Investigation of maxillofacial morphology and dental development in hemifacial microsomia.

Objective : Hemifacial microsomia (HFM) is a congenital anomaly characterized by unilateral underdevelopment of the mandible and ear. This study was conducted to characterize maxillofacial morphology and dental development in Japanese patients with HFM. Design : This is a retrospective hospital-based study. Patients : The subject population comprised 12 boys and 12 girls (average age, 9.3 years) diagnosed with HFM. Main Outcome Measures : We used posteroanterior (PA) and lateral cephalograms obtained at the first visit to analyze maxillofacial morphology and orthopantomograms to compare dental development between the affected and unaffected sides. Dental development was graded according to Nolla's stages of tooth calcification. Results : PA cephalogram analysis showed that the occlusal plane inclined upward on the affected side in each patient. The mandibular body and ramus were smaller on the affected side than on the unaffected side. Lateral cephalogram analysis showed that the patients tended to have steep mandibles, large gonial angles, and a slightly convex facial structure. The affected side/unaffected side ratio of the mandibular body and ramus correlated with SNB, ANB, convexity, and mandibular plane. The difference in dental development between the affected and unaffected sides was significant at the mandibular molars and the mandibular canine. Conclusions : This study demonstrates a correlation between lateral and frontal measurement parameters in patients with HFM. The data also showed delayed calcification in the mandibular molars on the affected side.