Familial Aggregation of Periodontal Indices

Abstract

Analysis of three measures of periodontal health (plaque index, gingival index, and attachment loss) was carried out on 178 individuals in 75 families examined as part of a family study of periodontal health. Original participants in this study were volunteers recruited from the University of Maryland Dental Clinic, and were selected independently of any specific dental disease or condition. Relatives were invited to participate in the family study so that the extent of familial aggregation of indices of periodontal health could be assessed. By means of an analysis of variance model for persons nested within families, evidence for familial aggregation of plaque index was found both before and after adjustment for covariates such as age, gender, race, and reported oral hygiene habits. While a substantial fraction of variance in gingival index and attachment loss was also due to differences among families, neither attained statistical significance in these data. Examination of familial correlations (e.g., parent-offspring, sib-sib, spouse correlations) confirmed that plaque index showed greater familial resemblance compared with other measures of periodontal health. Both mean gingival index and mean attachment loss showed a stronger correlation between mothers and offspring compared with fathers and offspring. This suggests that further analysis of models for separating genetic and environmental effects may be appropriate for plaque index, but complete analysis of other periodontal indices will require more flexible statistical models for separation of genetic and cultural inheritance while considering gender-specific expression and transmission, as well as incorporation of information from covariates.

Genetic and Heritable Risk Factors in Periodontal Disease

“…The familial aggregation of periodontal indices were more recently studied by Beaty et al 81 Plaque, gingivitis, and attachment loss were measured on 136 individuals in 41 families. The among-family variance for gingivitis and attachment loss accounted for 31% and 29%, respectively, of the total variance in these measures.…”

Genetic Influences in Caries and Periodontal Diseases

“…In a study of periodontal health in 75 families not selected for any dental condition, gingival and plaque indices and attachment loss were measured in 175 individuals (Beaty et al, 1993). The participants were predominantly African-American, women, and age 40 years or younger.…”

“…The family effect was not statistically significant for the gingival index or attachment loss, although it accounted for about 30% of variation for each variable. To examine further the patterns of correlations among relatives while simultaneously adjusting for the effects of periodontal disease risk factors, Beaty et al (1993) used the regressive models (described below). For the plaque index, the data were consistent with a multifactorial inheritance model, with a correlation of about 0.26 for parents and offspring and for siblings.…”

“…Although these researchers accounted for several important risk factors for periodontal disease, they did not include tobacco smoking; it would be interesting to know how inclusion of smoking affects the correlations, specifically if the gender differences are attenuated. Beaty et al (1993) emphasized the importance of considering gender-specific transmission and including periodontal disease risk factors when analyzing family data.…”

“…Measured genetic factors (e.g., "high-risk" HLA marker) can also be included as risk factors or to assess the interaction between the genetic marker and other periodontal disease risk factors. Aside from Beaty et al (1993), these types of analyses of family data have, to date, not been performed for adult periodontal disease or for periodontal health in adults.…”