To investigate the submandibular soft tissue changes related to the hard tissue changes after mandibular set-back surgery in skeletal Class III patients.

The subjects were adults with skeletal Class III malocclusion who underwent orthognathic surgery including mandibular set-back between June 2007 and January 2011 at Kyung Hee University Dental Hospital at Gandong. Standardized lateral cephalograms that were taken before and 6 to 12 months after surgery were collected. Sixty samples were selected. Each lateral cephalograms was traced and lines, angles and areas associated with submandibular soft tissues were measured and analyzed statistically.

Anteroposterior submandibular soft tissue length was reduced with reduction of mandibular body length. FH to mandibular plane angle was decreased and FH to submandibular line angle was increased. A gender difference was found in soft tissue changes. Males showed altered vertical soft tissue thickness and submandibular tissue area reduction after surgery. Several hard tissue changes were correlated with soft tissue changes and through multiple regression models with stepwise selection method, several regression equation models to predict soft tissue changes related to hard tissue changes were made.

After orthognathic surgery including mandibular set-back, the submandibular soft tissue profile changes. Equations to predict submandibular soft tissue changes after mandibular set-back surgery were developed.