December, 2010

Orthodontic Uprighting of Permanent Lower second Molars with Mini-Implants – Case Reports

Authors:

*Dr. Seema Gupta, BDS, MDS

**Dr. Sandeep Kumar, BDS, MDS

*Senior Lecturer

Department of Orthodontics and Dentofacial Orthopedics,

Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan.

**Senior Lecturer

Department of Prosthodontics and maxillofacial prosthetics

Surendera Dental College and Research Institute, Sri Ganganagar, Rajasthan.

For correspondence:

Dr. Seema Gupta

Senior Lecturer

Department of Orthodontics and Dentofacial Orthopedics.

Surendera Dental College and Research Institute

Sri Ganganagar

Rajasthan, India

e-mail: mdsseema31@yahoo.com

Phone: +919024606318

Abstract:

Aim: The purpose of these case reports is to present the methods of uprighting of the mesially tipped lower second molars into the extraction spaces of first molars to allow the placement of a fixed prosthesis and to avoid periodontal problems.

Background: The mesial tilting of lower second molars into the extraction spaces of missing first molars is a very common problem and it should be addressed immediately to prevent the loss of space and periodontal problems.

Case description: The methods of uprighting the lower second molars have been described in the form of two case reports, treated with the help of mini-implants.

Summary: Mesial tilting of lower second molars requires proper clinical, radiological, biomechanical evaluation and a good appliance selection for successful treatment results.

Clinical significance: The importance of uprighting the lower second molars and various methods of doing it according to patients’ requirements have been described in the form of case reports to help the clinician in choosing the right approach.

Keywords: molar uprighting, mini-implants, fixed prosthesis, first molar extraction

Introduction:

Loss of a first permanent mandibular molar should be immediately addressed by the prosthetic replacement or orthodontic space closure1. Otherwise, the second and third molars will incline and rotate mesiolingually, the lower canine and premolars will move distally into the molar space, and the upper first molar will extrude. These changes in the occlusal plane often cause the mandible to be displaced distally on the side of the lost molar. Mandibular molar uprighting is a common adult orthodontic procedure, performed in conjunction with periodontal and restorative therapy2-4. Treatment planning involves decision making by clinicians in addition to the orthodontist, with each adding a point of view reflecting his or her area of expertise. Understanding and appreciation of the treatment objectives result in improved comprehensive dental treatment for the patient. The over-all objective in molar uprighting is ideal positioning of the molar which will eventually become an abutment tooth for a fixed prosthesis1. The ideal position will provide an optimal periodontal environment for the molar(s) 5, 6. This, in turn, provides the protection against inflammatory periodontal disease, correction of vertical osseous defects7, 8, if present, through forced eruption and protection against occlusal traumatism. Numerous techniques for uprighting of molars have been described in the literature9-13. Recently, the micro-implants have been used widely for uprighting14, 15 as they are comfortable for the patient and reduce the side effects of conventional orthodontic therapy. In this article, two methods have been described for uprighting the mesially tipped lower second molar(s) into the extraction space(s) of first molar(s) with the help of case reports.

Case 1:

A 22 year old female came to the department of orthodontics complaining of protrusive incisors. Her facial appearance was mildly convex.  Intraorally, she had a missing lower left first molar with severe mesial tipping of the lower left second molar into the extraction space (Fig 1) leading to the loss of space for the first molar. Her treatment plan involved extraction of all first premolars, uprighting of the lower left second molar, followed by prosthetic replacement of the lower left first molar. After the extraction of the lower left first premolar, there was more space available for prosthetic replacement of the first molar. Therefore, it was decided to upright the lower left second molar with little mesial movement. Due to anchorage considerations, it was decided to place a mini-implant in the extraction space of the lower left first molar (Fig 2) to upright the second molar with some amount of mesial movement. L-shaped wire of 0.019×0.25 inch stainless steel was inserted into the accessory tube of the second molar to apply the forces in the line of implant with the help of closed coil spring. Uprighting was completed in 3months (Fig 3) which allowed the placement of a fixed prosthesis to replace the lower left first molar after completion of orthodontic treatment (Fig 4).

