May, 2011

A Simplified Edgewise Technique Used for Interceptive Orthodontics

Dr. Sarabjeet Singh
Prof. & Head of the department
Department of orthodontics & Dentofacial Orthopectics,
Bhojia Dental College & Hospital,
Budh, Nalagarh (H.P.)

Dr. Rita Kashyap
Senior Lecturer
Department of orthodontics & Dentofacial Orthopectics,
Bhojia Dental College & Hspital,
Budh, Nalagarh (H.P.)

Dr. Navreet  Sandhu
Reader
Department of prosthodontics
National Dental College and Hospital
Derabassi

 

 

Abstract

Management of orthodontic problems in the  mixed dentition stage is sometimes indicated to intercept or correct malocclusion that would otherwise be maintained or become progressively more complex in the permanent dentition or result in skeletal anomalies. Very few of these malocclusions could be treated with removable appliances alone. Partially bonded orthodontic appliance is an efficient alternative. It includes bonding teeth involved in malocclusion while using anchorage from 1^st permanent molars, 2×4 or 2×2 appliances in the form of utility arches. Partial bonding offers many advantages over alternative techniques as it provides complete control of anterior tooth position and rapid correction. The purpose of this article is to identify such common situations and malocclusions in the mixed dentition that lend themselves to early intervention and their correction using partially fixed orthodontics.

Introduction

Early treatment: Treatment started either in the primary or mixed dentition that is performed to enhance the dental and skeletal development before the eruption of the permanent dentition.

The primary objective of managing orthodontic problems in the mixed dentition stage is to intercept or correct malocclusions that would otherwise be maintained or become progressively more complex in the permanent dentition or result in skeletal anomalies. Such orthodontic intervention in the mixed dentition does not always prevent orthodontic problems from occurring in the permanent dentition; however, there can be significant advantages to early intervention. By identifying and treating certain problems at an early age it is often possible either to prevent more serious orthodontic problems from developing or to redirect skeletal growth and improve the occlusal relationship.¹

The purpose of this article is to identify common situations and malocclusions in the mixed dentition that lend themselves to early intervention and might be difficult to treat with removable appliances alone. Additional information is being provided about various ways to treat a few such malocclusions using partially bonded orthodontic appliances.

Principles in early intervention ²

ü      the elimination of primary etiologic factors if possible,

ü      elimination of occlusal discrepancies such as unilateral, bilateral posterior crossbites, anterior crossbite,

ü      the correction of skeletal dysplasia,

ü      managing arch length discrepancies to avoid the future extraction of teeth (premolars) to resolve crowding.

ü      Improving esthetics to reduce psychological effects.

Early treatments with proven benefits ³

Ø      Posterior and anterior crossbites,

Ø      Ankylosed teeth,

Ø      Excessive protrusions and diastemas,

Ø      Severe anterior or lateral open bites,

Ø      Ectopic eruptions and retained teeth,

Ø      Severe arch length discrepancies,

Ø      Pseudo Class III patients,

Ø      True Class III malocclusions due to a maxillary retrusion,

Ø      Cleft palate.

In the mixed dentition stages, few of these problems can be treated using removable appliances but not all. Only tipping movements can be achieved which is not always desirable. Thus, necessitating a partially fixed orthodontic appliance.

Various interceptive procedures

Excessive protrusions and diastemas, that invite injury or avulsions, need treatment at an early age to avoid permanent damage to the dentition, for instance, Class II division 1 malocclusions.⁴ (Figure 1a)

 

They are often reasons why youngsters get teased. Thus, they affect the child’s self-esteem. As the condition persists, the mandibular lip may become entrapped behind the maxillary incisors, further perpetuating the problem. Such a malocclusion can be corrected by using an activated labial bow using a Hawley appliance. But it causes tipping while retracting the proclined incisors thereby increasing an already existing deep bite and the visibility of incisors. With the use of a 2×4 appliance (fixed to four incisors and two molars), intrusion along with retraction can be achieved. (Figure 1b)

 

Example of one such appliance is a utility arch. It lies in the vestibule before engaging it in the anteriors because of 45 degree bends in the posterior arms of the wire. After ligating in anterior brackets it has an intrusive action. Posterior ends in the wire are bent back for retraction. (Figure 1c) The long horizontal arm is covered with a plastic sheath or tubing to prevent injury in the vestibular region.

 

 

Retroclined maxillary central incisors creating a deep bite can affect gingival health around lower incisors. (Figure 2a)

 

 

 

But a bigger problem is restricting the mandible from growing at a normal rate. (Figure 2b)

After aligning the incisors with a partially bonded appliance, a similar utility arch can be used to correct a deep bite. Alternatively, a 2×2 appliance can also be used with a similar design but with a protraction effect on the anterior teeth. By bonding only the central incisors, laterals incisors are prevented from any effect from fixed appliance and erupting canines, thus allowed to erupt normally (ugly duckling stage).

Severely rotated anterior teeth are equally difficult to treat with a removable appliance as a pure couple is required. Partially bonded appliances can be used wherein a pure couple is applied on a rotated tooth using 1^st molars as anchorage along with an aligning wire in the other anteriors for simultaneous correction of teeth angulations if indicated. (Figure 3)

A single tooth crossbite seen in the mixed dentition might be corrected with a removable appliance incorporating an activated Z-spring but crossbites associated with mandibular shifts may lead to a true skeletal discrepancy as the mandible develops asymmetrically in the direction in which it is shifting. Similarly, a true Class III relation might develop because of premature contacts in incisors. (Figure 4)

Such conditions are best treated early between the ages of 8-10. Aligning with a 2×4 appliance with bite blocks is all that might be required to correct few of anterior crossbites in non- compliant patients, whereas in crossbite cases involving more teeth, seen in mixed dentition, a protraction utility can be used. It’s fabricated in the form of a 2-3mm oversized arch. This is then ligated to the four anteriors along with molar stops to create a positive overjet using anchorage from 1^st molars which will ultimately allow both jaws to grow without any interference. A single tooth posterior crossbite can also be corrected by partial bonding using bondable buttons and cross elastics.

