Bone alterations at implant‐supported FDPs in relation to inter‐unit distances: a 5‐year radiographic study

Abstract

The aim of this 5-year study was to longitudinally evaluate bone alterations around implants with a conical implant-abutment interface in relation to implant-tooth and inter-implant distances. The patient sample comprised 43 partially dentate patients with a total of 48 implant-supported fixed dental prostheses (FDPs) supported by 130 Astra Tech implants. Following FDP placement (baseline), the patients were enrolled in an individually designed supportive care program. Radiographic examinations were performed at the time of FDP installation, 1 and 5 years of follow-up. Variables regarding implant position and proximal bone topography at tooth/implant units (n=36) and implant/implant units (n=67) were assessed with the use of a software program after scanning of the radiographs. At tooth/implant units, the mean 5-year marginal bone loss at the tooth, the implant and the mid-proximal bone crest was 0.1, 0.4 and 0.2 mm, respectively. The mean longitudinal bone loss at the implant/implant units was 0.5 mm at the implants and 0.3 mm mid-proximally. Multilevel regression analysis revealed that at implant/implant units, the change in the bone-to-implant contact level was a significant predictor with regard to the 5-year mid-proximal bone-level change, whereas the horizontal inter-unit distance showed a borderline significance (P=0.052). At tooth/implant units, no statistically significant associations were identified. The results of this 5-year study revealed differences between inter-implant and tooth-implant proximal areas with regard to bone crest alterations and associated factors.