Diederik Hentenaar

72 Chapter 3 neither this parameter seems to be a discriminating factor to decide which therapy to apply. However, it should be kept in mind that, for air-polishing systems, the risk for emphysema may be increased in difficult to reach areas. Especially when it is needed to tilt the air-polishing nozzle. Moreover, air-polishers are limited to the removal of attached biofilms whereas hard deposits should be removed by hand. Interestingly, as reported by the experienced dental hygienists in this study, access of the peri-implant pocket appeared more challenging using a thick nozzle compared to the lean ultrasonic tip. Hence, these factors may indicate to recommend a different decontamination method in specific cases. At last, when baseline characteristics of the successful group of patients were compared with these of the unsuccessful ones, interesting differences regarding PPD (4.0mm vs 4.9mm, respectively), MBL (3.0mm versus 4.0mm, respectively) and time in function before therapy took place (7.2 versus 9.5 year) were seen. Considering the success of these patients up to 12 months after therapy, these parameters might indicate the importance of early diagnosis and therefore early commencement of non-surgical therapy. Limitations The following limitations should be addressed when interpreting the results of this study. First, suprastructures were not removed during this study which might have led to inadequate peri-implant accessibility and inadequate clinical measurements. In addition, hampered access (e.g., due to overcontoured suprastructures) of the peri- implant pocket could have complicated the insertion of the ultrasonic or air-polishing tip, and therefore led to an inadequate therapy effect. Second, this study might lack a true control therapy. However, to date, no non-surgical intervention seems to be the gold standard in the treatment of peri-implantitis. As a means of non-surgical treatment, mechanical debridement of the implant surface is primarily recommended (Renvert et al. 2019). Therefore a randomized study design in which two promising mechanical interventions were compared was chosen. This so, to analyze if the aforementioned treatment interventions could lead to appointing a superior standard therapy. Third, the marginal bone level measurements were done on peri-apical radiographs as well as on panoramic pictures. In the latter case, a standardized angulation of the picture could not be secured. Therefore, the measurements on the overview x-ray pictures might not have been as accurate for comparison purposes. However, given