Mandibular Protraction Appliance Effects in Class II Malocclusion in Children, Adolescents and Young Adults.

Luana Farias Pontes,Francisco Ajalmar Maia,Marcio Rodrigues Almeida,David Normando,Carlos Flores-Mir

doi:10.1590/0103-6440201701032

Abstract

The aim of this study was to evaluate the effects of the mandibular protraction appliance (MPA) for treating mild to moderate Class II malocclusion at different stages of dentofacial development. Lateral radiographs were evaluated before (T0) and at the end (T1) of orthodontic treatment with fixed appliance associated with MPA. Sixty-five consecutively treated patients were divided according to the stage of dentofacial development: 21 children in late mixed dentition, 22 adolescents and 22 young adults with full permanent dentition. The differences between and within groups were analyzed by MANOVA at p<0.05. The correction of anteroposterior discrepancy (Wits) was significantly reduced in all development stages (p<0.01), with no difference between groups. Class II was corrected predominantly by dental changes in the mandibular arch, with accentuated proclination of the mandibular incisors and mesial displacement of mandibular molars. The MPA had no skeletal effects in any of the groups, except for a mild reduction of SNA (p=0.018) and ANB angles (p<0.0001) among the mixed dentition children. With regard to soft-tissue profile, facial convexity decreased significantly in all groups (p<0.01). In conclusion, the MPA associated with fixed appliance corrected the Class II occlusion, basically by a mandibular arch protrusion. A mild skeletal maxillary change was significant only when this treatment protocol began during mixed dentition.

Highlights

The ideal treatment for Class II malocclusions in the presence of a mild skeletal discrepancy is the modification of facial growth direction, which could be achieved by the restriction of maxillary growth and/or mandibular reposition
Orthodontic treatment of mandibular retrognathism in children and adolescents is usually made by mandibular propulsors
The group of adult patients had a different number of female (n=17) and male patients (n=5) and showed no significant interaction between dentition stage and sex for all investigated variables, except for Co-A (p=0.023)

Summary

Introduction

The ideal treatment for Class II malocclusions in the presence of a mild skeletal discrepancy is the modification of facial growth direction, which could be achieved by the restriction of maxillary growth and/or mandibular reposition. The growth spurt is the ideal time for this treatment type [1], but there are reports on the use of mandibular propulsor devices in adult patients for compensatory treatment or orthopedic response. There are several devices developed aiming to treat Class II malocclusions caused by mandibular retrognathism [24]. These appliances are divided into removable functional appliances, such as Fränkel regulator, Bionator and the Twin-block, and fixed appliances, including Herbst, Forsus, Twin-force, Xbow and the mandibular protraction appliance (MPA). One of the aspects contributing to the variation in therapy response to removable appliances is the cooperation of the patient [5]. Patient’s stage of growth was reported as the major source of variability in skeletal responses to treatment [1]

Objectives

Methods

Results

Conclusion