Diederik Hentenaar

54 Chapter 3 definitions and the use of a single type of investigative powder (i.e., glycine). Although beneficial clinical results (i.e., reduction of BoP and PPD) were found, complete disease resolution (e.g., no pockets with a PPD > 5mm, with concomitant bleeding and/or suppuration on probing and absence of progressive marginal bone loss > 0.5mm) seemed difficult to achieve. Glycine air-polishing could therefore not be appointed as favourable treatment method over others (i.e., plastic/titanium curettes, ultrasonic or laser therapy). Recently, a new air-polishing powder, i.e. erythritol, which is considered a sugar alcohol (similar to xylitol) and used as sugar substitute, has been introduced to the dental field. This powder is non-caloric, has a high gastrointestinal tolerance and does not increase blood glucose or insulin levels (de Cock 1999, de Cock 2018). In vitro studies report that erythritol seems to be more effective in terms of cleaning efficacy compared to previously used powders (e.g., glycine and sodium bicarbonate) (Drago et al. 2014, Moharrami et al. 2018). Moreover, studies describe a more effective reduction in the bacterial biofilm and inhibition of post-treatment biofilm re-growth, improved cell attachment, cell viability, and proliferation of osteoblasts (Drago et al., 2017, Matthes et al. 2017, Mensi, Cochis, Sordillo, Uberti, & Rimondini, 2018,). On the other hand, clinical periodontal maintenance studies on ultrasonic therapy, report comparable clinical and microbiological effects to subgingival air-polishing with erythritol powder (Müller, Moëne, Cancela, Mombelli, 2014). Ultrasonic therapy seems therefore another efficacious way to achieve infection control (Suvan et al., 2020). Compared to hand instrumentation, an ultrasonic device requires less effort and is less time consuming which makes it a preferable cleaning method in day- to-day clinical practice. Ultrasonic therapy seemed able to reduce clinical signs of inflammation (i.e., BoP) to a greater extent than carbon fiber/titanium curettes in the non-surgical treatment of peri-implantitis (Karring, Stavropoulos, Ellegaard, 2005; Renvert, Samuelsson, Lindahl, Persson, 2009). Yet, the effectiveness of both therapies (eryhtritol air-polishing and ultrasonic scaling) in the non-surgical treatment of peri- implantitis has not been investigated in a randomized controlled trial. Therefore, the current study was set up to test the hypothesis that air-polishing with erythritol powder has the same effect as ultrasonic therapy on clinical, radiographical and microbiological parameters in the non-surgical treatment of peri-implantitis. In addition, the aim was to evaluate the pain/discomfort of both therapies.