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Itch & Pain 2016; 3: e1165. doi: 10.14800/ip.1165; © 2016 by William J. Dunn, et al.
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RESEARCH HIGHLIGHT
Pain control in orthodontics using vibration
Wendy D. Lobre1, William J. Dunn2
1
Orthodontic Resident, Tri-Service Orthodontic Program Air Force Postgraduate Dental School 2133 Pepperrell Street, Bldg 3352
JBSA-Lackland, TX, USA
2
Air Force Consultant in Dental Research 1615 Truemper Street JBSA-Lackland, TX, USA
Correspondence: William J. Dunn
E-mail: [email protected]
Received: December 15, 2015
Published online: February 01, 2016
Pain is a common patient complaint during the orthodontic movement of teeth, especially immediately following
archwire placement. Vibration has been used to accelerate the orthodontic movement of teeth and some
observations by clinicians have indicated that vibration appeared to reduce the pain of orthodontic treatment.
The purpose of this parallel group, randomized clinical trial was to investigate the relationship between a micro
pulse vibration device and pain perception during orthodontic treatment. Fifty-eight patients meeting eligibility
criteria were assigned using block allocation to one of two groups: an experimental group using the vibration
device or the control group (n = 29 for each group). Patients used the device twenty minutes daily. Patients rated
pain intensity on a visual analog scale at appropriate intervals during the weeks after the separator or archwire
appointment. Data were analyzed using repeated measures analysis of variance at α=0.05. Over the four month
test period significant differences between the micro pulse vibration device group and the control group for
overall pain (P =.002) and biting pain (P=.003) were identified. The authors observed that perceived pain was
highest at the beginning of the month, following archwire adjustment. The micro pulse vibration device
significantly lowered the pain scores for overall pain and biting pain over the four month study period.
Keywords: Pain; vibration therapy; orthodontics
To cite this article: William J. Dunn, et al. Pain control in orthodontics using vibration. Itch Pain 2016; 3: e1165. doi:
10.14800/ip.1165.
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Introduction
Pain is a common occurrence during the orthodontic
movement of teeth, especially immediately following
archwire placement or adjustment. It is a complex
phenomenon involving multiple variants and is influenced by
factors such as age, gender, individual pain threshold and
amount of force applied [1]. In orthodontics, a mechanical
stimulus is introduced by placing fixed appliances on the
teeth resulting in tooth movement. To achieve this
movement, forces are applied to the dentoalveolar complex
via fixed orthodontic brackets and wires resulting in
inflammation or ischemia to the highly sensitive periodontal
ligament (PDL) which surrounds the roots of the teeth with
subsequent release of histamine, bradykinin, prostaglandins,
substance P and serotonin [2]. These mediators stimulate local
nerve endings and send pain signals to the brain.
Many methods have been used to alleviate pain arising
from orthodontic origins. Non-steroidal anti-inflammatory
drugs (NSAIDS) are the most common method to alleviate
discomfort. NSAIDS block the formation of arachidonic acid
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Table 1. Mean pain scores numerically generated from patients’ Visual Analogue Scale (VAS) information (0-100). P values are
compared to the corresponding control groups.
Overall Pain Score
With Device
1
2
3
4
8.78 (P=.039)
4.62 (P=.005)
3.83 (P=.012)
2.54 (P=.003)
Overall Pain Score
Control (no device)
Biting Pain Score
With Device
17.20
13.11
9.22
8.80
14.28 (P=.068)
8.33 (P=.016)
5.83 (P=.008)
4.45 (P=.001)
Biting Pain Score
Control (no device)
23.65
17.01
12.37
13.22
Pain scores from the first seven days were averaged to make the first week score. After the first week, pain was scored once weekly for the
following three weeks. The four weekly pain scores were averaged again to represent a monthly score. Univariate analysis of variance of
between subjects effects were used to detect differences between the control groups and the groups that used the micro pulse vibration
device (α=0.05)
in the production cycle of prostaglandin which would lead to
pain [3]. Other methods include low-level laser therapy [4],
transcutaneous electrical nerve stimulation (TENS) [5],
vibratory stimulation of the PDL [6], viscoelastic bite wafers
[7] and even chewing gum [8]. The mechanism of these
methods is to relieve compression of the PDL, restoring
normal vascular and lymphatic circulation to eliminate
edema and inflammation, reducing pain [9].
