COMPARISON OF CRANIOFACIAL AND DENTOALVEOLAR MORPHOLOGIES OF 3 JAPANESE MONOZYGOTIC TWIN PAIRS WITH CLEFT-LIP AND OR PALATE DISCORDANCY/

Objective: In this study, we analyzed the craniofacial and dentoalveol ar morphologies of three pairs of monozygotic twins discordant for cle ft lip and/or palate (CUP) in order to evaluate the effects of environ mental factors on growth and development. Design: Craniofacial and den toalveolar morphologies revealed by analyses of cephalograms and denta l casts were compared for each pair of twins discordant for CUP. Subje cts: In case 1, the subjects were 10-year-old male twins, one of whom had a repaired unilateral cleft lip and alveolus and one of whom had a n unrepaired unilateral cleft lip. In case 2, the subjects were 13-yea r-old female twins, one of whom had a repaired bilateral cleft lip and palate and one of whom had an unrepaired unilateral cleft lip. In cas e 3, the subjects were 9-year-old female twins, one of whom had a repa ired unilateral cleft lip and palate and one of whom had no cleft. Res ults: Cephalometric analysis disclosed distinguished intrapair differe nces in the maxillary and mandibular morphologies in cases 2 and 3, Ho wever, the tooth axes of the incisors in operated subjects were consis tently influenced in all three cases. Dental cast analysis indicated t hat the shapes and sizes of the alveolar and dental arches in the oper ated subjects were affected in case 2 and, more severely, in case 3, w hile they looked fairly similar in case 1. Conclusions: Cephalometric and dental cast analyses demonstrated characteristic intrapair differe nces between the twins discordant for CUP according to each cleft type . These morphological differences indicate that surgical closure of cl efts may have considerable effects on craniofacial and dentoalveolar g rowth and development in CUP patients.