| A thorough understanding of the morphology of the root canal system and its variations is crucial for successful endodontic therapy. Lack of knowledge of its variable and complex anatomy might lead to failure of endodontic treatment. In recent years, people are put forward new requirements for understanding of root canal anatomy, with the progress and development of root canal treatment technology. A high incidence of radicular groove, bifurcate and sulci leading to variable anatomy of root canal system in mandibular premolars. Some scholars think that the root canal morphology is closely related to the r oot surface anatomical structure.Therefore, it is critical to gain a thorough understanding of the relationship of betwwen root canal morphology and root surface anatomical structure so as to achieve successful therapy.In this study, Micro-CT was mainly applied to perform mandibular first premolar scanning and three-dimensional reconstruction to observe and analyze the relationship of betwwen root canal morphology and root surface anatomical structure, and to provide reference for dental diagnosis and treatment in clinic.The results as follows:1. In total, 52 teeth(40.9%) had radicular grooves in the 127 mandibular first premolars. Overall, 15 teeth(17.4%) had radicular grooves in the 86 type I mandibular first premolars; 41 teeth were identified as multiple and complex root canals(type III, type V, type VII, and other types), of which 90.2% teeth(37/41) had radicular grooves. The prevalence of a radicular groove in a single canal was statistically lower than in multiple and complex canals significant(P < 0.05).2. A total of 56 grooves were noted in the 52 mandibular first premolars; four specimens(7.7%) had double grooves. For all grooves, 75%(42/56) were located on the mesial surface of the root, 8.9%(5/56)wrer located on the distal surface of the root, 12.5%(7/56)and 3.6%(2/56) were located on the lingual and buccal surface of the root. The mean depth and length of groove in type V and other canal types were significantly deeper and longer than type I. Remark: there was no statistical significant, because of type III and type VII groups just have one sample.3. The prevalence of root canal isthmi was 44.2%(23/52) in mandibular first premolars with radicular grooves. The mean distances from the starting and terminal points of radicular grooves to the apex were 7.29 ± 1.38 mm and 4.93 ± 2.04 mm, which was approximately one-fifth of the mean root length. All isthmi were located within the scope of the radicular grooves.The mean minimum mesial wall thickness was significantly lesser than the distal wall thickness(P < 0.05). A significant negative correlation was observed between the minimum mesial wall thickness and groove depth( r =-0.648 to-0.988, P < 0.05). The MFF was 0.48 in this study, indicating a flat or irregular isthmus shape. Furthermore, a significant negative correlation was observed between FF and groove depth(r =-0.617 to-0.994, P < 0.05).4. To investigate the correlation between radicular grooves and complex canals using Micro-CT. We found that the position of the radicular grooves were strongly correlated with root cnanal variable. For instance, the mesial and distal invaginations may correspond with the furcation of canals in buccolingual directions, and the buccal and lingual invaginations may relate to the presence of accessory canals.In conclusion, Multiple and complex canals had a higher incidence of radicular grooves and more complicated root morphology than single and simple canals. In other words, the anatomy of radicular grooves may influence root canal morphology. Secondly, the radicular groove depth directly impacts the isthmus wall thickness and root canal shape, with a strong negative correlation of these two parameters with groove depth was analyzed. Moreover, the results of this study provide an important basis for further studies on the relationship between radicular grooves and root canal bifurcations. |
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