Caroliene Meijndert

128 Chapter 7 Discussion The results of this systematic review reveal a relationship between the type of implant- abutment connection configuration and peri-implant bone loss around implants placed in the anterior region of the maxilla. The PS-conical and PS-parallel connection configurations are comparable with less peri-implant bone loss than PM-parallel connections. The presence of a platform switch seems to have more influence on bone loss than the internal connection configuration itself. In the present review, PS-conical and PS-parallel connection configurations result in significantly less peri-implant bone loss than the PM-parallel connections. Although the Caricasulo (2018), Vetromilla (2019) and Yu (2020) studies confirmed that the least amount of bone loss occurs with conical connections, only Caricasulo (2018) researched the effect of platform switching. They found 0.30 mm more bone loss on applying PM connections than the PS-conical connection (significant), and that the PS-parallel only resulted in 0.05 mmmore bone loss than the conical connections (not significant). This is in agreement with our study’s outcome where there is no significant difference between the platform switched (PS) connection, but the difference with the platform matched (PM) is significant. Both Vetromilla (2019) and Yu (2020) did not look into the effect of platform switching which might explain why Yu (2020) found a significant difference between the conical and the non-conical group and why Vetromilla (2019) found fairly high amounts of bone loss in the internal-connection group (0.7 mm). This is closer to the 0.52 mm bone loss we found in our PM groups than to the 0.14 mm bone loss in our PS groups. Hsu et al. (2017) did compare platform-switching with platform-matching. They concluded that platform switched connections are accompanied with less peri- implant bone loss than the platform matched connections. Comparing the results of previous authors (Hsu et al., 2017; Caricasulo et al., 2018; Vetromilla et al., 2019; Yu et al., 2020) with the present review reveals that platform-switching plays an important protective role in preserving the level of peri-implant bone. Perhaps, supported by the Caricasulo (2018) results, it can even be cautiously stated that the presence of a platform switch has more influence on bone level change than the presence or absence of a conical component in the connection. According to our study, in contrast to bone level change platform switching seems to have little influence on the mid-buccal mucosa level. However, it must be noted that this is based on 3 PS-parallel groups and 5 PM-parallel groups, compared to 12 PS- conical groups. This uneven distribution might affect the statistical power of the meta- analysis. When searching for studies that compared implant abutment connections in