In this study, we could not find a significant relationship between insertion torque value and ISQ value. However, insertion torque value is an important indicator for predicting the progress of implant treatment, and ISQ value is considered to be an important indicator for observing the treatment state of the implant. Currently, the insertion torque value is used as the major decision index for the determination of the loading period on the implant body. Lozano-Carrascal et al. explained that if the insertion torque value shows between 32 to 50 N cm, the implant treatment with immediate loading protocol is able to apply [40]. Also, Anitua et al. applied immediate loading protocol when the insertion torque value was 40 to 65 N cm (the average insertion torque value is 55 ± 3.48 N cm) [29]. As described above, the insertion torque value used as a decision index of the loading period of the implant is yet undefined. Therefore, the loading period of the implant should not be determined immediately after insertion but should be determined after careful follow-up observation. When deciding to load period, the ISQ value will be an important decision index.

A bone quality of the treated area may affect primary stability as described above, preoperative analysis of bone quality is important for clarifying the primary stability of dental implants. This study analyzed bone quality using voxel values obtained using Digital Imaging and Communications in Medicine (DICOM) data from CBCT. According to the result of that analysis, it was suggested that insertion torque is high when inserting the implant body used in this study into the bone with high voxel value (Fig. 7). Moreover, in this study, the ISQ values of implant bodies showing insertion torque of 30 or more N cm were stabilized at a high value (ISQ was 73 or more) in 6 weeks after insertion (Figs. 5 and 6). These results may suggest that if the implant body used in this study is inserted into the bone of sufficient quality, high IT then intraosseous stability during the healing period can be expected, and osseointegration may be completed by 6 weeks after surgery. In addition, in order to judge the completion of osseointegration, an evaluation of intraosseous stability in the healing process after insertion of the implant body is necessary. There was a possibility that the implant body used in this study could be treated with the early loading method [1, 2]. In order to make this result more reliable evidence, it seems necessary to conduct a randomized controlled study on more participants.