Computational and clinical investigation on the role of mechanical vibration on orthodontic tooth movement

Proposal regarding potential causes related to certain complications with dental implants and adjacent natural teeth: Physics applied to prosthodontics

PURPOSE

Complications can and do occur with implants and their restorations with causes having been proposed for some single implant complications but not for others.

METHODS

A review of pertinent literature was conducted. A PubMed search of vibration, movement, and dentistry had 175 citations, while stress waves, movement, and dentistry had zero citations as did stress waves, movement. This paper discusses the physics of vibration, elastic and inelastic collision, and stress waves as potentially causative factors related to clinical complications.

RESULTS

Multiple potential causes for interproximal contact loss have been presented, but it has not been fully understood. Likewise, theories have been suggested regarding the intrusion of natural teeth when they are connected to an implant as part of a fixed partial denture as well as intrusion when a tooth is located between adjacent implants, but the process of intrusion, and resultant extrusion, is not fully understood. A third complication with single implants and their crowns is abutment screw loosening with several of the clinical characteristics having been discussed but without determining the underlying process(es).

CONCLUSIONS

Interproximal contact loss, natural tooth intrusion, and abutment screw loosening are common complications that occur with implant retained restorations. Occlusion is a significant confounding variable. The hypothesis is that vibration, or possibly stress waves, generated from occlusal impact forces on implant crowns and transmitted to adjacent teeth, are the causative factors in these events. Since occlusion appears to play a role in these complications, it is recommended that occlusal contacts provide centralized stability on implant crowns and not be located on any inclined surfaces that transmit lateral forces that could be transmitted to an adjacent tooth and cause interproximal contact loss or intrusion. The intensity, form, and location of proximal contacts between a natural tooth located between adjacent single implant crowns seem to play a role in the intrusion of the natural tooth. Currently, there is a lack of information about the underlying mechanisms related to these occurrences and research is needed to define any confounding variables.

Vibrational Force on Accelerating Orthodontic Tooth Movement: A Systematic Review and Meta-Analysis

This study aimed to systematically gather and analyze the current level of evidence for the effectiveness of the vibrational force in accelerating orthodontic tooth movement (OTM). This systematic review was conducted using three electronic databases: Scopus, PubMed, and Google Scholar until March 2022. The search was done through the following journals: European Journal of Orthodontics, American Journal of Orthodontics and Dentofacial Orthopedics, The Angle Orthodontist, Progress in Orthodontics, and Seminars in Orthodontics. Human or animal studies that have evaluated the effect of vibrational force on the rate of OTM were selected. A meta-analysis was performed for the rate of canine movement per month. Database research, elimination of duplicate studies, data extraction, and risk of bias assessment were performed by authors independently and in duplication. A fixed and random-effect meta-analysis was performed to evaluate the effect of vibrational forces. A total of 19 studies (6 animal and 13 human studies) that met the inclusion criteria were included. Meta-analysis was performed based on four human clinical trials. Three out of four studies showed no significant difference in the rate of canine movement between vibrational force and control groups. The limitation of this study was the small sample size and significant heterogeneity among the studies. Although vibrational forces have been shown to accelerate OTM in experimental studies, the results are inconsistent in clinical studies. The inability to apply desired peak load to the targeted teeth may be the main factor in inconsistent clinical outcomes.

Duration of canine retraction with fixed appliances: A systematic review and meta-analysis

INTRODUCTION

Space closure is a challenging and time-consuming phase of orthodontic treatment with fixed appliances. This systematic review evaluated canine retraction duration using fixed appliances after maxillary first premolar extraction.

METHODS

Unrestricted systematic literature searches were conducted in 8 databases for randomized clinical trials, assessing the duration and rate of maxillary canine retraction using fixed appliances with or without treatment adjuncts published up to July 2021. Study selection, data extraction, and risk of bias evaluation were conducted independently and in duplicate. Random-effects meta-analyses of average rates or mean differences (MD) and 95% confidence intervals (CI) were conducted at α = 5%, followed by sensitivity and Grading of Recommendations Assessment, Development, and Evaluation analysis.

