The study is a prospective clinical study during the 3-month healing period of implant. The study was approved by the Human Experimentation Committee, Faculty of Dentistry, Chiang Mai University. The study outline is shown in Fig. 1.

Ten patients, who were partially edentulous in the mandibular posterior region for whom a single nonsubmerged implant was planned, participated in this study. All of them presented at the Center of Excellence for Dental Implantology, Faculty of Dentistry, Chiang Mai University, Thailand, between February and August 2015. The inclusion and exclusion criteria were shown in Table 1.

At the examination, the patients were informed about the study’s purposes, procedures, and possible risks and signed an informed consent. Scaling of all the teeth and oral hygiene instructions were performed for each patient.

All surgical procedures were completed by the same implant surgeon. After clinical and radiographic examination, the latter using periapical, panoramic and cone beam computed tomography images, and 2 g of amoxicillin for antibiotic prophylaxis were administered to the patients 1 hour before surgery. One PW Plus® implant (PW Plus, Nakhon Pathom, Thailand) per patient was placed in the mature bone at bone level under local anesthesia (4% articaine with epinephrine 1:100,000). Midcrestal and sulcular incisions around the teeth were performed at the implant site. After full-thickness mucoperiosteal flap elevation, implant bed preparation was started by using custom surgical stents. Ten PW Plus® implants were placed according to the manufacturer’s recommendations. After implant insertion and stability measurement, the smooth (polished) healing abutment was screwed to the implant and the flaps were sutured using 4-0 polypropylene suture material. As post-operative instructions, the patients were asked to abstain from mechanical plaque control at the surgical sites, 0.12% chlorhexidine mouthwash was prescribed for microbial control, and 400 mg ibuprofen for analgesia.

At implant placement and after 1, 2, 3, 4, 6, 8, 10, and 12 weeks, RFA assessments were performed using the Osstell® ISQ (Integration Diagnostics AB, Goteborg, Sweden) according to the manufacturer’s instructions. A Smartpeg™ (type 47) (Integration Diagnostics AB) was screwed to the implant using a Smartpeg mount. After Smartpeg mount removal, the RFA assessment was performed with the measurement probe on the handheld Osstell® ISQ instrument. The measurement probe was held close to the top of the SmartPeg without touching it until the instrument emitted a beeping sound and the implant stability quotient (ISQ) value presented. Two measurements were performed, one from the buccal direction and one from the mesial direction. The two ISQ values were recorded.