The Effect of Master Apical Preparation Size on Healing Outcomes in Endodontic Treatment: A Systematic Review and Meta-Analysis

Introduction The aim of this systematic review was to assess the existing literature and examine whether or not the size of apical enlargement during mechanical preparation affects the outcome of treatment in patients undergoing non-surgical root canal therapy (NSRCT). Methods MEDLINE (PubMed), Embase, Cochrane Library, and gray literature were searched (January 2000–May 2023). Study selection and data extraction were performed in duplicate. Eligible studies were critically appraised for risk of bias and quality of evidence and were meta-analyzed to estimate the treatment effects. Results Two studies were included in the meta-analysis. The overall pooled success rate was 75.8%. The success rates of treatment with an apical size ≥ 30 and < 30 were 80.9% and 52.9%, respectively. Cases with an apical size ≥ 30 demonstrated significantly more favorable results (RR = 0.63, 95% Confidence Interval 0.46-0.79, P < 0.05). The overall quality of evidence was low. Conclusion With a low certainty of evidence, master apical preparation size ≥ 30 may result in an increased healing outcome in terms of clinical and radiographic evaluations.