Background: Dental caries is the result of a complex interplay among environmental, behavioral, and genetic\r\nfactors, with distinct patterns of decay likely due to specific etiologies. Therefore, global measures of decay, such as\r\nthe DMFS index, may not be optimal for identifying risk factors that manifest as specific decay patterns, especially\r\nif the risk factors such as genetic susceptibility loci have small individual effects. We used two methods to extract\r\npatterns of decay from surface-level caries data in order to generate novel phenotypes with which to explore the\r\ngenetic regulation of caries.\r\nMethods: The 128 tooth surfaces of the permanent dentition were scored as carious or not by intra-oral\r\nexamination for 1,068 participants aged 18 to 75 years from 664 biological families. Principal components analysis\r\n(PCA) and factor analysis (FA), two methods of identifying underlying patterns without a priori surface\r\nclassifications, were applied to our data.\r\nResults: The three strongest caries patterns identified by PCA recaptured variation represented by DMFS index\r\n(correlation, r = 0.97), pit and fissure surface caries (r = 0.95), and smooth surface caries (r = 0.89). However,\r\ntogether, these three patterns explained only 37% of the variability in the data, indicating that a priori caries\r\nmeasures are insufficient for fully quantifying caries variation. In comparison, the first pattern identified by FA was\r\nstrongly correlated with pit and fissure surface caries (r = 0.81), but other identified patterns, including a second\r\npattern representing caries of the maxillary incisors, were not representative of any previously defined caries\r\nindices. Some patterns identified by PCA and FA were heritable (h2 = 30-65%, p = 0.043-0.006), whereas other\r\npatterns were not, indicating both genetic and non-genetic etiologies of individual decay patterns.\r\nConclusions: This study demonstrates the use of decay patterns as novel phenotypes to assist in understanding\r\nthe multifactorial nature of dental caries.
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