ABSTRACT
AIM: This study aimed to analyze incidence of isthmus in human permanent mandibular first molar teeth using cone-beam computed tomographic imaging techniques in a South Indian population. MATERIALS AND METHODS: Three hundred permanent mandibular first molar teeth were collected, cleaned, and stored in normal saline. They were divided into groups (GPs) I and II based on number of roots, and were further subdivided (right and left [RL] subgroups A and B for GP I; and RL subgroups C and D for GP-II). Samples were processed and isthmus incidence was evaluated by cone-beam tomography, compared, and statistically analyzed. RESULTS: Overall in mandibular first molars, the isthmus incidence in mesial root was 97.2%, distal root was 39%, and distolingual root was 0%. There was no statistically significant difference between the right and left mandibular first molar teeth with regard to incidence of isthmus (P > 0.05). There was an incidence of type I (38.67%), type II (56.33%), type III (3%), and type IV (2%) isthmuses in mesial root and type I (12.33%), type II (16%), and type III (10.67%) in distal root. CONCLUSION: Incidence of isthmus was very high in the mesial root of the mandibular first molar and should be factored during nonsurgical and surgical endodontic treatment procedures to achieve successful treatment outcomes.
ABSTRACT
The presence of radix entomolaris (RE) in a mandibular first molar is a common occurrence in certain ethnic groups, but the presence of RE in a mandibular second molar is a rare occurrence. In the present case, RE was identified from preoperative radiographs and confirmed using cone-beam computed tomography (CBCT). The access cavity was modified to locate the RE. Cleaning and shaping were performed with nickel-titanium rotary instruments. Obturation was completed with gutta-percha cones using AH Plus (Dentsply Detrey GmbH) as sealer. From the CBCT axial images, the RE was determined to have a Type III curvature by the De Moor classification, Type B separate RE by the Carlsen and Alexandersen classification, and radiographically, a Type i image by the Wang classification. The presence of RE in the mandibular second molar makes it essential to anticipate and treat the distolingual root canal. This case report highlights the usefulness of CBCT for assessing RE in the mandibular second molar, which can help the clinician in making a confirmatory diagnosis and assessing the morphology of the root canal.
