Caroliene Meijndert

151 General discussion and conclusions Strengths and limitations Considering the results of all the studies described in this thesis, some strengths can be mentioned. As far as reasonably applicable, all the patients were treated under the same surgical and post-surgical conditions. Except for half of the patients in the tissue level study, all the patients were treated in the same university setting, by the same experienced surgical and prosthetic team. All the patients were included under the same criteria (periodontally healthy and non-smoking; single tooth replacement with neighbouring natural teeth) and the interventions were performed under a prophylactic antibiotic and chlorhexidine mouth rinse regime. Some limitations have to be addressed with respect to comparison of the different studies. Studies with healed sites as well as studies with post-extraction sites are present. In addition the treatment sites exhibited different grades of bone deficiencies. Different implant designs were used which have also been subject to different developments in micro- and macrostructure through time. Finally, the studies in this thesis had different follow-up periods and, as with the 5-year and 10-year studies, had different observers to collect the data during the first year- even though it was calibrated. A direct comparison of the results from the studies is, therefore, not possible. Future perspectives The studies described in this thesis evaluate a decade of treatment with Straumann implants in the aesthetic region. During these years, the manufacturer developed various implant components to meet the changing demands of the market following the advancing insights from research. The outcomes are favourable, from the oldest up to the most recent implant designs. However, the more recent implant designs (for example the tapered implants) were only evaluated for 1-year. To ensure the successfulness of these implants, long term evaluation is needed. When writing this thesis, it repeatedly emerged that the studies could not be properly compared with other studies available, due to the various measuring methods and reporting of the data outcomes. Implant survival and bone level change are often reported but important parameters, such as aesthetic outcome and patient centred outcome of a treatment, are forgotten. Forthcoming is a need to implement a uniform set of methods to evaluate and report aesthetic outcomes and patient satisfaction. 8