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[A micro-computed tomographic study of the isthmus in the root canal system of mandibular first molar]
Li-Sha Gu1, Jun-Qi Ling, Xiang-Ya Huang
1Department of Cariology and EndodonTology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510055, China.
Objective:
To investigate the prevalence and configuration of the isthmuses in the apical 6 mm of the mesial and distal roots of Chinese mandibular first molar by means of micro-computed tomography.
Methods:
Thirty-six extracted human mandibular first molars were selected. Specimens were subject to micro-CT and a slice thickness of 30 microm was obtained in the apical 6 mm of the roots examined. The number of sections showing isthmuses at each apical level was recorded. Three-dimensional images of isthmuses of mandibular first molars were reconstructed and observed.
Results:
The mesial roots of human mandibular first molars had a high incidence of isthmus. The isthmus incidence was greatest 4-6 mm from the apex in human mandibular first molar, with prevalence figures of 49.5%-66.1% and 17.3%-17.8% in mesial and distal roots, respectively. The chi-square test indicated a significant difference in the distribution of isthmuses between the two roots (P < 0.01).
Conclusions:
The mesial roots of human mandibular first molars have a high incidence of isthmus, which may have clinical implications especially when surgical endodontics is performed on the mesial roots of mandibular molars.
