Skeletal growth in class II malocclusion from childhood to adolescence: does the profile straighten?

Abstract

Background: There is relatively little appreciation of the changes in maxillary-mandibular relationships occurring during adolescence among subjects with normal and increased overjet. The aim of this study was to assess differences in changes in maxillo-mandibular relationships during the adolescent growth period based on the presence of a normal (< 4 mm) or increased (> 4 mm) overjet in childhood. Our hypothesis was that there is no difference in the change of the A point, nasion, B point (ANB) angle during growth between these two overjet groups. Lateral cephalograms were obtained from 65 subjects taken from the American Association of Orthodontists Foundation (AAOF) Craniofacial Growth Legacy Collections Project. Cephalograms were obtained at ages 7-10 (T0) and 14-17 (T1) with allocation into two groups based on baseline overjet (> 4 mm: group 1, 2-4 mm: group 2). Random effects linear regression was used to account for multiple within-patient measurements with dependent variables including anteroposterior skeletal pattern (based on sella, nasion, A point (SNA); sella, nasion, B point (SNB); and ANB angles). Results: We included a similar number of males (n = 34; 52.3%) and females (n = 31; 47.7%). The mean ANB was higher at baseline in group 1 (5.42, SD 2.16°) than in group 2 (3.08, SD 1.91°). The hypothesis was rejected as the ANB angle reduced by 1.92°more in the larger overjet group with the association being statistically significant after accounting for age and gender (P < 0.001; 95% CI 1.06 to 2.77). No significant gender-related effect (P = 0.624; 95% CI − 0.637 to 1.07) was observed overall. However, there was no significant increase in SNA angle in the > 4 mm overjet group compared to the 2-4 mm group (0.857°, P = 0.271; 95% CI − 0.669 to 2.383). The SNB angle increased by 1.15°m ore in the higher overjet group but there was only weak evidence of an association (P = 0.086; 95% CI − 2.464 to 0.164). Conclusions: A slight straightening of the facial profile was observed in both groups with a statistically significant greater reduction in ANB arising in the group with larger baseline overjet. This translated into a marginal reduction in the overjet in this group.

Relationship between Skeletal Class II Malocclusion and Morphology of Sella Turcica in Children Aged 7-10 Years

“…[12] Research by Ardani et al [13] on Javanese found skeletal class II malocclusion caused by micrognathia mandible. Other research was conducted by Taloumtzi et al [14] In patients aged 8-10 years, it was suggested that skeletal class II malocclusion was due to a prognathic maxilla (25%) and the remainder to a retrognathic mandible (75%). The results of this study are in agreement with the two studies, namely, that the average SNA angle to the cranium base is normal, and the average SNB angle to the cranial base is retrognathic.…”