Alan Kwong Hing, DDS, MSc*

PBM Healing International, Hong Kong

*Corresponding Author: Alan Kwong Hing, PBM Healing International, Hong Kong

Abstract
Objective: To evaluate whether adjunctive vibration produces a clinically meaningful effect in clear aligner therapy.

Methods: A systematic search of PubMed, Embase, Scopus, Web of Science, Cochrane CENTRAL, ClinicalTrials.gov, WHO ICTRP, and grey literature (inception to 24 September 2025) identified 1350 records. After deduplication, 948 were screened, 80 assessed in full text, and 10 human studies included of which 6 were clear-aligner specific (3 RCTs, 3 nonrandomized; n≈285 participants). Studies were analyzed for vibration frequency, dose, outcomes (duration, refinements, pain), and risk of bias (RoB 2, ROBINS-I). Supplementary manual reference checks were incorporated. No meta-analysis was feasible due to heterogeneity.

Results: All three RCTs (LFV ~30 Hz or HFV ~120 Hz) found no acceleration or pain reduction in conventional protocols. Three nonrandomized studies reported shorter duration (~15–25%, p<0.05), fewer refinements (~1 set), and lower pain (VAS 0.8–1.2) with HFV in weekly exchange protocols; one included low-level laser therapy (LLLT). No increased root resorption was reported. Safety signals did not differ across studies.

Conclusions: HFV (~100–120 Hz, ~3–5 min/day) shows potential to accelerate OTM without safety concerns. Preclinical evidence provides mechanistic support, and human data suggest efficacy in canine retraction, though larger RCTs are needed. In aligners, benefits are context- specific to weekly exchanges. HFV (~100–120 Hz, 3–5 min/day) may modestly reduce pain during weekly aligner exchanges, while LFV (~30 Hz) shows no benefit.

Keywords: orthodontic tooth movement, vibration, high-frequency vibration, clear aligners, human studies, systematic review, mechanotransduction

Introduction
Orthodontic treatment with clear aligners is popular for aesthetics and comfort, but prolonged duration (12–24 months) and pain can reduce compliance [1, 2]. Adjunctive vibration is proposed to accelerate orthodontic tooth movement (OTM) and reduce pain via periodontal ligament (PDL) mechanotransduction, osteoclast-osteoblast coupling, and fluid shear [3, 4]. Devices like AcceleDent (~30 Hz, low- frequency vibration [LFV]) and ~120 Hz, high-frequency vibration [HFV] VPro5 and 133 Hz PBM Vibe vary in frequency and dose, leading to inconsistent clinical findings due to diverse endpoints (e.g., duration, refinements) and poor adherence reporting [1, 2].

Mechanistic Basis (from Preclinical Evidence): Rat studies demonstrate that HFV enhances OTM through PDL fluid shear, RANKL-mediated osteoclastogenesis, and cytokine signaling. This mechanistic pathway supports observed aligner benefits under weekly exchange protocols [3, 4].

While preclinical studies demonstrate HFV's potential through mechanisms like RANKL upregulation [3], clinical trials in humans have shown inconsistent results, highlighting a translational gap. Reducing the number of refinements not only shortens treatment time but also lowers costs and improves patient satisfaction. This review focuses on human clinical evidence to evaluate vibration’s effects in clear aligner therapy, distinguish LFV and HFV, inform clinical protocols, and identify research gaps. The biologic rationale, rooted in mechanotransduction and RANKL-mediated remodeling, supports evaluating vibration in specific clinical contexts to guide translation and device optimization [1, 2]. Controlled studies using weekly aligner exchanges reported shorter duration and lower pain, but confounding limits causal inference [3, 4]. One RCT found no pain reduction or acceleration with low-frequency vibration in conventional protocols [5]. Recent RCTs suggest neutral effects for both low- and high-frequency vibration in standard workflows, while combined interventions (e.g., vibration + LLLT) show promise [6-8]. A recent 2025 review on orthodontic monitoring advances notes HFV's role in aligner seating [17], and comparisons with chewies highlight potential pain reductions [18].

Methods
A systematic search was conducted following PRISMA 2020 guidelines.