RESULTS

Fifty randomized clinical trials (6 parallel and 44 split-mouth designs) covering 811 participants (mean age 19.9 years; 34% male) were included. The estimated average pooled duration to achieve complete canine retraction was 4.98 months (2 trials; 95% CI, -2.9 to 12.88 months). Pooled average canine retraction was 0.97 mm at months 0-1 (23 trials; 95% CI, 0.79-1.16), 1.83 mm at months 0-2 (20 trials; 95% CI, 1.52-2.14), 2.44 mm at months 0-3 (23 trials; 95% CI, 2.10-2.79), 3.49 mm at months 0-4 (6 trials; 95% CI, 1.81-5.17) and 4.25 mm at months 0-5 (2 trials; 95% CI, 0.36-8.14). Surgically-assisted orthodontics was associated with greater canine retraction at all time points: months 0-1 (10 trials; MD, 0.52 mm; P = 0.004), months 0-2 (8 trials; MD, 0.53 mm; P = 0.04), months 0-3 (8 trials; MD, 0.67 mm; P = 0.01), and months 0-4 (3 trials; MD, 1.13 mm; P = 0.01), whereas subgroup analyses indicated significant effects of anchorage reinforcement method and bracket slot size on canine retraction.

CONCLUSIONS

The average time to achieve complete retraction of the maxillary canine using fixed appliances was around 5.0 months. Most studies used split-mouth randomization to investigate canine retraction for around 1-3 months, with substantial heterogeneity across studies. At 3 months of treatment, high-quality evidence supported greater canine retraction with surgically-assisted orthodontics.

A study on the performance and cost-effectiveness of robots in replacing manual nucleic acid collection method: Experience from the COVID-19 pandemic

Background

The COVID-19 pandemic has led nucleic acid collection and detection became a measure to ensure normal life in China. Considering the huge detection demand, it has emerged that robots replace manual sample collection. However, the cost-effectiveness of nucleic acid collection by robots instead of humans remain unknown.

Methods

This study was approved by the Ethics Committee of the Shenzhen Luohu District People’s Hospital, number 2021-LHQRMYY-KYLL-031a. All participants signed the written informed consent of this study. 273 volunteers were recruited on December 1^st 2021 from Shenzhen and divided into six groups: one group to be sampled by robots and the others to be sampled manually with varying specifications for swab rotation and insertion time. Questionnaires were distributed to the robot group to ask them sampling feeling. The effectiveness and safety of sampling were evaluated through the sampling efficiency, adverse events and sampling feeling of different groups. The economics of the different methods were judged by comparing the sampling cost for each.

Results

The sampling efficiency of the robot group was 96.9%, and there was no statistically significant difference between the other five manually sampled groups (p = 0.586). There were no serious adverse events in any of the six groups, but nasal soreness and tearing did occur in all group. Of the volunteers who underwent robotic sampling, 85.94% reported that the experience was either no different or more comfortable than the manual sampling. In economic terms, a single robot used to replace medical staff for sample collection becomes economically advantageous when the working time is ≥ 455 days. If multiple robots are used to replace twice the number of manual collections, it becomes more economical at 137 days and remains so as long as the robot is used.

Conclusions

It appears safe and effective for robots to replace manual sampling method. Implementation of robotic sampling is economical and feasible, and can significantly save costs when working over a long term.

Effect of customized vibratory device on orthodontic tooth movement: A prospective randomized control trial

AIMS:

The primary purpose of the present trial was to evaluate the effect of low-frequency (30Hz) vibrations on the rate of canine retraction.

