Surface Corrosion from Implant–Abutment Couplings with Different Connection Designs Influences Osteoblasts’ Function: A Novel Technique

The improved peri-implant bone response demonstrated when utilizing the platform-switching concept may result from the reduced levels of metal ions released from implant–abutment surfaces to the surrounding tissues. These corrosion products may play a major role in crestal bone remodeling around dental implants. This study evaluated the effect of different implant–abutment couplings (platform-matched vs. platform-switched) on osteoblasts’ function. Titanium alloy and cobalt–chrome alloy abutments were coupled with titanium cylinders, forming either platform-switched or platform-matched groups, and were incubated in human osteoblast cultures utilizing a novel direct-exposure technique. Viability was evaluated over 21 days using Alamar Blue assay. Apoptosis was measured after 24 h using flow cytometry. The expression of genes related to bone resorption was analysed over 21 days using a real-time quantitative polymerase chain reaction assay. Cell viability was reduced from day 4 to day 21 (p < 0.05), with higher rates of early apoptosis (p < 0.05) compared to the controls. Apoptosis was higher in the platform-matched groups (p < 0.05). The tested genes’ expression was up-regulated after 1 and 3 days of exposure to implant–abutment couplings (p < 0.05). The upregulation was more pronounced in platform-matched groups (p < 0.05). Exposure of osteoblasts to implant–abutment couplings induced adverse biological responses, which were more pronounced with platform-matched couplings. These reactions might be related to the increased amounts of metal ions released from the platform-matched couplings, highlighting the possible role of corrosion products in the mediation of crestal bone loss around dental implants.