Peri-implant soft tissue and bone crest alterations at fixed dental prostheses: a 3-year prospective study

Objectives The aim of this 3-year prospective study involving patients receiving implant-supported fixed dental prostheses (FDPs) was to longitudinally evaluate soft and hard tissue alterations from the time of implant placement. Material and methods Sixteen subjects with 18 implant-supported FDPs on 43 implants were included in the study. Peri-implant soft and hard tissue assessments were performed at implant placement, 2, 6, 12, 24 and 36 months. Variables describing the peri-implant soft tissue conditions and topography were assessed by clinical, photographic and study model assessments. Variables of implant position and bone topography were measured in radiographs taken at each examination interval. Multilevel regression models were formulated to identify factors of significance for proximal bone crest alterations and proximal soft tissue height. Results During the first 6 months after the one-stage implant placement surgery, the soft tissue margin receded about 0.6 mm at facial implant sites, while a mean increase was observed at tooth-facing proximal sites (1.1 mm) and no change at inter-implant sites. Loss in proximal bone crest height was more pronounced at inter-implant than tooth-implant units at 6 months (0.6 vs. 0.1 mm). Between 6 and 36 months, no further significant soft or hard tissue changes were observed. Multilevel regression analysis revealed that the proximal bone crest level significantly influenced the proximal soft tissue height assessed from the implant/abutment level. Significant predictors for loss in proximal bone crest level over the 3 years were horizontal inter-unit distance, type of proximal unit (tooth/implant or inter-implant) and peri-implant bone-level change. Conclusions Soft and hard tissue changes around implant-supported FDPs took place primarily during the first 6 months after the one-stage implant installation surgery. The pattern of tissue alterations during the follow-up differed between tooth-implant and inter-implant proximal sites. To cite this article:Chang M, Wennstrom JL. Peri-implant soft tissue and bone crest alterations at fixed dental prostheses: a 3-year prospective study.Clin. Oral Impl. Res. 21, 2010; 527-534.doi: 10.1111/j.1600-0501.2009.01874.x.