Isthmuses of the mesial root of mandibular first molar - An spiral computed tomographic study

Abstract

Aim: To investigate invitro the incidence and position of root canal isthmuses in the apical 5 mm of the mesial root of mandibular first molars by means of high resolution spiral computed tomography (SCT) and to describe the morphology of the isthmuses. Methodology: Forty extracted mandibular first molars that had fully formed roots were selected. The mesial roots were sectioned from the distal roots and subjected to SCT. The number of sections showing isthmuses in each of the apical 5 mm of the root canals was recorded. In each one of the apical 5 mm of the 40 roots, a total of 400 sections observed. Data were analysed for the presence of isthmuses at all the sections in each of the apical 5 mm of each root and the morphology of isthmus was also evaluated. Results: Isthmuses were found to be present at all levels with prevalence figures between 18.25 and 50.25%. A significant difference in the distribution of isthmuses within section and it was found that sections in the third millimetre from the apex had more isthmuses Calcifications were found to be present in most isthmuses, occasionally lateral canals originated from the central part of the isthmuses. Conclusion: the incidence of root canal isthmus in the mesial root of the mandibular first molars was high. Particularly in the apical 3-5 mm from the apex. Cleaning the isthmus is a major challenge during root canal treatment. The results of clinical and surgical endodontic procedures performed in the mesial root of mandibular molars may be affected by this aspect of the root canal anatomy.