# Long-Term Stability of Er:YAG Laser Non-Surgical Periodontial Treatment
## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{8}{c}{**Laser Group**} & \multicolumn{8}{c}{**Control Group**} \\ \hline
**CAL** & **N** & \(\overline{\pi}\) & **S\({}_{\mathbf{X}}\)** & **Mean Diff.** & **t** & \(p\)**-Value** & **N** & \(\overline{\pi}\) & **S\({}_{\mathbf{X}}\)** & **Mean Diff.** & **t** & \(p\)**-Value** \\ \hline CAL—baseline & 572 & 4.71 & 0.78 & \multirow{2}{*}{1.37} & \multirow{2}{*}{29.787} & \multirow{2}{*}{_0.00_} & 527 & 4.66 & 0.74 & \multirow{2}{*}{1.09} & \multirow{2}{*}{23.322} & \multirow{2}{*}{_0.00_} \\ CAL—1 month & 572 & 3.34 & 1.15 & & & & & & & & & \\ CAL—3 months & 572 & 3.05 & 1.19 & \multirow{2}{*}{0.28} & \multirow{2}{*}{5.671} & \multirow{2}{*}{_0.00_} & 527 & 3.56 & 1.20 & \multirow{2}{*}{0.45} & \multirow{2}{*}{9.221} & \multirow{2}{*}{_0.00_} \\ CAL—6 months & 572 & 3.07 & 1.22 & \multirow{2}{*}{\(-\)0.02} & \multirow{2}{*}{\(-\)0.045} & \multirow{2}{*}{0.96} & 527 & 3.10 & 1.25 & \multirow{2}{*}{\(-\)0.03} & \multirow{2}{*}{0.657} & \multirow{2}{*}{0.51} \\ CAL—6 months & 572 & 3.07 & 1.22 & \multirow{2}{*}{\(-\)0.04} & \multirow{2}{*}{\(-\)1.224} & \multirow{2}{*}{0.22} & 527 & 3.15 & 1.20 & \multirow{2}{*}{\(-\)0.11} & \multirow{2}{*}{2.438} & \multirow{2}{*}{_0.02_} \\ CAL—12 months & 572 & 3.11 & 1.12 & & & & & & & & & \\ \hline CAL—baseline & 572 & 4.71 & 0.78 & \multirow{2}{*}{1.59} & \multirow{2}{*}{34.068} & \multirow{2}{*}{_0.00_} & 527 & 4.66 & 0.74 & \multirow{2}{*}{1.09} & \multirow{2}{*}{29.872} & \multirow{2}{*}{_0.00_} \\ CAL—12 months & 572 & 3.12 & 1.12 & & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Dynamic changes in the level of clinical attachment after treatment in both groups. Table 6 presents the differences between both instrumentation methods in terms of bleeding on probing up to one year. In the first and third month after treatment, it is found that Er:YAG laser-treated pockets demonstrate almost 8% and 10% less bleeding sites, respectively, than those instrumented with hand instruments (\(p<0.05\)). The values achieved in the sixth month do not indicate statistically significant differences. Regarding the data at 12 months post treatment, the biggest intergroup difference for BOP is demonstrated, with more significant reduction in the number of bleeding sites in the Er:YAG laser-treated group. There are nearly 15% less bleeding sites in the test group than in the control group (\(p<0.05\)). In total, the bleeding sites in the test group decreased almost 6 times as a long-term result (1 year after therapy). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**BOP**} & \\ \cline{2-9}
**Visit** & **Yes** & **No** & **Difference\%** & **\(\mathbf{\chi^{2}}\)** & \(\boldsymbol{p}\)-Value** \\ \cline{2-9}  & **\%** & **\%** & **\%** & & & & \\ \hline
**Control\_baseline** & 87.9 & 12.1 & & & & & & \\ Laser\_baseline & 85.6 & 14.4 & & 2.3 & 1.168 & 0.28 \\ \hline
**Control\_1 month** & 33.7 & 66.3 & & & & & \\ Laser\_1 month & 25.9 & 74.1 & & 7.8 & 7.984 & **0.01** \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of bleeding on probing between both groups up to one year. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**PPD**} & \multicolumn{3}{c}{**Control Group**} & \multicolumn{3}{c}{**Laser Group**} & \\ \cline{2-9}  & **N** & \(\mathbf{\bar{x}}\) & **S\({}_{\mathbf{X}}\)** & **N** & \(\mathbf{\bar{x}}\) & **S\({}_{\mathbf{X}}\)** & **Difference** & **t** & \(\boldsymbol{p}\)** \\ \hline
**Initial visit** & 527 & 4.59 & 0.69 & 572 & 4.58 & 0.69 & 0.01 & 0.206 & 0.84 \\ \hline
**1 month** & 527 & 3.36 & 1.09 & 572 & 3.16 & 1.09 & 0.20 & 3.023 & _0.00_ \\ \hline
**3 months** & 527 & 2.91 & 1.14 & 572 & 2.84 & 1.06 & 0.08 & 1.143 & 0.25 \\ \hline
**6 months** & 527 & 2.95 & 1.06 & 572 & 2.82 & 1.06 & 0.13 & 1.982 & _0.05_ \\ \hline
**12 months** & 527 & 3.02 & 1.00 & 572 & 2.88 & 0.99 & 0.15 & 2.482 & _0.01_ \\ \hline \hline \end{tabular}
\end{table}