Differences in dento-facial morphology in lip competence and lip incompetence

Clinicians have hypothesized that lip competence is related to dental inclination, overjet, and overbite. Though some studies have been made to clarify this interrelation, a distinctive conclusion has not been reached. Studies have further shown that some subjects with normal occlusion show lip incompetence. Considering this, it could be hypothesized that dento-facial morphology plays a role in the causes of lip incompetence. To establish this it is necessary to distinguish dento-facial morphology factors from occlusal conditions such as overjet or overbite.