## 3 Results
### Statistical Analysis
#### 3.5.1 Clinical Studies  
The results from the statistical analysis among the study groups showing significantly better, indifferent, or significantly worse color and sensitivity outcomes (groups +1, 0, and \(-1\) respectively) are shown in Table 8.  
(a) Color change  
Regarding the color change, only the H\({}_{2}\)O\({}_{2}\) gel concentration can significantly affect this outcome. Therefore, this factor was further analyzed as shown in Figure 4.  
The difference in median dose levels applied was found to be significantly lower for the \(-1\) group than it was for the 0 group (\(p\) = 0.0032), with a mean \(\pm\) 95% confidence interval (CI) difference in (\(w/w\))% dose of \(-24.15\pm 10.15\)% H\({}_{2}\)O\({}_{2}\). From this, it can be concluded that the non-laser-treated control group required a H\({}_{2}\)O\({}_{2}\) dose level which was, on average, 24.15% (\(w/w\)) higher in order to achieve a status which is equivalent to that of the laser-activated bleaching group.  
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline \multirow{2}{*}{**Reference**} & \multirow{2}{*}{**Wavelength** **(nm)**} & \begin{tabular}{l} **Bleaching Gel** \\ **(Product Name)** \\ \end{tabular} & \multirow{2}{*}{**Fluence**} & \multirow{2}{*}{**Iradiation**} & **Pulp** \\  & & **(J/cm\({}^{2}\))** & & **Time (s)** & **Time (s)** \\ \hline \hline \multirow{2}{*}{[PERSON] [76]} & 532 & \begin{tabular}{l} Opalescence \\ Boost \\ \end{tabular} & 84 & 20 & 5.13 \\ \cline{2-6}  & 532 & \begin{tabular}{l} Beyond \\ \end{tabular} & 84 & 20 & 3.71 \\ \hline [PERSON] [91] & 980 & \begin{tabular}{l} Whiteness HP \\ \end{tabular} & 17.7 & 20 & 6.7 \\ \hline \hline \multirow{2}{*}{[PERSON] [89]} & 980 & \begin{tabular}{l} Opalescence \\ Xtra Boost \\ \end{tabular} & 180 & 30 & 14.06 \\ \hline \hline \multirow{2}{*}{[PERSON] [84]} & 980 & \
\begin{tabular}{l} Laserwhite 20 \\ \end{tabular} & 72 & 30 & 2.63 \\ \cline{2-6}  & 940 &
\begin{tabular}{l} Laserwhite 20 \\ \end{tabular} & 43 & 30 & 1.99 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Studies examining pulp temperature changes, including information on wavelength, bleaching gel, laser fluence, irradiation time, and temperature.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameter Examined** & **Color Change** & **Sensitivity** \\ \hline Gel concentration (median \\ H\({}_{2}\)O\({}_{2}\) dose grade) & \(p\) = 0.007 & ns \\ \hline Gel thickness & ns & ns \\ \hline Contact time (min) & \(p\) = 0.069 & ns \\ \hline Fluence & ns & ns \\ \hline Wavelength (nm) & ns & ns \\ \hline Handpiece type & ns & ns \\ \hline \hline \end{tabular}
\end{table}
Table 8: The parameters examined and the respective \(p\) values found regarding the two treatment outcomes. Abbreviations: ns, not significant (threshold significance level \(\alpha\) = 0.05).  
Nevertheless, for the contact time, this did not show any significant difference in terms of the color outcome (\(p\) = 0.069). However, on examining the contact times of each group (test and control), the values were significantly different (\(p\) = 0.002). Hence, it can be stated that, for no difference in whitening effect to be observed (score 0), a mean contact time of only 31.92 min was required for the test group, whereas 41.00 min for the control group was necessary, and this led to a clinically significant difference.  
The other examined parameters (gel thickness, fluence, wavelength, and handpiece type) did not exert a statistically significant effect on the color outcome (Table 7).  
(b) Sensitivity  
One-way ANOVA or its non-parametric equivalent (Kruskal-Wallis test) showed that no significant differences were detected in any of the weighted parameter values examined on the sensitivity outcome.