Sandblasted and acid-etched implant surfaces with or without high surface free energy: Experimental and clinical background

The scientifically most investigated technique for creating a micro-rough surface topography on dental implants is the sandblasting and acid-etching procedure, creating the well- known, moderately rough SLA surface topography. The sandblasting procedure induces a macro-rough surface topography and is followed by an acid-etching procedure that superimposes the micro-rough topography. This SLA surface can be produced on commercially pure titanium as well as on titanium- zirconium alloys or on zirconium dioxide ceramics. In recent years, this hydrophobic SLA surface has been further developed, by a completely new and elaborated production process, creating a similar SLA topography but with increased chemical activity resulting in surface hydrophilicity and surface energy (modSLA surface). In vitro studies have shown that osteoblasts grown on the SLA surface exhibit properties of highly differentiated bone cells, which suggest that this surface is more osteoconductive compared to smoother surfaces. Compared to SLA, modSLA titanium surfaces further decreased cell proliferation and osteoclast activity and additionally enhanced osteoblastic cell differentiation and production of angiogenic factors. In vivo studies have demonstrated that, in comparison to implants with turned/machined surfaces, the increased roughness topography enhances bone tissue responses, such as greater bone-implant contact (BIC) and increased removal torque-out values (RTQ). These implants with increased surface hydrophilicity revealed accelerated bone (signifi- cantly increased BIC, RTQ) and soft tissue healing within the first 4 weeks after placement compared to implants with an SLA surface. Clinically, it has been shown that implants with an SLA surface topography can be successfully loaded 6-8 weeks after implant placement, thus, significantly reducing the healing period compared to implants with a turned or machined surface topography. With regard to the modSLA surface, it has been demonstrated that implants can successfully be loaded immediately or 3-6 weeks after placement, thus, further reducing the healing time. The SLA as well as the modSLA implant surface revealed comparable survival and success rates of more than 95 % up to and after 3 years of investigation; however, for SLA, also similar survival and success rates up to and after 10 years are available. Thus, both types of implant surfaces (SLA and modSLA) show highly successful comparable clinical outcomes; however, the modSLA surfaces allow for earlier bone and soft tissue healing and implant loading without compromising the overall survival and success rates.