A prospective multicenter 5-year radiographic evaluation of crestal bone levels over time in 596 dental implants placed in 192 patients.

BACKGROUND: Dental implants have been used to replace missing teeth to provide function and esthetics. One goal of such restorations is to maintain host tissue around the implants. The purpose of this prospective multicenter human clinical trial was to evaluate radiographic marginal bone levels around non-submerged hollow cylindrical and solid-screw implants for 5 years after loading.
METHODS: Patients older than 18 years of age with sufficient native bone to surround a dental implant without imposing on a vital structure were recruited at five sites. Solid-screw or hollow-cylinder implants with a titanium plasma-sprayed implant surface were placed in the anterior maxilla or anterior mandible and restored with fixed restorations. Baseline radiographs were taken at the time of implant placement. Subsequent radiographs were taken at the time of final prosthesis placement, at 6 months after prosthesis placement, and annually from prosthesis placement for 5 years.
RESULTS: The results of 596 implants in 192 patients at five international sites revealed that clinically significant remodeling of the marginal bone occurred during the first 6 months after implant placement, with a mean (+/- SD) marginal bone loss of 2.44 +/- 1.20 mm. After that, clinically insignificant mean changes in the bone were observed. Overall, 0.22 +/- 0.42 mm of bone loss occurred between the time of prosthesis placement and 1-year postloading. Between 1-year postloading and the last 5-year recall, 0.18 +/- 0.88 mm bone loss occurred. Because 2.84 +/- 1.63 mm of bone loss occurred between implant placement and the 5-year postloading follow-up, 86% of the total mean bone loss over the course of 5 years was accounted for at the time of prosthesis placement. These same trends occurred if the data were analyzed with regard to implant design (solid screw and hollow cylinder), type of restoration (single and multiple), and length of implant (8 to 10, 12, and 14 to 16 mm).
CONCLUSIONS: These data demonstrate that, in general, clinically significant marginal bone remodeling occurred between the time of implant placement and final prosthesis placement around one-stage non-submerged titanium implants with a titanium plasma-sprayed surface. Subsequent to that, bone loss observed around implants up to 5 years postloading was minimal. These results suggest that the factors that influence early healing around implants are significantly different from those that affect later marginal bone remodeling.