SETTING AND DESIGN:

Single-center, split mouth prospective randomized controlled clinical trial

METHODS AND MATERIAL:

100 screened subjects (aged18–25 years) were selected; out of which 30 subjects having Class I bimaxillary protrusion or Class II div 1 malocclusion, requiring upper 1^st premolar therapeutic extractions, were selected for the study. A split-mouth study design was prepared for the maxillary arch of each selected individual and was randomly allocated into vibration and nonvibration side (control) groups. A customized vibratory device was fabricated for each subject to deliver low-frequency vibrations (30 Hz). Scanned 3D models were prepared sequentially to assess the amount of tooth movement from baseline (T0),(T1), (T2), (T3), and (T4)-4^th month of canine retraction.

STATISTICAL ANALYSIS USED:

Independent “t” test.

RESULTS:

There was no statistically significant differencein the rate of individual canine retraction among the experimental and control groups when the intergroup comparison was done using independent “t” test at T1-T0, (P = 0.954), T2-T1 (P = 0.244), T3-T2 (P = 0.357), and T4-T3 (P = 0.189).

CONCLUSION:

The low-frequency vibratory stimulation of 30 Hz using a customized vibratory device did not significantly accelerate the rate of orthodontic tooth movement.

TRIAL REGISTRATION:

Registered at ctri.nic.in (CTRI/2019/05/019043).

EFFECTIVENESS OF VIBRATION (CYCLIC LOADING) IN ACCELERATING BONE REMODELING AND ORTHODONTIC TOOTH MOOVEMENT: A SHORT REVIEW

This paper assesses the effectiveness of vibration in accelerating bone remodeling and orthodontic tooth movement. Databases of PubMed, Web of Science, and ScienceDirect were searched from January 2017 to March 2019 for randomized or quasi-randomized controlled trials that evaluated the effectiveness of vibration in accelerating bone remodeling and orthodontic tooth movement. The inclusion criteria were as follows: (i) studies that assessed the efficacy of vibration (cyclic loading) in bone remodeling and orthodontic tooth movement and (ii) those that employed groupings (experimental vs. control/placebo groups) on the basis of the use of vibration (cyclic loading). Eight clinical trials were included in this short review. Five studies met the eligibility criteria for bone remodeling and orthodontic tooth movement. Four studies found that low-magnitude high-frequency vibration could accelerate bone remodeling. However, contradictory results were obtained with regard to the acceleration of orthodontic tooth movement by vibration in human participants. Low-magnitude high-frequency vibration can accelerate bone remodeling and orthodontic tooth movement. However, this acceleration is dependent on the magnitude and frequency. Further research is necessary to determine the most feasible protocols for investigating the effects of magnitude and frequency of vibration on the acceleration of orthodontic tooth movement in human participants.

The effect of 12 weeks of mechanical vibration on root resorption: a micro-CT study

OBJECTIVE

The aim was to investigate the effect of mechanical vibration on root resorption with or without orthodontic force application.

MATERIAL AND METHODS

Twenty patients who required maxillary premolar extractions as part of orthodontic treatment were randomly divided into two groups of 10: no-force group and force group. Using a split-mouth procedure, each patient's maxillary first premolar teeth were randomly assigned as either vibration or control side for both groups. A buccally directed vibration of 50 Hz, with an Oral-B HummingBird device, was applied to the maxillary first premolar for 10 min/day for 12 weeks. After the force application period, the maxillary first premolars were extracted and scanned with micro-computed tomography. Fiji (ImageJ), performing slice-by-slice quantitative volumetric measurements, was used for resorption crater calculation. Total crater volumes were compared with the Wilcoxon and Mann-Whitney U tests.

RESULTS

The total crater volumes in the force and no-force groups were 0.476 mm3 and 0.017 mm3 on the vibration side and 0.462 mm3 and 0.031 mm3 on the control side, respectively. There was no statistical difference between the vibration and control sides (P > 0.05). There was more resorption by volume in the force group when compared to the no-force group (P < 0.05).

CONCLUSION

Mechanical vibration did not have a beneficial effect on reducing root resorption; however, force application caused significant root resorption.

