Root canal morphology and variations in the permanent mandibular molars of Malaysian subpopulation: a cone beam computed tomography study

Abstract

Among the Asian population, variations in the root canal morphology of permanent mandibular molars (PMM) are highly prevalent, and different ethnic backgrounds have been found to greatly affect these variations. This study was carried out to determine the root canal morphologies variation of PMM and their prevalence among the Malaysian subpopulation using cone beam computed tomography (CBCT). The extracted PMMs were also collected to assess the precision of CBCT via clearing technique as evaluation tools for root canal morphology. CBCT images of PMM were collected retrospectively based on the predetermined criteria from the Faculty of Dentistry of Universiti Kebangsaan Malaysia and Universiti Sains Islam Malaysia. The root canal morphologies were categorized using Vertucci’s classification and the new classification system for root and root canal morphology proposed by Ahmed et al. 20 extracted PMMs were collected and underwent CBCT scanning followed by clearing technique by injecting India ink into the canals and soaked in 10% nitric acid for five days with daily solution replacement. 582 CBCT images with 1124 PMM were acquired. 85% of the first PMM were two-rooted and 65% had three-rooted canals. Type IV Vertucci’s classification was most found in mesial roots with a prevalence of 51%, and females displayed a significantly higher prevalence than males (p < 0.05). The overall prevalence of C-shaped canal was 28%, which was commonly found in the Chinese population (49%). It was also dominated by females (31%) compared to males (23%) (p < 0.05). A minority of Malaysians presented with radix entomolaris, radix paramolaris, and middle mesial canal with a prevalence of 6.7%, 0.2%, and 0.3%, respectively. The Cohen’s kappa value between CBCT and clearing technique evaluated from 20 PMM root canal configuration was 0.857 (p < 0.05). The evaluation of CBCT images revealed the disparity of root canal morphology. The highest prevalence of mesial root canal configuration of the first PMM was type IV Vertucci’s classification. The root variations also greatly differed among the different ethnic groups, with C-shaped canal and radix entomolaris mostly presented in the Chinese group. CBCT images can be effectively used as a clearing technique to evaluate root canal morphology.