The Link Between Apical Periodontitis and Gastrointestinal Diseases—A Systematic Review

Introduction This systematic review aimed to examine a potential link between apical periodontitis (AP) and gastrointestinal diseases (GIDs). Methods The protocol of the review has been registered in PROSPERO (CRD42022330771). The following engines were used with the aim of searching for relevant literature: PubMed, Web of Science, Scopus, Cochrane Central Register of Controlled Trials, and grey literature, from inception to May 2022. There were no language restrictions included. Study selection, data collection, and synthesis have been performed by 2 independent reviewers. For the purpose of estimating the quality of studies, the Newcastle-Ottawa Scale was used. Results Four matched case control studies, as well as a single longitudinal cohort study were included in the final review. These were published between 2012 and 2017, and comprised 537 participants whose age range was 18 to 87 years. It was not possible to perform a meta-analysis due to different study designs and evaluated outcomes of included studies. Except for one study that was categorized as "Good," overall, for 4 out of 5 studies the quality was assessed as "Fair". Conclusions This review highlighted sparse knowledge present in the literature concerned with the association between AP and GIDs. Available evidence reveals a potential link between impaired endodontic status, assessed by the number of root-filled teeth with periapical radiolucency, and GIDs. More research is needed to ascertain this association.