Peak loads on teeth from a generic mouthpiece of a vibration device for accelerating tooth movement

INTRODUCTION

The effect of vibrational force (VF) on accelerating orthodontic tooth movement depends on the ability to control the level of stimulation in terms of its peak load (PL) on the tooth. The objective of this study was to investigate the PL distribution on the teeth when a commercial VF device is used.

METHODS

Finite element models of a human dentition from cone-beam computed tomography images of an anonymous subject and a commonly used commercial VF device were created. The device consists of a mouthpiece and a VF source. The maxilla and mandible bites on the mouthpiece with the VF applied to it. Interface elements were used between the teeth and the mouthpiece, allowing relative motion at the interfaces. The finite element model was validated experimentally. Static load and VF with 2 frequencies were used, and the PL distributions were calculated. The effects of mouthpiece materials and orthodontic appliances on the PL distribution were also investigated.

RESULTS

The PL distribution of this kind of analyzed device is uneven under either static force or VF. Between the anterior and posterior segments, the anterior segment receives the most stimulations. The mouthpiece material affects the PL distribution. The appliance makes the PL more concentrated on the incisors. The VF frequencies tested have a negligible influence on both PL magnitude and distribution.

CONCLUSIONS

The device analyzed delivers different levels of stimulation to the teeth in both maxilla and mandible. Changing the material property of the mouthpiece alters the PL distribution.

Performance comparison of vibration devices on orthodontic tooth movement - A systematic review and meta-analysis

Background

To evaluate the efficiency of vibratory devices in altering rate of orthodontic tooth movement.

Methods

A literature search up to January 31, 2020 was conducted in three electronic databases: PubMed, Cochrane Central Register of Controlled Trials (CENTRAL) and Science Direct, to identify studies on vibratory devices reporting any alteration in tooth movement as a primary outcome. Only articles published in English language were included. A meta-analysis was done to compare the amount of tooth movement (in mm) in patients treated with vibratory devices compared to control groups, to quantify weighted treatment effects.

Results

A total of two split mouth studies, six parallel arm randomized control trials (RCT) one split mouth RCT, and three regular RCTs were assessed qualitatively. Quantitative assessment was done for 8 randomized trials using a forest plot (310 patients). Pooled data showed increase in the amount of tooth movement by 0.34 ​mm (95% CI:0.25,0.42). There was a statistically significant difference noted for this result at p ​< ​0.00001.

Conclusion

Current evidence suggests a moderate to high level of certainty in regard to included studies in this systematic review and meta-analysis. Vibratory devices when used in conjunction with fixed orthodontic appliances show significant increase in the rate of tooth movement. These devices can be used by clinicians to reduce treatment duration and patient discomfort.

PROSPERO registration

CRD42020169675.

Orthodontists' and patients' perceptions regarding techniques to reduce the orthodontic treatment duration

BACKGROUND

The purpose of this study was to evaluate patients' and orthodontists' perspectives on knowledge of techniques for reducing orthodontic treatment time and acceptance of these techniques.

METHODS

A total of 200 individuals were interviewed and equally divided into two groups: orthodontist group (62 female and 38 male; mean age, 38.07 years) and patient group (52 female and 48 male; mean age, 22.61 years; in the active stage of fixed orthodontic treatment). One questionnaire for each group was administered, including questions about the duration of orthodontic treatment and techniques used for treatment optimization, such as corticotomy, distraction osteogenesis, vibration, and laser therapy. The associations between variables were analyzed by the χ² test at a significance level of 5%.

RESULTS

Among orthodontists, 76% knew at least one technique to reduce the treatment duration, with corticotomy being the most frequently cited (66%); however, only 12% used one or more of these techniques. Laser therapy was the most frequently implemented technique (7%). Regarding the duration of orthodontic treatment, the mean time reported by orthodontists was 19 to 24 months, regardless of the technique or the experience of the orthodontist. Furthermore, 39% of patients expected their treatment to last for more than 24 months, with 50% accepting to undergo further procedures to reduce this duration.

