15 years. The authors stated that although it may be possible to accomplish expansion in older patients, the results are neither as predictable nor as stable. Proffit12 and McNamara and Brudon13 supported this opinion by suggesting that the feasibility of palatal expansion in the late teens and early twenties is questionable. Surgically assisted RME combined with fixed orthodontic treatment has been suggested to overcome this problem.14

Iseri and Ozsoy6 suggested the dentoskeletal changes after the use of SRME were maintained satisfactorily in the long term in older adolescents and adults. Ramoglu and Sari stated that SRME produced stable dentoalveolar effects in a mean age group of 8.63 years (table I).5

Table 1 - Summary of studies of SRME.

AMOUNT OF EXPANSION

In general, an orthodontist can camouflage transverse maxillomandibular discrepancies less than 5 mm with orthopedic or orthodontic forces alone.15 In the literature authors have used occlusal radiographs to confirm midpalatal suture opening at the end of the RME activation and before starting with SRME activation. Screw activation was done to achieve 5mm of expansion with additional 2 mm of overcorrection (first activated with RME protocol followed by SRME).5

Krebs16 found that the amount of sutural opening was equal to or less than one-half the amount of dental arch expansion. Sarnas et al.17 found that the distance between the bilateral implants was increased by about two mm, whereas 7.2 mm widening was achieved between the upper molars by RME in a 12-year-old girl.

Iseri et al.6 achieved a mean expansion of 7.3 mm in 20 patients with SRME. At the end of 3.5 years of follow-up 7.26 mm of expansion was maintained. Kilic and Oktay18 achieved a mean maxillary dental expansion of 7.53 ± 1.47

mm and mean skeletal expansion of 2.80 ± 1.06 mm.

DESIGN

Numerous RME appliances have been widely used by the clinicians such as Haas-, Hyrax-, and Minne-type banded appliances. Alpern and Yurosko19 reported the use of full occlusal coverage palatal expansion appliances that limits the vertical effects of interocclusal forces resulting in the release of the maxilla, it also plays an important role in expansion and protraction. They also suggested that this device could provide control of the vertical dimensional changes that occur in vertically growing patients during maxillary expansion.

Kilic and Oktay18 and Ramoglu et al5 used acrylic bonded expansion appliance as advocated by Iseri et al in their study for SRME treatment (table I). The appliance was a tooth and tissue-born rigid, acrylic appliance with posterior bite planes, bonded to the upper posterior teeth. The appliance was bonded until the midpalatal suture had opened. When the midpalatal suture had opened (which was confirmed with an occlusal radiograph), the appliance was debonded and used as a removable expansion appliance. It was then used as a retainer once expansion was complete.

Memikoglu et al and Iseri et al claimed that tooth and tissue-borne SRME appliances, especially bonded appliances with occlusal acrylic coverage, produce more skeletal expansion than do the others.6,20 In addition, semi-rapid maxillary expansion (SRME) and slow maxillary expansion have some advantages, such as less relapse tendency and more physiologic results.

ACTIVATION

In rapid maxillary expansion (RME) protocols, a twice daily activation schedule, which is most commonly proposed in the literature, was shown to produce residual loads during early treatment.21

Iseri et al suggested a slow expansion protocol immediately after the separation of the intermaxillary suture by RME in order to produce less tissue resistance.22 Iseri et al6 used semi-rapid maxillary expansion (SRME) which is different to the SRME protocol described by Mew (1977, 1983, 1997).

Mew and Sandikcioglu and Hazar23 used an activation rhythm of 1 mm per week whereas Iseri and Ozsoy6 used a schedule of 2 × 0.2 mm per day for the first 5 – 6 days and 3 × 0.2 mm per week for the rest of the expansion in older adolescents and adults. Bai and Mao24 in their study demonstrated that best activation time for patients with RPE was around 21 o’clock and concluded that human circadian rhythm could affect the rapid palatal expansion.

SKELETAL AND DENTAL EFFECTS

Iseri et al observed significant amounts of linear and angular transverse changes in the zygomatic bone, lower nasal cavity, maxillary base, and maxillary dentoalveolar structures. In this study the author used metallic implants to analyze the effects of maxillary expansion with SRME. Studies suggest a significant amount of increase in the zygomatic width.20 Anatomically, there was an increase in the width of the nasal cavity immediately after expansion which was 1.3 mm using SRME compared to 1.5 mm using RME, particularly at the floor of the nose adjacent to the midpalatal suture.6 As the two maxillae separate, the outer walls of the nasal cavity move laterally, whereas the more superior areas might move medially.22

Kilic and Oktay concluded that SRME caused a small, but statistically significant, forward movement of the upper facial skeleton, a small downward and backward rotation of mandible and a small increase in face height. The effects were similar to that of RME.18

Ramoglu and Sari reported a counter clockwise rotation of the palatal plane and concluded that this alteration did not affect the vertical and sagittal position of the mandible; the changes occurred only at the level of PNS. Significant amount of widening was obtained in the maxillary base (7.4 mm) with SRME treatment, and this widening was maintained at the end of retention period.5 Treatment with SRME showed an increase of upper incisor interapex width by 1.3 mm.6 studies show that SRME produce molar tipping (combination of alveolar and molar tipping) which is similar to RME.

RETENTION, STABILITY, AND RELAPSE

One of the most challenging issues in patients treated with RME has been the prevention of relapse in the long term. A number of researchers have studied the stability of RME. Various factors affecting stability are:

• Age of patient.

• Rate of expansion.21,25

• Design of the device.

• Length of the retention period.

• Cooperation during the retention period.

• Severity of the maxillary collapse.19

• Response of the midpalatal suture and surrounding structure.

• Adaptation of the soft tissues to the new positions.25

Long-term stability of RME was evaluated by several authors, and the results showed inevitable relapse during the retention period of the widening procedure. On the other hand, SRME followed by rapid separation of the midpalatal sutured stimulated the adaptation processes in the nasomaxillary structures and also resulted in less relapse potential in the retention and postretention periods.

Transverse skeletal and dental changes were stable over a period of 3.5years after initiation of SRME treatment.6 Ramoglu et al used bonded SRME appliance with its screw secured to a ligature wire as a fixed retainer for 14 days and then debonded. After debonding, a removable appliance was fabricated for retention. Kilic and Oktay reported a retention period of 6.02 ± 0.17 months for SRME applaince.18 No long term study evaluating the stability of SRME has been reported.

RISKS, LIMITATIONS, AND COMPLICATIONS

Several complications have been reported, and the orthodontist must be aware of these before recommending SRME to a patient. Complications associated with expansion reported in the literature include significant gingival recession, root resorption, pain, periodontal breakdown, extrusion of teeth attached to the appliance, relapse, and unilateral expansion. Additional complications that are related to the expansion appliance include its impingement on palatal soft tissue, loosening, and breakage and stripping or locking of the appliance screw.8,26

Needleman et al reported that vast majority of children undergoing the active phase of rapid palatal expansion with a Hyrax appliance report pain. The pain generally occurs during the initial phase of expansion and diminishes thereafter.26 Transverse forces delivered during RPE have been shown to create undesirable orthodontic and orthopedic side effects in patients exhibiting skeletal open bite tendency, large interlabial gap, or severe Class II skeletal patterns, with long lower facial height and increased facial convexity. Bonded appliance with occlusal coverage overcame most of the undesirable effects. SRME is not free of risks, and careful planning and execution of treatment are necessary to ensure an acceptable outcome.

RME vs SRME

Iseri et al evaluated the resistance of RME generated by the surrounding structures by using the finite element method as applied to the three-dimensional model of a human skull. The findings of this study indicated that high forces are generated by RME on various structures in the craniofacial complex and that these structures offer resistance of different degrees depending on their location and orientation relative to the center and direction of force.22

Rapid displacement or deformation of the facial bones would result in a marked amount of relapse in the long term, whereas relatively slower expansion of the maxilla would probably produce less tissue resistance in the nasomaxillary complex.6 Therefore, rapid expansion followed by slower rates of expansion (SRME) would allow for physiologic adjustment at the maxillary articulations and surrounding skeletal structures and would prevent the accumulation of large residual loads within the maxillary complex. This would help to minimize relapse in the long term. Nevertheless, further long-term studies at least five years out of retention are still necessary.

In the RME protocol, as the activation is faster than the SRME, shorter active treatment periods and chair side time is an advantage. Another advantage may be the shorter bonded appliance wear which negatively affects the oral hygiene.

CONCLUSIONS

SRME proves to be promising in the treatment of MTD. However, there is sparse information on many issues pertaining to this approach. Studies report that SRME is advantageous when it comes to stability. Whether the amount of relapse would be less with SRME due to a decrease in residual stresses in dentofacial structures and less tissue resistance should be evaluated further with long term studies.

REFERENCES

1. Angell EC. Treatment of irregularities of the permanent or adult teeth. Dent Cosmos 1860;1:540-4.

2. Haas AJ. The treatment of maxillary deficiency by opening the midpalatal suture. Angle Orthod 1965;35:200-17.

3. Mesnard L. Immediate separation of the maxillae as a treatment for nasal impermeability. Dent Rec 1929;49:371-372.

4. Da Silva Filho OG, Boas MC, Capelozza Filho L. Rapid maxillary expansion in the primary and mixed dentitions: a cephalometric evaluation. Am J Orthod Dentofacial Orthop 1991;100:171-9.

5. Ramoglu SI, Sari Z. Maxillary expansion in the mixed dentition: rapid or semi-rapid? Eur J Orthod. 2010 Feb;32(1):11-8.

6. Iseri H , Ozsoy S. Semirapid maxillary expansion — a study of long term transverse effects in older adolescents and adults . Angle Orthodontist. 2004;74 : 71 – 78.

7. Kilic N, Oktay H, Selimoglu E, Erdem A. Effects of semirapid maxillary expansion on conductive hearing loss. Am J Orthod Dentofacial Orthop. 2008 Jun;133(6):846-51.

8. Suri L, Taneja P. Surgically assisted rapid palatal expansion: a literature review. Am J Orthod Dentofacial Orthop. 2008 Feb;133(2):290-302.

9. Redmond WR. Digital models: a new diagnostic tool. J Clin Orthod 2001;35:386-7.

10. Ghoneima A, Abdel-Fattah E, Eraso F, Fardo D, Kula K, Hartsfield J. Skeletal and dental changes after rapid maxillary expansion: a computed tomography study. Aust Orthod J. 2010 Nov;26(2):141-8.

11. Bishara SE, Staley RN. Maxillary expansion: clinical implications. Am J Orthod Dentofacial Orthop. 1987;91:3–14.

12. Proffit WR. Contemporary Orthodontics. St Louis, Miss: Mosby; 1986: 618–619.

13. McNamara JA Jr, Brudon WL. Orthodontic and Orthopedic Treatment in the Mixed Dentition. Ann Arbor, Mich: Needham Press; 1993.

14. Bell WH, Epker BN. Surgical orthodontic expansion of the maxilla. Am J Orthod. 1976;79:517–528.

15. Bailey L J, Proffit W R, White R. Assessment of patients for orthognathic surgery. Seminars in Orthodontics.1999 Dec; 5(4): 209-222.

16. Krebs A. Expansion of the midpalatal suture studied by means of metallic implants. Eur Orthod Soc Rep. 1958;34:163–171.

17. Sarnas KV, Bjork A, Rune B. Long term effect of rapid maxillary expansion studied in one patient with the aid of metallic implants and roentgen stereometry. Eur J Orthod. 1992;14:427–432.

18. Kilic N, Oktay H. Effects of rapid-slow maxillary expansion on the dentofacial structures. Aust Orthod J. 2010 Nov;26(2):178-83.

19. Alpern MC, Yurosko JJ. Rapid palatal expansion in adults with and without surgery. Angle Orthod 1987;57:245-63.

20. Memikoglu UT, Iseri H. Effects of bonded rapid maxillary expansion during orthodontic treatment. Angle Orthod. 1999;69:251–256.

21. Zimring JF, Isaacson RJ. Forces produced by rapid maxillary expansion. 3. Forces present during retention. Angle Orthod 1965;35:178-86.

22. Iseri H, Tekkaya E, Oztan O, Bilgic S. Biomechanical effects of rapid maxillary expansion on the craniofacial skeleton, studied by the finite element method. Eur J Orthod. 1998;20:347–356.

23. Sandikçioğlu M , Hazar S. Skeletal and dental changes after maxillary expansion in the mixed dentition . American Journal of Orthodontics and Dentofacial Orthopedics 1997; 111 : 321 – 327.

24. Bai YM, Mao J. Correlation between circadian rhythm and rapid palatal expansion. Zhonghua Kou Qiang Yi Xue Za Zhi. 2010 Nov;45(11):655-8.

25. Isaacson RJ, Murphy TD. Some effects of rapid maxillary expansion in cleft lip and palate patients. Angle Orthod 1964; 34:143-54.

26. Needleman HL, Hoang CD, Allred E, Hertzberg J, Berde C. Reports of pain by children undergoing rapid palatal expansion. Pediatr Dent. 2000 May-Jun;22(3):221-6.

Closed Versus Open Eruption in Management of Impacted Canines

ray — Wed, 18 Jan 2012 15:06:43 +0000

Dr. Mohamad Azhar Ibrahim Kharsa, DDS. PhD. Orth.

Consultant Orthodontist

King Fahad Hospital-Madinah, Saudi Arabia

Fellow of World Federation of Orthodontists

Member of American Association of Orthodontics

Postal Address:

PO Box 50492, Madinah 41523

Saudi Arabia

Phone: (+966) 557688385

Email: dr.orth@gmail.com

Abstract:

Orthodontic eruption of impacted canines is a common procedure in the practice of orthodontics; however, such a procedure varies widely in techniques and in potential difficulties.

The purpose of this article is to discuss techniques, prognosis and difficulties of the orthodontic eruption of impacted teeth from a clinical standpoint.

The common approaches for orthodontic eruption are:

1- Open exposure or open orthodontic eruption.

2- Closed orthodontic eruption.

Examples of closed and open eruption are presented with indications for both approaches and potential complications. Eruption techniques are compared clinically and theoretically.

The importance of a synoptic treatment plan is taken into account in each orthodontic eruption case including: space creation for the impacted tooth, traction “Direct or One-Stage vs. Two-Stage” techniques and anchorage preparation.

Key Words:

Open Orthodontics Eruption, Closed Orthodontic Eruption, Direct Traction, Indirect Enforced Eruption, Two-Stage Traction.

Objectives:

Orthodontic eruption of impacted teeth is a common procedure in orthodontic practice, nonetheless challenges that accompany the process vary widely with position, inclination, physiologic status and space. The more accessible the impacted tooth, the better the prognosis. The closer the tooth is to the surface the more manageable. Sufficient space creation is of paramount importance.

Additionally, the treatment plan should address the following criteria:

1. What is the patient’s chief complaint? (Figure 1)

2. What is the best approach of orthodontic eruption? (Closed, open, two-stage etc…)

3. What are the anchorage requirements? (Figure 2)

4. What appliance modifications will be needed? (Figure 3)

5. What is the prognosis of the impacted tooth? (Figure 4)

Figure 1. An impacted maxillary left canine, under a long standing bridge, in a 42 year-old female patient. The patient is more interested in preserving her ceramic bridge than orthodontic eruption of the canine.

Figure 2. A modified transpalatal arch is used to increase anchorage during traction of an impacted canine positioned between the roots of the maxillary right central and lateral incisors. The technique aims to free the targeted tooth from the adjacent structures.

Figure 3. An Orthopantomogram of figure 2 before exposure for orthodontic eruption. The X-ray demonstrates the position of the impacted canine proximal to the roots of central and lateral incisors.

Figure 4. An impacted maxillary left canine, dilacerated and positioned close to the floor of the maxillary sinus. An impacted tooth with a poor prognosis.

Materials and Methods:

The article discusses two techniques pertinent to the orthodontic eruption of impacted canines, which are:

1. Open exposure or open orthodontic eruption.

2. Closed orthodontic eruption.

The open eruption, or “window” is done when the impacted canine is relatively “superficial”, aiming to gain an access for attachment placement and orthodontic traction (Figure 5).

It is recommended that sufficient arch space be established for the impacted tooth. (Figure 6) Logically, the next step after window creation is installment of a “suitable” attachment for traction (Figure 7).

Figure 5. A “window” has just been prepared for open exposure of an impacted canine.

Figure 6. Figure 5 before exposure showing adequate arch space for the impacted canine.

Figure 7. An attachment has been placed and traction commenced.

In contrast to open eruption which includes a “window creation”, closed eruption entails creation of a flap, uncovering the impacted tooth, installing an attachment and closing the flap.

In other words, the steps of closed eruption resembles open eruption except the surgical aspect that requires a flap creation and closure (Figure 8).

Also in closed eruption, the attachment must be placed at the time of surgery while in open eruption is possible placement may be postponed for a short time. (Figures 9,10, 11).

Figure 8. A case of closed eruption. Here the surgical a flap has been created, the canine uncovered and the attachment is ready to be installed.

Figure 9. The attachment is installed at the time of surgery.

Figure 10. The flap is sutured and traction started.

Figure 11. The case in figures 8, 9 and 10 after completion of orthodontic eruption.

It is worth mentioning that though the surgical steps of open or closed eruption are of paramount importance, there are other challenges that the clinician needs to overcome, as traction of the impacted tooth is not always easy. Each case of orthodontic traction requires planning for that specific situation. Traction of an impacted tooth can be as simple as power chains in “trouble-free” cases, or may require complicated appliances. (Figures 12, 13, 14). Sometimes modified springs like “Ballistae”, double wires and pseudo super elastic arch wires can be invaluable.

Additionally, orthodontic traction is either “One-Step” traction, or “Two-Step”.

Figure 12. A previously supine impacted canine, required a modified 016"X022" Stainless steel spring formed as a "Ballista" or Catapult for its traction

Figure 13. The aforementioned case, the supine impacted canine at the exposure visit, is uprighted by the ballista.

The rationale of “direct” versus “indirect” traction:

Direct traction or “one-stage” is the traction of the impacted canine directly into its planned position after orthodontic enforced eruption (Figure 14).

Figure 14. A case of direct traction, at the exposure visit, and the same case right after debonding.

Alternatively, indirect traction as part of a “two-step” technique is necessitated when direct traction is either not available because of tooth position or there is danger of a collision with adjacent roots. This situation requires the practitioner to circumvent the adjacent roots by “freeing” the impacted tooth from these structures in the first stage, then moving the tooth into the desired position in the second stage. (Figures 15, 16)

Figure 15. Demonstrating stage one of the "two-stage” or “indirect" forced eruption, by traction of the impacted canine away from the adjacent teeth. (The left photograph shows a retained deciduous canine that has been extracted later.)

Figure 16. Stage two of the indirect forced eruption, as the canine now finds its way into the planned position.

Conclusion:

Impacted teeth vary according to their positions, depth, patients’ general status and “manageability”. Such variations and distinctions impose additional burdens on the practitioner to establish and successfully execute a treatment plan. One must realize that a single treatment plan will not suffice for all cases, but must be designed for each instance. However, the cornerstones in impaction cases are: Synoptic treatment plan, establishing the position of the Impacted tooth and finding the traction techniques that ultimately lead the impacted tooth into its correct anatomical position.

References:

1-Becker A: Palatally impacted canines. In The orthodontic treatment of impacted teeth. Second edition. Andover, Hampshire: Thomson Publishing Services; 2007:93-142.

2- Chaushu S, Becker A, Zeltser R, Branski S, Vasker N, Chaushu G. Patients

perception of recovery after exposure of impacted teeth: A comparison of closed versus open-eruption techniques. J Oral Maxillofacial Surg. 2005;63:323.

3-Bishara SE. Impacted maxillary canines: a review. Am J Orthod Dentofacial

Orthop. 1992;101:159–171.

4- Nordenram A, Strömberg C. Positional variations of the impacted upper canine. Oral Surg Oral Med Oral Path, 1966; 22: 711-4.

5- Kokich VG, Mathews DP. Surgical and orthodontic management of impacted teeth. Dent Clin North Am 1993;37:181–204.

6-Ericson S, Kurol J. Incisor resorption caused by maxillary cuspids: a radiographic study. Angle Orthod 1987;57:332–46.

7- Jacobs SG. The impacted maxillary canine: further observations on aetiology, radiographic localization, prevention/interception of impaction, and when to suspect impaction. Aust Dent J 1996;41:310–6

Diagnosis of Facial Asymmetry Using Conventional PA Cephalometric Analysis and a Maxillofacial 3-Demensional CT Analysis: A Comparative Study

ray — Sat, 14 Jan 2012 21:04:34 +0000

Abstract

The advent of computed tomography has greatly reduced magnification errors from geometric distortions that are common in conventional radiographs. Recently introduced 3-dimensional (3D) software enables 3D reconstruction and quantitative measurement of the maxillofacial complex. 3D images are also useful in understanding asymmetrical structures. This article compares 3D and 2D images as well as right and left side of the face of an individual which helps to diagnose the facial asymmetry.

