Early correction of anterior crossbite in deciduous dentition

INTRODUCTION

Anterior crossbitecan be defined as an abnormal labiolingual relationship between one or more maxillary and mandibular anterior incisor teeth.¹ It is differentiated into dental, skeletal and functional crossbite. Dental anterior crossbite is reported to be caused by various factors such as lingual eruption of maxillary anteriors, trauma to the deciduous anteriors resulting in lingual displacement of permanent tooth buds, presence of supernumerary teeth and inadequate arch length.² Skeletal crossbite is associated with a discrepancy in the size of maxilla and the mandible resulting is Class III malocclusion. Early dental interference forcing the mandible to move forward to obtain maximum intercuspationresults in functional crossbite or pseudo Class III.³

An anterior crossbite in primary dentition is usually identified by the dentists during the routine dental visits or by parents, who upon noticing often enquire as to whether treatment is required or not. Early correction of crossbite is often considered as a controversial issue with few investigators considering it to be of primary importance while others believe that these crossbites show spontaneous correction during the transition to permanent dentition.

This paper aims at presenting various views on early treatment of anterior crossbites in children, the treatment objectives and different treatment strategies discussed in the literature.

Dilemma on correction of crossbite in primary and early mixed dentition periods

Over the years, dental practitioners have been hesitant about correcting crossbites in primary dentition, probably because of lack of substantial clinical data on the stability of the early corrections in the permanent dentition or may be due to the behavioral considerations in young patients.

Clifford (1971)⁴ strongly advocated early correction of crossbites, especially the pseudo Class III malocclusions. He stated that at early age, these deviations involve only dentoalveolar structures in deciduous dentition and if left untreated, could lead to severe structural deformities in permanent dentition affecting the deeper skeletal structures of the maxilla and mandible. If a crossbite is corrected early, normal function is restored thereby facilitating normal development. He also highlighted the favorable personality changes that could occur if the child’s facial appearance is corrected at an early age. He strongly put forth that any advice against early correction of crossbites is not just incorrect but is a gross neglect of a patient in need of orthodontic treatment.

Vadiakas G (1992)3 also opinioned that anterior crossbites usually have a strong skeletal component and majority of pseudo Class III in early years grow through time into Class III malocclusions.

Many other reports favoring the early correction of primary crossbites can be found in literature. Breitner’s (1940)⁵ experimental findings in young rhesus monkeys where the primary teeth were moved using orthodontic appliances, showed that uneruptedsuccedaneous teeth tend to move along with their predecessors. These findings were applied to humans by Mathews (1969)⁶ . He published a case report providing additional evidence for the orthodontic movement of unerupted permanent teeth along with primary teeth.

Kutin and Hawes (1969)⁷ advocated early correction of posterior crossbites as they observed that posterior crossbites do not improve with the eruption of permanent teeth. Several authors^1,3 have suggested various reasons for early correction of anterior crossbites which includes: establishing proper muscle balance and preventing adverse growth before the dentoskeletal changes becomes well established; improving facial appearance thereby favoring positive personality changes; preventing abnormal, excessive wear of incisors in crossbite and avoiding risk of periodontal diseases due to abnormal forces exerted on teeth in crossbite.

However, some authors believe that self-correction might occur in some patients during the transition from primary to permanent dentition.^8-10 It was also mentioned that patients’ may develop crossbite again during the transition dentition, even if crossbites in primary dentition has been corrected orthodontically, thus requiring further treatment.¹¹

Nagahara K (1997)¹⁰ examined 44 deciduous anterior crossbite patients on a regular 3-month intervals between the primary and the transitional dentition. The subjects were divided into three groups: Group N where the crossbite involved all the primary incisors that corrected on its own when the permanent incisors erupted; Group R1, where the range of crossbite was same as Group N but crossbite persisted after the eruption of permanent incisors; Group R2 where the range of crossbite was beyond the two groups and persisted following eruption of permanent incisors. They observed that the skeletal characteristics of each group differed from each other and measurements that were statistically significant were identified and were used to develop an equation known as ‘Deciduous Indicator (DI)’. They observed that lower the DI value (negative), higher is the probability of the crossbite to self-correct at the transitional phase. Whereas, a positive or high score indicates the necessity for crossbite correction in primary dentition stage.¹¹

YuanShu Ge (2011)¹² applied Deciduous indicator by Nagahara K (2001)¹¹ to evaluate the necessity of early treatment for primary crossbites. They used posterior bite raising and 2X4 appliance therapy and found it to be effective interceptive treatment of primary anterior crossbites which were predicted to persist during transitional period according to DI. Few of the corrected cases relapsed in the transitional stagesbut authors opinioned that out of 44 subjects predicted to have persistentcrossbite according to DI, only 11 of them had negative overjet or edge to edge incisor relation at the end of 6 years, while all the patients achieved positive overjet during the treatment.

They observed that the expected treatment objectives of primary anterior crossbite should be preventing the existing problem from deteriorating, providing a more favorable environment for normal growth and improving facial esthetics for more psychosocial development. They identified the relapse group to be associated with a severe Class III pattern than stable group at the end of treatment.

Ghiz MA (2005)¹³ reported that the relapse patients had a more forward position of mandible relative to the cranial base, a longer mandible, shorter ramus and an increased gonial angle.

