MORPHOMETRIC ANALYSIS OF THE PRIMARY AND PERMANENT DENTITIONS IN HEMIFACIAL MICROSOMIA - A CONTROLLED-STUDY

Hemifacial microsomia (HFM), a developmental abnormality involving the first and second branchial arches, is one of the most common craniofa cial abnormalities. Although the general presentations of hemifacial m icrosomia-such as unilateral microtia, macrostomia, and hypoplasia of the mandibular ramus and condyle-are well-known, the effects on the te eth are not well-documented. This study examined the primary and perma nent tooth dimensions of dental casts of 50 hemifacial microsomia pati ents compared with those of 50 normal control patients matched for sex and dental status. The results showed that the mesiodistal dimensions of the mandibular second primary molar and the mandibular permanent f irst molar teeth on the affected side in hemifacial microsomia were si gnificantly smaller compared with those of control teeth (p < 0.001). Furthermore, in the maxillary and mandibular first permanent molars an d the maxillary and mandibular first and second primary molars, the te eth in the apparently ''normal'' side of hemifacial microsomia were al so significantly reduced in the mesiodistal dimensions. Comparison of overall dimensions revealed that all primary and permanent molars in h emifacial microsomia were significantly smaller in the mesiodistal dim ensions compared with control teeth. A general gradient effect was obs erved, with the most posterior tooth in each arch being the most sever ely affected and no effect being seen in the canines and the incisors. These findings suggest that the dental lamina in hemifacial microsomi a is affected, and support the hypothesis that its pathogenesis involv es an abnormality of the neural crest. Furthermore, these results also support the concept that hemifacial microsomia is a bilateral rather than a unilateral condition.