Alveolar and Skeletal Chin Dimensions Associated with Lower Facial Height Among Different Divergent Patterns.

INTRODUCTION: Alveolar and skeletal chin dimensions with facial height have an impact on diagnosis and treatment planning in orthodontic patients and serves as a reference landmark for facial aesthetics. AIM: To evaluate the alveolar and skeleton chin dimensions among different divergent patterns, to evaluate the lower face height in different divergent growth patterns, to give an estimate to the oral surgeon for any adjunctive procedure. MATERIALS AND METHODS: The study includes a total sample of 45 non-growing individuals (26 males and 19 females) from the archival records of the Orthodontic Department with age ranging between 18-25 years, classified into different divergent patterns based on the mandibular plane angle. The sample was divided into three groups, of which 15 patients in each group were evaluated: Group-1: Normodivergent, Group-2: Hypodivergent and Group-3: Hyperdivergent patterns respectively. Standardized digital lateral cephalograms and antero-posterior cephalograms of these patients were obtained in Natural Head Position (NHP). RESULTS: The results of the retrospective cephalometeric study were statistically analyzed by using ANOVA and Tukey's multiple post hoc test which showed that hard tissue chin measurement were greater in hypodivergent group (13.7mm) and the increased lower facial height showed statistically significant difference in high mandibular plane angle group (59.6mm). In antero-posterior cephalograms the transverse width showed statistically significant difference in normodivergent group (32.60mm). CONCLUSION: The anterio-posterior width of the symphysis was higher in hypodivergent growth pattern, whereas vertical height of the symphysis was greater in hyperdivergent group. The lower facial height among three groups showed statistically significant difference among hyperdivergent group. In comparison of all the three groups in Anterio-Posterior (AP) cephalograms, statistically significant difference was noted in normodivergent group when compared with the other two groups.