The effect of platform switching on the levels of metal ion release from different implant–abutment couples

The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant–abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt–chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (P<0.05). Titanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant–abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant–abutment couples. A potential link has been established between bone response and metal corrosion near dental implants. Platform switching, in which smaller diameter restorative components, or abutments, are positioned on large implant platforms, minimizes loss in the bone that supports the tooth—a requirement for successful implantation. However, mechanisms governing this positive peri-implant bone response remain unclear. Haralampos Petridis and coworkers from University College London, UK, investigated the role of corrosion by-products near implants by evaluating metal ion release from platform-switched and matched (matching abutment and implant platform diameters) systems immersed in lactic acid. Active corrosion mainly occurred on the outer edges of the implant–abutment interface for all systems, causing metal ion discharge at their vicinity. Platform-matched systems produced the highest amounts of metal ions, suggesting that platform switching limits bone loss by reducing this discharge.