Trunk asymmetry and facial symmetry in young adults.

The aim of the present study was to detect possible associations between trunk and cervical asymmetry and facial symmetry. Frontal cephalograms prepared in the natural head position, representing 79 subjects (40 males, 39 females) with mild to moderate trunk asymmetry, were analyzed separately for thoracic humps, lumbar prominences, and cervical inclination by discriminating two groups: right-sided-dominant and left-sided-dominant. The differences between the groups were analyzed using an unpaired 2-group t test. The results showed that location of the thoracic humps and inclination of the cervical spine was predominantly right-sided, while the location of lumbar prominence was predominantly left-sided. Craniofacial morphological variables of the head and face were nearly equal for right-sided and left-sided thoracic humps and lumbar prominences, showing that moderate trunk asymmetry does not affect facial symmetry. Further, it was found that frontal head position in relation to the true vertical (VER/ORB) is stable in that the angle between the supraorbital and vertical lines is constantly maintained close to 90 degrees regardless of moderate trunk asymmetry, indicating that visual perception control is most important in orienting the head in frontal plane. Maintenance of the head position takes place by cervical spine adaptation.