Abstract
In order to analyze the effectiveness of upper and lower incisors on the position of upper and lower lips, 100 students , 50 males and 50 females, aged 18-25 years from mosul university are selected with class I normal occlusion, good facial esthetic, normal overbite and overjet, having no history of orthodontic treatment. A standard cephalometric film was taken showing the soft tissue profile with the underlying skeletal frame work. Tracing of these films including the cranial, maxillary and mandibular bases, upper and lower incisors and soft tissue out line. Eight variables entered SPSS computer analysis to evaluate the mean value of the variables. The sample is distributed according to skeletal classification into skeletal class I, II, and III, and a high correlation was found only in position of upper incisors with lower incisors and upper lip with lower lip.
