Mandibular symphysis morphology and lower incisor angulation in different anteroposterior jaw relationships wi̇th normodivergent skeletal growth pattern

The aim of this study was to compare the lower incisor inclinations of patients with skeletal sagittal class I, class II and class III relationships and to investigate the effects of differences in the lower incisor inclinations of MS morphology on lateral cephalometric radiographs. The material of our study consisted of digital cephalometric radiographs taken at the beginning of treatment of patients treated at Ankara Yıldırım Beyazıt University, Faculty of Dentistry, Department of Orthodontics. The patients were divided into 3 groups as follows: Class I, Class II and Class III. Patients of the same ethnicity, similar age group and normal skeletal growth pattern were included in our study. Various linear and angular measurements to study symphyseal morphology were performed using ImageJ. Statistical comparisons of the three groups in the study were made using one-way ANOVA, Tukey multiple comparison test, Kruskal-Wallis H test and Mann-Whitney U test with Bonferroni correction. Pearson and Spearman correlation analyses were used to examine relationships between variables. In all statistical analyses (p<0.05) was accepted as the level of statistical significance. The mandibular symphysis length and width are higher in males than in females. No statistically significant difference was found between class I, II and III groups in effective symphysis, symphysis length, symphysis width, LA, LP, H1 and H2 linear measurements and Id-B-MP angular measurements (p>0.05). In the measurement of symphysis anterior prominence and symphysis concavity, the values of the Class III group were found to be significantly higher than those of the Class II group (p<0.05). A negative correlation was found between lower incisor inclination (α1) and actual symphysis, effective symphysis and symphysis concavity. As a result, in class III patients, the anterior prominence of the symphysis is greater and its concavity is less. The actual symphysis, effective symphysis and symphysis concavity values are influenced by the inclination of the lower incisors. As the inclination of the lower incisors (α1) increases, the actual symphysis, effective symphysis and symphysis concavity values decrease.