Introduction

As the demand for improved facial esthetics increases, more patients complain of the development or the progression of facial asymmetry, particularly mandibular asymmetry, during or after orthodontic treatment. Patients who undergo orthognathic surgery for sagittal relationship problems, such as maxillary protrusion or mandibular prognathism, also tend to become aware of facial asymmetry after the surgical procedure. Because a misdiagnosis of facial asymmetry can result in the wrong treatment for a patient, accurate evaluations of facial asymmetry are crucial in orthodontic practice.

In most cases, the presence and degree of facial asymmetry can be diagnosed by using posteroanterior (PA) cephalometry.¹^,²^and³ However, a PA cephalometric radiograph does not provide sufficient information for identifying the causes of asymmetry or determining a suitable treatment plan. Chin deviation is a common form of facial asymmetry. It usually develops from a right and left side difference in ramus length, but there are also other possible causes, such as a difference of body length in the mandible. Distinguishing a problem-causing structure is extremely important in treatment planning, but PA cephalometry does not always provide accurate information, even with the aid of lateral and submentovertex projections. Conventional radiographic images can be misleading in interpreting the cause of the deviation because complex 3-dimensional (3D) structures are projected onto flat 2-dimensional (2D) surfaces, creating possible distortion of the images and subsequent magnification errors.⁴^and⁵ The development of computed tomography (CT), however, has greatly reduced the possibility of these errors and improved our ability to understand the 3D nature of facial structures.⁶ In addition, recently introduced 3D CT software enables 3D reconstruction and accurate measurement of the maxillofacial complex.⁷^and⁸ Exact measurement is the key element in evaluating asymmetry: 3D images can provide accurate and detailed information for the diagnosis and treatment planning of facial asymmetry by means of quantitative measurement and comparison between the right and left sides of the structures.

CT scans are currently widely used to acquire 3D information on craniofacial complexes.⁹ The development of CT and computer technology allows easy access to maxillofacial 3D images.

In spite of its usefulness, however, clinicians and patients have been hesitant to use conventional CT because of the long procedure in a cramped space and the high level of radiation. The introduction of the spiral CT resolved these concerns. Creating a simultaneous patient translation through the continuous rotation of the source detector assembly, spiral CT, with its spiral sampling locus, acquires raw projection data in a relatively short time.^10,11

Hence this study was designed to compare the differences in the diagnosis of facial asymmetry, using two different methods, three dimensional image (3D-CT) analysis with the conventional (Postero-Anterior ceph, Lateral ceph and Submentovertex) radiographic analysis.

Methodology

The sample consisted of ten patients selected from the outpatients to the Department of Orthodontics and Dentofacial Orthopedics, Rajarajeswari Dental College and Hospital, Bangalore. The patients were selected based on the following inclusion and exclusion criteria.

Inclusion criteria:

1. Patients within the age group of 18 to 25 years.

2. Patients with the full complement of permanent teeth (excluding third molars).

Exclusion criteria:

Patients who have undergone Orthodontic/ Orthopedic/ Orthognathic surgical

treatment.

Patients with history of trauma.
Patients with obvious/ gross facial asymmetry.

Standard radiographs of the selected patients were obtained in the postero-anterior, lateral and submentovertex views using Rotograph Plus – panceph machine (Fig 1). Three dimensional computed tomographic digital images were also obtained from the patients using Xvision GX, Toshiba (Fig 2).

Fig. 1: Rotagraph plus Panceph machine on which the PA ceph, lateral ceph and submentovertex view radiographs were taken.

Fig.2: X vision GX machine on which the spiral 3D computed tomographic images were taken.

All the radiographs were taken using a Panceph machine (250 Kvp, 25 ma) using a 8.5” x 10” sized radiographic film CT scans of the same 10 subjects were obtained by using a spiral CT scanner with a mode with 2.5 mm thickness, slice pitch 3, and a scanning time of 0.8 seconds. The acquired 2D CT digital image data were then input onto a personal computer.

Conventional Computed Axial Tomography (CAT) ^12,13

The technique of X-ray CT was invented by Godfrey Hounsfield in 1972. The basic principle behind CT is that the two-dimensional internal structure of an object can be reconstructed from a series of one-dimensional “projections” of the object acquired at different angles.

Disadvantage of conventional CT

In the conventional CT systems, if multiple slices are required to cover a larger volume of the body, then the patient table has to be moved in discrete steps through the plane of the X-ray source and detector. A single slice is acquired at each discrete table position, with an inevitable time delay between obtaining each image. This process is both time-inefficient and can result in spatial misregistrations between slices if the patient moves.

Spiral/ Helical Computed Tomography ^13,14

In the early 1990s a technique called spiral, or helical, CT was developed to overcome these problems by acquiring data as the table position is moved continuously through the scanner. The trajectory of the X-ray beam through the patient traces out a spiral, or helix: hence the name. Typical spiral CT scanners have dual-focal-spot X-ray tubes with three kVp settings possible.

3D landmarks used in the study were (Fig 3 and 4) (Table I):

Fig.3: Landmarks used for assessment of facial asymmetry in the PA ceph.

Fig.4: Landmarks used for the assessment of facial asymmetry in the 3D CT image.

Table I: Parameters used to assess the facial asymmetry.

The parameters used to assess facial asymmetry were:¹⁴

1.Maxillary Height: First molar to FH (Po-Or-Po) – distance between the FH plane and the occlusal fossa of the maxillary first molar (in mm, Fig 5).

Fig 5: Measurement of maxillary height in CT and PA ceph.

2.Mandibular Height: Canine to mandibular plane (Ag-Me-Ag), distance from the canine cuspal tip perpendicular to the mandibular plane (in mm, Fig 6).

Fig. 6: Measurement of mandibular height in CT and PA ceph.

3.Ramus Length: Condylion superior – Gonion inferior – distance between the

highest point of the condyle and the lowest point of the gonion area(in mm, Fig 7).

Fig. 7: Measurement of ramal length in CT and lateral ceph.

4.Mandibular Body Length: Menton – Gonion posterior, distance between menton and the most posterior point of the gonion area (in mm, Fig 8).

Fig. 8: Measurement of mandibular body in CT and submental vertex ceph.

5.Frontal Ramal Inclination: Condylion lateral – Gonion lateral to midsagittal

reference plane (Op-Cg-ANS) – angle formed by the FH plane and the posterior

border of the ramus (in degrees, Fig 9).

Fig. 9: Measurement of frontal ramal inclination in CT and PA ceph.

6.Lateral Ramal Inclination: Condylion posterior – Gonion posterior to FH (Po-Or- Po), angle formed by the FH plane and the posterior border of the ramus (in degrees, Fig 10).

Fig. 10: Measurement of lateral ramal inclination in CT and lateral ceph.

Results

Comparison of the differences between the right and left sides in both three dimensional CT images and conventional radiographic images showed that there was no statistical significance for the differences in Maxillary height (p=0.69), Mandibular height (p=0.69), Ramal Length (p=0.33), Mandibular body length (p=0.30) and Frontal Ramal Inclination (p=0.92). But the difference in the Lateral Ramal Inclination between right and left sides in three dimensional CT images and conventional radiographic images (Graph I) was found to be statistically significant (p=0.05).

Graph I : Comparison of the difference in the various parameters between right and left sides in 3D CT and conventional radiographic measurements.

Discussion

In most cases, the presence and degree of facial asymmetry can be diagnosed by using posteroanterior (PA) cephalometry.² But PA cephalometry does not always provide accurate information, even with the aid of lateral and submentovertex projections. Conventional radiographic images can be misleading in interpreting the cause of the deviation because complex three dimensional structures are projected onto flat two dimensional surfaces, creating possible distortion of the images and subsequent magnification errors.^15,16 The development of computed tomography (CT), however, has greatly reduced the possibility of these errors and improved our ability to understand the 3D nature of facial structures.¹⁷ In addition, recently introduced 3D CT software enables 3D reconstruction and accurate measurement of the maxillofacial complex.^18,19 3D images can provide accurate and detailed information for the diagnosis and treatment planning of facial asymmetry by means of quantitative measurement and comparison between the right and left sides of the structures. The rotating function and the computer-aided 3D measure function enable precise analysis, clear visualization and quantification of the right and left difference of the structure. The present study was conducted to compare three dimensional CT scan with conventional radiographic techniques in diagnosing and quantifying facial asymmetries are discussed 3 headings.

1. Comparison of the three dimensional CT image analysis with the conventional PA cephalometric analysis in diagnosing facial asymmetries.

Comparison of the differences between the right and left sides in both three dimensional CT images and conventional radiographic images (Table II) (Graph II) showed that there was maximum difference in the Lateral ramal inclination (1.5⁰) followed by Ramal length (1.29 mm) and Mandibular body length (1.04 mm). ). But except for the difference in the Lateral ramal inclination, all the above differences were statistically not significant.

Table II: Comparison of the difference in various parameters between right and left sides in 3D CT and conventional radiographic measurements. (+ indicates P value < 0.05)

Graph II: Comparison of difference of measurement between 3D CT and conventional radiograph for the difference of left and right sides.

The present study revealed that values derived from three dimensional CT are more accurate than conventional radiographic techniques in diagnosing facial asymmetry. Moreover 3DCT has the added advantages of ease of manipulation and better quantification and three dimensional view of the structures.

2. Reliability of three dimensional CT image analysis in assessing facial asymmetries.

Numerous studies have investigated the reliability of various techniques of diagnosing facial asymmetry: anthropometry⁷, photographs^20,21,22,23, conventional two dimensional radiographs, stereophotogrammetry^24,25,26 and three dimensional (3D) CT^{27,28,29,30,31,32,33,34}.

In the present study comparison of the initial values with the repeated readings (inter examiner measurements) for the various parameters showed a high correlation for all the parameters on both right and left side in the three dimensional CT image measurements (Table III). This indicates a high reliability of the measurements done on three dimensional CT images for assessing facial asymmetry. These findings are in accordance with Hwang et al¹⁴, Katsumata et al²⁸, Maeda et al³², Oosterkamp et al³³ and Yáñez-Vico et al³⁴, who demonstrated that the 3D-CT imaging technique was a practical and reliable method of evaluating the morphology of facial asymmetry. They also added that 3DCT had greatly reduced magnification errors from geometric distortions that are common in conventional radiographs. A 3-dimensional software also enables 3D reconstruction and quantitative measurement of the maxillofacial complex.

