Caroliene Meijndert

118 Chapter 7 platform switching might have a positive effect on preserving peri-implant bone levels was also mentioned by Hsu et al. (2017). However, Caricasulo (2018) and Hsu (2017) did not focus specifically on the aesthetic region or on a possible effect on the aesthetic outcome. Vetromilla et al. (2019) did perform a systematic review on implant abutment connections in the aesthetic region. They concluded from the PES/WES that the internal hexagon performs better aesthetically, but were not able to quantify their observations. Additionally, they did not distinguish between platform-switched and platform-matched connections, but this might be a noteworthy nuance when considering Caricasulo’s (2018) outcome. Since the aesthetic outcome of a restoration in the aesthetic region is so important, it would be interesting to know if the implant abutment connection can contribute to achieving the best possible results. So far, to the best of our knowledge, a systematic review with a meta-analysis of the effect of solely internal connections in the aesthetic region, distinguishing between platform switching and –matching, is not available. Therefore, the aim of our systematic review was to determine whether the type of implant connection configuration, i.e. platform switched conical connections (PS- conical), platform switched parallel connections (PS-parallel) or platform matched parallel connections (PM-parallel), has a significant impact on peri-implant bone changes, whether an implant-abutment connection influences implant survival, and whether the stability of the mid-buccal mucosa level, as a factor determining the aesthetic outcome, is influenced by the connection configuration. Materials and Methods Research protocol This systematic review was conducted following the Cochrane Handbook for systematic reviews and was reported according to the PRISMA Statement guidelines 2009 (Moher et al., 2009). The protocol of this systematic review was entered under the PROSPERO registration number: ID: 225092. The research question was formulated by means of a PICO: P - single titanium implants in the maxillary aesthetic region I - conical implant-abutment connections C - parallel walled implant-abutment connections with and without a platform switch O - peri-implant bone level change