A resonance frequency analysis assessment of maxillary and mandibular immediately loaded implants

This study evaluated the stability of implants in 51 patients following a clinical protocol of immediate functional loading. The stability during the first 3 months following implant placement was assessed according to bone type, implant location, and patient gender.

Twenty-two male and 29 female patients were treated with 344 Brånemark System implants placed in edentulous bone or extraction sites and put into functional loading using the Teeth in a Day protocol. Each implant was tested for primary stability with resonance frequency analysis (RFA) at the time of implant placement, and RFA was performed at examinations 30, 60, and 90 days following surgery.

The analysis was based on the 276 implants that were successfully measured using RFA at all postoperative intervals. The clinical implant survival rate was 98.5% for the total population. RFA showed a decrease in bone-implant stability in the first month after implant placement from 70.35 +/- 0.5 to 66.38 +/- 0.50, followed by increases in stability in the second and third months (68.01 +/- 0.50 and 68.82 +/- 0.49, respectively), suggesting a process of adaptive bone remodeling around the implant. In general, lower initial stabilities were seen in softer bone types, in the posterior portions of the jaw compared to anterior areas, and in the female population.

The results of this study suggest an immediate loading protocol should have an undisturbed period of healing for the first 2 months following implant placement. The determination of "predictor" stability levels for different clinical conditions were based on multiple splinted implants, allowing a larger surface area to withstand the distribution of the load. The most significant "predictor" values from a surgical and prosthodontic perspective are those determined in soft bone, in reduced bone, or in areas where lever arms are created as a result of long spans between the implants.