Circumpubertal maxillomandibular growth in untreated subjects with skeletal Class II relationship: A controlled longitudinal study according to the third finger middle phalanx maturation.

Introduction: Despite the substantial prevalence of skeletal Class II Division 1 malocclusion, only a few studies analyzed the maxillomandibular growth changes in these subjects with contrasting results. This study compared the longitudinal maxillomandibular growth changes in growing subjects with Class I and II skeletal relationships, specifically during the circumpubertal growth phase assessed by the modified third finger middle phalanx maturation (MPM) method. An attempt to uncover any maxillomandibular growth peak in subjects with Class II relationship has been followed.

Methods: From the files of the Burlington Growth Study, a total of 32 subjects (13 males, 19 females) with at least 7 annual lateral cephalograms taken at 9 and 16 years old were included and equally distributed between Class II and Class I groups matched for sex. Overall changes in 12 cephalometric parameters were calculated, and maxillomandibular growth peak was also identified individually and used to register subjects according to the year of growth peak ± 2 years. According to this procedure, annualized changes (trends) were analyzed along with the corresponding prepubertal, pubertal, and postpubertal MPM stages.

Results: No significant differences were seen between subjects with Class I and II skeletal relationships at 9 and 16 years, except for the parameters of the sagittal maxillomandibular relationship, such as ANB angle. Overall, changes for all the cephalometric parameters were similar between the groups, except for the CoGn distance increment that was significantly lower in the subjects with a Class II relationship. In both groups, the annual changes in CoA, CoGn, and CoGo distances showed a clear peak at the time point corresponding to a median MPM stage 3.

Conclusions: In subjects with a skeletal Class II relationship, mandibular deficiency appears to be mostly established during the prepubertal growth stage and further aggravated during puberty. However, the maxillomandibular growth trend in subjects with Class II relationship is generally similar to that of subjects with a Class I relationship, including the existence of a pubertal peak.