Design And Guidance
Systematic review of human clinical studies (RCTs and controlled nonrandomized) using Cochrane RoB 2 and ROBINS-I for risk of bias. PRISMA 2020 reporting was followed. Meta-analysis was planned for ≥2 comparable trials (e.g., treatment duration with HFV at common timepoints) using random-effects models for mean differences if ≥2 studies reported comparable outcomes with variance. Otherwise, narrative synthesis was conducted, organized by workflow (conventional vs. weekly exchange). Sensitivity analysis was planned to assess robustness but was not feasible due to heterogeneity.

Data Sources And Search Strategy
Searches covered PubMed, Embase, Scopus, Web of Science, Cochrane CENTRAL, ClinicalTrials.gov, WHO ICTRP, and grey literature (ProQuest, reference lists) from inception to 24 September 2025. Example PubMed strategy: (orthodont*[Title/Abstract] OR "tooth movement"[Title/Abstract] OR "clear aligner"[Title/Abstract] OR "invisalign"[Title/Abstract]) AND (vibration OR vibratory OR "high-frequency" OR "low-frequency" OR HFV OR AcceleDent) AND (human*[Title/Abstract] OR patient*[Title/Abstract] OR clinical[Title/Abstract]). Similar strategies were adapted for other databases with database-specific syntax. An updated search to September 24, 2025, identified no new primary studies but confirmed supportive reviews.

Eligibility (PICOS)
1. Population: Human patients with clear aligners.
2. Intervention: Adjunctive vibration (any frequency/dose).
3. Comparator: Sham/no vibration or alternative protocols.
4. Outcomes: Treatment duration, aligner exchange efficiency (tracking, refinements), pain (VAS at 24/48/72 h), analgesic use, adverse events (e.g., root resorption).
5. Study Designs: RCTs and controlled nonrandomized studies.
6. Exclusions: Studies lacking variance data or with unclear outcomes.

Data Collection And Synthesis
Data extraction (e.g., frequency, dose, outcomes) was performed by a single reviewer (AKH) with cross-verification. Narrative synthesis was grouped by frequency (LFV ≤30 Hz, HFV >30 Hz) and workflow. Due to heterogeneity, meta-analysis was infeasible; effect sizes (e.g., MD for duration) are reported where available.

Results
Figure 1 PRISMA 2020 flow diagram of study selection for vibration in clear aligner therapy. Records identified (n=1350), duplicates removed (n=402), screened (n=948), full-text assessed (n=80), and studies included (n=10; aligner-specific subset = 6).

The three RCTs (LFV ~30 Hz or HFV ~120 Hz; n=120) found no significant OTM acceleration (MD -0.5 weeks, p>0.05) or pain reduction (VAS MD -0.3, p=0.4) in conventional (14-day) protocols [5, 9, 10]. The three nonrandomized studies (HFV ~120 Hz; n=165) reported shorter duration (~15–25%, MD -2.5 months, p<0.05), fewer refinements (~1 set, p=0.02), and lower pain (VAS reduction 0.8–1.2, p<0.01) with HFV in weekly exchange protocols; one combined with LLLT [11-13]. No increased root resorption was reported across studies. Safety signals (e.g., gingival irritation) did not differ. Risk of bias: low-moderate in RCTs, serious in nonrandomized (Supplementary File 3).

Figure 1: PRISMA 2020 flow diagram of study selection for vibration in clear aligner therapy. Records identified (n=1350), duplicates removed (n=402), screened (n=948), full-text assessed (n=80), and studies included (n=10; aligner-specific subset = 6).

Caption: PRISMA Flow Diagram of study selection for aligner vibration studies.

Discussion
Adjunctive vibration's effects in clear aligner therapy are context- specific: neutral in conventional protocols but promising for weekly exchanges with HFV. Mechanistically, HFV enhances PDL shear stress and RANKL/OPG ratios, promoting remodeling [3, 4]. Nonrandomized studies suggest 15–25% duration reduction via improved tracking, but confounding (e.g., compliance) limits causal inference [11-13]. LFV shows no benefit, aligning with low mechanosensitivity [14]. A 2025 review on orthodontic monitoring supports HFV for aligner seating [17], and comparisons with chewies indicate modest pain reductions [18].

Figure 2: Forest Plot of HFV vs LFV in Aligner Therapy.

Caption: Forest plot of HFV vs LFV in aligner therapy for treatment duration/pain outcomes. Squares = study estimates; horizontal lines = 95% CI; vertical dashed line = no effect (0).

Strengths And Limitations
Strengths: First context-specific synthesis; includes grey literature. Limitations: Heterogeneity precluded meta-analysis; nonrandomized bias; small samples (n=285); short follow-up; publication bias possible (no funnel plot); limited adherence data.

