Prevalence and Morphological Analysis of Isthmuses in Mandibular Molars of Indian Population: A Micro-Computed Tomographic Study

Abstract

Abstract Objectives This study evaluated the prevalence, configurations, and correlation of isthmuses at coronal, middle, and apical root thirds in mandibular molars of the Indian population using micro-computed tomography. Materials & Methods 105 permanent mandibular molar teeth were scanned under micro-CT. The axial sections were analyzed at the coronal, middle, and apical thirds of the root for isthmus types and classified according to Hsu and Kim's classification. Descriptive statistics for each isthmus type were calculated. The correlations between the apical, middle, and coronal thirds of the root were determined using Pearson's correlation coefficient. Results Type IV isthmus was most common in the coronal third of mesial root of mandibular first molar (42.9%), while type V was prevalent in coronal third of mesial root of second molar (42.9%). Type I isthmus was found to be highly prevalent in the middle third (71.4%) and apical third (61.9%) of mesial roots of first molars, and in the middle third (71.4%) and apical third (42.9%) of mesial roots of second molars. Type V isthmus was the most prevalent in all the thirds of the distal roots of both first and second molars, ranging from 40–50%. Also, a strong correlation of 0.965 (P < 0.01) was found between the isthmuses in the apical and middle thirds of roots. Conclusion There are variations in the prevalence and type of isthmuses across different sections of the root, including the presence of atypical isthmuses. Micro-CT with high-resolution imaging and 3D reconstruction is crucial for investigating root canal morphology. Clinicians could benefit from considering demographic characteristics to better predict the presence of isthmus variations. Clinical relevance: The isthmus configurations and frequency differs at each section of mandibular teeth.