A supernumerary tooth (mesiodens) might prevent eruption or lead to ectopic eruption and so can retained teeth. Such problems should be dealt with when diagnosed. (Figure 5)

Mesiodens additionally affects esthetics. Its removal and closure of space using a 2×4 appliance or partially bonding 2 or 4 incisors and closure of space is more advantageous than a removable appliance. This creates enough residual space for future canine eruption or available space might be used to correct proclinations or deep bites.

Discussion

In mixed dentition stages, only a few of the malocclusions can be treated using a removable appliance. Most necessitate partially fixed orthodontic appliances incorporating erupted permanent teeth.

The 2×4 appliance is a highly efficient system that has multiple applications in orthodontics, particularly in the initial stages of treatment. This appliance offers many advantages over alternative techniques as it provides complete control of anterior tooth position, is extremely well tolerated, requires no adjustment by the patient and allows accurate and rapid positioning of the teeth. A partially bonded appliance is useful in various developing malocclusions like proclination related to Class II Div 1, retroclination related to Class II Div 2, crossbites related to class III, single tooth anomalies, without affecting the erupting permanent teeth.

 

There has been much debate in the literature regarding the ideal timing of orthodontic treatment. Studies have looked at many aspects of orthodontics but the optimal timing of treatment of children with malocclusions remains controversial. Tung and Kiyak⁵ investigated the psychological influences on treatment timing. They questioned 75 children (mean age of 10.85 years) and their parents and concluded that younger children are good candidates for early treatment, have high self-esteem and body image and expect orthodontics to improve their lives. Shaw et al.⁸ investigated the extent to which dental features expose children to nicknaming, teasing and harassment. They found that dental features were the fourth most common target for teasing. However, comments about teeth were considered more hurtful than other features, especially in the 9–10-year-old group, and a short phase of orthodontic treatment in the mixed dentition may prevent this hurtful teasing.

Few developing malocclusions in primary/mixed dentition demand correction. Baccetti et al ⁶ have shown that all Class II features in the primary dentition are maintained or worsen during transition to mixed dentition and the vast majority of treatment decisions are made in the mixed and early permanent dentition. Proclined upper central incisors, if they extend beyond esthetic line (E-line: a line connecting nose and chin), they are more prone to fracture and thus require early treatment. Developing Class III malocclusions are clinically expressed as anterior crossbites in the primary dentition and several authors have recommended that dental anterior crossbites in primary/mixed dentition be corrected when identified to allow for normal dental development and more favorable skeletal growth. ⁷ Anterior deep bites in the primary dentition are fairly common but are rarely treated and may be associated with the presence of developing class II malocclusion. However, treatment is sometimes indicated in the primary or mixed dentition if associated with impingement on palatal mucosa or interfering with mandibular growth.

Removable appliances are appropriate for correcting anterior teeth malpositions, retroclined teeth or narrow maxillary arches. But the problems with removable appliances are the lack of control they have over tooth position and the fact that they can exert only single-point contact on teeth, leading to unsophisticated tipping movements in most cases. In addition, these appliances will not be worn if they are either too loose or too tight causing excessive pressures on the teeth. Patients often have a tendency to flick the appliances in and out, which leads to stress fracture of the retaining cribs or clasps, and the resulting loss of retention will encourage the patients to leave them out. ¹⁰

The versatility of the partially fixed appliance and the 2×4 appliance in the correction of anterior crossbites and alignment of the incisors is shown in this article. The treatment objectives are achieved with a short course of treatment with controlled dental movements.

Conclusion

The essence of early treatment is timing. Early phase one treatment is beneficial in reducing the incidence of incisor trauma and may be useful in correction of eruption disturbances. A desire to help patients with concerns and self-esteem considerations might be fulfilled using a partially fixed orthodontic appliance without waiting for the full permanent dentition for ideal results. A 2×4 appliance and a 2×2 appliance are quite effective and versatile in action and also overcome shortcomings of conventional removable appliances.

References

1.      Bishara. The textbook of orthodontics. Orthodontic treatment in primary dentition. 2001; 248.

2.      Michael G. Arvystas. The rationale for early orthodontic treatment. AJO DO 1998; 113(1):15-18.

3.      White L. Early Orthodontic Intervention. American Journal of Orthodontics and Dentofacial Orthopedics 1998; 113(1):24-28.

4.      Verma V, Mehrotra A, Sikri A. Early orthodontic treatment. JIDA 2009; 3(12): 423-426.

5.      Tung AW, Kiyak HA. Psychological influences on the timing of orthodontic treatment. AJO DO 1998; 113: 29–39.

6.      Shaw WC, Meek SC, Jones DS. Nicknames, teasing, harassment and the salience of dental features among school children. Br J Orthod 1980; 7: 75–80.

7.      Baccetti T. et al. Early dentofacial features of class II malocclusion: A longitudinal study from deciduous through mixed dention. AJO DO 1997. 111(5): 502-09.

8.      Grim S E. Treatment of pseudo class III relationship in primary dention: A case history. ASDC J Dent Child 1991. 58(6) : 484-88.

9.      Mckeown H. and Sandler J. The two by four appliance:a versatile appliance. Dent Update 2001; 28: 496–500.

 

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