Fig 1: Case 1: Close up o panoramic view showing mesial tipping of lower left second molar

Fig 2: Case 1: Close up of panoramic view showing placement of mini-implant in the extraction space of lower left first molar for uprighting of second molar.

Fig 3: Case 1: Close up of panoramic view showing complete uprighting of the lower left second molar.

Fig 4: Case 1: Intra oral photograph showing placement of fixed prosthesis for replacement of lower left first molar.

Case 2:

A 33 year old female came to the department of orthodontics complaining of protrusive lower incisors. She had a bilateral cleft of lip and palate with multiple missing teeth in the upper arch including the lower first molars. The lower second molars were tipped mesially with 3mm mesial movement into the extraction spaces. There was gingival recession and an infrabony pocket mesially in relation to the lower left second molar with Grade 1 mobility (Fig 5, 6). She had a Class III jaw relationship with proclined lower anteriors. Her treatment plan involved placement of retromolar implants (Fig 7) to upright the lower second molars with distal movement to gain space for prosthetic replacement of the lower first molars and to retract the lower incisors. The bilateral retromolar implants were placed on the ascending ramus and an S-shaped hook was tied to the implants with the ligature (Fig 8). The uprighting was achieved with the 3mm of distal movement using a closed coil spring tied from the S-shaped wire to the hook of second molar tubes (Fig 9, 10) in 4months. There was marked improvement in the periodontal condition of the lower left second molar with reduction in its mobility and sufficient space was gained for the parallel placement of fixed prostheses for the lower first molars. After the completion of two years of orthodontic treatment, the patient got married and left the place. She was instructed to get periodontal flap surgery for the lower left second molar and placement of fixed prostheses for the lower first molars.

Fig 5: Case 2: Panoramic radiograph showing severe mesial tipping of lower second molars.

Fig 6: Case 2: Intra oral photograph showing mesially tipped lower right (A) and left (B) second molars

Fig 7: Case 2: Intraoral radiograph showing placement of mini-implant in the retromolar area.

Fig 8: Case 2: Intraoral radiograph showing S-shaped hook tied to the implant with the ligature to apply distal uprighting force on the second molar.

Fig 9: Case 2: Panoramic radiograph showing complete uprighting of lower second molars achieved with the mini-implants

Fig 10: Case 2: Intra oral photograph showing complete uprighting of lower right (A) and left (B) second molars.

Discussion:

Adult and elderly patients often present with extracted lower first molars due to caries with mesially moved and inclined lower second molars. Tipping of the molar can initiate a vicious cycle of traumatic occlusion and of periodontal problems5-8 mesial to the tipped tooth like plaque accumulation leading to periodontal inflammation, pockets and vertical osseous defects. Although a number of authors have presented simple appliances for molar uprighting9-13, their methods do not take individual patient variations into account. Mesially inclined molars should be differentiated not only by degree of impaction, but also by the types of tooth movement required for correction in all three planes of space. For any particular tooth movement, there is only one correct force system with respect to the center of resistance13.

In the sagittal plane, the appropriate combination of vertical movement and uprighting must be determined. When the molar is to be extruded, the uprighting is often performed with simple tipback mechanics. If significant extrusion is needed, the force delivered to the bracket should be relatively large compared to the moment. If little or no extrusion is desired, the moment should be larger and the cantilever as long as possible. When molar intrusion is required, the biomechanics become more complex. The law of equilibrium requires that the moment added to the molar be smaller than the moment added to the anterior unit.

In the present article, two cases were treated with different approaches and biomechanics based on their individual case requirements. In the first case, uprighting along with mesial movement of the lower left second molar was desired. The anchorage considerations in the case demanded the use of micro-implants to minimize the adverse reactionary forces (lower left first molar was missing and first premolar was extracted to retract lower incisors). Desired forces were achieved with the placement of a mini-implant in the extraction space. In the second case, mini-implants were needed to gain the lost 3mm of extraction spaces of the first molars and also to retract the proclined lower anterior teeth. Distally directed forces with tip back moments were required. Hence, the mini-implants were placed in the retromolar area. In both cases uprighting of the mesially tipped second molars lead to correction of vertical osseous defects and allowed the single path of insertion for fixed prostheses.

