Prevalence of dentofacial asymmetries in 14-17 Year old Tehran students, 2004

Perfect facial symmetry is exceedingly rare. In most individuals one side of the face is larger than the other side. Asymmetries large enough to be easily noted on clinical examination are important for patients and orthodontists, because of functional and esthetic problems. The purpose of this study was to determine the prevalence of mandibular asymmetries in high school students. Eight hundred twenty students were selected randomly from 14 high school including 400 girls and 420 boys in north eastern Tehran province. The diagnostic criteria for skeletal asymmetry was chin deviation more than 2mm from a vertical reference plane confirmed by unilateral cross-bite or different right–left cuspid relationship. For functional asymmetries, apparent lateral shift of the mandible from most retruded position to maximum intercuspation and for dental asymmetries, midline shift accompanied by missing teeth or early loss of teeth was noted. 44.6% of girls and 46.4% of boys demonstrated at least one form of asymmetry. The prevalence of skeletal, dental and functional asymmetry in girls was 20%, 21% and 10% respectively, while for boys the prevalence was 23.6%, 20.9% and 7.6%. In 62.5% of students with skeletal asymmetry chin was deviated to the right side. There was a positive correlation between history of trauma r=0.39 and unilateral mastication r=0.22 with asymmetry. The signs and symptoms of TMD was significantly more prevalent in students with skeletal asymmetry than others. Asymmetry of lower third of the face is a common finding. Early diagnosis and proper treatment planning prevents further functional and aesthetic problems.