## 4 Discussion
### High-Frequency Studies  
In the RCTs evaluated, it was found that in one of the first articles not only of high frequency but also of vibrations as an adjuvant in orthodontic treatment in the study of [PERSON] et al., they reported the use of conventional brackets (Victory Series, 3M Unitek, Monrovia, CA, USA), and they used a device that provides a dental massage at 111 Hz, 0.06 N, for 20 min a day for 10 weeks; however, it showed no statistically significant difference for the resolution of crowding during the initial stage compared to the control group [22]. On the other hand, these results are opposite to those obtained by [PERSON] et al. who, although using high-frequency vibrations (125 Hz), performed them with a battery-powered electronic vibrating toothbrush (Colgate(r) Motion-Multi Action electric toothbrush) and conventional brackets (3M Gemini brackets; 3M Unitek Corporation, Monrovia, Calif). They observed a significant increase in canine movement in the experimental group compared to the control group (\(p\) < 0.001) [25]. [PERSON] et al. also used an electric toothbrush with an orthodontic head specially designed (Oral-B Triumph, OD17; Procter & Gamble, Cincinnati, OH, USA) as a vibration device (125 Hz), and they used MBT prescription brackets (3M Gemini brackets; 3M Unitek Corporation, Monrovia, Calif). The study was carried out on 28 patients of both sexes in a period of \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Evaluation Period** & **Study Design** & **Limitations** & **Number of Patients** & **Inconsistency of Results** & **Indirect Evidence** & **Other Considerations** & **Evidence Quality** & **Feedback** \\ \hline \hline \begin{tabular}{c} Tooth \\ movement \\ rate during \\ alignment \\ phase \\ \end{tabular} & RCT & \begin{tabular}{c} Serious \\ limitations. 1,2 \\ phase \\ \end{tabular} & \begin{tabular}{c} Studies 7 \\ (380) \\ \end{tabular} & Serious. 5 & Not & Serious. 6 & \begin{tabular}{c} There seems \\ not to be any \\ clinical \\ advantage in \\ the use of the \\ vibratory \\ apparatus. \\ \end{tabular} & \begin{tabular}{c} The amount of \\ movement was \\ the same with \\ use of the \\ vibratory \\ apparatus. \\ \end{tabular} & RCT & \begin{tabular}{c} Serious \\ limitations. 3,4 \\ \end{tabular} & \begin{tabular}{c} Studio 8 \\ (270) \\ \end{tabular} & Serious. 5 & Not & Serious & \begin{tabular}{c} Serious \\ serious. 5 \\ \end{tabular} & \begin{tabular}{c} The same with \\ the use of the \\ vibratory \\ apparatus. \\ \end{tabular} & \
\begin{tabular}{c} The use of \\ vibratory \\ apparatus. \\ \end{tabular} \\ \hline \hline
\begin{tabular}{c} Alignment: [PERSON] 2012, [PERSON] 2012, [PERSON] 2016, [PERSON] 2018, [PERSON] 2018, [PERSON] 2018, [PERSON] 2018. Canine retraction: [PERSON] 2015, [PERSON] 2016, [PERSON] 2017, [PERSON] 2019, [PERSON] 2019, [PERSON] 2019, [PERSON] 2020, [PERSON] 2020. 1 Unclear risk in random sequence generation, assignment concealment, participant blinding, incomplete information, and other biases. 2 Seven studies with a limited sample size were included (n = 380). 3 High risk of bias in the randomization, blinding, and other biases. 4 Eight studies with a limited sample size were included (n = 270). 5 Considerable heterogeneity. 6 Orthodontic technique, vibrational stimulus varied between studies. 7 Confidence in the estimation of the effect and its magnitude could change with new studies. \\ \end{tabular}
\end{table} 
Table 3: Population: Patients with orthodontic treatment. Intervention: Vibratory stimuli. 9 days, in which the degree of canine movement was evaluated. However, unlike the study by [PERSON] et al., the results showed no increase in dental movement (\(p>0.05\)) [29].