Table III: Correlaton with the inter-examiner values showing the reliability of 3D CT images measurements.

The present study found that measurements done on three dimensional CT images are reliable and repeatable.

3. Prevalence of facial asymmetry

The maximum asymmetry was seen in the Mandibular body length and the least in the Mandibular height. In both 3DCT and X-ray, maxillary height showed moderate asymmetry.

These findings are in concurrence with that of Peck et al⁶ showed that the orbital region exhibited the least asymmetry (0.87 mm) and the mandibular region the most (3.54 mm) with the zygomatic region exhibiting a moderate asymmetry of 2.25 mm. They found that more the structures were away from the cranium, greater was the asymmetry. These findings are also in agreement with that of Maeda et al ³² who found that asymmetry was observed most frequently in the mandibular body region and only about 6.1% of the patients examined demonstrated a mild degree of maxillary asymmetry

In the conventional radiographs, the right side measurements were greater compared to the left side of the face in Maxillary height, Mandibular height, Ramal length and Frontal ramal inclination. Only the Mandibular body length and Lateral ramal inclination showed predominance on the right side of the face in conventional radiographs. These findings are in accordance with those of Shah et al¹, Peck et al⁶ and Farkas et al⁷, who also reported that normal, pleasing facial features, with normal occlusion showed a statistically significant difference between their right and left sides, with the right side being slightly larger than the left.

The present study found that the facial asymmetry was more as one progresses caudally from the cranium, with the mandibular components exhibiting the most asymmetry. The right and the left sides showed equal predominance in their asymmetry.

Conclusion

Both 3D and 2D images are useful to better understand asymmetrical structures. Although most patients with facial asymmetry are well diagnosed by using cephalometric radiographs, some occasions require 3D imaging analysis to obtain more accurate information. By observing and accurately gauging the factors that contribute to facial asymmetry, 3D imaging analysis will enable us to comprehend its cause more accurately.

Bibilography

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Bannister C, Lendrum J, Gillepsie J, Isherwood I. Three-dimensional computed tomographic scans in the planning of procedures for reconstructive craniofacial surgery. Neurol Res. 1987 Dec;9(4):236-40.
Kumiko Togashi, Hideki Kitaura, Koichi Yonetsu, Noriaki Yoshida, Takashi Nakamura. Three-Dimensional Cephalometry Using Helical Computer Tomography: Measurement Error Caused by Head Inclination. Angle Orthod 2002;72:513–520.
Katsumata A, Fujishita M, Maeda M, Ariji Y, Ariji E, Langlais RP. 3D-CT evaluation of facial asymmetry. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005 Feb;99(2):212-20.
Akira Nakajima, Glenn T. Sameshima, Yoshinori Arai, Yoshito Homme, Noriyoshi Shimizu, Harry Dougherty Sr. Two- and Three-dimensional Orthodontic Imaging Using Limited Cone Beam–Computed Tomography. Angle Orthod 2005;75:895–903.
Maeda M, Katsumata A, Ariji Y, Muramatsu A, Yoshida K, Goto S, Kurita K, Ariji E. 3D-CT evaluation of facial asymmetry in patients with maxillofacial deformities. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006 Sep;102(3):382-90. Epub 2006 Apr 21.
Oosterkamp BC, Damstra J, Jansma J. Facial asymmetry: the benefits of cone beam computerized tomography. Ned Tijdschr Tandheelkd. 2010 May;117(5):269-73.
Yáñez-Vico RM, Iglesias-Linares A, Torres-Lagares D, Gutiérrez-Pérez JL, Solano-Reina E. Three-dimensional evaluation of craniofacial asymmetry: an analysis using computed tomography. Clin Oral Investig. 2010 Jul 15.

Dr.Dharmesh.H.S MDS, ¹

Dr.Rajkumar S Alle MDS, DNB ²

Dr.Suma.T MDS ³

Department of Orthodontics & Dentofacial Orthopaedics

Rajarajeshwari Dental College and Hospital

Bangalore.

Correspondence address:-

Dr.Dharmesh. H.S,

Geetha Multispeciality Dental Clinic

#5, 5^th Main, Tata Silk Farm,

Basavangudi, Bangalore-560004

Ph.No. 98453-38403, 080-25928195

E-mail: drdharmi@gmail.com

Primary Failure of Eruption (PFE) of Multiple Permanent Teeth: A diagnostic and Rehabilitation challenge

ray — Sat, 14 Jan 2012 21:01:31 +0000

ABSTRACT

The objective of this article is to help the dentist diagnose a case of primary failure of eruption (PFE) appropriately and distinguish it from other causes of eruption failure. The literature on the possible etiology of PFE was reviewed and correlated with our patient. A systematic approach towards the diagnosis and treatment by surgical prosthodontic or orthodontic modalities has been given. This case report presents a rare clinical situation of failure of eruption of multiple permanent teeth in all four quadrants and a methodological approach towards diagnosis along with the treatment plan for rehabilitation.

INTRODUCTION

Tooth eruption, a process involving multiple factors primarily depending on the tooth germ, is defined as the axial or occlusal movement of a tooth from its developmental position in jaw towards its functional position within the occlusal plane^1-6. It is a localised event that appears to be regulated by genes expressed in the dental follicle at chronologically critical times. The normal eruptive process involves navigation of the tooth through the bone and oral epithelium in a precise, bilaterally timed sequence that must be co-ordinated with the growth of the jaws in all three planes of space. It is incorrect to think that the erupting tooth forces its way through the overlying tissues. Instead, the controlling factors are resorption of overlying bone, tooth roots and alveolar mucosa. However, significant deviation in the process, as well as timing of eruption are often observed in clinical practice.

Failure of eruption has been divided into three distinctive categories by Sylvia A and Frazier Bowers⁷ into

1. Primary failure of eruption (PFE).

2. Mechanical failure of eruption (MFE).

3. Indeterminate failure of eruption (IFE).

The diagnostic criteria for these are:

1. PFE:

Eruption pathway cleared, no erupting movement along path.
Teeth distal to most mesially affected tooth also involved.
Any or all posterior quadrants involved.

2. MFE:

Radiographic appearance of submergence due to ankylosis.
No clear path of eruption.
Teeth distal to most mesially affected tooth apparently normal.

3. IFE:

Distinction between PFE and MFE not clear.
Too young to determine whether teeth distal to most mesially affected tooth are affected or normal.

Primary failure of eruption was described for the first time by Proffit and Vig⁸ in the year 1981 to describe a condition in which malfunction of the eruption mechanism causes non-ankylosed teeth to fail to erupt. The main identifying characters of this condition are 1) Failure of an affected tooth to move along the eruption path that has been cleared for it. The teeth involved partially erupt and then cease to erupt becoming relatively submerged though not ankylosed. 2) Another important feature of this condition is that only posterior teeth are affected resulting in posterior open bite. All teeth distal to the most mesially affected tooth are also affected. This condition is usually unilateral but can affect all the posterior quadrants. 3) A key characteristic of this condition is an abnormal or complete lack of response to orthodontic force, so that the involved teeth fail to move into proper position.

The etiopathogenesis of various causes of multiple failures of eruption are summarized ( Table 1) by Sivakumar et al⁹.

Table 1

Thus, it is apparent that a few patients may present in the dental clinic with multiple unerupted permanent teeth, with no associated symptomatic illness, no underlying endocrine dysfunction and no associated genetic abnormalities. This article deals with a report of one such case.

CASE REPORT

A 23 year old male reported to the Department of Oral and Maxillofacial surgery, DAV(c) Dental College & Hospital, Yamunanagar, India for consultation regarding his missing posterior teeth. His past medical history was completely unremarklable. He was the product of a normal term delivery and had experienced no serious illness. The family history was equally unremarkable and no other family members had the problem of missing teeth. The results of general physical examination were within normal limits and the haematocrit and WBC counts were also within normal range. Temporomandibular joints were palpable bilaterally with no crepitus/clicking/grating. Mouth opening was found to be normal i.e approximately 40 mm. Intra orally, the patient showed unerupted 26,27,37,48 and partially erupted 16, 17, 36, 38, 47. No other oral mucosal lesions were seen. (Figures 1-6)

Figure 1: Frontal facial profile: No gross asymmetry observed.

Figure 2: Teeth in occlusion.

Figure 3: Posterior open bite on right side.

Figure 4: Posterior open bite on left side.

Figure 5: Maxillary arch showing partially erupted 16, 17 and unerupted 26, 27.

Figure 6: Mandibular arch showing partially erupted 36,38, 47 and unerupted 37.

Panoramic x-ray revealed unerupted 16, 17, 26, 27,36, 37 and horizontally impacted 38 and 48 teeth. No obvious obliteration of the periodontal space was noticed. Root development of all unerupted teeth was complete. (Figure 7)

Figure 7: Panoramic radiograph showing multiple unerupted maxillary and mandibular teeth.

The treatment plan called for application of orthodontic force on the partially erupted 36 by orthodontic extrusion forces generated by extrusion cantilever appliance. The appliance was applied for a time period of 4 months and no movement was noticed, thus confirming the diagnosis of PFE. In order to prevent the intrusion of adjacent teeth, all teeth in the mandibular arch were consolidated to serve as a unit to dissipate the reactionary intrusion forces. (Figure 8)

The planned rehabilitation of the patient is removal of both impacted mandibular molars 38 and 48 which has already been done. The second step is to provide onlay crowns on 16, 17 and uprighting of 47 which would bring these teeth into occlusion on the right side. For the left side removal of 26, 27 and 36, 37 followed by bone grafting and prosthetic rehabilitation with the help of implants has been planned.

Figure 8: Extrusion cantilever appliance applied on 36 to facilitate its eruption.

DISCUSSION

Disorders of tooth eruption can be difficult to diagnose, given the lack of knowledge about the eruptive process. The diagnosis is based on clinical and radiographic characteristics and sometimes on the response to treatment. In the diagnosis of eruption failures, the first step is to rule out any local, systemic, and endocrine factors. Finally, the main differential diagnosis is mechanical obstruction (ankylosis) vs failure of the eruption mechanism. Distinguishing between the two is the key to determining the prognosis for the affected teeth. Unfortunately, MFE and PFE can have similar presentations in the early stages. If so, a definitive diagnosis cannot be made without sufficient longitudinal data and therapeutic diagnosis. However, diagnosis of PFE demands a logistic and systematic approach. The following flow chart ⁹ (Table 2) provides a direction for methodological pathway to reach upto the ultimate diagnosis of this idiopathic rare entity.

