## Results
### Main Outcome of the Study
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Investigators** & **Changes in PPD (mm) Comparing Test and Control Groups** \\ \hline [PERSON] et al. [14] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 4.66 \(\pm\) 0.39 & T0: 4.95 \(\pm\) 0.95 \\  & Follow-up:3.56 \(\pm\) 0.69 \({}^{*}\) & Follow-up: 3.93 \(\pm\) 0.23 \({}^{*}\) \\ \hline [PERSON] et al. [15] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 5.13 \(\pm\) 0.34 & T0: 5.27 \(\pm\) 0.069 \\  & Follow-up:2.23 \(\pm\) 0.67 \({}^{*}\) & Follow-up: 3.67 \(\pm\) 0.75 \({}^{*}\) \\ \hline [PERSON] et al. [16] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 6 \(\pm\) 1.1 & T0: 5.9 \(\pm\) 0.99 \\  & Follow-up: 3.5 \(\pm\) 0.8 & Follow-up: 3.5 \(\pm\) 0.6 \\ \hline [PERSON] et al. [18] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 6.0 \(\pm\) 1.1 & T0: 5.9 \(\pm\) 0.99 \\  & Follow-up: 4.3 \(\pm\) 0.94 \({}^{*}\) & Follow-up: 5 \(\pm\) 0.66 \({}^{*}\) \\ \hline [PERSON] et al. [19] & aPDT + SRP (\(\geq\)4 mm) & SRP (\(\geq\)4 mm) \\  & T0: 5.79 \(\pm\) 1.06 & T0: 5.45 \(\pm\) 0.77 \\  & Follow-up: 4.29 \(\pm\) 0.95 & Follow-up: 4.54 \(\pm\) 0.88 \\ \hline [PERSON], et al. [20] & aPDT + SRP (\(\geq\)6 mm) & SRP (\(\geq\)6 mm) \\  & T0: 4.96 \(\pm\) 1.11 & T0: 4.91 \(\pm\) 1.02 \\  & Follow-up: 3.54 \(\pm\) 0.94 & Follow-up: 3.5 \(\pm\) 1 \\ \hline [PERSON] et al. [17] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 5.11 \(\pm\) 0.56 & T0: 5.15 \(\pm\) 0.46 \\  & Follow-up: 2.83 \(\pm\) 0.47 \({}^{*}\) & Follow-up: 2.83 \(\pm\) 0.4 \({}^{*}\) \\ \hline [PERSON] et al. [21] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 6.04 \(\pm\) 0.82 & T0: 6.08 \(\pm\) 0.73 \\  & Follow-up: 3.53 \(\pm\) 0.58 \({}^{*}\) & Follow-up: 5.08 \(\pm\) 0.66 \({}^{*}\) \\ \hline [PERSON] et al. [22] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 4.71 \(\pm\) 0.863 & T0: 5.22 \(\pm\) 0.924 \\  & Follow-up: 2.27 \(\pm\) 1.024 \({}^{*}\) & Follow-up: 3.28 \(\pm\) 0.749 \({}^{*}\) \\ \hline [PERSON] et al. [23] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 3.37 \(\pm\) 0.47 & T0: 3.37 \(\pm\) 0.46 \\  & Follow-up:1.3 \(\pm\) 0.36 \({}^{*}\) & Follow-up: 2.19 \(\pm\) 0.48 \({}^{*}\) \\ \hline [PERSON]\(\acute{\text{c}}\), Z., et al. [25] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 3.75 \(\pm\) 0.7 & T0: 3.78 \(\pm\) 0.75 \\  & Follow-up: 2.79 \(\pm\) 0.61 \({}^{*}\) & Follow up: 2.92 \(\pm\) 0.61 \({}^{*}\) \\ \hline [PERSON], et al. [26] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 6.5 \(\pm\) 0.61 & T0: 6.4 \(\pm\) 0.75 \\  & Follow-up: 3.7 \(\pm\) 0.86 & Follow-up: 4.8 \(\pm\) 0.77 \\ \hline  & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 7.9 \(\pm\) 1.71 & T0: 7.53 \(\pm\) 1.31 \\  & Follow-up: 5.43 \(\pm\) 1.36 & Follow-up: 5.37 \(\pm\) 0.85 \\ \hline [PERSON] et al. [24] & aPDT + SRP (\(\geq\)5 mm) & SRP (\(\geq\)5 mm) \\  & T0: 4.7 \(\pm\) 0.2 & T0: 4.5 \(\pm\) 0.07 \\  & Follow-up: 1.3 \(\pm\) 0.2 & Follow-up: 1.5 \(\pm\) 0.1 \\ \hline \end{tabular} aPDT, antimicrobial photodynamic therapy; SRP, scaling and root planing. The asterisk “\({}^{*}\)” indicate the presence of a statistically significant difference from baseline to the follow-up (\(p<0.05\)).  
\end{table} 
Table 2: Outcomes (PPD) of the research articles included in the current review. Concerning the clinical attachment level (CAL) out of eleven studies evaluated this parameter, two studies noted a statistically significant improvement after three months in the test group compared to the control group, [PERSON] et al. (2016) (test 1.8 mm \(\pm\) 0.88 vs. control group 2.9 mm \(\pm\) 0.7), [PERSON] et al. (2012) (test: 3.06 \(\pm\) 1.756 vs. control: 4.06 \(\pm\) 1.725). In most articles (nine) we found no significant difference in parameters between the test group and the control one (14; 16; 17; 19; 20; 21; 24; 25; 27). However, in the study by [PERSON] et al. (2011), there was a further increase in CAL after six months in the test group compared to the control one.