A RETROSPECTIVE COMPARISON OF FUNCTIONAL APPLIANCE TREATMENT OF CLASS-III MALOCCLUSIONS IN THE DECIDUOUS AND MIXED DENTITIONS

This retrospective study compared the effectiveness of treatment of Cl ass III malocclusions with the removable mandibular retractor in the d eciduous and mixed dentitions. A group of 20 children with Class III m alocclusions started treatment at a mean age of 5 years 1 month +/- 7 months (deciduous dentition), while a group of 18 children with Class III malocclusions started treatment at a mean age of 8 years 2 months +/- 9 months (mixed dentition). The mean observation period was 2 year s 3 months +/- 6 months for the first group, and 2 years 4 months +/- 7 months for the second group. Matched control groups of children with untreated Class III malocclusions in the deciduous and in the mixed d entition (16 subjects and 15 subjects, respectively) were used. The ce phalometric analysis was based on a stable basicranial reference syste m appropriate for longitudinal studies that begin at early development al ages. The results showed that treatment of Class III malocclusions in the deciduous dentition produced a more significant anterior morpho genetic rotation of the mandible, due to a more upward and forward dir ection of condylar growth (P < 0.01). This leads to significantly smal ler increments in mandibular total length (Co-Pg) in children with Cla ss III malocclusions undergoing very early treatment (P < 0.01). On th e contrary, maxillary dento-alveolar protrusion induced by therapy was greater in Class III subjects treated in the mixed dentition (P < 0.0 1). The optimum timing to improve skeletal relationships in Class III malocclusions by means of a functional appliance appears to be in the deciduous dentition.