PURPOSE: When soft tissue flaps are reflected for implant placement, the blood supply from the periosteum to the bone is disrupted. The aim of this study was to compare the effects of the flapless (FL) and full-thickness flap (FT) techniques on implant stability. Methods : Nine patients received 22 implants. The implants were placed using the FL technique on the contralateral side of the jaw; the FT technique was used as the control technique. Resonance frequency analysis (RFA) was performed at the time of implant placement and at 6 and 12 weeks after implant placement. RFA values were compared between the FL and FT groups and between time intervals in the same group. Results : The median (interquartile range [IQR]) RFA values at the time of implant placement were 75.00 (15.00) for the FL technique and 75.00 (9.00) for the FT technique. At 6 weeks, the median (IQR) values were 79 (3.30) for the FL technique and 80 (12.70) for the FT technique. At 12 weeks, the median (IQR) values were 82.3 (3.30) for the FL technique and 82.6 (8.00) for the FT technique. There were no significant differences between the 2 techniques at the time of implant placement, after 6 weeks or after 12 weeks, with p values of 0.994, 0.789, and 0.959, respectively. There were significant differences between the RFA values at the time of implant placement and after 6 weeks for the FL technique (p=0.028) but not for the FT technique (p=0.091). There were also significant differences between the RFA values at 6 weeks and the RFA values at 12 weeks for the FL technique (p=0.007) and for the FT technique (p=0.003). Conclusion : Periosteum preservation during the FL procedure will speed up bone remodeling and result in early secondary implant stability as well as early loading.