Table 2

Our patient was growing at a normal rate, was within normal limits with respect to facial and skeletal growth, and was of normal intelligence. Through careful clinical and radiological examination any local and systemic causes for obstruction in eruption pathway were ruled out. There was no family history of the disorder, and once again a defect in eruption of the primary dentition has not been reported in this syndrome. Some other syndromes enlisted in table were also ruled out on the basis of lack association with any clinical or radiographic symptoms. No abnormalities in thyroid function were noted and serum calcium, phosphorus, and alkaline phosphatase levels were within the normal range. On the basis of absence of any systemic and local findings diagnosis of PFE was figured out.

PFE appears to be a condition that predominantly affects the posterior dentition, the eruption failure can be preceded by a period of normal eruption, but any attempt to extrude an affected tooth orthodontically is likely to result in ankylosis^{8, 10, 11, 12}

(Proffit and Vig, 1981). Although these teeth might have a slight response to orthodontic forces, the response is abnormal and the teeth invariably become ankylosed before reaching occlusion. In our case we tried to facilitate the eruption of 36 through orthodontic extrusion forces generated by an extrusion cantilever. But no movement of the tooth was observed over a period of four months. Moreover, some case studies demonstrate that not only do affected teeth fail to respond to treatment, but also adjacent normal teeth are adversely affected by intrusion to the level of the affected teeth^13,14. In order to prevent the intrusion of adjacent teeth, all teeth from 36 to 46 in the mandibular arch were consolidated to serve as a unit to dissipate the reactionary intrusion forces.

The treatment modalities of PFE are complicated not only because diagnosis of this condition depends mainly on exclusion, where all possible causative factors are to be considered and eliminated. Active orthodontic force will most likely result in localized ankylosis and failure to extrude an affected tooth into occlusion, a finding that is essentially diagnostic⁸ (Proffit and Vig, 1981). Moreover, after obtaining the diagnosis, treatment options are challenging and limited. Patients and orthodontists have to satisfy themselves with premolar occlusion or try for more invasive techniques, which may not succeed. In very mild cases, teeth can be restored with onlays and crowns¹⁵ and further definitive restorations can be planned once vertical growth is completed. For moderately severe cases, extraction of teeth with placement of implants might be an option, but bone grafts before implants are likely to be required. Cases where multiple teeth are involved are more difficult to manage; the only available method of bringing them into occlusion is a segmental osteotomy (Proffit and Vig⁸, 1981; Piattelli and Eleuterio¹⁶, 1991). In severe cases, as in this case, a significant deficit in alveolar bone height precludes subapical osteotomy. However, careful planning in these cases is essential to ensure that no damage is caused to adjacent teeth. While surgical repositioning may not move teeth into an entirely acceptable position, it will certainly aid prosthetic management.

Distraction osteogenesis has been reported to correct an extreme posterior open bite thereby it can be considered as an alternative treatment modality¹⁷.

CONCLUSION:

Idiopathic multiple failure of eruption of teeth is a very rare anomaly and can be regarded as an eruption defect, manifesting as a complete failure of eruption or cessation of initial eruption with no obvious local or systemic aetiology. Therefore, it is imperative for clinicians to follow a methodical approach towards the diagnosis and rehabilitation of the patient through surgical, orthodontic or by prosthodontic measures.

REFERENCES

1.      Massler M, Schour I. Studies in tooth development: theories of eruption. American Journal of Orthodontics and Oral Surgery 1941;27:52-76.
2.      Berkovitz BKB. The effects of root transaction and partial root resection on the unimpeded eruption rate of the rat incisor. Archives of Oral Biology 1971;16:1033-43.
3.      Moxham BJ, Berkowitz BKB. The effects root transaction on the unimpeded eruption rate of the rabbit mandibular incisor. Archives of Oral Biology 1974;19:903-9.
4.      Cahill DR, Marks SC. Tooth eruption: evidence for the central role of the dental follicle. Journal of Oral Pathology 1980;9:189-200.
5.      Marks SC Jr, Cahill DR. Experimental Study in the dog of the nonactive role of the tooth in the eruptive process. Archives of Oral Biology 1984;29:311-22.
6.      Wise GE, Marks SCJr, Cahill DR. Ultrastructural features of the dental follicle associated with formation of tooth eruption pathway in the dog. Journal of Oral Pathology 1985;14:15-26.
7.      Sylvia A. Frazier-Bowers, Karen E. Koehler, James L. Ackerman, William R. Proffit Primary failure of eruption: Further characterization of a rare eruption disorder. American Journal of Orthodontics and Dentofacial Orthopedics 2007; 131:578.e1-578.e11.
8.      Proffit WR, Vig KW. Primary failure of eruption: a possible cause of posterior open-bite. American Journal of Orthodontics 1981;80:173-90.
9.      Sivakumar A, Valiathan, Gandhi S, Mohandas A. Idiopathic failure of eruption of multiple permanent teeth: Report of 2 adults with a highlight on molecular biology. American Journal of Orthodontics and Dentofacial Orthopedics 2007; 132:687-92.

10. Biederman W. Etiology and treatment of tooth ankylosis. American Journal of Orthodontics 1962;48:670-84.

11. Mancini G, Francini E, Vichi M, Tollaro I, Romagnoli P. Primary tooth ankylosis: report of case with histological analysis. Asdc Journal of Dentistry For Children 1995;62:215-9.

12. Mitchell DL, West JD. Attempted orthodontic movement in the presence of suspected ankylosis. American Journal of Orthodontics 1975;68:404-11.

13. Raghoebar GM, Boering G, Jansen HW, Vissink A. Secondary retention of permanent molars: a histologic study. Journal of Oral Pathology and Medicine 1989;18:427-31.

14. Winter GB, Gelbier MJ, Goodman JR. Severe infra-occlusion and failed eruption of deciduous molars associated with eruptive and developmental disturbances in the permanent dentition: a report of 28 selected cases. British Journal of Orthodontics 1997; 24:149-57.

15. Yatani H, Watanabe EK, Kaneshima T, Yamashita A, Suzuki K. Etched-porcelain resin-bonded onlay technique for posterior teeth. Journal of Esthetic Dentistry 1998; 10:325-32.

16. Piattelli A, Eleuterio A 1991 Primary failure of eruption. Acta Stomatologica Belgica; 88 : 127 – 130

17. Kater WM, Kawa D, Schafer D, Toll D. Treatment of posterior open bite using distraction osteogenesis. Journal of Clinical Orthodontics 2004;38:501-4.

Authors

1. DR SHRUTI NAVEEN CHHABRA

BDS, MDS

Reader, Dept. of OMFS,

D.A.V Dental College and M.M General Hospital, Yamunanagar – 135001,

India.

Contact No. 09813147040

Email- naveenprisha@yahoo.co.in

2. DR NAVEEN CHHABRA

BDS, MDS, DNB

Professor, Dept. of OMFS,

DAV Dental College and MM General hospital,

Yamunanagar –135001, India.

Contact No: 09813013083

Email- naveenprisha@gmail.com

3. DR RAHUL SHARMA

MDS 3^RDyear resident, Dept of OMFS

DAV Dental College & MM General hospital,

Yamunanagar– 135001, India.

Contact No: +919466437123

Email –sharmadr.rahul@yahoo.com

4. DR SAURABH NAGRATH

MDS 2^nd year resident, Dept of OMFS

DAV Dental College & MM General hospital,

Yamunanagar– 135001, India.

Contact No:+919896503262

Email- saurabh_nagrath@yahoo.co.in

Effects of Recycling on the Tensile Strength of Beta Titanium and Nickel Titanium Wires

ray — Sat, 14 Jan 2012 16:11:41 +0000

ABSTRACT

The purpose of this study was to evaluate changes in tensile strength of 0.016″ Beta- Titanium and Nickel Titanium wires after recycling. Four common methods of sterilization /Disinfection methods – Dry heat, Autoclave, Ultrasonic cleaner and 2% Glutaraldehyde, were evaluated in three test trials involving zero, one and five sterilization cycles. For each of the test trials, five pieces each of 0.016″ Beta-Titanium and Nickel Titanium wires were sterilized using a standard dry heat sterilizer. Five other pieces of each of the same wires were sterilized in an autoclave, five pieces in ultrasonic cleaner, while an additional five pieces of each of the two wire types were sterilized using 2% glutaraldehyde.The ultimate tensile strengths of the wires were determined using an universal testing machine. The data were compared for statistical difference using analysis of variance. The results showed that dry heat sterilization significantly increased the tensile strength of TMA wires after one cycle but not after five cycles. Autoclaving, Ultrasonic cleaning and Gluteraldehyde did not significantly alter the tensile strength of TMA wires. Dry heat and autoclave sterilization also significantly increased the tensile strength of Nickel Titanium Wires, but the mean strength after five sterilization cycles was not significantly different than after one cycle. Ultrasonic cleaner and gluteraldehyde did not significantly alter the tensile strength on the Nickel Titanium Wires.

KEY WORDS: Recycle, Sterilization, Wire, Tensile strength.

INTRODUCTION:

Recent advances in orthodontic material technology have resulted in a varied array of wires that exhibit a wide spectrum of properties. With continued research, several other alloys with desirable properties have been adopted in orthodontics. These include Cobalt – Chromium, nickel-titanium, beta-titanium, multistranded stainless steel wires and many others.

The newer orthodontic wires display an excellent combination of strength, resiliency and low-load deflection rates. But, one of the drawbacks of these wires remains their comparatively high cost. Beta-titanium wires are approximately three times more expensive than stainless steel arch wires, while nickel-titanium wires are usually twice as expensive. These two types of titanium wires are extremely popular and it is unlikely that orthodontists will discontinue their use due to high price. As a consequence of both cost factor and indispensable desired mechanical properties, some clinicians are prompted to sterilize and reuse these wires. ^1,2,3

The reports of surveys done on the use of recycled wires in orthodontic practice indicate a high rate of prevalence. However, majority of the clinicians using recycled wires were found to be concerned with the deterioration of mechanical properties of the wires after subjecting them to sterilization.⁴The changes in the tensile strength will have a direct impact on clinical re-use of the wire. If a wire’s ultimate tensile strength is decreased due to sterilization / disinfection, it is more prone to breakage, which presents a problem for the patient and orthodontist alike. ^3,5

The ability to recycle orthodontic wires relies on effective sterilization prior to re-use without resulting in deterioration of their clinical properties and without causing health hazard to the patient. The present study was undertaken to evaluate the changes in the tensile strength of Beta titanium and Nickel Titanium wires after recycling.

