# Acceleration Techniques for Teeth Movements in Extractive Orthodontic Therapy
## 4 Discussion
### Vibration Therapy  
Several trials suggest that mechanical vibratory devices, in their current setting, do not offer significant advantages for orthodontic OTM. In the study by [PERSON] et al. (2022), the effect of a customised vibratory device on the speed of OTM, particularly during canine retraction, was analysed [43]. The canine retraction was initiated at least four months after the first maxillary premolars extraction to eliminate any effects due to post-extraction regional acceleratory phenomena. Additionally, a customised vibratory device was used to reduce cost, which was economically advantageous compared to commercial devices and maintained a frequency of 30 Hz and a force of 0.25 N.  
The study's primary objective was to evaluate the effect of low-frequency vibrations (30 Hz) on the speed of OTM through the customised vibratory device by comparing canine retraction between the vibrated and non-vibrated sides. The present study concluded that low-frequency vibratory stimulation (30 Hz) applied for 20 min per day using a customised vibratory device does not significantly accelerate the rate of canine retraction [43]. The trial conducted by [PERSON] et al. (2020) aimed to compare two groups of adolescents undergoing complete orthodontic treatment with and without using the AcceleDent Aura device [59,71]. The study results showed that the total amount of OTM did not show statistically significant differences between the groups at any of the three time intervals. The study attempted to minimise bias and observed an average monthly OTM rate of 1.21 \(\pm\) 0.32 mm in the CGr and 1.12 \(\pm\) 0.20 mm in the ExGr. Figure 4: Mechanism of action of MOPs. In conclusion, using the AcceleDent Aura device did not significantly affect accelerating maxillary canine retraction or reducing perceived pain during orthodontic treatment [59]. [PERSON] et al. (2017) investigated the effects of vibration-enhanced OTM and the underlying mechanisms [48]. The vibration was applied to the buccal surface of canines for 10 min daily for 28 days, using an Oral B (USA) Hamming Bird vibrating unit. The amplitude of the vibrating force was measured at approximately 0.2 N (20 g), and the frequency of the vibrations was 50 Hz. The results showed that the total space closure and distalisation of canines were significantly more significant on the vibration side than on the non-vibration side. The research concluded that applying low to medium-frequency vibration, such as 50 Hz in this study, can accelerate OTM without causing adverse effects like tissue necrosis or other undesirable outcomes [72]. The study suggested that the mechanism for OTM acceleration may be more biologically based than mechanically based, as the short duration of vibration application seems to stimulate OTM-related cells and factors via temporarily sustained and dynamic amplification of the pressure levels within the periodontal ligament (PDL). Therefore, applying mechanical vibrations could increase the speed of OTM and may be considered a promising method for accelerating extraction-based orthodontic treatments [48]. [PERSON] et al. (2020) evaluated the rate of orthodontic movement in adolescent patients combined with low-frequency mechanical vibrations in passive self-ligating and conventional appliances [44]. The customised vibrating device used had a frequency of 30 Hz and was used by patients for 20 min per day during the space closure phase. The primary objective was to measure the space closure rate (mm/month). The results showed no statistically significant differences regarding the space closure rate among the three groups. Therefore, the null hypothesis was confirmed, namely that there was no difference in the rate of orthodontic movement between passive self-ligating and conventional appliances in patients with low-frequency vibrations [44; 73]. Another method described is the pulsed electromagnetic field (PEMF) used to reduce TT, as described in the study by [PERSON] (Patil) and [PERSON] (2022) [32].