Diederik Hentenaar

152 Chapter 7 implant infection (Costa et al. 2019, Han et al. 1998, Johansson et al. 1998). Hence these triggers might be another important factor that might partially explain the limited clinical effect found in the studies presented in chapter 3, 4 & 5. Recent reviews on titanium particle release, underline that titanium particles in peri-implant tissues are a common finding and that peri-implantitis sites revealed a higher number of particles compared to healthy conditions (Delgado-Ruiz R. & Romanos G. 2018, Noronha Oliveira et al. 2018, Suárez-López Del Amo et al. 2019, Romanos et al. 2021). In addition, titanium dissolution products have been shown to act as a modifier in the peri-implant microbiome structure and diversity (Daubert et al., 2018). However, even though there is an association between the presence of titanium particles and biological complications, evidence for a direct causal relationship is still missing (Mombelli et al. 2018). More research is needed to find out what factors cause destruction of the protective titanium dioxide layer and how particle release and corrosion of dental implants influences peri-implant tissues. Regenerative approach and bone defect morphology With the aim to evaluate the single influence of mechanical or chemical implant surface debridement, irrespective of the bone defect morphology, a resective approach was chosen in both surgical studies presented (see chapter 4, 5). One might advocate that a regenerative approach would have been more successful in circumferentially or infrabony defect configurations and preferable regarding maintenance of soft tissue height (Schwarz et al. 2010). However, although the literature is emerging, studies evaluating regenerative treatments thereby taking into account different bone defect morphologies remain scarce (Tomasi et al. 2019). Only recently, Renvert et al. (2021) compared the use of deproteinized bovine bone mineral and native bilayer collagen membrane in ≥ 3 wall defects to a non-regenerative surgical approach in a randomized clinical trial. The results showed no significant difference in terms of BoP, SOP and PPD reduction between both groups. Although low success rates were found, the regenerative approach appeared to achieve a successful outcome more often (32% versus 21%). Another recent study by Roccuzzo et al. (2021) evaluating a surgical regenerative approach recording different bone morphology defects, was able to recreate and maintain peri-implant healthy conditions around most of the treated implants for a period of 5 years’ time, regardless of the initial defect configuration (according to Schwarz et al. 2007). Hence, one might expect considerable success from a regenerative approach although it should be kept in mind that the research on this topic remains limited. Whether a specific type of bone defect is more favorable to regenerate with stability of successful outcomes (on the long term) remains to be found.