Micro-computed tomographic analysis of the mesial root of mandibular first molars with bifid apex

The aim of the present study was to evaluate the influence of bifid and non-bifid configurations of the mesial root of mandibular first molars in the canal anatomy using micro-computed tomography (micro-CT).

Thirty mesial roots with bifid apex were pair-matched with 30 non-bifid roots by means of micro-CT. Bifid and non-bifid mesial roots were compared regarding morphological aspects at the apical third, dentin thickness, and the presence of isthmus and middle mesial canal (MMC). Data were analyzed using Chi-square test and Student's t-test with a significant level of 5 %.

Main foramen of mesiobuccal (MB) and mesiolingual (ML) canals were positioned within 2.5 mm from the anatomic apex, and origin and exit of accessory canals were observed mostly between 1.0 and 2.0 mm from the apex in the groups. Despite no statistical difference was observed between bifid and non-bifid roots regarding the number of canal orifices (p > 0.05), the frequency of accessory canals was significantly higher in bifid roots (p < 0.05). Regarding the dentin thickness, a statistically significant difference was observed between bifid and non-bifid roots at the furcation level (p < 0.05). Only 3 mesial roots with bifid apex (10 %) had isthmuses, mostly at the coronal third, while a high incidence of MMC was observed in this group (n = 10, 33.3 %).

Presence of bifid apex in the mesial root of mandibular first molars might be a predictive factor for a complex canal anatomy at the apical third with an increasing number of accessory canals.