Title: 0267 - Longitudinal Development of Deep Mandibular Antegonial Notches
Gregory Antonarakis (Presenter)
University of Geneva
Christian Schütz, University of Geneva
Balazs Denes, University of Geneva
Stavros Kiliaridis, University of Geneva
Objectives: The mandibular antegonial notch is a morphological characteristic visible on lateral cephalograms. Controversy exists in the literature if its development is related to the facial growth pattern. How this antegonial notch develops is not clear however. The aim of this investigation was: a) to identify those who have a deep antegonial notch at the age of 18 years; b) to analyse longitudinally how deep antegonial notches develop from the ages of 7 to 18 years.
Methods: Using the AAOF legacy collection material, the lateral cephalograms of 340 orthodontically untreated 18 year-old subjects were analysed to measure the depth of the mandibular antegonial notch. For those who had a deep antegonial notch (≥ 3.6mm) at the age of 18 years, lateral cephalograms of the same subjects at the ages of 7 and 13 years were also analysed, and antegonial notch depth measured. The total sample was analysed with ANOVA and the longitudinal subsample with a Friedman test, while post-hoc tests were performed with separate Wilcoxon signed-rank tests with Bonferonni correction.
Results: Based on the 340 lateral cephalograms of 18 year-old orthodontically untreated subjects, the antegonial notch was deeper in males (2.3mm ± 1.1mm) than in females (1.5mm ± 0.7mm; p<0.001) on average. Within the total sample, 21 individuals had a deep antegonial notch (≥ 3.6mm), all of them being males. The mean antegonial notch depth of these 21 individuals was 2.6mm ± 0.7mm at 7 years, 2.5mm ± 0.7mm at 13 years, and 4.2mm ± 0.5mm at 18 years. While no statistically significant differences were found between ages 7 and 13 years, the antegonial notch depth was greater at 18 years than at 7 or 13 years (p<0.001).
Conclusions: In adults presenting a deep mandibular antegonial notch, the depth of this notch does not seem to increase during the pre-pubertal period, but increases during pubertal growth. It is possible that this increase in depth is linked to the increase of muscle mass during the pubertal growth spurt.
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE