The insertion torque value in this study showed broader (10 to 50 N cm) than the previous publication (Table 2) [22, 32], and the cause of reasons for the difference are as follows: Primary stability may be affected by the bone quantity and bone quality in the treatment area, the micro- and macro-level design of the implant body, and the accuracy of the surgical technique [18, 25]. In this study, the 17 dentists performed implant treatment. The deviation of each insertion torque value was thought by the surgical technique of each dentist. In clinical situation, the insertion torque value is considered to indicate various values.

The insertion torque value in this study showed no significant difference between each treatment area. Therefore, all of the implant bodies were considered as one population and that population was classified into three groups by insertion torque value and analyzed. In a recent literature, Anitua et al. reported that the insertion torque values were 59.29 ± 7.27 N cm at type I bone, 56.51 ± 1.62 N cm at type II bone, 46.40 ± 1.60 N cm at type III bone, 34.84 ± 2.38 N cm at type IV bone, and 5 N cm at type V bone [29]. Since the average value of insertion torque in this study was 32.7 ± 9.2 N cm, it was inferred that this study evaluated implant treatment for relatively soft bone quality.

The intraosseous stability of the healing period was evaluated by mobility measurement and/or resonance frequency analysis. A resonance frequency analysis has been reported as a non-invasive procedure that is useful for evaluating osseointegration [13, 33]. The results of the resonance frequency analysis were represented in the present study as the ISQ.

An ISQ is reportedly affected by the condition of the bone surrounding the implant, such as the range of contact between implant body and bone [33,34,35]. Other studies have suggested that ISQ immediately after implant insertion should be about 60 [24, 36], with ISQ subsequently decreasing over weeks 0–4 and increasing over weeks 4–8 after surgery [13, 24, 34]. ISQ values 57–70 may indicate that intraosseous stability of the implant body is constant [34, 37].