ASSESSMENT OF SYMPHYSIS MORPHOLOGY AS A PREDICTOR OF THE DIRECTION OFMANDIBULAR GROWTH

The purpose of this study was to determine whether symphysis morpholog y could be used as a predictor of the direction of mandibular growth a nd to assess growth changes of the symphysis. Cross-sectional data inc luded lateral cephalometric radiographs of 115 adults (58 women, 57 me n) with the longitudinal sample a subset of 62 subjects (30 females, 3 2 males) at four age groups. The direction of mandibular growth was ev aluated with seven cephalometric measurements that included Y-axis, SN to mandibular plane, palatal plane to mandibular plane, gonial angle, sum of saddle, articulare and gonial angles, percentage lower facial height, and posterior/anterior face height. The mandibular symphyseal dimensions studied were height, depth, ratio (height/depth), and angle . Symphysis morphology was found to be associated with the direction o f mandibular growth, especially in male subjects with symphysis ratio having the strongest relationship. A mandible with an anterior growth direction was associated with a small height, large depth, small ratio , and large angle of the symphysis. Conversely, a posterior growth dir ection was associated with a large height, small depth, large ratio, a nd small angle of the symphysis. Symphysis dimensions continued to cha nge until adulthood with male subjects having a greater and later occu rring change compared with female subjects.