With an increasing demand for facial esthetics, orthodontic treatment has been in demand quite often today. Patients are looking for quicker modalities of treatment and reduced treatment duration. Considering the risks associated with orthodontic treatment such as root resorption and demineralization, it is certain that orthodontists are looking for modalities and ways to decrease treatment times to reduce these risks for their patients. Thus, the prospect of accelerating the biologic response of the periodontal ligament (PDL) and alveolar remodeling is alluring, as it could concede speedy tooth movement and shorter treatment duration. Orthodontic treatments vary widely, approximately 2 or more years in fixed appliance therapy. Regardless of this, with patients desiring significantly shorter treatments of only 6–12 months, this places tremendous pressure on orthodontic clinicians to find ways to accelerate treatment. There is little evidence to support nonsurgical adjunctive interventions to increase the rate of tooth movement, as suggested by a recent Cochrane review which advocates that a well-designed randomized clinical trial is needed. A popular noninvasive method to accelerate tooth movement is the application of intermittent vibrational forces to the dentition. Previous researches involving the use of vibrational appliances for orthodontic tooth movement in animal models have been demonstrated and they have shown encouraging results. 15%–30% faster tooth movement in Macaca Fuscata monkeys and rats was reported using a device delivering vibrational force. Amplified RANKL expression in the PDL was believed to be a reason for the accelerated tooth movement. However, there were other studies conducted on rats and mice which on the contrary showed that cyclical forces inhibited orthodontic tooth movement.
To achieve the desired tooth movement, certain forces are applied to the dentition and alveolar bone resulting in ischemia or inflammation of the PDL with the successive release of prostaglandins, bradykinin, histamine, serotonin, and substance P. These mediators invigorate local nerve endings and send pain signals to the brain. Several methods have been employed to reduce pain arising from orthodontic tooth movement. Among the most common methods, nonsteroidal anti-inflammatory drugs (NSAIDS) are most frequently used for pain relief. Other methods include acupuncture and acupressure techniques, low-level laser therapy, viscoelastic bite wafers, transcutaneous electrical nerve stimulation, vibratory stimulation of the PDL, and even chewing gum. These methods have been proved effective in alleviating pain. The focus of this study is only on vibratory stimulation to reduce pain. Previous studies have demonstrated that vibration effectively reduces pain originating from teeth or the surrounding tissues. A device generating vibrations named AcceleDent was designed in the U. S for faster orthodontic treatment. It was patented as a “vibrating orthodontic remodeling device” by the U. S. Department of Commerce's United States Patent and Trademark Office. There are reports from Orthodontic clinicians who have noticed pain reduction as an additional benefit for those patients using AcceleDent. Several such devices have been used which help in increasing the rate of tooth movement and also help in reducing pain at the same time. The purpose of this systematic review and meta-analysis is to cumulatively analyze the effect of vibrational devices on pain in patients undergoing orthodontic treatment. This systematic review was planned to critically evaluate the existing evidence with respect to the effect of vibrational devices on pain levels during orthodontic treatment.
MATERIALS AND METHODS
Protocol development and registration
This review was registered on priori based on the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020186584). It was conducted and reported according to the Cochrane Handbook of Systematic Reviews of Interventions Version 5.1.0 and following the preferred reporting items for systematic reviews and meta-analyses (PRISMA).
The following focused question in the patient, intervention, comparison, and outcome (PICO) format was posed “Does use of vibrational devices have any effect on the pain intensity in patients undergoing orthodontic treatment?”
Information sources and literature search
An electronic search was carried out by two review authors (RL and GK) in multiple electronic databases without the restriction of language on PubMed/MEDLINE, Directory of open access journal, Cochrane Central Register Controlled Trials, and Google Scholar until June of 2020. In addition, a specific electronic search in the following journals was also conducted: American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, APOS trends in Orthodontics, Progress in Orthodontics, European Journal of Orthodontics, Seminars in Orthodontics. Searched in the ClinicalTrials.gov database and in the references of included studies (cross-referencing), were also conducted.
MeSH terms, keywords, and other free terms related to PICO questions were used with Boolean operators (OR, AND) to combine searches. The same keywords were used for all search platforms followed the syntax rules of each database. The search strategy and PICOS tool are presented in Table 1.
