## 3 Results
### Population Pool  
Thirteen trials for a total of 21 groups of treatment reported data on 706 implants and 399 patients with a follow-up from 3 to 7 years after surgical intervention for peri-implantitis (Table 2). The most commonly used clinical parameters to diagnose peri-implantitis were:  
* Bone loss (BL), reported in % to the length of the implant [26; 27], millimeters [14; 28; 29; 30; 31; 32; 33], number of threads exposed [34], defect morphology [9; 14; 27; 32], or evidence of progressive bone loss [35; 36; 37];
* Pathologic probing depth (PD), with a cutoff between health and disease that ranged between >4 mm [27] and >6 mm [9];
* Marginal tissue inflammation reported as bleeding on probing (BoP) or suppuration on probing (SoP) [14; 27; 33; 34; 35; 36; 37; 31; 33]. * The sample size of individual studies ranged between 19 implants [14; 34] and 168 implants [29]. Studies included a combination of minimally rough and moderately rough implant surfaces, as well as tissue level and bone level macro-designs. Biological criteria to evaluate success after treatment were missing in many trials [26; 29; 32; 35; 36; 37]. When reported, cut-off probing depth to consider the treatment successful was set as 4 mm [33] or at 5 mm [9; 27; 28; 30; 31]. Radiographic criteria for biological success were defined in seven studies [9; 14; 27; 30; 31; 33; 34] and varied from no further bone loss to 25% of defect fill [31]. Absence of BoP and SoP was required by five studies [9; 27; 28; 30; 31]. The mean follow-up in years ranged from 3 years [26; 27; 28; 36; 37] to 7 years [9]. Figure 1: Flow chart for the article selection according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Study** & **Initial** & **Initial** & **Final** & **Final** & **Implant** & **Implant Type** & **Diagnosis** & **Biological Success** & **Follow-Up** \\
**Reference** & **Patient** & **Implant** & **Patient** & **Final Implant** & **Implant Type** & **Diagnosis** & **Biological Success** & **Follow-Up** \\ \hline  & & & & & & & & PD \(<\) 5 mm & \\ [PERSON] et al. & & & & & & & PD \(>\) 4 mm & BoP/SoP\(-\) & \\ [PERSON] et al. & & & & & & & BoP/SoP\(+\) & Further BL \(<\) 10\% & \\
2018 & 30 & 30 & 30 & 30 & N/P & B\(+\) \(>\) 20\% & REC \(<\) 0.5 mm for & 3 y \\  & & & & & & Crater defect & anterior implants & \\  & & & & & & Function for \(>\)2 years & REC \(<\) 1.5 mm for & \\  & & & & & & & posterior implants & \\ \hline  & & & & & & & & \\ [PERSON] et al. & 29 & 15 test & 11 test & 11 test & Astra Tech & PD \(\geq\) 5 mm & \\
2018 & 29 & 14 contr. & 9 contr. & 9 contr. & Straumann & BoP/SoP\(+\) & No further BL & 5 y \\  & & & & & & & & Angular BL \(\geq\) 3 mm & \\ \hline Heitz-Mayfield & & & & & & & & \\  & 24 & 36 & 20 & 26 & N/P & PD \(\geq\) 5 mm & \\  & & & & & & BoP/SoP\(-\) & No further BL & \\ \hline [PERSON] et al. & & & & & & & & \\
2017 & 26 & 12 SLA & 12 SLA & 12 SLA & Straumann & PD \(>\) 6 mm & PD \(\leq\) 5 mm & \\  & & 14 TPS & 12 TPS & 12 TPS & 12 TPS & Straumann & Crater defects & BoP/SoP\(-\) & 7 y \\ \hline  & & & & & & & & No further BL & \\ \hline  & & & & & & & & \\  & 2017 & 100 & 179 & 83 & 148 & Nobel Bicare & PD \(\geq\) 6 mm & PD \(\leq\) 5 mm & \\  & & & & & & & & BoP/SoP\(+\) & 3 y \\  & & & & & & Straumann & BoP/SoP\(+\) & BoP/SoP\(-\) & \\  & & & & & & & & \\  & & & & & & Neoss & & Further BL \(\leq\) 0.5 mm & \\ \hline  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \end{tabular}
\end{table} 
Table 2: Demographics and diagnostic criteria of included articles. Abbreviations, BoP: bleeding on probing (+/-). BL: bone loss (mm). N/P: not provided. PD: probing depth (mm). REC: recession (mm). SLA: sandblasted acid-etched. SoP: supuration on probing (+/-). TPS: titanium plasma-sprayed.