Résumé
The root canal morphology of teeth is often extremely complex. Of particular interest is the complexity of mesiobuccal root of maxillary first molar. The purpose of this study was to evaluate the root canal configuration of maxillary first permanent molar in a part of population of Qazvin. In this descriptive-analytic study, 114 extracted maxillary first permanent molar were collected from different dental clinics in Qazvin. The crowns of all specimens were sectioned from the CEJ. The teeth with depressions on their mesiobuccal roots and with two separate orifices and two apical foramens were selected. On these specimens, the length of mesiobuccal roots in buccal and palatal aspects, the length of mesiobuccal and mesiopalatal canals, and the maximum mesiodistal width [in three parts: midroot, 1 millimeter apical and coronal to the midroot] of buccal and palatal aspects of mesiobuccal root were measured using a micrometer. Indian ink was injected into the pulp system of all mesiobuccal roots. The specimens were rendered clear by demineralization, dehydration, and immersion in methyl salicylate. The evaluation of root canal system was based on Vertucci's classification. Data were analyzed using SPSS version 12 and T test. The mean length of mesiobuccal roots in buccal and palatal aspects and the mean length of mesiobuccal and mesiopalatal canals were 14.30, 13.34, 14.84, and 14.09, respectively. Statistically, there was a significant difference in length between the buccal and palatal aspects [p<0.000]. Also, the mean mesiodistal width of midroot, 1 millimeter apical and coronal to the midroot, in buccal and palatal aspects of mesiobuccal root were 3.09, 3, 3.26, 2.24, 2.11, and 2.31 millimeters, respectively. Similarly, a statistically significant difference in width between the buccal and palatal aspects was found, [p<0.000]. Based on Vertucci's classification, the mesiobuccal root canal anatomical system consisted of 21.9% as type I, 58.8% type II, 0.8% type III, 21% type IV, 2.6% type V, and 2.6% type VI. Based on data found in our study, a considerable variety of root canal configurations were found in mesiobuccal root of maxillary first molars. The mesiobuccal root often contains a double root canal system