Influence of the timing of periodontal intervention on periapical/periodontal repair in endodontic-periodontal lesions: a systematic review

Introduction This study is aimed at answering the following question: "Does the timing of periodontal intervention influence the periapical/periodontal repair in endodontic-periodontal lesions? ". Material and methods Six electronic databases were systematically searched for studies published up to April 2022, without restriction of language or year of publication, following the PIOS strategy: (P) adult patients with a diagnosis of endodontic-periodontal lesions, (I) endodontic and periodontal treatment, (O) periapical and periodontal healing, and (S) clinical studies. Risk of bias assessment was performed with the revised Cochrane risk of bias tools for randomized trials (RoB 2) and non-randomized interventions (ROBINS-I). The overall quality of evidence was assessed through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool. Results Three studies (one prospective, one retrospective, and one randomized clinical trial) were included in the present review. Non-randomized studies had a critical and serious risk of bias. The randomized clinical trial had some concerns risk of bias. Non-randomized studies reported that the endodontic intervention should be performed previous to the periodontal intervention. Randomized clinical trial reported improvements when endodontic and periodontal interventions were performed simultaneously. GRADE analysis showed a very low quality of evidence for both randomized and nonrandomized studies. Conclusions Based on the evidence from the included studies, although it is suggested that the endodontic treatment should be performed prior to periodontal treatment, it is not possible to assure the best treatment sequence for endodontic-periodontal lesions.