Natural changes of the maxillary first molars in adolescents with skeletal Class II malocclusion

IntroductionThe objective of this study was to evaluate natural changes in maxillary posterior alveolar height (MPAH) and axial inclination of the maxillary first molars (AIMFM) in subjects with Class II malocclusion to determine the validity of predictive equations.MethodsLongitudinal records of 30 untreated white subjects (13 girls, 17 boys) with skeletal Class II malocclusion were collected at ages 9, 12, 14, and 16 years. They had participated in the Burlington Growth Centre study, and cephalograms were analyzed with Dentofacial Planner Plus software (version 2.0, Dentofacial Planner, Toronto, Ontario, Canada). Serial means were compared with the Bonferroni post-hoc test (P <0.05). Predictive equations were obtained and studied with the analysis of agreement.ResultsGradually, means of MPAH had statistical increments with sexual dimorphism from 14 to 16 years of age. A distal mean of AIMFM was found at 9 years of age that decreased significantly during growth, with sexual dimorphism between the ages of 9 and 12 years. Changes in AIMFM varied among subjects in distinct stages. Values of MPAH were predicted with high validity at intervals of 3 years or longer, whereas estimations for AIMFM were unreliable.ConclusionsIn this study group, there was significant alveolar growth, with a natural tendency to upright the distal inclination at the maxillary first molars.