Methods: A total of 138 implants were inserted in 45 patients, equally distributed at three centers. Minimums of two implants were placed in the posterior mandible in each patient. Functional load was applied 6-7 weeks after implant placement. Implant Stability Quotient (ISQ) was measured by resonance frequency analysis at implant placement, 2 and 6 weeks after surgery and also at 1, 3, 6 and 12 months after permanent restoration. Intraoral radiographs were taken at implant placement and 6 weeks later. Radiographs were also taken at 3, 6, 12, 24 and 36 months after permanent restoration. Soft tissue status was evaluated by means of plaque and bleeding on probing.
Results: 43 patients reached the 3-year follow-up, 2 drop-outs occurred. 4 implants were subject to delayed loading. The cumulative survival rate is 100%. Mean ISQ values were 72±7 at implant placement (IP) (n=131), 7±8 at IP+2 weeks (n=132), 71±8 at IP+6 weeks (n=134), 73±7 at permanent restoration (PR)+1 month (n=127), 75±8 at PR+3 months (n=130), 77±7 at PR+6 months (n=129) and 77±7 at PR+1 year (n=130). Mean marginal bone levels were 0.6±1.2mm at IP (n=129), 1.0±1.0mm at IP+6 weeks (n=134), 0.9±1.0mm at PR+3 months (n=122), 0.8±0.8mm at PR+6 months (n=130), 0.6±0.6mm at PR+1 year (n=130) and 0.9±1.0mm at PR+2 years (n=123) and 0.8±1.5mm at PR+3 years (n=122). Soft tissue conditions were reported to be stable during follow-up time.
Conclusion: The results indicate that the Fixture MicroThread™ OsseoSpeed™ placed in the posterior mandible can be used for early loading with good results and maintains marginal bone levels and soft tissue health.