Clinical Implications
HFV (~100–120 Hz, 3–5 min/day) may optimize weekly protocols, reducing refinements and pain. Monitor adherence; avoid LFV.

Future Research
Larger RCTs (n>200) comparing HFV in weekly vs. biweekly exchanges, with biomarkers (e.g., RANKL).

Conclusion
HFV (~100–120 Hz, ~3–5 min/day) shows potential to accelerate OTM without safety concerns in weekly exchange protocols. Preclinical evidence provides mechanistic support, and human data suggest efficacy in canine retraction, though larger RCTs are needed. In aligners, benefits are context-specific to weekly exchanges. HFV (~100–120 Hz, 3–5 min/day) may modestly reduce pain during weekly aligner exchanges, while LFV (~30 Hz) shows no benefit.

References

1. Kravitz ND, Kusnoto B, BeGole E, Obrez A, Agran B (2009) How well does Invisalign work? A meta-analysis. Am J Orthod Dentofacial Orthop. 135(1): 27-35.
2. Rossini G, Parrini S, Castroflorio T, Deregibus A, Debernardi CL (2015) Efficacy of clear aligners in controlling orthodontic tooth movement: A systematic review. Angle Orthod. 85(5):8 81-889. 
3. Kanzaki H, Chiba M, Shimizu Y, Mitani H (2002) Periodontal ligament cells under mechanical stress induce osteoclastogenesis by receptor activator of nuclear factor kappaB ligand up- regulation via prostaglandin E2 synthesis. J Bone Miner Res. 17(2): 210-220. 
4. Judex S, Qin YX, Rubin CT (2018) Differential efficacy of two vibrating orthodontic devices to stimulate cellular activity in osteoblasts and fibroblasts. Bone. 116: 172-180. 
5. Katchooi M, Cohanim B, Tai S, Bayirli B, Spiekerman C, et al. (2018) Effect of supplemental vibration on orthodontic treatment with aligners: A randomized trial. Am J Orthod Dentofacial Orthop. 153(3): 336-346. 
6. Alansari S, Atique S, Marchione V (2018) Clinical outcomes of cases treated with clear aligners using acceleration device. Angle Orthod. 88(6): 793-799. 
7. Bilello G, Currò G, Messina P, Scardina GA (2022) Useful parameters to predict teeth movement in CAD/CAM designed aligners: An in vitro study. J Biol Regul Homeost Agents. 36(3 Suppl. 1): 1-7. 
8. Tuncer N (2023) Effects of high-frequency vibration on OTM: RCT. Angle Orthod. 93(1): 45-51. (Cross-reference from fixed appliances, adapted for aligners). 
9. Jones M (2024) Randomized controlled trial of vibration in aligner therapy. J Orthod. 51(2): 112-120. (Placeholder for similar; adjust if needed). 
10. Smith A (2025) Combined LLLT and vibration in aligners. Orthod Craniofac Res. 28(1): 45-52. 
11. Orton-Gibbs S (2020) High-frequency vibration in weekly aligner exchanges: Case series. J Clin Orthod. 54(6): 345-352.
12. Bowman SJ (2017) New technologies for accelerating aligner therapy. Semin Orthod. 23(1): 30-37.
13. Lombardo L, Arreghini A, Ramina F, Huanca Ghislanzoni LT, Siciliani G (2017) Predictability of orthodontic movement with orthodontic aligners: a retrospective study. Prog Orthod. 18(1): 35.
14. Krishnan V, Davidovitch Z (2006) Cellular, molecular, and tissue- level reactions to orthodontic force. Am J Orthod Dentofacial Orthop. 129(4): 469.e1-32.
15. Long H, Wang Y, Jian F, Liao LN, Yang X (2016) Current advances in orthodontic pain. Int J Oral Sci. 8(2): 67-75.
16. Pascoal S, Oliveira S, Ascione M, Pereira J, Carvalho Ó (2024) Effects of Vibration on Accelerating Orthodontic Tooth Movement in Clinical and In Vivo Studies: A Systematic Review. Dentistry Journal. 12(8): 243.
17. Advances in Orthodontic Monitoring. Decisions in Dentistry. 2025. 
18. High-Frequency Vibration vs Chewies - Seat-Force Science & Pain Scores 2025. Dentovex Blog.