The focus of our study was vibratory stimulation to reduce
pain. Previous studies have demonstrated that vibration
effectively reduces pain originating from teeth or the
surrounding tissues [10]. Vibration may help relieve
compression of the PDL, promoting normal circulation to
prevent the proliferation of inflammatory by-products.
Another possibility is the "gate control" theory, which
suggests pain can be reduced by simultaneous activation of
nerve fibers that conduct non-noxious stimuli [11]. Similar to
the pain relieving effects from TENS, the effect of vibration
seems consistent with the gate control theory, relying on
activation of rapidly adapting mechanoreceptors in the skin,
periosteum, muscle and bone, and an interaction between
large fibers and small pain fibers. In essence, the receptors
activated by vibration could mask the pain signals and
prevent them from reaching the central nervous system
(CNS). The possible release of endorphins secondary to the
vibratory stimulus is another plausible theory.
AcceleDent® is patented as a “Vibrating Orthodontic
Remodeling Device” (U.S. Department of Commerce's
United States Patent and Trademark Office, 2013). It is an
FDA approved, Class II medical device designed for faster
orthodontic treatment. The manufacturer states that the
device applies cyclic forces to the dentition for the safe
acceleration of the bone remodeling process to complement
conventional orthodontic treatment. The application of
cyclical forces induces accelerated remodeling of alveolar
bone. In a series of rabbit experiments, Mao [12] demonstrated
that cyclical forces applied at 2N with frequencies of 0.2 and
1Hz for 20 minutes daily, in conjunction with typical static
orthodontic forces 24-hours per day, induced increased
cranial growth, sutural separation, and proliferation of
osteoblast-like cells. The primary purpose for using
AcceleDent® is to decrease overall orthodontic treatment
time. Moreover, cyclic force has been used and approved for
use in other areas of the body (e.g., the Juvent™ 1000 device
for maintaining and/or enhancing muscle strength, function,
and postural stability).
There are reports from clinicians who have noticed pain
reduction as an additional benefit for those patients using
AcceleDent®. The purpose of our clinical study was to
investigate the relationship between micro pulse vibration
therapy for dental pain relief compared to a control group of
no pain therapy during the first four months of orthodontic
tooth movement and adjustment, and to see if age and gender
were significant factors in the perception of orthodontic pain.
This research highlight will familiarize readers with a clinical
technique to reduce dental pain from the orthodontic
movement of teeth that is relatively unexplored in
dentistry—vibration.
Methods
This parallel group, randomized clinical trial was
approved by the local Institutional Review Board (IRB) and
was determined to be no greater than minimal risk. It was
determined that a sample size of thirty subjects per group
would be sufficient to answer the research question at the
95% confidence interval. Pain scores were examined daily
for the first week and weekly thereafter, and also by
averaging the scores for a monthly score. A total of seventy
subjects (thirty-five per treatment group) were selected from
patients who presented for initial orthodontic treatment.
Subjects were selected based on the following inclusion
criteria: healthy child (age 10 and older) and adult patients
approved for comprehensive orthodontic treatment. Subjects
were recruited by orthodontic staff members and residents in
the orthodontic department directly assigned to the study.
Subjects were excluded from recruitment if the subject
currently had any pre-existing pain conditions, or if the
subject was not able to comply with the restriction on using
any analgesic drugs (acetaminophen, ibuprofen, aspirin,
topical anesthetic, etc.) during the course of the study.
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Figure 1. VAS pain scores for overall pain.
