Heritable patterns of tooth decay in the permanent dentition: principal components and factor analyses

The 128 tooth surfaces of the permanent dentition were scored as carious or not by intra-oral examination for 1,068 participants aged 18 to 75 years from 664 biological families. Principal components analysis (PCA) and factor analysis (FA), two methods of identifying underlying patterns without a priori surface classifications, were applied to our data.The three strongest caries patterns identified by PCA recaptured variation represented by DMFS index (correlation, r = 0.97), pit and fissure surface caries (r = 0.95), and smooth surface caries (r = 0.89). However, together, these three patterns explained only 37% of the variability in the data, indicating that a priori caries measures are insufficient for fully quantifying caries variation. In comparison, the first pattern identified by FA was strongly correlated with pit and fissure surface caries (r = 0.81), but other identified patterns, including a second pattern representing caries of the maxillary incisors, were not representative of any previously defined caries indices. Some patterns identified by PCA and FA were heritable (h2 = 30-65%, p = 0.043-0.006), whereas other patterns were not, indicating both genetic and non-genetic etiologies of individual decay patterns.This study demonstrates the use of decay patterns as novel phenotypes to assist in understanding the multifactorial nature of dental caries.Dental caries is a disease affecting most adults and caused by the complex interplay of numerous environmental, behavioral [1,2], and genetic risk factors [3-12]. The etiology of dental caries is further complicated by the non-uniform risk across tooth surfaces of the full dentition leading to distinct patterns of dental decay, as previously described [13-25]. Patterns of decay have been used to explore caries etiology under the assumption that different risk factors lead to distinct caries patterns. A well-known example is the maxillary anterior pattern of decay (i.e., "baby bottle" caries) in young children