Objective: The knowledge of the internal anatomy of the root canal system and its variations has a significant impact on the quality and outcome of endodontic treatment. The aim of this study was to evaluate the three-dimensional anatomical features of the root canals of mandibular first molars by using micro-computed tomography.
Material and methods: Sixty mandibular first molars were scanned using a high-resolution micro-computed tomography device. The 2- and 3-3-dimensional anatomical features of each root such as distance between anatomical apex and apical foramen, the number of the lateral canals and configuration of the isthmuses, were evaluated.
Results: The average distance between the anatomical apex and the apical foramen was 1.047 mm. Lateral canals were present in 85% of the cases, while 76% of them were localized in the apical third of the root. 80% of the mesial roots had isthmuses and the configuration of Type I, according to the Fan classification, was the most prevalent (35%).
Conclusion: The results of this study revealed the wide variations of internal root canal anatomy in mandibular first molars, including lateral canals and isthmuses. A clinician should always consider the possible difficulties of anatomical variations before starting root canal treatment, to select the best and optimal treatment strategies.