Anatomical Variations in Root Canal Configuration of Maxillary Second Premolars: A Narrative Review

The maxillary second premolar, while frequently single rooted, exhibits a high degree of morphological diversity in its internal canal system. This unpredictability can lead to clinical oversights if a simple anatomy is assumed. The aim of this study was to review current knowledge regarding the number of roots and root canal configurations in permanent maxillary second premolars across different populations. A comprehensive literature search was conducted using the PubMed database for studies published between 2015 and December 2025, with the keyword "maxillary second premolar anatomy." Out of 358 identified articles, 27 studies met the inclusion criteria and were analyzed. Only human-based studies on maxillary second premolars that used CBCT imaging and were written in English were included. The reviewed studies revealed that single-rooted maxillary second premolars are the most prevalent morphology, occurring in over 70% of cases, although significant variations exist among different ethnic groups. The presence of two roots was the second most common configuration, while three-rooted teeth were rare (<2%). Gender-related differences were also observed, with a higher prevalence of two-rooted teeth in males. Analysis of root canal configurations based on Vertucci's classification demonstrated that all eight types can occur, with Type I being the most frequent in most populations with a result of more than 50% of all teeth. However, substantial variability was noted, with certain studies reporting a higher prevalence of more complex configurations such as Types IV and V. The findings emphasize the importance of thorough knowledge of root canal anatomy and its variations to ensure successful endodontic outcomes. Advanced imaging techniques, particularly cone beam computed tomography (CBCT), play a crucial role in improving diagnostic accuracy and proper endodontic treatment. Further research is needed to better understand anatomical differences across populations and enhance clinical decision-making in endodontics.