MATERIALS AND METHODS:

The sterilization methods investigated were dry heat (Techno media, at 375 F for 20 mins), Autoclave( Kavoklave, at 250 F for 20 mins under 15 psi pressure), Ultrasonic cleaner (Biosonic,Whaledent, for 15 mins ) and 2% gluteraldehyde (korsolex for 8-10 hours). (A)Beta Titanium ( TMA,ORMCO) and (B)Nickel titanium ( Ortho organizers) wires were tested. 7” segments of straight lengths of 0.016” round wires were selected in each case. Three test trials were made using zero (A₀,B₀),one (A₁, B₁), and five (A₅, B₅) sterilization cycles.

For the first test trial, five segments of each TMA and Nickel Titanium (Subgroups A₁ and B₁) were sterilized one time using one of the four sterilization/disinfection methods: dry heat, autoclave, ultrasonic cleaner or 2% glutaraldehyde. The ultimate tensile strength of each wire segment was then tested.

The samples were prepared for tensile strength testing by embedding the ends of the wire into acrylic blocks. Lengths of all wire samples were standardized to 7 inches. The acrylic blocks aided in attaching the wire samples to the universal testing machine.

A 500 kg load-cell was attached to the universal testing machine and was set with a cross-head speed of 1mm/min. The tensile strength recorded was the maximum stress value in KgF just prior to fracture of the test wires. Only those breaks which occurred within the inter-grip span were recorded.

For the next test trials, the same procedure was repeated for five segments of 0.016TMA and five segments of 0.016” Nickel Titanium wire (subgroups A₅, B₅), which were sterilized five times, using one of the four sterilization techniques. As before, the wire’s tensile strengths were tested and recorded. All the listed samples were tested within seven days of their respective sterilization treatments.

The final group of five segments of each type of wire (subgroups A₀, B₀) served as the control group and their tensile strengths were determined without any sterilization / disinfection procedures.

Statistical Analysis: Tensile strength was expressed as Mean and Standard deviation. Intergroup comparisons were made by one factor ANOVA followed by Newman-Keul’s Range test for pair wise comparisons.

RESULTS

The results of the ANOVA tests evaluating the tensile strength of Beta Titanium and Nickel titanium wires were as follows.

Beta-Titanium: - The tensile strengths of the Beta-Titanium wires after zero, one and five cycles of dry heat sterilization revealed that dry heat significantly increased the tensile strengths of the Beta-Titanium wires after one cycle. However, there were no significant differences in the tensile strengths of unsterilized wires and wires sterilized five times. Autoclave sterilization of TMA wires showed no statistical differences in the tensile strengths following zero, one and five cycles. Ultrasonic cleaning and cold sterilization with 2% Glutaraldehyde did not have any effect on the tensile strength of Beta-Titanium wires after zero, one and five cycles.

Nickel-Titanium: - The tensile strengths of Nickel-Titanium wires after zero, one and five cycles of dry heat sterilization demonstrated a significant increase when compared. Yet, Newman-Keul’s Range test did not demonstrate a significant difference in tensile strengths between one and five cycles.

Autoclaving Nickel-Titanium wires produced a statistically significant increase in the tensile strengths after one and five sterilization cycles. However, the mean tensile strength after five cycles was not significantly different than after one cycle.

Ultrasonic cleaning and cold sterilization with 2% glutaraldehyde did not have any effect on tensile strength of Nickel-Titanium wires after zero, one and five cycles.

The average tensile strength of the two types of wires following sterilization is summarized in the table.

The average Tensile strength of 0.016” wires with Standard deviations in N/mm²

Wire	Sterilization method	0 cycle	1 cycle	5 cycles
TMA	Dry heat	1087±48	1282±57	1212±95
NiTi	Dry heat	1226±11	1382±60	1364±31
TMA	Autoclave	1087±48	1251±75	1238±161
NiTi	Autoclave	1226±11	1366±54	1382±29
TMA	Ultrasonic cleaning	1087±48	1086±41	1084±65
NiTi	Ultrasonic cleaning	1226±11	1232±8	1233±19
TMA	Glutaraldehyde	1087±48	1091±38	1088±47
NiTi	Glutaraldehyde	1226±11	1222±15	1234±14

DISCUSSION

When considering the reuse of Orthodontics wires one must evaluate the effect of sterilization/disinfection on the physical properties of wires.

The purpose of the present study was to examine the effect of repeated cycles of four different methods of sterilization/disinfection on tensile strengths of Beta-Titanium and Nickel-Titanium wires. Tensile strength was chosen as the parameter as it has a direct impact on the clinical use of a wire.

The four different sterilization/disinfection techniques adopted in the present study were those which are commonly practiced in an orthodontic set-up. The results of the present study suggest that sterilisation and reuse of Orthodontic wires does not alter the tensile strength as expected.

In this study the tensile strengths of both Beta-Titanium and Nickel-Titanium wires increased after sterilization using dry heat or autoclave. Dry heat sterilization produced statistically significant increase in the tensile strength of Beta-Titanium wire following one cycle, and produced no further statistically significant increase in the same following five cycles.

Dry heat sterilization of Nickel-Titanium wires produced increase in its tensile strength, when sterilized one time than when sterilized five times. However, these differences were not statistically significant.

Autoclave sterilization did not significantly alter the tensile strength of Beta-Titanium wires. This sterilization procedure however significantly increased the tensile strength of Nickel-Titanium wires, though the mean strength after five sterilization cycles was not significantly different than that after one cycle.

Cold sterilization using Glutaraldehyde or Ultrasonic cleaning did not alter the tensile strengths of any of the two types of wires.

Hence, the results of the present study suggest that the currently accepted regimes for sterilization/disinfection do not have any detrimental effects on the mechanical properties (viz., tensile strength) of the Beta Titanium and Nickel-Titanium wires. The results are in accordance with findings of Buckthal and Kusy (1988)⁶, Mayhew and Kusy (1988)⁷and Sung Ho Lee and Young II Chang (2001) ⁸

In a 1986 survey, Buckthal et al⁶ had reported that 52% of the orthodontists using Nickel-Titanium wires were recycling them, and 55% of these orthodontists were concerned about the changes in the physical properties of the Nickel-Titanium wires resulting from heat sterilization. This explains the reluctance of the orthodontists in using heat sterilization for recycling. This is despite the fact that the temperatures used in the manufacturing process are far higher than those encountered during heat sterilization procedures. Furthermore, the findings that autoclaving was not detrimental to the wires’ performance should allay the concerns of those who avoid heat sterilization techniques (Thompson and Bogues, 1977; Buckthal et aI., 1986) for recycling them.⁵

The results of this investigation added scientific credence to the clinicians’ who have been saying that the performance of recycled BetaTitanium and Nickel-Titanium wires were clinically acceptable, as there was no overall statistically significant difference in tensile strengths of as received versus sterilized wires. These findings agree with the work of Smith, Von Fraunhofer and Case⁹ did on Nickel-Titanium and BetaTitanium wires.

Thus wire recycling maybe one method of reducing Orthodontic practice overhead. However not every wire maybe recycled. Beta Titanium wires with bends are not candidates for recycling since the same bends will rarely fit more than one patient. Nickel Titanium wires are usually placed without orthodontic bends which make these wires ideal for sterilization and reuse. Still, breakage and patient abuse of these wires may prevent them from being recycled.

One must consider whether reduction of overhead achieved through recycling outweighs the risk of contamination between patients. Whether or not recycling is a practical method of reducing overhead must be left for every practitioner to decide.

CONCLUSION

The results of this study suggest that the Orthodontists who choose to recycle Beta Titanium and Nickel Titanium wires need not be concerned about reducing the wires’ ultimate tensile strength by sterilization procedure.

REFERENCES

Kapila S., Haugen J.W. and Watanabe L.G.,1992, “Load-deflection characteristics of Nickel-Titanium alloy wires after clinical recycling and dry heat sterilization.” Am.J.Dentofac.Orthop.102:120-126.
Kapila S., Reichhold G.W.,Anderson R.S. and Watanabe L.G.,1991, “Effects of clinical recycling on mechanical properties of NickelTitanium alloy wires.” Am.J.Orthod.Dentofac Orthop .. 100:428-435.
Staggers J.A. and Margeson.D.,1992, “The effects of sterilization on the tensile strength of orthodontic wires.” Angle Orthod ..63:141-144.
Buckthal J.E., Mayhew M.J., Kusy R.P. and Crawford J.J.,1986, “Survey of sterilization and disinfection procedures.” J.Clin.Orthod.•20:721-765.
Crotty O.P., Davis E.H. and Jones S.P.,1996, “The effects of crossinfection control procedures on the tensile and flexural properties of superelastic Nickel-Titanium wires.” Br.J.Orthod. 23 : 37-41
Buckthal J.E. and Kusy R.P .,1988, “Effects of Cold disinfectants on the mechanical properties and the surface topography of Nickel-Titanium arch wires”, Am.J. Orthod. Dentofac. Orthop.. 94:117-122.
Maylew M.J. and Kusy R.P.,1988, “Effects of sterilization on the mechanical properties and

the surface topography of Nickel-Titanium archwires,

Am.J.Orthod.Dentofac.Orthop.93:232-236.

Sung Ho Lee and Young II Chang., 2001, “Effects of recycling on the mechanical properties and the surface topography of nickel titanium alloy wires.” Am. J. Orthod. Dentofacial Orthop. 2001; 120: 654-63.
Smith G.A., Von Fraunhofer J.A. and Case G.R.,1992, “The effect of clinical use and sterilization on selected orthodontic arch wires.” Am.J. Orthod.Dentofac.Orthop. 102:    153-159Corresponding author 1)      Dr. Hemalatha Sanjay
Professor, Dept of Orthodontics

Raja Rajeshwari Dental College

Bangalore

iamdrhema@gmail.com

2)      Dr. Nandini S Nelvigi

Professor, Dept of Orthodontics

Bangalore Institute of Dental College,

Bangalore

3)      Dr. S.R.K. Reddy

Professor, Dept of Orthodontics

Sibar Dental College,

Bangalore

4)      Dr. Prashanth. C.S

Reader, Dept of Orthodontics

College, Bangalore

5)      Dr. Sanjay Mohanchandra

Professor, Dept of Oral & Maxillofacial Surgery

Oxford Dental College and hospital,

Bangalore.