- Population (P): Orthodontic patients without any gender or age predilection
- Interventions (I): Patients using a vibratory device
- Comparison (C): Patients who do not use any vibratory device (control)
- Outcome (O): There was no restriction on possible data acquisition sources for the primary outcome for the assessment of pain with questionnaire, patient interview, and visual analog scale (VAS)
- Study design (S): We evaluated only randomized controlled trials (RCTs) conducted in humans.
- Time (T): Follow-up period kept at 1 week–4 months.
Cross-sectional studies, animal studies, nonclinical studies, case reports and reviews, and nonrelevant studies were excluded. In addition, studies reporting only a single intervention were excluded.
Assessment of intensity of pain.
This review included RCTs, controlled trials, and clinical trials that evaluated the effect of vibratory devices on pain intensity used by patients undergoing orthodontic treatment. The search and screening process was carried out by two independent reviewing authors, following the previously established protocol, first analyzing titles and abstracts. Relevant articles were read in full text and judged against the inclusion/exclusion criteria for a final judgment. Discrepancies among authors/reviewers were resolved through careful discussion by the third author. The search agreement between the two reviewers was evaluated by the Cohen's Kappa (k) test. If needed, the authors of the included studies were contacted by E-mail for the clarification of any doubts.
Data Collection and data items
The following data items were extracted from the included studies (when available) by two independent reviewing authors: study identification, setting, authors, study design, follow-up, number of subjects, age, gender, type of vibratory device, pain therapy in control group, measurement methods, and outcomes [Table 2]. Disagreements were resolved through discussion with a third reviewer.
Risk of bias in individual trials
Risk of bias assessment was performed independently by two review authors and any disagreement was resolved through a discussion with another review author. Quality assessment of the selected studies was executed using the Cochrane Collaboration's Tool for RCTs including random sequence generation, allocation concealment, blinding of participants, incomplete outcome data, selective reporting, and other biases. A bias judgment of low, high, or unclear bias based on the details mentioned in the individual studies.
Summary measures and approach to data synthesis
It was considered appropriate to pool the studies if similar interventions and outcomes were presented. Prioritizing the qualitative interpretation of all the studies was undertaken. For continuous data, the mean change scores and their standard deviations (SDs) were pooled, were chosen as a summary effect measure along with its 95% confidence interval. Differences in means and effect size were used as principal summary measures. Forest plots and funnel plots were created to visualize the differences between groups and publication bias. The overall estimated effect was categorized as significant where P < 0.05. Both absolute and relative between-study heterogeneity was quantified using the Tau2 and I2 statistics. Clinical heterogeneity was inspected by looking into the populations, the different interventions, and outcomes. In all cases, the unit of analysis was the individual patient. Review Manager 5.3 was used for statistical analysis.
We performed sensitivity analyses to gauge the effects of individual studies on the overall effect estimate and to isolate the effects of studies judged with an overall low-risk bias. The evidence was thus determined using grading of recommendations assessment, development, and evaluation (GRADE).
The initial electronic database search resulted in 4540 titles. Forty articles were cited as duplicates. After screening the abstracts, 423 relevant titles were selected by two independent reviewers and were excluded for not being related to the topic. Following examination and discussion by the reviewers, 17 articles were selected for full-text evaluation. Hand searching of the reference lists of the selected studies did not deliver additional papers. After prescreening, the application of the inclusion and exclusion criteria, and handling of the PICO questions, nine studies remained (two studies with no post-intervention data, four studies were inappropriate for the outcome of interest, and two studies did not have the measures of effect as per the protocol). Nine studies were included in the qualitative synthesis which was used for data extraction and statistical analysis. Out of the nine, two studies were included in the quantitative synthesis. Figure 1 illustrates the PRISMA flowchart.
There are nine studies included in this review, the general characteristics of which are presented in Table 2. Two studies were conducted in the continent of Australia, one each in Pakistan, the United Kingdom, three studies in the United States, one in India, and one study had no mention of the place. The study design of all the studies was RCT except one which was a split-mouth technique. The age of participants ranged from 10 years and older throughout the interventions' conducting period, a total of 411 participants were part of the studies' analyses, with 173 in the intervention group and 238 in the control group. Significant methodological variability was found among the interventions performed in the included studies. Thus, the interventions described by the studies were categorized as follows:
- All studies used similar vibratory devices as interventions namely – AcceleDent Aura, Tooth Masseus, and Oral B Triumph powered toothbrush appliances for daily usage
- Additional delivery of information was directed to the daily usage of the appliances for a specific time period
- The control group was subjected to: Sham device or no vibration device
- The intervention study period ranged from 1 week to 4 months.
