Expanding the occlusal phenotype of non-syndromic orofacial clefting

Introduction: Patients with oral clefts can present with variable occlusal anomalies often thought to be a result of surgical intervention, which makes it difficult to characterize the occlusal phenotypic spectrum of orofacial clefting. Little research has been performed on the prevalence of occlusal anomalies and whether the prevalence of these anomalies is elevated in unaffected relatives of individuals with overt oral clefts. To date, this study is the largest international collection of children with non-syndromic clefts, their relatives and controls that aim to characterize the spectrum of cleft-related occlusal anomalies compared to the general population. Methods: A total of 1017 subjects were rated: 108 subjects with clefts, 314 unaffected relatives, and 595 controls. Occlusal anomalies were identified from intraoral photographs and case-control differences were tested using logistic regression. Results: When comparing cases vs. controls, cases were more likely to have negative overjet, a posterior crossbite, and an anterior crossbite. Controls were 14 times more likely to have positive overjet than cases (P=0.0003). Cases were 13 times more likely to have a posterior crossbite than controls (P=0.0005). Cases were 17.2 times more likely than controls to have an anterior crossbite (P=0.0006). No significant differences in occlusal discrepancies were found when comparing non-affected siblings of affected probands to matched siblings of controls. Unaffected parents of cases were more likely to have spacing in both the upper arch (1.8 times, P=0.0456) and the lower arch (1.8 times, P=0.0422) when compared to control parents. Conclusions: These findings suggest that except for arch spacing, first-degree relatives of children with clefts do not have a higher genetic risk for occlusal anomalies than the general population. Our finding on increased arch spacing in the unaffected parents could point at the presence of smaller teeth overall, which has been shown before for children with clefts. In general the higher prevalence of occlusion anomalies in cases is primarily a physical consequence of the cleft and surgical interventions.