Risk Factors: Genetic & Bacterial Transmission

Genetic factors also are being studied in adult periodontitis, although the relationship is less clear than LJP. Results of twin studies have shown that at least some of the risk for attachment loss may be inherited. Probing depth and attachment loss are similar in pairs of twins whether they have been reared together or apart.11,23 The identification of a familial pattern in periodontal disease has lead to questions about whether it may be transmissible. Transmission requires sufficient concentrations of bacteria for survival during passage and acceptance of the organism by the recipient. Are periodontal pathogens transmitted between spouse?...between parent and child? Research is being conducted to examine these questions. It appears that both Aa and Porphyromonas gingivalis Pg are transmissible; however, not all infected individuals develop periodontal disease. The significance of bacterial transmission is still being examined. It has been shown that Aa is transmissible among family members in families of children with LJP. And, in adult periodontitis, at least one parent will be positive for pathogens found in the child - whether it be Aa, Prevotella intermedia(Pi) or Pg. We have always thought that plaque bacteria are indigenous, but perhaps some are exogenous.13-15 One finding which supporting the exogenous pathogen theory is that Pg, a pathogen in adult periodontitis, has been shown to be transmitted between spouses. Although the bacteria are transmitted, the effect on periodontitis is not known.

In one study the periodontal status of spouses of healthy subjects was compared to the periodontal status of spouses with periodontitis. Findings indicated that spouses of periodontitis patients had greater involvement. It is unclear whether these findings are related to bacterial transmission or to environmental factors (e.g., stress, diet, nutrition, alcohol or drug abuse, etc.)15 Theories of bacterial transmissibility and genetic influences are not as strongly implicated in adult periodontitis as they are in LJP, like in Andy's case.