The results of this study show that, at the time of implantation, the ISQ values ranged between 67.5 and 83. The mean initial ISQ value was 77.0 ± 1.32. These findings are in harmony with those of previous studies. Tallarico et al. (2011) reported that the macro-design of dental implant affects the primary anchorage. They suggested that the high initial ISQ value is a factor in making decisions about immediate loading on dental implants. The three-thread-design implants used in this study showed a high primary stability (ISQ value ≥65 to 70).

In the first 3 weeks, the mean ISQ values decreased and then increased and reached the initial values in the fourth week. The values then constantly increased in the following weeks. The lowest ISQ value in an implant was 51.5, found in the first week, and the highest value was 84, found in the tenth week. These results are in harmony with the findings of other clinical studies in that the ISQ values decreased within the first 3 weeks after implantation, and then increased and reached the initial values in the following weeks. These findings advise the presence of an interval between primary and secondary stability. An animal study, using a bone chamber model, which investigated the different phases of wound healing surrounding dental implants, showed that in areas of primary stability at the pitch region of the implant, osseointegration occurred after a resorptive process. Thus, the primary mechanical stability was destroyed for a short period of time. However, the results of another study showed no difference in the ISQ values over 12 weeks.