Abstract
Aim The objective of this study was to assess the existing literature to determine if a relationship exists between hypothyroidism and periodontitis. Methods We used a modified approach to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses by searching five databases in addition to the gray literature. Keywords in the title and abstract fields, as well as subject headings for both periodontal disease and hypothyroidism, were used to search the existing literature for publications relevant to evaluation of the thyroid-periodontitis relationship. Results The authors screened 847 unique publications which, after applying inclusion and exclusion criteria, yielded 29 publications, which were further analyzed for relevance and applicability. Most of the included papers were cross-sectional studies and retrospective chart reviews. Following critical analysis, four publications, including one abstract, were used to further assess the hypothyroid-periodontitis relationship. Conclusions There are very few high-quality studies describing the potential association between hypothyroidism and periodontitis. In general, and among the included papers with the fewest confounding factors, a positive relationship between hypothyroidism and periodontitis was found. Further well-controlled, prospective clinical and immunologic studies will be required to confirm that relationship.