Therefore, all interventions selected for this review are vibratory devices from various manufacturers and compared with no vibration device. All the articles were published in English. The follow-up loss ranged from 0% to 12.5%. Details on the different forms of interventions were given in all studies at baseline with different periods of reinforcement depending on the duration of the study [Table 2].
Risk of bias within individual studies
All studies included were judged to have an overall low risk of bias [Figure 2]. Quality assessment of the 11 RCTs was executed according to the Cochrane Risk of Bias Tool. Several shortcomings were observed because of the lack of blinding of the participants as well as the investigators. One study had a high potential risk of bias, others showed a low potential risk of bias [Figures 2 and 3].
Results of individual studies and data synthesis
A quantitative synthesis (meta-analysis) was done on the selected two studies. The studies with groups that got any sort of intervention versus controls concerning the pain assessment outcomes were analyzed. On forest plot deduction for the two studies, the mean difference was 1.83 (−7.18,10.84) with a fixed effect model based on the heterogeneity value of I2 [Figure 4] not favoring the intervention group, resulting that the vibrational devices had no effect on reducing pain when compared to control group. The funnel plot for pain assessment VAS meta-analysis is presented in Figure 5.
The patient-reported outcome is not a specific outcome but a category of all. Under this domain, none of the studies assessed the type of pain experienced along with its time or duration. Compliance was not assessed in all the studies hence; pain assessment still can be inconclusive.
Quality of evidence
GRADE approach [Table 3] suggested that the quality of evidence was moderate for the explored and intended outcomes. Downgrading was due to shortcomings in the methodological quality of few of included RCTs.
Pain, which includes varied sensations evoked by, and reactions to, noxious stimuli, is a complex experience and often experienced and feared in orthodontic appointments. Many patients have avoided orthodontic treatment because of the stated reasons. It is one of the most significant reasons why patients are discouraged from seeking orthodontic treatment.
Vibration devices claim to reduce pain and discomfort during orthodontic treatment by re-establishing the blood supply through loosening of the PDL fibers and intercepting the ischemic response. There are a variety of vibratory devices available as an alternative option for pain control creating the need to summarize the evidence and give an elucidation for establishing it as an effective modality.
In this systematic review and meta-analysis, we aimed to investigate the different types and regimens of vibratory devices used and assessing pain with an intention to analyze any reduction in discomfort and pain, in patients undergoing orthodontic treatment. We, selected studies with all the interventions using vibratory devices prescribed by orthodontist compared with a control group. The best evidence on vibration and orthodontic therapy after following the meticulous selection criteria, we finalized 9 studies which were RCTs for this systematic review. With the exception of five studies, none of the other studies had a rigorous study design which was because of the absence of blinding of participants and outcome assessors. Without a doubt, all the included studies had successfully accomplished their study objectives. Summarizing Azeem et al. we judged to have a high risk of bias since there was no allocation concealment and blinding of participants and investigators.
There were only two studies assessing the pain outcome using VAS survey which could be considered for meta-analysis with favorable outcome. The two studies showed that there was a significant difference between the groups, supported the control group, ultimately indicating that vibrational devices had no effect in reducing pain. VAS assessment gives the respondent the freedom to choose the exact intensity of the pain, and it is a reliable and sensitive method of measuring pain and the effect of pain-reducing methods. This interpretation advertently indicated that vibratory devices may not be functional in reducing pain as compared to its existing alternatives (commonly NSAIDs), in addition, there was insufficient information regarding the compliance from the patients' side.