Various appliances reported in the literature for the early correction of anterior crossbite

Various appliances have been advised for early interceptive treatment of crossbites. Vadiakas G (1992)³ has differentiated these into three categories. First category includes the ones that deliver heavyintermittent forces such as inclined plane, reversed stainless steel crowns, strip crowns, Planas’ Direct Tracks. The force exerted by these appliances is dependent on chewing action by the patient and therefore is unpredictable. Heavy forces exerted by these appliances can traumatize deciduous teeth. The second category includes the appliances that deliver light continuous forces such as removable appliances with auxiliary springs, screws and fixed light arch wire appliances like 2X4 appliance. The light continuous forces delivered are more biologic and effective in achieving the required correction without discomfort especially in young children. The last category includes the appliances for correction of skeletal problems such as chin cups, reverse headgears and various other functional appliances.

Removable appliances

Simple acrylic appliance with expansion screw with or without posterior bite plane is the most common removable appliance reported in the literature for the correction of anterior crossbite (Figure 1). This forms an easy, safe and esthetically acceptable method with reduced chairside time as the appliance is fabricated in the laboratory. Reports of correction of crossbite in few weeks to few months can be found in the literature.^14,15 However, compliance is always a concern in this mode of treatment.

Clifford FO (1971)⁴ reported a case of crossbite correction in deciduous dentition period in a 41/2-year-oldchild using a small, removable black rubber positioner. The rubber positioner was constructed on ‘corrected’ plaster casts, after removing the maxillary anterior teeth on the casts and repositioned in normal alignment with lower arch. Author reported the correction of crossbite within 6 weeks with the patient being very cooperative even though only 41/2 years old.

Cemented appliances

Several case reports16 on use of reversed stainless steel crowns for the correction of anterior crossbite can be found in the literature. However, this method was not well accepted due to the difficulty in adapting the crown to fit a tooth in crossbite and especially the unaesthetic appearance associated with use of stainless steel crowns in the anterior segment. Later, esthetic crowns such as preformed strip crowns were used both for patients with and without caries in the maxillary anterior teeth. This technique involves the tipping of the long axis of the maxillary anterior crowns buccally, thereby positioning the mandible backwards. Reports of crossbitecorrection in deciduous dentition in 1 or 2 weeks were published in literature using this method.^17,18 (Figure 2)

Based on similar principle, technique involving usage of Planas’ Direct Tracks (PDTs) has been reported to treat both anterior and posterior crossbites in primary dentition.¹⁹ This involves built up of composite on deciduous molars, guiding the mandible backwards and permitting the tongue to deliver optimal force on upper incisors. However, good patient cooperation is necessary to build and adjust the PDTs on deciduous molars.

Other cemented appliances include lower acrylic bite planes²⁰ and bonded resin composite slopes²¹ on lower incisors.

Functional appliances

Functional appliances such as Bionator III, ²² Bruckl appliance, ²³ protraction head gear, ²⁴ chincup therapy²⁵ has been reported in the literature. These appliances are used to correct the skeletal crossbites in the growing periods. Bruckl appliance is a simple, removable functional appliance which consists of a fixed, lower inclined plane which stimulates the forward movement of maxillary incisors in crossbite and a mandibular Hawley’s for retraction of mandibular incisors. Muscle forces causes movement of maxillary incisors while the labial bow exerts retrusive forces on mandibular incisors leading to correction of anterior crossbite.

Fixed appliances

Fixed appliances are advantageous over removable ones in terms of compliance especially when it comes to young children. Several fixed appliances are reported in the literature for the early correction of anterior crossbite. Frey CJ (1988)²⁶ reported use of W appliance and labial arch wire for the correction of both anterior and posterior crossbite in primary dentition. Total treatment time for correction of both anterior and posterior crossbites was reported as 6 months.

Few investigators reported correction of anterior crossbite using rapid palatal expanders anchored on deciduous teeth in the early mixed dentition period. Rosa M et al (2012)²⁷ reported a study involving 50 patients (mean age 8y, 5m) conducted to evaluate the effectiveness of HAAS Rapid Palatal Expander, for inducing spontaneous correction of crossbite involving permanent incisors. The patients were treated with HAAS Rapid Palatal Expander anchored on second deciduous molars and bonded on primary canines without application of any direct forces on permanent teeth. They observed spontaneous correction of permanent incisor crossbite within 6 weeks of treatment in all cases and opinioned early maxillary expansion by rapid palatal expander anchored on deciduous teeth to be an effective and efficient procedure for inducing self-correctionofanteriorcrossbitein early mixed dentition period without involvement of permanent teeth and with no compliance.

Another popular fixed appliance is the 2X4 appliance, comprising of bands on the first permanent maxillary molars, brackets on maxillary incisors and wire with advancing loops (Figure 3).Hagg U et al (2004)²⁸ investigated the longtermoutcome of simple fixed 2X4 appliance in 27 young patients with pseudo Class III malocclusions in early mixed dentition period. They observed that the first phase of treatment resulted in positive overjet, which was maintained in the long-term with only minority of patients requiring fixed appliance therapy in the second phase.

CONCLUSION

Early correction of crossbite can help in restoring normal function, thereby leading to normal development. It may prevent need for further orthodontic treatment in the future. At the least, the severity of the malocclusion and the treatment timing can be reduced with the early correction. However, the compliance of the patients at this young age is always of concern. With many treatment options available, clinicians should beprudent in making appropriate choice for each patient for successful management of the anterior crossbites involving primary teeth.