Evaluation of factors influencing resonance frequency analysis values, at insertion surgery, of implants placed in sinus-augmented and nongrafted sites

Background The immediate loading technique requires a high primary stability. Resonance frequency analysis (RFA) has been proposed to assess this stability with a quantitative method. Purpose The aim of the present study was to evaluate if a good primary stability could be achieved in sites that had undergone a sinus augmentation procedure and also to evaluate the importance of different clinical factors in the determination of resonance frequency values at implant insertion. Materials and Methods In 14 patients, 80 implants were inserted. Sixty-three implants were inserted in a site previously treated with a sinus augmentation procedure, while 17 implants were inserted in healed or postextraction sites. For each implant, diameter, length, bone density, insertion torque, RFA value, and percentage of implant fixed to a nongrafted bone were recorded. Results Grafted sites showed high RFA values. A statistically significant positive correlation was found between resonance frequency values and implant diameter (p=0.007), implant length (p=0.02), diameter of the last bur used (p=0.01). No statistically significant correlation between RFA values and all the other variables considered was found. Conclusions Sites treated with sinus augmentation procedures can offer good primary stability after 6 months of healing. The length and diameter of the implants, together with the geometry of the implant used, are important to obtain high RFA values.