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Open Access Highly Accessed Research article

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

John R Shaffer11223*, Eleanor Feingold1235, Xiaojing Wang2346, Karen TCuenco23467, Daniel E Weeks15, Rebecca S DeSensi2346, Deborah E Polk2378, Steve Wendell2346, Robert J Weyant27, Richard Crout29, Daniel W McNeil10 and Mary L Marazita1112346

Author Affiliations

1 Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA

2 Center for Oral Health Research in Appalachia, University of Pittsburgh, Pittsburgh, PA 15261, USA

3 West Virginia University, Morgantown, WV 26506, USA

4 Center for Craniofacial and Dental Genetics, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA

5 Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA

6 Department of Oral Biology, School of Dental Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA

7 Department of Dental Public Health and Information Management, University of Pittsburgh, School of Dental Medicine, Pittsburgh, PA 15261, USA

8 Department of Behavioral and Community Health Sciences, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA

9 Department of Periodontics, West Virginia University School of Dentistry, Morgantown, WV 26506, USA

10 Dental Practice and Rural Health, West Virginia University of Dentistry, Morgantown, WV 26506, USA

11 Clinical and Translational Science Institute, and Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA

12 Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto St., Pittsburgh, PA 15261, USA

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BMC Oral Health 2012, 12:7  doi:10.1186/1472-6831-12-7

Published: 9 March 2012

Abstract

Background

Dental caries is the result of a complex interplay among environmental, behavioral, and genetic factors, with distinct patterns of decay likely due to specific etiologies. Therefore, global measures of decay, such as the DMFS index, may not be optimal for identifying risk factors that manifest as specific decay patterns, especially if the risk factors such as genetic susceptibility loci have small individual effects. We used two methods to extract patterns of decay from surface-level caries data in order to generate novel phenotypes with which to explore the genetic regulation of caries.

Methods

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.

Results

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.

Conclusions

This study demonstrates the use of decay patterns as novel phenotypes to assist in understanding the multifactorial nature of dental caries.

Keywords:
Dental caries genetics; Heritability; Permanent dentition; Pit and fissure surfaces; Smooth surfaces; Tooth surfaces; Principal components analysis; Factor analysis; Patterns of tooth decay; Patterns of dental caries