Geographic patterns of the number of root canals in permanent molars

Published: 11 June 2024| Version 2 | DOI: 10.17632/xvgf59n75k.2


This systematic review focuses on the quantitative synthesis of the results of primary studies not to estimate a particular effect, but to generalize about the number of root canals in permanent molars globally. A narrative synthesis of the findings was made, grouping the studies by geographic regions and describing the reported prevalences of different root canal configurations (number of canals) in maxillary and mandibular molars for each population. Global and regional heat maps, plots and tables was generated showing the geographic distribution of the prevalence of different root canal number configurations in maxillary and mandibular molars. This will allow spatial patterns to be clearly visualized. For the sensitivity analysis of the studies, we performed descriptive statistics separately for each group and compared the results to assess the impact of methodological quality. RStudio® 2024.04.1 Build 748 will be used for data processing


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Calibration was performed among the authors to evaluate the articles to be selected. The degree of coincidence of the evaluations made by the reviewers was determined using Orwin's method of 1994, and a Kappa statistic was performed to measure the agreement among the reviewers who would make simple decisions about inclusion/exclusion. Kappa values between 0.40 and 0.59 were considered to reflect acceptable agreement, 0.60 to 0.74 to be an adequate agreement, and 0.75 or more to reflect excellent agreement. The records obtained in the databases were processed into a document from the bibliographic manager EndNote through which export files were managed for the screening process on the Rayyan® site ( With this tool, duplicates and other records that did not match the primary inclusion/exclusion criteria were eliminated, and the researchers blindly determined which articles were suitable for inclusion and which were not. In case of discrepancy or doubts, a 3rd author was in charge of deriving the inclusion result.


Universidad Autonoma de Chile, Universidad de Ciencias Medicas de La Habana


Dentistry, Geography, Endodontics, Systematic Review