Prevalence and morphological analysis of isthmuses in mandibular molars of the Indian population: A micro-computed...

This study evaluated the prevalence, configurations, and correlation of isthmuses at coronal, middle, and apical root 3^rd in mandibular molars of the Indian population using micro-computed tomography μCT).

One hundred and five permanent mandibular molar teeth were scanned under μCT. 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.

Type IV isthmus was the most common in the coronal third of the mesial root of mandibular 1^st molar (42.9%), while Type V was prevalent in the coronal third of the mesial root of 2^nd molar (42.9%). Type I isthmus was found to be highly prevalent in the middle 3^rd (71.4%) and apical 3^rd (61.9%) of mesial roots of 1^st molars, and in the middle 3^rd (71.4%) and apical 3^rd (42.9%) of mesial roots of 2^nd molars. Type V isthmus was the most prevalent in all the thirds of the distal roots of both 1^st and 2^nd molars, ranging from 40% to 50%. Furthermore, a strong correlation of 0.965 (P < 0.01) was found between the isthmuses in the apical and middle thirds of roots.

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 three-dimensional reconstruction is crucial for investigating root canal morphology. Clinicians could benefit from considering demographic characteristics to better predict the presence of isthmus variations.

The isthmus configurations and frequency differ at each section of mandibular teeth.