A multilevel analysis of craniofacial growth in subjects with untreated Class III malocclusion.

Abstract

To analyse the craniofacial growth of a long-term semi-longitudinal sample of Caucasian subjects with untreated Class III malocclusion. A total of 144 Caucasian subjects (of North American and Italian origin) with untreated Class III malocclusion. Subjects aged 2years and 9months up to 21years and 7months were selected. A multilevel model was used to calculate growth curves for ten variables for both each individual subject and for the whole sample. There was a statistically significant increase for total mandibular length (Co-Gn. T2-T1=8.4mm), midfacial length (Co-A. T2-T1=3.4 mm) and lower anterior facial height (ANS-Me. T2-T1=3.8 mm). The multilevel analysis showed two points of acceleration of growth (about 3-5years of age and 11-15years of age) for seven out of ten variables. For Co-Gn and Co-A variables, males presented points of maximum growth delayed by 1year in comparison with females, with a greater duration (1year longer) and a greater total growth of about 5mm. Active mandibular growth continued for a long time after the pubertal spurt: increases in mandibular length ended at about 17years of age in females and at 21years and 7months in males. Untreated Class III malocclusion showed a specific growth curve, especially for the mandible, whose excesses added up over time. In males, the amounts of mandibular and midfacial growth during the whole observation time were greater and lasted longer than in females.