The etiology of mandibular prognathism has been attributed to various genetic inheritance patterns and some environmental factors. The variation in inheritance patterns can be partly due to the use of different statistical approaches in the respective studies. The objective of this study was to investigate the role of genetic influences in the etiology of this trait. We performed segregation analysis on 37 families of patients currently being treated for mandibular prognathism. Mandibular prognathism was treated as a qualitative trait, with cephalometric radiographs, dental models, and photographs used to verify diagnosis. Segregation analysis of a prognathic mandible in the entire dataset supported a transmissible Mendelian major effect, with a dominant mode of inheritance determined to be the most parsimonious.

Univariate logistic regression detected reduced trauma risk among subjects of high income families (P = 0.009) and among subjects attending private schools (P = 0.026). Sports and physical activities were more prevalent in boys than in girls (P = 0.000) and associated with trauma in the sample as a whole (P = 0.001), but not separately in boys and girls. No effect was detected of obesity, number of siblings and increased caries experience. Univariate analyzes also detected increased trauma risk in boys (P = 0.000) and in subjects with increasing intervals of overjet (P = 0.000). Following use of multiple regressions with forward selection, only male gender, increasing overjet, and high family income were included in the final prediction model. Our findings suggest that behaviors associated with high family income and private school attendance reduce the risk of incisor trauma among adolescents in Kuwait, and that the gender difference in sports activities is an unlikely explanation for the gender difference in trauma.

Objectives: Our objective was to test the hypothesis that thermoplastic clear aligners (Invisalign®; Align Technology, Santa Clara, CA, USA) are more pleasant for patients than conventional fixed orthodontic appliances. Subjects and Methods: This was an observational retrospective study in which subjects were matched for age, treatment modality, and the treating orthodontist. A total of 60 adult patients (30 in the Invisalign group and 30 in the conventional buccal fixed appliance group) who met the inclusion criteria completed a validated self-reporting questionnaire, rating their experience after appliance activation in regard to oral impact experience and satisfaction of both treatment modalities. Categorical variables were compared using the χ² test, Fisher’s exact test, and the Z test. Continuous variables such as pain level and age were analyzed using the 2-sample t test. Results: Patients on clear aligner therapy reported significantly more difficulty in speech (p = 0.035) necessitating change in speech delivery (p = 0.003). In addition, they reported better chewing ability (p < 0.001), no restrictions on amounts or types of food (p = 0.02), and less mucosal ulcerations (p = 0.01). Effects on daily routine, use of analgesics, and overall treatment satisfaction were not significantly different between the 2 groups. Conclusion: Clear aligner therapy is not necessarily more pleasant, but it is more tolerable as it satisfies patient needs over food consumption and absence of mucosal ulcerations. However, clear aligners affect pronunciation and speech delivery in the short term.