Children with oral clefts exhibit a wide range of dental anomalies, making it difficult to understand the phenotypic spectrum of orofacial clefting. However, there is mixed evidence, based on small samples, as to whether the prevalence of dental anomalies is elevated in unaffected relatives.

A number of researchers, including Brian J. Howe, Margaret E. Cooper, Alexandre R. Vieira, Seth M. Weinberg, Judith Resick, Nichole Nidey, George L. Wehby, Mary L. Marazita, and Lina Moreno Uribe, set out to conduct the largest international cohort to date of children with nonsyndromic clefts, their relatives, and controls. The study, titled “Spectrum of Dental Phenotypes in Nonsyndromic Orofacial Clefting,” was published recently by the International and American Associations of Dental Research (IADR/AADR) and appears in the Journal of Dental Research.

The study characterizes the spectrum of cleft-related dental anomalies and evaluates whether families with clefting have a significantly higher risk for such anomalies compared to the general population. The study looked at a total of 3,811 individuals, of which 660 cases were clefts; 1,922 unaffected relatives; and 1,229 controls.

Dental anomalies were identified from in-person dental exams or intraoral photographs, and case-control differences were tested using chi-square statistics. Cases had higher rates of dental anomalies in the maxillary arch than controls for primary and permanent dentitions but not in the mandible. Dental anomalies were more prevalent in cleft lip with cleft palate than other cleft types.

More anomalies were seen on the same side of the cleft. Failure of tooth formation and tooth displacements were the most common dental anomalies found in cases. Compared to controls, unaffected siblings and parents showed a trend for increased anomalies of the maxillary permanent dentition. Yet, these differences were nonsignificant after multiple-testing correction, suggesting genetic heterogeneity in some families carrying susceptibility to both overt clefts and dental anomalies.

According to the study, the findings collectively suggest that most affected families do not have higher genetic risk for dental anomalies than the general population and that the higher prevalence of anomalies in cases is primarily a physical consequence of the cleft and surgical interventions.