## 3 Results  
The mean age of the participants was 17.5 (\(\pm\)1.54), with 15 females and 17 males. A Mann-Whitney test indicated that there was no significant difference in the PP scores at T1 point of evaluation for the placebo and active groups (Mdn = 32.50). However, PP scores were significantly different at T2 point of evaluation for the active group and placebo groups were Mdn = 18.91 and Mdn = 46.81, respectively, at the end of the 1 st week after treatment, U = 54, \(z=-6.302\), \(p<0.00\). Similarly, at the end of the 4 th week after treatment, there was a significant difference in PP scores at T3 point of evaluation for the active group (Mdn = 17.19) and placebo group (Mdn = 47.81), thus indicating a predictable beneficial effect of the active group U = 22, \(z=-0.6730\), \(p<0.00\). The results of mean rank score in the active group indicate that the pain perception reduced over time, i.e., from T1 to T3, suggesting a reduction of pain perception by the participants over a period of time (Figure 1 and Table 2).  
A Pearson correlation coefficient was computed to assess the relationship between the PP in the active and placebo groups over time from T1, T2, and T3. A positive correlation between the two variables, r = 0.985, \(n\) = 32, \(p\) = 0.05, was observed. These findings summarize the results (Table 3). Overall, there was a strong, positive correlation between time and the active and placebo groups. Increases in the time of application of active gel were correlated with increased reduction in PP.  
\begin{table}
\begin{tabular}{c c c} \hline \hline Randomization of patients into treatment & A computer software program was used to code each participant for the NBFG and placebo-gel application to avoid bias. \\ \hline NBFG application & Initially a trained dental assistant applied the NBFG and placebo-gel followed by training of the patients by a dental assistant. The patients were instructed to follow the same protocol. \\ \hline \multirow{6}{*}{Pain perception} & The numerical rating scale (NRS) questionnaire was used to measure PP. The numerical scale consisted of segments ranging from 0 to 10, with 0 being “no pain” and 10 being “the worst pain imaginable”. The participants picked (verbal version) or drew a circle around (written version) the number that best describes the pain dimension, usually intensity. A trained dental assistant recorded initial baseline data (T1), immediately after case and control selection. The participants were asked to record pain on both sides (active and placebo side) using 2 sets of questionnaires at the 7 th day (T2) and the 28 th day (T3). In addition, telephone calls/message were made on the 7 th day and the 28 th day (T3) to ensure collection of data. \\ \hline \multirow{6}{*}{Statistical analysis} & Statistical analysis was performed using IBM SPSS Statistics version 22.0 (IBM Co., Armonk, NY, USA). The mean rank values of PP among the 2 groups were obtained by descriptive analysis. Mann–Whitney U-test was used to compare the level of PP between the 2 groups and disparities between time points, i.e., T1, T2, and T3. \\ \cline{1-1}  & Spearman correlation test was used to evaluate the correlation between PP and time of application of active and placebo-gel. \\ \hline \hline \end{tabular}
\end{table}
Table 1: _Cont._  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**(\(n\) = 64)**} & **T1** & **T2** & **T3** \\ \hline Mann–Whitney U & 512 & 54 & 22 \\ Wilcoxon W & 1040 & 582 & 550 \\ Test Static & 512 & 54 & 22 \\ Standard Error & 71.49 & 72.67 & 72.80 \\ Standardized Test Statistic & 0.000 & \(-6.302\) & \(-6.730\) \\ Asymptotic Sig. (2-sided test) & 1.000 & \(<\)0.001 1  & \(<\)0.001 2  \\ \hline \hline \end{tabular}
\end{table}
Table 2: PP in active vs. placebo group in T1, T2, and T3 (Mann–Whitney U-test).