The Guiding Effect of Digital Image Based on Cone-Beam Computed Tomographic on Oval Root Canal Preparation

Abstract Background: To evaluate the guiding effect of digital image based on cone-beam computed tomographic in improving the quality of single oval root canal preparation.Methods: A premolar was selected by CBCT and a 3D-printed root canal model was made. Twenty postgraduates from the Department of Stomatology of Shanghai Ninth People's Hospital were selected to perform root canal preparation on 3D printed oval root canal model teeth. They were randomly assigned to two groups(n=10) according to the guiding method received: CBCT original image (control group) and CBCT-based digital image (experimental group). CBCT scans were performed on the models before and after the guidance. The changes in root canal cleanliness, residual minimum thickness, transportation and over-preparation amount were analyzed.Results: The experimental group caused significantly more increased amount of cleanliness compared to control group(P<0.05)：6.0373% ±6.0766% in the control group and 13.7193%±6.7102% in the experimental group. There was no significant difference in the reduction of residual minimum wall thickness between the two groups (P>0.05)： 0.0154mm±0.2110mm in the control group and 0.0362±0.0444mm in the experimental group. In the control group, the transportation after second preparation was generally increased (increased 0.0084mm on average). In the experimental group, the transportation was generally reduced after second preparation (reduced 0.0081mm on average). But there was no significant difference in the transportation change between the two groups (P>0.05). After the second preparation, there was no significant difference in the amount of increased over-preparation between the two groups（P＞0.05）: 1.7029%±3.6622% in the control group and 3.5144%±4.8075% in the experimental group.Conclusions: Compared with traditional CBCT image guidance, the digital image method can significantly improve the cleaning effect of the oval root canal preparation. It didn’t result in more over-preparation and the amount of residual wall thickness was ensured. At the same time, it has a certain effect on reducing transportation after the guidance.