6)      Dr. Chandrashekar. M. Halloli

Reader, Dept of Orthodontics

Oxford dental college,

Bangalore

7)      Dr. Basanagouda Patil

Reader, Dept of Orthodontics

HKE Dental College, Gulbarga

.

Treatment Effects in an Anterior Open Bite Class II Malocclusion with Two Different Functional Appliances

ray — Mon, 02 Jan 2012 17:14:25 +0000

Abstract

AIM: The aims of this study were to determine whether the modified bionator appliance and open bite bionator by Balters encourages correction of an anterior open bite and Class II maloclusion, whether there is any superiority of one appliance over other.

MATERIALS AND METHODS: 58 patients with open bite, Class II division I malocclusion and functional disorders were selected. 31 patiens (15 boys and 16 girls, mean age of 8 years 9 months) were treated with the modified bionator appliance and 27 patients (12 boys and 15 girls, mean age of 9 years 1 month) with open bite bionators by Balters. The dentoalveolar and skeletal changes that occured were compared on lateral cephalograms taken before treatment (T1) and after active treatment (T2).

RESULTS: The modified bionator appliance demonstrated a statistically significant increase in upper incisor retraction (U1/NA -3,5mm and U1/PP –8,1°), increase in lower incisors retraction (L1/NB –5,1°, -2,9mm and L1/MP –5,3°, 2,7mm) and interincisal angle ( 8,6°) compared with the group treated with open bite bionator. Also, in both groups SNB angle increased and ANB angle decreased and corrected the Class II malocclusion, but without statistically significant changes between groups.

CONCLUSION: The modified bionator appliance (MBA) is a functional orthodontic-orthopedic appliance and is useful and an effective therapeutic alternative for the treatment of an anterior open bite and skeletal Class II malocclusion.

Introduction

Malocclusions characterized by anterior open bite are often difficult to treat successfully. Anterior open bite is a malocclusion characterized by a deviation in the vertical relationship between the maxillary and mandibular dental arches, with absence of contact between the incisal edges of the maxillary and mandibular teeth in the vertical plane. The severity varies, from an almost edge-to-edge relationship to a severe handicapping open bite (1,2).

The presence of an anterior open bite is contributed by functional disorders, thumb suckling and tongue thrusting, (3,4) as well as skeletal factors (5). An anterior open bite, which is caused by a habit, has a favorable prognosis, provided that the habit is terminated (6).

The goal of early orthodontic treatment is to correct existing and developing skeletal, dentoalveolar and functional imbalances, which could help to minimize the possibility of complicated orthodontic treatment involving permanent tooth extraction or orthognatic surgery. Several types of functional appliances are currently in use for open bite treatment aimed to improving existing skeletal imbalances, arch form and orofacial function. Among contemporary functional appliances, one of the most popular is the »open bite bionator« by Balters (7).

The modified bionator appliance (MBA) is a functional orthodontic-orthopedic appliance and is useful and an effective therapeutic alternative for the treatment of an anterior open bite and skeletal Class II division I malocclusion. The modified bionator appliance is a modification by Balters bionator and was invented by Anita Fekonja and constructed and performed at Orthodontic Department in Health Centre dr. A. Drolca Maribor.

Aims of the study

The purpose of this researsh were to evaluate:

- cephalometrically the possible effects produced by modified bionator appliance (MBA) and open bite bionator by Balters on dentoalveolar and skeletal components in patients with an anterior open bite and Class II division I malocclusion (retrognatic mandible)

- there is any superiority of one appliance over the other

This paper describes the principle of the MBA mechanism and discusses its dentoskeletal effects as compared with an open bite bionator by Balters.

Description of the modified bionator appliance and principle of its mechanism

The MBA is a rigid appliance with a delicate design of less bulky acrilyc base (Photos 1,2). The acrylic base of the appliance is closed in the front but it should not contact the incisors or the dentoalveolar margin so that the open bite can close. This area can be blocked out with wax before the application of the acrylic, or be trimmed free after its finishing. This part of the acrylic base prevents the intrusion of the tongue between the teeth which is very important. The acrylic base included upper and lower labial archwire that, when activated, contributed to upper and lower incisor uprighting (through palatal crown tipping). The Coffin spring is bent distally closed. The position of the tongue is influenced by the Coffin spring.

Photo 1: The modified bionator apliance

Photo: 2 The modified bionator apliance

Also can be incorporating a special type of jackscrew if mild compresion exist.

The functional action of the appliance is effected through the way that removable part desirable mandibular position. The construction bite determines the position of the mandible: the mandible is brought by the clinician to Class I position and 2-3 mm of opening at the vertical. The maximum permissible mandibular protrusion is considered to be 7mm in order to avoid stomatognathic dysfunction. Appropriate activation of both labial arch provides retrusion of upper an lower incisors for the proper alignment of the teeth in their apical bases (Fig 1); furthermore, transverse dentoalveolar intermaxillary relationship can corrected with the jackscrew.

Figure 1. Principles of orthodontic-orthopedic mechanism

Indication of the MBA functional appliances:

- the patient must still be growing, preferably approaching a phase of rapid growth

- the labial tipping of the upper and lower incisors is evident

- the patient must be well motivated

Orthodontic treatment goals for this patient treated with MBA included:

- achivement of normal dental occlusion through correction of overbite and overjet

- rehabilitation of jaw relationship in the sagital plane

- improvement of function and facial esthetics

Material and methods

The material used in this clinical study comprised the clinical examination, interview, and lateral cephalometric radiographs of 58 patients with an anterior open bite, Class II malocclusion and abnormal tongue function. Patients treated at the Orthodontic Department of Health Centre dr. A. Drolc Maribor between 2004- 2009

Selection criteria included:

- no previous orthodontic treatment

- lateral cephalograms were available pretreatment and post treatment

- anterior open bite, Class II division I malocclusion, abnormal tongue function

- complete eruption of upper and lower incisors

- no craniofacial deformities

Based on this criteria, records of 58 patients were colected. The 31 patiens (15 boys and 16 girls, with initial mean age of 8 years 9 months) treated with MBA and 27 patients (12 boys and 15 girls, with initial mean age of 9 years 1 month) treated with open bite bionator by Balters.

The patients were instructed to wear the appliance for a minimum of 14 hours a day.

Methods

Data on tongue thrust swallowing was obtained at the time of clinical examination. In order to examine the presence of tongue thrusting, the patients were asked to swallow their saliva three times during the same visit. Tongue thrust was defined as protrusion of the tongue between the upper and lower incisors or during swallowing.

For each patient, lateral cephalometric radiographs at the start and end of active treatment were taken. Lateral cephalograms were taken under standard conditions: distance from the focus to the median plane of the patient’s head was 150cm, and the median plane-film distance was 10cm. The cephalograms were taken with the subject standing and the head positioned in the cephalostat and orientated to the Frankfort horizontal plane with the teeth in maximum intercuspidation.

Cephalometric angular and linear measurements:

Skeletal cephalometric variables

- SNA: sella-nasion-point A angle

- SNB: sella-nasion-point B angle

- ANB: point A- nasion-point B angle

- SNPg: sella-nasion-pogonion angle

- SN/PP: angle formed by SN line and palatal plane (Sna-Snp)

- SN/MP: angle formed by SN line and mandibular plane(Go-Gn)

- LAFH: lower anterior facial height

Dentoalveolar cephalometric variables

- U1/PP: angle between maxillary incisor long axis and palatal plane

- U1-PP: perpendicular distance between incisal edge of maxillary central incisor and palatal plane ( maxillary incisors dentoalveolar height )

- U1/NA: angle between maxillary incisor long axis and NA line

- U1-NA: distance between most anterior point of the maxillary central incisor and the NA line

- L1/NB: angle between mandibular incisor long axis and NB line

- L1-NB: distance between most anterior point of the mandibular incisor and NB line

- L1/MP: mandilular incisor long axis to mandibular plane angle

- L1-MP: perpendicular distance between incisal edge of mandibular central incisor and mandibular plane ( mandibular incisors dentoalveolar height )

- overbite: distance between incisale edges of maxillary and mandibular central incisors, perpendicular to functional occlusal plane

- overjet: horizontal distance between incisal edges of maxillary and mandibular central incisors in sagital plane

- interincisal angle: angle between maxillary incisor long axis and mandibular incisor long axis

Statistical analysis

All radiographs were traced on good quality acetate paper using a 3H pencil under optimum lighting conditions by the same orthodontist (AF), twice, at different times to eliminate measurement errors, and the mean findings were statistically evaluated. 15 landmarks and 18 parameters (linear and angular) were measured in the study.

Mean and standard deviations (SD) for the two groups were calculated for all cephalometrics variables at T1 an T2. To apply the t test, the results showed that all variables were normally distributed in both groups. Therefore, independent t test were used for comparison of the changes during treatment (T2-T1). The results were regarded as significant at P<0.05

Results

The results of the pre-treatment lateral cephalograms measurements are shown in Table 1 and describe the initial values for each groups. Compararisons of the changes occurring during the treatment period are shown in Table 2 .

