The Effectiveness of Repetition or Multiplicity of Different Surgical and Non-Surgical Procedures Compared to a Single Procedure Application in Accelerating Orthodontic Tooth Movement: A Systematic Review and Meta-Analysis.

In this study, we aimed to assess the current scientific evidence concerning the effectiveness of combining two acceleration techniques or repeating an acceleration procedure in comparison with the single application in terms of the speed of the orthodontic tooth movement (OTM). We performed a comprehensive electronic search to retrieve relevant studies on 10 databases. Randomized controlled trials (RCTs) on fixed orthodontic treatment patients who received multiple types of acceleration techniques or underwent a repeated acceleration procedure compared to a single application were included. Version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2) was used for assessing the risk of bias of retrieved studies. A total of six RCTs were included in this review. Regarding multiple acceleration methods, it seems that the combination of low-level laser therapy (LLLT) with a surgical technique outperforms the single application of each technique separately. Additionally, the combination of two surgical interventions may have a synergistic effect leading to reduced treatment time compared to the application of a single intervention. Regarding acceleration method repetition, it seems that the re-application of surgical procedures twice is more efficient than the single application. The meta-analysis showed a non-significant difference in the canine retraction rate between the four-weekly micro-osteoperforations (MOPs) (three times of applications) and both the eight-weekly MOPs (two times of applications) [mean difference (MD) = 0.24; 95% CI: -0.2-0.77; p = 0.36], as well as 12-weekly MOPs (two times of applications) (MD = 0.06; 95% CI: -0.14-0.27; p = 0.55). Based on very low evidence, combining two acceleration techniques is superior over a single application in accelerating tooth movement. Again, very low evidence suggests that the efficacy of repetition of surgical procedures twice and three times is similar. Further high-quality RCTs are required to assess the benefit of repeating an acceleration procedure or combining two different methods. In addition, more insight is needed into the possible side effects associated with the repetition or multiplicity of procedures.