The effects of a new stepwise magnetic functional appliance on craniofacial growth and development of Class II mandibular deficient patients: a prospective clinical study

Abstract

Title: The effects of a new stepwise magnetic functional appliance on craniofacial growth and development of Class II mandibular deficient patients. Introduction: Functional appliances have been a mainstay of Class II orthodontic treatment. The timing of treatment is thought to impact clinical success with optimal results achieved when treatment coincides with peak mandibular growth velocity. Increasingly, novel appliances are being created to improve patient tolerance and compliance with the aim of increased treatment success. There has been an emergence of magnetic functional appliances that have shown promising results. Incremental advancement of the mandible has previously been compared with complete mandibular protrusion and is thought to increase patient comfort and improve growth modification. Aim: To report on the effects on growth and development of a new stepwise magnetic functional appliance that advanced the mandible incrementally, in Class II patients with mandibular deficiency. Materials and Methods: 18 male (n=12) and female (n=6) Class II patients (CVM stage 3-4) with mandibular deficiency were selected for participation in the study. The appliance comprised of an upper and lower component with attractive magnetic force used to advance the mandible. Treatment lasted 36 weeks. At the initial appliance delivery the mandible was advanced 3mm, with further 3mm advancement at each activation period (12 weeks; 24 weeks). The appliance was activated by removing the magnets in the lower component of the appliance and placing a subsequent magnet specifically constructed to advance the mandible a further 3mm. Cephalometric analysis was used to compare pre-treatment and post-treatment values. Results: Mandibular length gain (Co-Gn) was statistically significant with an increase of5.02 ± 2.97mm (p < 0.001). The reflection of this increase was more in the vertical dimension as the mean differences in ANB and Wits were not statistically significant (ANB: 0.31 ± 1.57°, p <0.5; Wits: 0.75± 2.33mm, p < 0.5). There was a statistically significant increase in lower anterior facial height with a difference of 3.56 ± 2.35mm (< 0.001). Mean overjet reduction was 1.13 ± 1.95mm (p < 0.05). All other measurements were not statistically significant. Conclusion: Further research into the new stepwise magnetic functional appliance is required to improve appliance design and success.