CONCLUSIONS

Patients are willing to undergo additional procedures to reduce the treatment duration and to bear additional costs. However, despite their knowledge, orthodontists do not apply or offer these techniques to the patients.

The effectiveness of supplemental vibrational force on enhancing orthodontic treatment. A systematic review

BACKGROUND AND OBJECTIVES

The results from the literature regarding the influence of supplemental vibrational forces (SVFs) on orthodontic treatment are controversial. Therefore, this systematic review aimed to evaluate whether SVFs have positive effects, such as in accelerating tooth movement, alleviating pain, and preventing root resorption, in orthodontic patients.

SEARCH METHODS

Searches through five electronic databases (PubMed, MEDLINE, EMBASE, Web of Science, and Cochrane Central) were complemented by hand searches up to January, 2019.

SELECTION CRITERIA

Randomized controlled trials and controlled clinical trials reporting on the effects of SVFs in orthodontic patients in English were included.

DATA COLLECTION AND ANALYSIS

Study selection, data extraction, and a risk of bias assessment were independently performed by two reviewers. Study characteristics and outcomes were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A qualitative analysis of the effects of SVFs on orthodontic tooth movement, pain experience, and root resorption was conducted.

RESULTS

Thirteen studies, including nine clinical trials, were eligible for inclusion in the systematic review. There was no significant evidence to support the positive effects of SVFs in orthodontic patients, neither in accelerating tooth movement nor in alleviating pain experience. According to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria, the quality of the evidence was very low for all the outcomes in the qualitative analysis.

LIMITATIONS

The results of this systematic review are based on a limited number of studies and the methodological heterogeneity and non-comparability of original outcomes made it difficult to conduct a meta-analysis.

CONCLUSIONS

There is insufficient evidence to support the claim that SVFs have positive clinical advantages in the alignment of the anterior teeth. The potential positive effects of vibrational forces on space closure, pain experience, and root resorption in orthodontic patients are inconclusive with no sufficient information at present. High-quality clinical trials with larger sample sizes are needed to find more comprehensive evidence of the potential positive effects of vibrational forces.

REGISTRATION

The protocol for this systematic review was registered on PROSPERO (CRD42018098788).

FUNDING

This study has not received any contributions from private or public funding agencies.

CONFLICT OF INTEREST

None.

Examination of the effect of combined use of Er:YAG laser irradiation and mechanical force loading on bone metabolism using primary human gingival fibroblasts

Prolonged treatment and painful tooth movement are major problems for patients undergoing orthodontic treatment. Accelerating the movement of teeth leads to shortening of the treatment period, so various studies on the movement of teeth have been conducted in the field of orthodontics. In previous studies, we performed a fiber incision-like fiberotomy using an Er:YAG laser in rats and confirmed acceleration of tooth movement. Therefore, in this study, the effect of Er:YAG laser irradiation on human gingival fibroblasts was investigated in vitro. Human gingival fibroblasts (2.0 × 10⁵ cells) were seeded in a 6-well plate and reached 80% confluence 24 h later. A control group not undergoing any irradiation and 3 groups undergoing laser irradiation at 0.6 W, 1.0 W, and 1.2 W were investigated. Laser irradiation was performed 24 h after cell seeding. The cells were then recovered 24 h later, and the cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), bone morphogenetic protein-2 (BMP-2), and BMP-4 genes were confirmed by PCR. In addition, a control group not undergoing any procedures, a group undergoing only Er:YAG laser irradiation, a group undergoing only centrifugal loading, and a group undergoing both Er:YAG laser irradiation and centrifugal force loading were investigated. After 24 h, cells were collected and PCR was performed. Twenty-four hours after laser irradiation, gene expressions were examined by quantitative RT-PCR, which showed that the gene expressions of COX-2, IL-1β, TNF-α, BMP-2, and BMP-4 increased depending on the amount of irradiation energy, with the largest value at 1.2 W. Gene expressions of COX-2, IL-1β, TNF-α, BMP-2, and BMP-4 were significantly higher in the laser with centrifugal load group than in the load group. These results suggest that genes related to bone metabolism are activated in human gingival fibroblasts when mechanical stimulation and laser irradiation are combined. This helps to elucidate the effects of Er:YAG laser irradiation during tooth movement.