Participants were assigned to comparison groups using a
block allocation sequence which was concealed from the
investigators. All subjects were given routine post treatment
instructions and asked to complete a pain scale survey at
appropriate intervals during the weeks after the separator or
archwire appointment. The pain scale survey was in the
format of a multi-page booklet that contained a series of
10-cm horizontal visual analog scales (VAS) on which the
patient marked the degree of discomfort (none to worst pain
imaginable) at the indicated time periods. The patients were
instructed to make a mark on a new scale sheet at each time
interval to record the perceived severity of pain in two
categories: chewing/biting and overall pain. Patients using
the AcceleDent® Aura micro pulse vibration device were
instructed to mark the pain scales within one hour after using
the device. Patients had archwires placed and adjusted each
month. Incidence and severity of pain was recorded by the
patient after separator or archwire placement appointment
daily for the first seven days after each monthly orthodontic
appointment and then weekly for the remainder of the month
for four months. The primary investigator monitored
compliance regarding usage of the device via the integrated
USB interface of the AcceleDent® Aura.
Patients in both groups were directed not to take any pain
medication or analgesics, to include OTC medications and
topical ointments. If “rescue” medication was needed for
pain control of any kind the patient was instructed to indicate
on the pain scale survey the date, time, dosage, reason and
specific rescue medication taken. If rescue medication was
not used on the day of or the day after adjustment, and if the
patient did not take more than one dose of medication then
the patient was allowed to remain in the study.
The hands-free micro pulse vibration device was used
following manufacturer’s recommendations. Biting on the
mouthpiece activated the device, and the vibration was
transferred to the teeth. Patients assigned to the experimental
group were instructed to use the device for 20 minutes daily
beginning the day separators were placed and continued daily
for the first four months of leveling and aligning.
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Figure 2. VAS pain scores for biting pain.
Subjects were continuously reminded to complete their
VAS and record pain scores and whether they were taking
rescue medications. At the end of the four month trial
patients returned the pain scale data to the PI. Univariate
analysis of variance (ANOVA) of between subject effects
were used to detect differences between the AcceleDent and
Control groups (α = 0.05).
Results
Average monthly pain scores were numerically generated
from the patients’ VAS information and are reported in Table
1. In each group, twenty-nine of thirty-five subjects remained
in the study after the four month trial. Six subjects from each
group were excluded from the study. Four of six subjects
from the device groups used a quantity of rescue medication
that was considered excessive, mostly for non-dental pain.
The other two subjects were non-compliant with their pain
diary. In the control group, three subjects used rescue
medication too often (headache, body pain) and three others
were non-compliant with respect to the pain diary. Over the
four month test period, repeated measures ANOVA detected
significant differences between the micro pulse vibration
device group and the control group for overall pain (P =.002)
and for biting pain (P =.003) at α =.05. From graphical data
the authors also observed that perceived pain was highest at
the beginning of the month, following archwire adjustment.
Graphical representation of average overall pain scores for
the device and control groups over the four month study
period is shown in Figure 1. Graphical representation of
average biting pain for the device and control groups over the
four month study period is depicted in Figure 2. Stratified
nalysis was used for gender and age; however, the study was
not powered adequately to look at subgroup differences. No
harms or unintended effects were noticed. All subjects who
were given a device reported that they were in less pain when
using the device.
