## 4 Discussion  
Peri-implantitis treatment is a crucial topic widely discussed in dentistry. During the last few years, various protocols for peri-implantitis have been developed, without clear evidence of which is the best way to approach this unwilling complication [16]. In the present study, we aim to establish if there are differences between surgical or non-surgical approach to peri-implantitis. A recent randomized clinical trial by [PERSON] et al. [19] compared surgical and non-surgical debridement with a 12-month period of observation, evidencing no statistical differences between the two groups; the authors concluded that non-surgical debridement should be considered the first therapeutic choice for peri-implantitis, mainly mild to moderate cases. On the contrary, in an in vitro study, [PERSON] et al. [20], comparing air polishing efficacy conveyed through surgical or non-surgical modality, concluded that a surgical approach results in significant better surface decontamination. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Test Group** & **Control Group** & \(p\) **Value** \\ \cline{2-4}  & **Mean \(\pm\) SD** & **Mean \(\pm\) SD** & \(p\) **Value** \\ \hline BoP & 2.14 \(\pm\) 0.49 & 2.16 \(\pm\) 0.51 & \textless{}0.014 * \\ P.S. & 0.94 \(\pm\) 0.19 & 0.97 \(\pm\) 0.21 & \textless{}0.017 * \\ P.D. & 5.79 \(\pm\) 0.21 & 5.84 \(\pm\) 0.18 & \textless{}0.015 * \\ \hline \hline \end{tabular} BoP—bleeding on probing; PS.—presence of suppuration P.D.—peri-implant depth; *—\(p\) value \textless{} 0.001 statistically significant.  
\end{table} 
Table 6: Peri-implant parameters among test group and control group pre-treatment. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**OHLLT S.A.** & **Upper** & **Lower** & **Tot** \\ \hline Total Amount & 54 & 34 & 88 \\ Bone Loss Post-Operative & 2.1 mm & 2.4 mm & 2.3 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Bone loss post-operative (t1) for implants with surgical approach (S.A.). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**OHLLT Non-S.A.** & **Upper** & **Lower** & **Tot** \\ \hline Total Amount & 67 & 72 & 139 \\ Bone Loss Post-Operative & 3.9 mm & 3.8 mm & 3.8 mm \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Bone loss post-operative (t1) for implants with non-surgical approach (non-S.A.). Non-surgical treatment of peri-implantitis has been widely discussed in the literature. [PERSON] et al. [21] conducted a 12-month clinical and radiographical case series utilizing ultrasonic scaler debridement, glycine air abrasive, and metronidazoleazole followed by supportive maintenance; the authors reported effectiveness in reducing peri-implant pocket depth and suppuration, but no effects in reducing bleeding on probing. A systematic descriptive review by [PERSON] [22] reported that non-surgical treatment of peri-implant mucositis achieved significant positive results while peri-implantitis lesions cannot be completely resolved with only this treatment modality. Another important key factor in determining usability of non-surgical approach is the timing of peri-implant diagnosis: [PERSON] et al. [23] stated that early diagnosis of peri-implantitis could lead to a higher possibility of success of non-surgical management; similarly, [PERSON] et al. [24] stated that non-surgical treatment is recommended for marginal bone loss less than 2 mm around the implant, whilst surgical treatment (apically positioned flap or flap surgery) is recommended for marginal bone loss greater than 2 mm. Therefore, earlier detection of the disease may result in less-invasive treatment modality for peri-implantitis treatment. On the other hand, in the literature, there are many studies focusing on the surgical approach to peri-implantitis. [PERSON] et al. [25] conducted a retrospective study in which peri-implant probing depth, bleeding on probing and crestal bone level demonstrated a considerable enhancement, even considering long-term time span (2 to 11 years). [PERSON] et al.