History of Dental Infections Associates with Cancer in Periodontally Healthy Subjects: A 24-Year Follow-Up Study from Sweden

BACKGROUND Infections of teeth are highly prevalent, often leading to tooth extractions. Missing teeth can thus be considered as proxy for chronic dental infections, caries or periodontitis. We followed-up a cohort for 24 years investigating the association between missing teeth and the incidence of cancer with the hypothesis that dental chronic inflammation links to cancer. METHODS WHO ICD-7-9-10 malignant diagnoses were recorded from the Swedish Cancer Registry from 1985 to 2009 in 1 390 individuals who had underwent clinical oral examination in 1985. The subjects appeared periodontally healthy and thus the probable reason for tooth extractions was deep caries. Using Fisher's exact t-test and multiple logistic regression analysis the results were analysed for the association between cancer incidence and baseline oral health parameters and a number of other explanatory factors. RESULTS Of the 1 390 subjects 71 had got cancer by year 2009. The results of the multiple regression analysis showed that between any type of cancer as a dependent variable, and several independent explanatory variables, missing second molar in the right mandible and age appeared as the principle independent predictors significantly associating with cancer, with an odds ratio (95% confidence interval) of 2.62 (1.18-5.78) and 1.91 (1.06-3.43), respectively. CONCLUSIONS In periodontally healthy subjects extracted molars, proxy for past dental infections, seemed to predict cancer risk in the studied age group - hence supporting a role of chronic dental infection/inflammation in carcinogenesis.