Mandible Integrity and Material Properties of the Periodontal Ligament during Orthodontic Tooth Movement: A Finite-Element Study

We used the finite-element method (FEM) to investigate the effects of jawbone model integrity and the material properties of the periodontal ligament (PDL) on orthodontic tooth movement. Medical imaging software and computer-aided design software were used to create finite-element models of a partial and complete mandibles based on dental cone beam computed tomography images of the human skull. Additionally, we exerted an orthodontic force on the canine crown in the direction of an orthodontic miniscrew under a lower molar root to compare the von Mises strain on the canine PDL in three models: a partial mandible model under orthodontic force (Model 1), a complete mandible model under orthodontic force (Model 2), and a complete mandible model under orthodontic force with clench occlusion in the intercuspal position (ICP; Model 3). Additionally, in the complete mandible model under orthodontic force with ICP occlusion, we analyzed the effects of a PDL with a low (Model 4), moderate (Model 5), and high (Model 6) linear elastic modulus and a PDL a bilinear elastic modulus (Model 7). The simulation results for mandible integrity indicated that the maximum von Mises strains on the canine PDL for Models 1, 2, and 3 were 0.461, 0.394, and 1.811, respectively. Moreover, for the models with different PDL material properties, the maximum von Mises strains on the canine PDLs for Models 4, 5, 6, and 7 were 6.047, 2.594, 0.887, and 1.811, respectively. When the FEM was used to evaluate tooth movement caused by orthodontic force, the transformation of a complete mandible model into a partial mandible model or alteration of the elastic modulus of the PDL influenced the biomechanical responses of the PDL. Additionally, the incorporation of daily ICP occlusion resulted in a larger effect.

Public Concern About Monitoring Twitter Users and Their Conversations to Recruit for Clinical Trials: Survey Study

Background

Social networks such as Twitter offer the clinical research community a novel opportunity for engaging potential study participants based on user activity data. However, the availability of public social media data has led to new ethical challenges about respecting user privacy and the appropriateness of monitoring social media for clinical trial recruitment. Researchers have voiced the need for involving users’ perspectives in the development of ethical norms and regulations.

Objective

This study examined the attitudes and level of concern among Twitter users and nonusers about using Twitter for monitoring social media users and their conversations to recruit potential clinical trial participants.

Methods

We used two online methods for recruiting study participants: the open survey was (1) advertised on Twitter between May 23 and June 8, 2017, and (2) deployed on TurkPrime, a crowdsourcing data acquisition platform, between May 23 and June 8, 2017. Eligible participants were adults, 18 years of age or older, who lived in the United States. People with and without Twitter accounts were included in the study.

Results

While nearly half the respondents—on Twitter (94/603, 15.6%) and on TurkPrime (509/603, 84.4%)—indicated agreement that social media monitoring constitutes a form of eavesdropping that invades their privacy, over one-third disagreed and nearly 1 in 5 had no opinion. A chi-square test revealed a positive relationship between respondents’ general privacy concern and their average concern about Internet research (P<.005). We found associations between respondents’ Twitter literacy and their concerns about the ability for researchers to monitor their Twitter activity for clinical trial recruitment (P=.001) and whether they consider Twitter monitoring for clinical trial recruitment as eavesdropping (P<.001) and an invasion of privacy (P=.003). As Twitter literacy increased, so did people’s concerns about researchers monitoring Twitter activity. Our data support the previously suggested use of the nonexceptionalist methodology for assessing social media in research, insofar as social media-based recruitment does not need to be considered exceptional and, for most, it is considered preferable to traditional in-person interventions at physical clinics. The expressed attitudes were highly contextual, depending on factors such as the type of disease or health topic (eg, HIV/AIDS vs obesity vs smoking), the entity or person monitoring users on Twitter, and the monitored information.