Table 1. Comparison of pre-treatment cephalometric measurements

variable	Modified bionator appliance (MBA) mean DS		Open bite bionator by Balters mean SD
SNA (°)	80,5	3,7	80,1	3,9
SNB (°)	76,8	3,5	76,4	3,3
ANB (°)	2,9	2,2	2,7	2,3
SNPg (°)	78,1	3,4	78,3	4,4
SN/PP (°)	7,7	3,3	7,6	2,3
SN/MP (°)	36,1	4,6	35,9	5,6
LAFH(mm)	55,5	5,7	55,3	4,5
U1/NA (°)	28,5	4,3	29,3	5,7
U1/NA (mm)	7,5	1,9	6,8	2,2
U1/PP (°)	115,8	7,1	115,4	6,8
U1/PP (mm)	26,6	1,9	27,3	1,8
L1/NB(°)	28,2	6,5	28,4	5,6
L1/NB(mm)	6,5	2,1	5,4	1,9
L1/MP (°)	94,5	5,6	93,4	5,5
L1/MP(mm)	38,4	2,7	38,2	2,9
Overbite (mm)	-2,7	1,8	-2,8	1,6
Overjet (mm)	6,1	2,1	5,8	2,7
Interincisal angle degrees	129,3	11,5	127,3	5,7

Table 2. Difference in mean changes ( T1 to T2 ) standeardized to 18 months

Variable	Modified bionator appliance mean SD		Open bite bionator by Balters mean DS		P
SNA (°)	0,1	1,6	0,3	1,8	NS
SNB (°)	1,8	1,3	1,4	1,1	NS
ANB (°)	-1,5	1,3	-1,2	1,1	NS
SNPg (°)	1,6	1,4	1,5	0,9	NS
SN/PP (°)	0,2	1,6	0,3	1,3	NS
SN/MP (°)	0,4	2,2	0,5	1,9	NS
LAFH(mm)	1.9	1,6	2,1	1,8	NS
U1/NA (°)	-6,3	5,5	-4,2	4,8	NS
U1/NA (mm)	-3,5	3,4	-0.9	2,1	*
U1/PP (°)	-8,1	5,2	-4,1	4,7	*
U1/PP (mm)	2,1	1,6	2,3	1,3	NS
L1/NB (°)	-5,1	3,8	-1,2	3,7	*
L1/NB(mm)	-2,9	1,3	0,7	1,5	*
L1/MP(°)	-5,3	4,1	-1,1	4,8	*
L1/MP (mm)	2,7	1,3	1,4	1,4	*
Overbite (mm)	2,2	1,2	1,8	1,9	NS
Overjet (mm)	-4,2	2,4	-3,8	2,2	NS
Interincisal angle degrees	8,6	5,6	2,1	4,5	*

* statistically significant P<0.05

Of the 18 variables analysed, 7 were statistically significant. All of these were dentoalveolar measurements.

The MBA group showed statistically significant differences with the open bite bionator group in the distance of the upper incisor to the NA line, in the inclination from upper incisor tip to the palatal plane, in the inclinacion and distance of the lower incisor to the mandibular plane, and the inclinacion and distance of the lower incisor to the NB line, indicating uprighting of the incisors and deepening bite.

Point B appeared to have moved forward as a result of orthodontic-orthopedic therapy in both treatment groups, but without statistically significant differences.

In the group treated with MBA, the mean anterior open bite closure was 2,2mm. Treatment provided closure of the anterior open bite in all 31 individuals. However, in the group treated with open bite bionator by Balters the mean change in overbite was 1,8mm and treatment provide closure of anterior open bite in 23 of the 27 individuals.

The maxillary and mandibular incisors showed in MBA group greater extrusion and retrusion ( uprighting ) than in open bite bionator group.

Discussion

The study was conducted on growing patients, and the groups should nacessarily present similar chronological and skeletal ages to allow reliable comparison. The initial cephalometric characteristic of both groups should also be similar.

At the start of treatment all cephalometric measurements were comparable in both groups.

This study compared the effect of the appliances over a 18 months period. The modified bionator appliance (MBA) is a functional orthodontic-orthopedic appliance and is useful and effective therapeutic alternative for the treatment of anterior open bite with abnormal tongue function and skeletal Class II malocclusion.

It is reported that functional appliance therapy increases the lenght of the mandible and results in an anterior relocation of point B and pogonion (8, 9). In the present study, the values of SNB and SN-Pg support these findings, demonstrating that the mandible moved forward as a result of active therapy in both treatment groups with no statistically significant differences.

Both study groups demonstrated a small increase in SN/PP, SN/MP and LAFH, although the appliances for patients for both treatment groups were designed to prevent further increase of facial height, i.e. use of an untrimmed interoclusal acrylic prevent eruption of the buccal segment.

During treatment, there were only significant differences in the maxillary and mandibular dentoalveolar components between the groups. Retroinclination of the maxillary incisors is a consistent finding in many Bionator studies. In the present study, the upper incisors were more retracted in the MBA group. The more pronounced retrusion in the MBA group may be due to the upper labial archwire control. This is expected treatment outcome of functional appliance therapy due to their Class II »traction effect« and the findings support those of Op Heij et al.(10) and Bolmgren and Moshiri (11). The effect of appliance therapy on the position of lower incisors varied statistically significant between the appliance groups. Statistically significant reduction in the proclination of the lower incisors was seen in the MBA group. This effect was expected as the labial bow may come into contact with the incisors during appliance wear. It would apper that the MBA is a more logical treatment approach in Class II patients with protrusive upper and lower incisors and anterior open bite.

As a result of therapy, the overjet decreased in both groups. The greatest reduction was observed in the MBA group. As the open bite bionator appliance showed effect on the upper incisors retroinclinacion and minimal effect on the lower incisors, this would account for incomplete correction Class II molar relationship. It could be speculated that the Bionator appliance did not show such rapid anteroposterior correction, the changes may be superior in terms of the effect on incisor inclinacion.

Conclusion

This paper demonstrates that a modified bionator appliance can be succesfully used to treat an anterior open bite and Class II division I malocclusions.

The success of treatment lies in correction of the anterior-posterior, vertical and mild transverse discrepancies and the most important also correction irregular function. The importance of correcting the inter- incisal angle is paramount for stability. It is essential to reduce the interincisal angle towards 125 degrees, bringing the upper and lower incisor into correct axial position. This avoids the need for an another appiance.

From a clinical impresion, the MBA appeared to be the most readily tolerated and was advantageous in terms of rapidity of correction of the effects on the lower incisors. It must be stressed that this study reports the initial effects and no conclusions can be drawn about stability.

References

Graber TM. Orthodontics principles and practice. 2nd ed. Philadelphia: WB Saunders Co 1961.
Nanda SK. Patterns of vertical growth in subjects with long and short faces. Am J Orthod Dentofac Orthop 1990; 98:247-258.
Gellin ME. Digital sucking and tongue thrusting in children. Dental Clin North Am 1979;22:603-619.
Speidel TN. Isaacson RJ, Worms FW. Tongue thrust therapy and anterior dental open bite. Am J Orthod 1972;62:287-295
Nielsen BIL. Vertical maloclusion: etiology, developmant, diagnosis and somem aspects of treatment. Angle Orthod 1991;61:247-260.
Proffit WR, Fields HW: The etiology of orthodontic problems. In: Contemporary orthodontics. St Louis: CV Mosby, 2003: 134-136.
Graber TM, Rakosi T, Petrovic AG. The bionator – a modigied activator. In: Graber TM, Rakosi T, Petrovic AG, eds. Dentofacial orthopedics with functional appliances. St. Louis: CV Mosby, 1985: 209-218.
Bastiftci FA, Uysal T, Büyükerkmen A, Sari Z. The effect of activator treatment on the craniofacial structures of Clacc II division I patients. Eur J Orthod 2003;25: 87-93
Ruf S, Baltromejus S, Pancherz H. Effective condylar growth and chin position changes in activator treatment: a cephalometric roentgenographic study. Angle Orthod 2001;71: 4-11.
Op Heij DG, Callaert H,Opdebeeck HM. The effect of the amount of protrusion built into the bionator on condilar grovth and displacement: a clinical study. Am J Orthod Dentofac Orthop 1989; 95:401-409.
Bolmgren GA, Moshiri F. Bionator treatment in Class II division 1. Angle Orthod 1986; 56:255-262.

Author and address for correspondence:

Anita Fekonja

Department of Orthodontics

Health Centre dr.A. Drolc Maribor

Partizanska 14a

2000 Maribor

e-mail: anita.fekonja1@guest.arnes

An Easy Approach for Diagnostic Setup in Moderate to Severe Crowding Cases

ray — Wed, 14 Dec 2011 20:55:26 +0000

Moderate to severe crowding cases have always presented a challenge to the orthodontist. Thorough diagnosis and treatment planning is required to treat such cases. In a majority of such cases orthodontic treatment is usually instituted by extraction therapy. However, planning extractions in such cases is critical and hence certain diagnostic aids are necessary to decide upon the extraction protocol necessary.

Diagnostic setups have been used in orthodontics for a long time to decide upon treatment plans individual patients. Numerous methods of have been described for diagnostic setups^1-5. However while preparing diagnostic setups it is always difficult to slice out all individual teeth from a single model especially in moderate to severe crowding cases.

Hence a simple approach is presented to prepare diagnostic setups in moderate to severe crowding cases.

STEP 1: Obtain 2 set of models of patients original malocclusion.

Fig.1. 2 sets of patient’s original malocclusion. Gnathostatic models made of 1 set. Teeth numbered on both sets with different coloured marking pens.

STEP 2: Prepare gnathostatic model out of 1 set.

Fig. 2 a-f. Alternate teeth slicing done on either models sacrificing adjacent teeth if necessary.

STEP 3: Number individual teeth on either models with two different coloured marking pens.

Fig. 3. Full set of maxillary and mandibular teeth obtained.

STEP 4: Obtain alternate teeth from either models ensuring complete width of the tooth being sliced (even if adjacent is sacrificed) and one complete set of individual teeth is obtained.

Fig. 4 a-b. Teeth arrangement done according to treatment plan decided on gnathostatic models. (reproximation of upper central incisors and extraction of mandibular left central incisor).

STEP 5: From the gnathostatic models remove the teeth that were sacrificed so that teeth arrangement can be done.

STEP 6: Arrange teeth according to treatment plan decided (extractions, reproximation etc).

References

1. Knierim, R.W.: A simple wax setup technique, J. Clin. Orthod. 9:305-397, 1975.

2. Kleemann, P. and Janssen, C.: The speed positioner, J. Clin. Orthod. 30:673-680, 1996.

3. JCO visits Professional Positioners, Inc., J. Clin. Orthod. 9:563- 575, 1975.

4. Chiappone, R.C.: Constructing the gnathologic setup and positioner, J. Clin. Orthod. 14:121-133, 1980.

5. Resnick, B.N.: A simplified diagnostic setup technique, J. Clin. Orthod. 13:128-129, 1979.

Authors

Dr. Saurabh Rajanikant Birla, B.D.S., M.D.S
Birla Dental Clinic & Orthodontic Centre
Shop No. 5 Vastu Samruddhi, Bhosale Nagar, Hadapsar
Pune – 411028. Maharashtra, India.

Dr. Arvind Thakur, B.D.S., M.D.S
8, New Subedar Layout, Near Baseshwar Statue
Nagpur- 440024. Maharashtra, India.

Dr. Jaideep Sehgal, B.D.S., M.D.S.
Surat India.

Corresponding Author

Dr. Saurabh Rajanikant Birla

Addresses

Office

Birla Dental Clinic & Orthodontic Centre,

Shop No. 5 Vastu Samruddhi, Bhosale Nagar, Hadapsar,

Pune – 411028. Maharashtra, India.

Phone No. +912030438801.