Characterization of Root and Canal Morphology of Permanent Mandibular First and Second Molars in a Yemeni Population Using Cone-Beam Computed Tomography

Abstract

This study aimed to describe and characterize roots and canals morphology of mandibular first molars (MFMs) and mandibular second molars (MSMs) in a Yemeni population using cone-beam computed tomography (CBCT). CBCT images of 1600 right and left untreated MFMs and MSMs with fully developed roots from 400 Yemeni individuals (200 male and 200 female) comprised the sample size of this study. The following anatomical features were recorded: (1) number of roots and their type (either fused or separated) and morphology (shape in cross section), (2) total number of canals orifices within the tooth and in each root, (3) type of canal configuration in each root, (4) presence of C-shaped canal and (5) primary variations in the morphology of the root and canal systems. Results in MFMs showed a higher prevalence of two roots (97%). A third root was found in 3%, more in females (4.5%) than males (1.5%). No fused roots were found. Mesial root was mainly ribbon-shaped (93.4%) and distal root was kidney-shaped in 58.1%. Two canals orifices were found in mesial root of 96.5% and one canal orifice was found in distal root of 93.6%. Type II canal configuration was the most frequent (55%), followed by type IV (38.5%) in mesial root. Type III canal configuration was the most prevalent (49.8%), followed by type I (37.1%) in distal root. No C-shaped canals were found. Variant 3 represented the most common root and canal morphology (87.5%). MSMs with separated two roots predominated (90.7%), fused two roots were 7.5%, separated three roots were 0.9% and one root MSMs were 0.9%. Molars with three canals orifices were the most common (80.1%). In MSMs with separated roots, mesial root was mainly ribbon-shaped (66.4%) and distal root was mainly kidney-shaped (52.6%). Type II and Type I canal configurations were the most frequent in mesial root (57.6%) and distal root (87.9%), respectively, in MSMs with separated roots. C-shaped canals were found in 7.5%. Seven variants of root and canal morphology were found with variant 3 was the most common (75.3%). It was concluded that permanent MFMs and MSMs in the studied sample of Yemenis have mainly two separated roots. Radix Entomolaris disto-lingual root was found in both MFMs and MSMs in low percentages with a higher occurrence in females than males. No Radix Paramolaris mesio-buccal root was found in both molars. Mainly, mesial root was ribbon-shaped and distal root was kidney-shaped in cross-section in both molars. Vertucci type II canal configurations showed the higher incidence in mesial roots of both molars. Vertucci type III and type I canal configurations were predominant in distal roots of MFMs and MSMs, respectively. Variant 3 was the most common morphology in both molars. C-shaped roots and canals were found in 7.5% of MSMs, with higher occurrence in females than males. No fused roots or C-shaped canals were found in MFMs.