Five RCTs reported no difference in pain/discomfort perception but 4 RCTs did indicate that there was reduced pain during the initial alignment. The over bias was well accepted and reported in all the studies. The studies cumulatively suggested that there was a trend in the pain levels which were higher in the experimental groups as compared to control in the initial 24 h but after 1 week to 10 days, the pain reduced to similar levels in both the groups. Thus indicating that vibratory devices do not accomplish the task of reducing pain when compared to analgesics to a superior level in the commencing period of orthodontic treatment. Although two of the studies did suggest that vibratory devices were effective in reducing pain the compliance and type of device are also significant along with the duration of use which was reported to be varying from 10 min to 20 min with different intervals in a day and with a range from 1 week to 4 months' usage. The consistency of these effects can be seem to collaborate with most of the studies that reported pain levels were high on 1st and 2nd day after the treatment initiation but reduced after a week. Most of the studies involved used AccelDent Aura as the intervention, seconded to Tooth Masseus.
Vibration is an attractive technology for patients since it does not involve invasive surgery. It is an alternative treatment for managing pain for orthodontic patients, which prevents overmedication or avoidable exposure to analgesics. The vibratory stimulus is known to improve blood flow to the PDL at regular intervals which can be productive in reducing pain perception. However, in context of our results, inclination toward that vibratory device may not actually bring about a reduction in pain modulation, improvement in (quality of life), and also subjectivity to use of the device, which may further add up to the patient's discomfort. Compliance still remains a major concern for use of these devices, which is subjection to the pain perception varying from patient to patient. There are contrasting findings to the intervention time period which is not uniform to recommend the devices. In comparing the financial status, vibrational devices are expensive as compared to analgesics.
Miles et al. reported no effects of vibrational appliances on the rate of extraction space closure. This study combined different extraction patterns in their experimental group (first- and second-premolar extractions), and thus retracted canines and first-premolars depending on the specific extraction pattern. Lobre et al. examined the effects of the mechanical vibratory stimuli on perceived pain. They observed micropulse vibrational devices significantly lowered pain levels over the 16-week period of their study. This conflicting evidence inspired us to conduct this review to investigate the efficacy of vibrational devices on perceived pain levels.
The major limitation observed in most of the included studies in the short-term duration of use along with the lack of continuous reinforcement from the orthodontist. The compliance factor to the device was not assessed and the possibility of bias can also be foreseen to have an influence on the responses. The lack of blinding was major lacunae observed in all the studies. Further studies are needed in this area of vibratory stimulus and pain modulation. Most of the studies could not be included in meta-analysis because of inadequate and inconclusive data outcomes (mean ± SD). Furthermore, a variability was seen in the devices used and the heterogeneity of the type of controls used (sham device/no device).
The use of supplemental vibrational force has been advocated as a simple noninvasive method of improving the efficiency and cooperation of orthodontic treatment with fixed appliances. In particular, as a method of increasing rates of tooth movement during alignment, leveling, and translation; however, this evidence is conflicting. In addition to faster orthodontic tooth movement, it has been proposed that vibratory stimulation can decrease pain following orthodontic adjustments. Ottoson et al. found that applying vibration at 100 Hz to various points in the skull and facial region reduced pain in 30 of 33 patients suffering from dental pain of various types. Other research demonstrated a reduction in musculoskeletal pain in 69% of patients by using vibratory stimulation while vibrotactile stimulation was shown to reduce musculoskeletal pain by as much as 40%.
We hope that this systematic review will assist future investigators with the design and conduct of studies assessing vibrational devices with appropriate modifications in the methodology for better outcome assessment and concrete evidence on the use of vibrational devices to reduce pain.
Recommendations for future research
More and future RCTs should be designed to detect differences between intervention groups through a priori sample size which is larger. Investigators are encouraged to report all possible outcomes, risk of bias, and associated side effects with outcome measures which can be analyzed. The ideal time period to use the vibrational devices should also be decided to reduce pain and discomfort after the treatment or pretreatment protocol. Prospective RCTs should be designed to determine the which device is better in reducing pain in initial alignment and also with appropriate outcomes which can be further assessed for meta-analysis.
The ability of vibrational devices to reduce pain among orthodontic patients has been studied in several RCTs. The results indicated by the meta-analysis show that there is no significant difference in the pain outcome after the use of vibrational devices as compared to the control group which was correlated with majority of the studies included in the qualitative analysis. Thus, we concluded that vibrational devices have no effect on the reduction of pain in patients undergoing orthodontic treatment.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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