Abstract: Objective: This study took use of CBCT(Cone Beam Computed Tomography) to measure and to ana-lyze the lingual concavity of the mandibular posterior region. When implanted in the mandibular posterior region, it provided some certain imaging references to preoperative diagnosis design and effective avoid-ance of concavity. Methods: According to the inclusion and discharge criteria, 318 of CBCT raw datas were there for measurement, upon which statistical analysis was performed through SPSS 22.0 statistical software package. Results: 1. The incidence of concavity was statistically different from age and tooth po-sition. 2. The indentations of different tooth positions were statistically different in the ABC area for differ-ent teeth. 3. There were statistical differences among three groups of measurements from different tooth positions. 4. The three groups of measurements in the ABC area were statistically different. Conclusion: This study suggested that when large concavity occurred in the AB region, the chance of lingual perfora-tion increased. Another finding of this study was that in the position of the second premolar of the lower jaw, sometimes there was a large undercut on the lingual side, and simultaneously an undercut on the buc-cal bone wall would be there, the rigorous design before surgery was especially important together with the presence of the buccal pupil.

Key words: oral implantology, CBCT, mandibular lingual concavity