Periodontal Findings in Adult Twins

Abstract

Gingivitis and periodontitis are among the most common diseases known to man. Although bacterial plaque is generally accepted as the primary etiologic agent, little information is available concerning the influence that host genetic factors have on these diseases. The purpose of the present study was to examine the relative contribution of environmental and host genetic factors to clinical measures of periodontal disease through the study of both reared-together twins and monozygous twins reared apart. Probing depth, clinical attachment loss, gingivitis, and plaque were assessed from the Ramfjord teeth in 110 pairs of adult twins (mean age 40.3 years), including 63 monozygous and 33 dizygous twin pairs reared together and 14 monozygous twin pairs reared apart. Bootstrap sampling was used to estimate and provide confidence limits of between-pair and within-pair variances, intraclass correlations and heritability. Based on ratios of within-pair variances or heritability estimates, a significant (P less than 0.05) genetic component was identified for gingivitis, probing depth, attachment loss and plaque. Heritability estimates indicated that between 38% to 82% of the population variance for these periodontal measures of disease may be attributed to genetic factors. While there is general agreement that bacteria are important in the pathogenesis of the periodontal diseases, future etiologic studies should consider the role of host genetic influences.

What is the Contribution of Genetics to Periodontal Risk?

“…Evidence for the role of genetics in periodontitis has been gained from population, family and twin studies (23)(24)(25)(26). Studies in twins and especially in monozygotic twins are a strong and preferred model to study heritability of a disease.…”

“…Studies in twins and especially in monozygotic twins are a strong and preferred model to study heritability of a disease. Michalowicz et al (24) studied 110 twin pairs (63 monozygotic and 33 dizygotic twin pairs) with CP and showed that among monozygotic twins a higher concordance of alveolar bone loss patterns was seen than in the dizygotic twins. The heritability estimates for alveolar bone loss among reared-apart monozygotic twins was 38% (24).…”

TBX21-1993T/C (rs4794067) polymorphism is associated with increased risk of chronic periodontitis and increased T-bet expression in periodontal lesions, but does not significantly impact the IFN-g transcriptional level or the pattern of periodontophatic bacterial infection

“…2 As previously mentioned, it is noteworthy that the sole bacterial infection is not sufficient to explain the complex pathological processes of periodontitis, being the nature and extent of host´s response ultimately responsible for the disease occurrence and outcome. 3 While microbial and environmental factors (lifestyle factors [as smoking and stress] or acquired diseases [as diabetes]) characteristically modulate host responses (and consequently periodontitis outcome), studies suggest that as much as 50% of the risk of disease can be determined by genetic factors, [4][5][6] and that numerous disease modifying genes may be involved in the pathogenesis of periodontal diseases by modulating the host's response and his susceptibility to infection. 3,7,8 Recently, the interaction between host genetic factors that can impact the ability of pathogens to invade and proliferate on host's tissues has been termed infectogenomics.…”

El papel de la genética en la aparición y desarrollo de la periodontitis: I: evidencias científicas de la asociación entre periodontitis y genética

“…Los estudios de gemelos más importantes son los conducidos en Minnesota por Michalowicz (26)(27)(28)(29). Este grupo estudió los parámetros periodontales de una muestra amplia de gemelos monocigotos y dicigotos criados juntos y separados.…”