Orthodontic tooth movement is often limited by available anchorage. Forces are required to move the teeth and every appliance exerts equal and opposite forces on another subject. Such forces are usually not desired and the clinician should adopt the approach to minimize or eliminate them. With the introduction of implants14, 15, desired forces can be applied to bring about the tooth movement without any adverse effect on other teeth.

Conclusion:

Mesial tilting of lower second molars into the extraction spaces of first molars is a very common problem which requires proper clinical, radiological, and biomechanical evaluation and a good appliance selection for successful treatment results.

References:

1.      Norton L. A., Proffit W.R. Molar uprighting as an adjunct to fixed prostheses. J. Am. Dent. Assoc. 1968;76: 312-315.

2.      Simon R.L. Rationale and practical technique for uprighting mesially inclined molars. J. Prosth. Dent. 1984;52:256-259.

3.      Canut JA. Clinical management of the mandibular molars. Am J Orthod 1975:68:277-89.

4.      Gottlieb EL. Uprighting of 5′s and 7′s. J Clin Orthod 1971;5:12-19.

5.      Diedrich PR. Orthodontic procedures improving periodontal prognosis. Dent Clin North Am 1996; 40: 875-87

6.      Brown I. S. The effect of orthodontic therapy on certain types of periodontal defects-Clinical findings. J. Periodontol. 1973;44: 742.

7.      Ingber J. Forced eruption. Part I. A method of treating isolated one and two wall infrabony osseous defects— Rationale and case report. J. Periodontol. 1974;45: 199.

8.      Weinmann, J. Bone changes related to eruption of the teeth, Angle Orthod. 1941;11: 831.

9.      Kogod M, Kogod HS. Molar uprighting with the piggyback buccal sectional arch wire technique. Am J Orthod Dentofac Orthop 1991:99:276-80.

10.  Orton HS. Jones SP. Correction of the mesially impacted lower second and third molar. J Clin Orthod 1987:21:176-81.

11.  Rubinstein BM. Uprighting second molars with direct bonding. J Clin Orthod 1975:9:377-8.

12.  Warise TR, Galella SA. Controlled, rapid uprighting of molars: a surprisingly simple solution the pivot arm appliance. J Gen Orthod. 2000;11:9–19.

13.  Roberts W.W, Burstone C.J. Segmental approach to mandibular molar uprighting. Am J Orthod 1982;81:177–184.

14.  Odman J, Lekholm U, Thilander B. Osseointegrated implants as orthodontic anchorage in the treatment of partially edentulous adult patients. Europ J Orthod 1994;16:187-201

15.  Matthews DC. Osseointegrated implants: Their application in orthodontics. J Can Dent Assoc 1993;59:454-63

Figure legends:

Fig 1: Case 1: Panoramic view showing mesial tipping of lower left second molar.

Fig 2: Case 1: Panoramic view showing placement of mini-implant in the extraction space of lower left first molar for uprighting of second molar.

Fig 3: Case 1: Panoramic view showing complete uprighting of the lower left second molar.

Fig 4: Case 1: Intra oral photograph showing placement of fixed prosthesis for replacement of lower left first molar.

Fig 5: Case 2: Panoramic radiograph showing severe mesial tipping of lower second molars.

Fig 6: Case 2: Intra oral photograph showing mesially tipped lower right (A) and left (B) second molars.

Fig 7: Case 2: IOPA showing placement of mini-implant in the retromolar area.

Fig 8: Case 2: IOPA showing S-shaped hook tied to the implant with the ligature to apply distal uprighting force on the second molar.

Fig 9: Case 2: Panoramic radiograph showing complete uprighting of lower second molars achieved with the mini-implants.

Fig 10: Case 2: Intra oral photograph showing complete uprighting of lower right (A) and left (B) second molars.

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