Six-Year Radiographic, Clinical, and Soft Tissue Outcomes of Immediately Loaded, Straight-Walled, Platform-Switched, Titanium-Alloy Implants with Nanosurface Topography

Purpose: This prospective, longitudinal study evaluated the survival, marginal bone levels, and soft tissue conditions for immediately loaded, straight-walled, platform-switched, titanium-alloy implants with an internal connection and nanosurface topography. Materials and Methods: Patients were enrolled at a single center. The immediate loading protocol required a final insertion torque ≥ 25 Ncm, an implant stability quotient (ISQ) > 55, and placement of the provisional prosthesis on the same day as implant placement. Posttreatment follow-up examinations were scheduled at 3, 6, and 12 months and annually thereafter. Soft tissue evaluation consisted of assessment of the implant sites for signs of peri-implant infection including mucosal inflammation, bleeding on probing or suppuration, and progressive bone loss. Oral hygiene was evaluated, and radiographic marginal bone levels were analyzed and compared to baseline at the time of provisional loading. Results: Forty-eight consecutively treated patients received 122 implants; 112 qualified for immediate loading and were included. ISQ scores ranged from 51 to 87, with a mean value of 75.1 (SD = 6.8). One implant failed (after 3 months). After an average follow-up period of 6.2 years (SD = 0.37; range, 5.4 to 6.9), no further losses occurred, leading to an overall cumulative survival rate of 99.1%. Average bone loss for the 111 implants after 6 years was 0.35 mm (SD = 0.45; range: -0.35 to 2.20). Four implants (3.6%) in two patients showed concomitant peri-implant infections associated with bleeding on probing and/ or purulence after 2 years in function. Exploratory surgery revealed residual submucosal cement. After its removal, the progressive bone loss stopped, and peri-implant tissue in both patients returned to a healthy condition. Conclusion: This study based on 40 patients treated with 112 straight-walled, platform-switched, titanium-alloy implants with nanosurface topography yielded a 99.1% survival rate after a mean followup time of 6.2 years. Additionally, mean crestal bone loss was limited to 0.26 mm (SD = 0.38) after 1 year and 0.35 mm (SD = 0.45) after 6 years. Peri-implant infection associated with excessive bone loss above 2 mm was only encountered in one implant, and residual cement was shown to be responsible. Keywords: bone volume, dental implants, immediate loading, NanoTite, peri-implantitis, platform switching