Conclusions

The data and findings from this study contribute to the critical dialogue with the public about the use of social media in clinical research. The findings suggest that most users do not think that monitoring Twitter for clinical trial recruitment constitutes inappropriate surveillance or a violation of privacy. However, researchers should remain mindful that some participants might find social media monitoring problematic when connected with certain conditions or health topics. Further research should isolate factors that influence the level of concern among social media users across platforms and populations and inform the development of more clear and consistent guidelines.

Effects of two frequencies of vibration on the maxillary canine distalization rate and RANKL and OPG secretion: A randomized controlled trial

OBJECTIVES

To investigate the effects of 30 and 60 Hz vibratory stimulus on canine distalization and RANKL and OPG secretion.

SETTING AND SAMPLE POPULATION

Sixty patients requiring canine distalization at the Orthodontic Clinic, Prince of Songkla University.

MATERIALS AND METHODS

Patients were randomly assigned to 30 Hz vibration (n = 20), 60 Hz vibration (n = 20), or the control group (n = 20). Modified electric toothbrushes were used to apply vibration to the randomly selected canine for 20 min/day by the investigator combined with 60 cN continuous distalization force from day 1 to day 7. RANKL and OPG were analysed before (T1) and 24 hours (T2), 48 hours (T3) and 7 days (T4) after initiation of distalization. From day 8, vibratory devices were used by the subjects at home. Rate of canine distalization (T1 to 3 months after initiation [T5]) was calculated. Kruskal-Wallis tests were used for multiple comparisons (significance level, 0.05).

RESULTS

Canine distalization rate was not different between groups (median; 0.82, 0.87, and 0.83 mm/month for 30, 60 Hz, and control group, respectively; P > 0.05). No within- or between-group differences in RANKL and OPG were observed (P > 0.05), except RANKL on the compression side of the control group was significantly higher at T2, T3 and T4 than T1 (P < 0.001).

CONCLUSION

In the clinic, 30 and 60 Hz vibratory stimulus have no additive effect on rate of canine distalization rate, RANKL and OPG secretion or RANKL/OPG ratio.

Vibration paradox in orthodontics: Anabolic and catabolic effects

Vibration in the form of High Frequency Acceleration (HFA) is anabolic on the craniofacial skeleton in the absence of inflammation. Orthodontic forces trigger an inflammation-dependent catabolic cascade that is crucial for tooth movement. It is unknown what effect HFA has on alveolar bone if applied during orthodontic treatment. The objectives of this study are to examine the effect of HFA on the rate of tooth movement and alveolar bone, and determine the mechanism by which HFA affects tooth movement. Adult Sprague Dawley rats were divided to control, orthodontic force alone (OTM), and different experimental groups that received the same orthodontic forces and different HFA regimens. Orthodontic tooth movement was assessed when HFA parameters, frequency, acceleration, duration of exposure, and direct or indirect application were varied. We found that HFA treatment significantly enhanced the inflammation-dependent catabolic cascade during orthodontic tooth movement. HFA treatment increased inflammatory mediators and osteoclastogenesis, and decreased alveolar bone density during orthodontic tooth movement. Each of the HFA variables produced significant changes in the rate of tooth movement and the effect was PDL-dependent. This is the first report that HFA enhances inflammation-dependent catabolic cascades in bone. The clinical implications of our study are highly significant, as HFA can be utilized to enhance the rate of orthodontic tooth movement during the catabolic phase of treatment and subsequently be utilized to enhance retention during the anabolic remodeling phase after orthodontic forces are removed.