Root and root canal morphology of four-rooted maxillary second molars: a micro-computed tomography study

This study examined the anatomy of 4-rooted maxillary second molars by using micro-computed tomography.

Twenty-five 4-rooted maxillary second molars were scanned to evaluate the size and curvature of the roots; the distance and spatial configuration between some anatomical landmarks; the number of root canals and the position of apical foramina; the occurrence of fusion of roots and enamel pearls; the configuration of the canal at the apical third; the cross-sectional appearance, the volume, and surface area of the root canals. Data were compared by using analysis of variance post hoc Tukey test (α = 0.05).

The specimens were classified as types I (n = 16), II (n = 7), and III (n = 2). The size of the roots was similar (P > .05), and most of them presented straight with 1 canal, except the mesiobuccal that showed 2 canals in 24% of the samples. The configuration of the pulp chamber was mostly irregular quadrilateral-shaped. The lowest mean distance of the orifices was observed between the buccal roots (P < .05). Accessory canals were present mostly in the apical third. Location of the apical foramina varied considerably. Fusion of roots and enamel pearls occurred in 44% and 8% of the samples, respectively. Mean distance from the pulp chamber floor to the furcation was 2.15 ± 0.57 mm. No statistical differences were found in the bi-dimensional and 3-dimensional analyses (P > .05).

All analyzed parameters showed differences between roots, except for the length of the roots, the configuration of the canals at the apical third, cross-sectional appearance, volume, and surface area of the canals.