## 4 Discussion  
The systematic literature search showed that several systematic reviews and meta-analyses that addressed air powder water jet technology were performed in the past decade. Whereas the proof for equality in the supportive periodontal treatment is well demonstrated by several studies, systematic reviews on the effect of APWJT as a single measure in active periodontal treatment are scarce. Most of the clinical trials included in the systematic reviews for active periodontal treatment used low-abrasive air powder water jet technology as an adjunct to conventional subgingival debridement with curettes or (ultra)sonic devices. Regarding peri-implantitis/mucositis, systematic reviews exist for both active and maintenance therapy, but the underlying clinical studies, although evenly distributed, are few. The focus questions, as formulated above, can be, based on the results of this umbrella review, discussed as follows. Does low-abrasive (glycine, erythroid or trehalose powder) APWJT have a beneficial effect on clinical parameters compared to standard mechanical debridement in active or supportive periodontal and peri-implantitis therapy? The included reviews for periodontal treatment on teeth, as active or supportive therapy, showed that APWJT is a validated adjunct in active periodontal therapy and can be used alone in supportive therapy. The use of APWJT devices either alone or as an adjunctive measure showed similar results to conventional subgingival debridement with hand instruments or ultrasonic devices. For the treatment of peri-implant mucositis, APWJT devices may be used as an alternative. [PERSON] et al. [7] and [PERSON] et al. [41] reported that APWJT as a standalone therapy leads to comparable clinical results. [PERSON] et al. [39] even reported higher PPD reduction by APWJT after 6 months, as a meta-analysis of two included studies showed. While [PERSON] et al. [39] included three studies reporting on APWJT as a standalone, [PERSON] et al. [7] and [PERSON] et al. [41] included only one, which was not used by [PERSON] et al. [39] (Table 4). This might be the reason for the slightly different conclusions and discloses the low level of evidence. The use of APWJT as an adjunct in the treatment of peri-implant mucositis does not lead to further improvements [7; 39; 41]. All of the reviews included the same two studies. While one study [47] showed improved results concerning BOP and PPD reduction, the other included study [46] showed no improvements. The meta-analysis by [PERSON] et al. that compared PPD reduction showed no significant differences [41]. In the treatment of peri-implantitis, the alternative use of air powder water jet technology may yield better results, while its use as an adjunct does not lead to further improvements [7; 41; 45]. A meta-analysis that compared PD and BOP reduction using APWJT as an alternative technique to conventional measures showed results that favored APWJT regarding BOP reduction [7]. Additionally, [PERSON] et al., [PERSON] et al. and [PERSON] \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Author** & **Year** & **Test Measures** & **Control Measures** & **Clinical Outcomes** & **Microbiological Outcomes** & **Patient-Related Outcomes** \\ \hline \multirow{6}{*}{[PERSON] et al. [38]} & \multirow{4}{*}{2022} & 1. GPAP & 1. HI + CHx & No m-a available: & \multirow{4}{*}{(\(N=0\))} \\  & 2. HI + GPAP + & 2. HI + SB + & & \\   prophylaxis brush & prophylaxis brush & prophylaxis brush & & & \\  3. HI + GPAP + & 3. HI + SB + & & & \\   prophylaxis brush + & prophylaxis brush & & & & \\   CHx varnish & & + CHx & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Results of the included systematic reviews on supportive peri-implantitis therapy (PIT) and peri-implant mucositis therapy (PIM). (BOP: bleeding on probing reduction; CAL: clinical attachment level gain; CHx: Chlorhexidine; GPAP: glycine powder air polishing; HI: hand instruments; M-a: meta-analysis; N: number of included studies; n.a.