The range of interobserver kappa values was −0.008 to 1.00. When the frequency of a certain trait is low, such as for agenesis of the maxillary

central incisors, a single disagreement can have a major effect on the kappa. The negative kappa value for the interobserver agreement of maxillary central incisors in the non-cleft side was the result of only 2 disagreements between the 2 observers. Furthermore, this had no effect on the see more reliability of our data, as an uncertain observation concerning the presence or absence of a tooth at one point in time, could be verified on other OPTs at later time points. We choose to analyze our data separately for the cleft side and non cleft side as differences between sides may be expected. A recent meta-analysis confirmed that the majority of publications on tooth agenesis in OFCs did not do so. In their meta-analysis the authors attributed higher quality scores to studies that took the side, jaw and tooth type into consideration.18 In this cohort, we identified, in total, 13 different tooth agenesis patterns. The lateral incisor in the cleft quadrant was involved in 7 of these 13 different patterns. The maxillary lateral incisor at the non-cleft quadrant was absent in 8.7% of the patients, and was part of only two patterns. The most common selleck chemicals llc symmetric patterns in the maxilla were the lateral

incisors (5.2%), and the second premolars (0.9%) in the mandible. enough Our study confirmed the earlier observation that left-sided clefts are more common than right-sided clefts.9 We also found a statistically significant difference for the number of missing teeth in the cleft and the non-cleft quadrants (p = 0.020). Our findings regarding the sidedness of the cleft and tooth agenesis are confirmed by the existing literature. 9, 19 and 20 In our study however, children with a cleft on the right side were far less likely to have missing teeth. Although the prevalence of a cleft and tooth agenesis is significantly and consistently higher on the left side, as were clefts and tooth

agenesis separately, as for the combined phenotype, the underlying genetic aetiology for this general finding has not yet been explained. One way to speculate on this preferable sidedness of clefts and tooth agenesis, could be the observation of cleft sidedness and tooth agenesis of cleft syndromes, where clefts are associated with congenital defects of sided organs, like heart defects. An example is the OFCD (Occulo-facio-cardio-dental) syndrome, in which it has been shown that the causative gene (BCOR-gene) contributes to the left/right sidedness of organ development. 21 and 22 If the interaction of BCOR with clefting genes can be demonstrated, this could provide at least one of the clues for the higher prevalence of left sided clefts.