Diederik Hentenaar

97 Erythritol air-polishing in surgical peri-implantitis treatment DISCUSSION To the best of our knowledge, this is the first study that compared the use of erythritol powder air-polishing with saline soaked gauzes as implant surface debridement methods during a resective surgical treatment of peri-implantitis. The results showed no significant clinical differences between both groups in terms of our primary outcome BoP and secondary outcomes PPD, Plq and marginal bone loss, up to 1-year after therapy. Neither microbiological differences nor differences in full mouth clinical parameters were found between the groups. Only levels of SoP differed after 12 months follow-up. Hence, our null-hypothesis of erythritol air-polishing being not better than saline sauked gauze as cleansing method in terms of clinical, radiographical and microbiological effects could be adopted. Comparable clinical studies using erythritol air-polishing as implant surface decontamination method were not found in the literature. However studies that evaluated the use of air-polishing as single decontaminating method in a resective peri- implantitis treatment approach, as such, recently appeared in the literature (Toma, et al. 2019; Lasserre, et al. 2020). Both previous studies evaluated the use of glycine powder and applied this through a handpiece with plastic (subgingival) nozzle insert. After 6 months follow-up, it was concluded that glycine air-polishing and the use of a titanium brush both were more effective than plastic curettes (Toma, et al. 2019) and glycine air-polishing was as effective as implantoplasty (Lasserre, et al. 2020). As compared to the present study, glycine air-polishing did not appear significantly more effective than control therapies in terms of BoP reduction. Neither for the secondary parameter ‘presence of plaque’ differences were found, which also seems to corroborate our findings. Regarding PPD reduction, the study by Lasserre et al. (2020) showed no difference in PPD reduction between both groups. A significant result was however found (mean ±2.2mm vs ± 1.7mm) in study by Toma et al. (2019) favoring the use of air-polishing. Whether these differences with the present study could be explained by the use of a different powder, different handpiece insert or shorter length of follow- up remains to be found. For levels of SoP, of which no data was found in the studies by Toma et al. (2019), no difference between both groups was found in the study by Lasserre, et al. (2020). Since the present study found a significant difference between both groups, the literature seems inconclusive thus far with regard to SoP. Why air- polishing more than saline sauced gauzes caused this reduction remains unclear. To better understand the role of suppuration in peri-implant health, future studies should include this parameter more often. Considering that stable marginal bone levels and comparable (low) success rates were found (at implant level; 29%, 26%, respectively) this might suggest that mechanical cleaning with air-polishing in a resective surgical 4