Discussion
Dental pain from orthodontic treatment provides pain
researchers an excellent model to study. The pain is
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relatively predictable from an intervention to a highly
sensitive ligament apparatus surrounding the roots of the
involved teeth. Researchers attribute initial and delayed pain
responses following orthodontic treatment to compression
and hyperalgesia of the periodontal ligament, respectively
[13]
. The periodontal ligament becomes sensitive to released
substances such as histamine, bradykinin, prostaglandins,
and serotonins [14]. These pain mediators are found in high
levels when a pain response occurs. Given that pain is a
subjective experience it is difficult to assess and few in vivo
studies have measured and quantified it. Multiple studies
found that pain after orthodontic procedures peaked at
approximately 24 hours post treatment. Ngan et al. [3] and
Scheurer et al. [1] found that pain increased 4 hours posttreatment and gradually returned to baseline levels at 7 days
post-treatment; whereas Erdinç and Dinçer [15] found that
pain was perceived at 2 hours and then decreased by day 3,
with no difference found either between gender or size of the
initial archwire. In our study, pain quickly increased and
peaked at approximately 24 hours post-initial archwire or
separator insertion. Figures 1 and 2 illustrate the differences
in pain perception over the four month study period for
device and control groups for overall and biting pain,
respectively. Pain scores were higher throughout the course
of treatment for biting pain. This agrees with the current
concept that sustained PDL pressure from orthodontic
adjustment decreases blood flow and recruitment of the pain
producing substances over time [14]. Therefore, increasing
blood flow to the PDL by vibratory stimulation at regular
intervals may be effective in reducing the perception of
orthodontic pain.
Blinding was not possible for this study and we cannot
totally dismiss the possibility that a placebo effect from the
device may have influenced the results. A sham device was
not used in the current study for several reasons. First,
possible skewed results could have occurred because a bite
plate could essentially function as a bite wafer and secondly,
a sham device could be interpreted as misleading or
deceptive to the patient. Murdock et al. [16] found that plastic
bite wafers chewed by the patient were as effective as
over-the-counter pain medications after initial archwire
placement. Hwang et al. [17] found that pain relief occurred in
56% of patients after using a bite wafer, however, the other
44% of the patients reported increased discomfort. In
contrast, Otasevic et al. [18] found that their bite wafer group
reported more pain than the group that avoided masticatory
activity. Because of possible unwanted treatment effects of
bite wafers on pain reporting, the authors chose not to use a
sham device that may have a bite wafer effect.
Table 1 compared the pain data for the study groups and
whether there were significant differences by month. The
data reveal that for all groups except one there were
significantly lower pain scores for the device group
compared to the control groups for both overall pain and for
biting pain. Only the first month data set for biting pain was
not statistically different (P = .068). However, when repeated
measures ANOVA was performed on all four months of data,
significantly lower pain scores were recorded for overall pain
and biting pain when the device was used. Gender and age
data were collected, but there were not a sufficient number of
subjects in these subjects to make any statistical conclusions.
Several authors have found that vibration will diminish
pain responses [19, 20]. However, at least one study
demonstrated no pain relief with the use of a vibratory device
[21]
. Vibration therapy in this randomized clinical trial
resulted in significantly lower perceived pain and less OTC
medication use. Vibration therapy has not been researched
extensively in dentistry. A recent review of the literature in
MEDLINE®/PubMed® revealed only 30 scholarly articles in
the peer-reviewed literature using the search terms “dental
pain” + “vibration therapy” [22]. The majority of research on
vibration therapy in dentistry has studied the effect of
vibration on dental anesthetic injections [23, 24]. In medicine,
vibration therapy has been studied more extensively but still
is not accepted as a first-line intervention [25, 26]. Zafar et al.
[25] examined the current evidence regarding the effects of
whole-body vibration in patients with osteoarthritis in a
meta-analysis and found that vibration therapy reduces pain
and improves function in patients with knee osteoarthritis. In
another systematic literature review Collado-Mateo et al. [26]
concluded that whole-body vibration could be an adequate
treatment for fibromyalgia as a main therapy or added to a
physical exercise program to improve balance, disability
index, health-related quality of life, fatigue and pain. Results
from this study and other studies in medicine suggest that
vibration therapy holds promise in the reduction of pain for a
variety of conditions. Based on the parameters of this
randomized clinical trial, the use of a micro pulse vibration
device significantly reduced the perception of overall and
biting pain in patients undergoing orthodontic treatment.
Conflict of interests
The authors have declared that no conflict of interests
exist.
Acknowledgements
The authors would like to thank the Orthodontic
Department at the Tri-Service Orthodontic Residency at the
Uniformed Services University of the Health Sciences, JBSA
Lackland, Texas for their support of this research project, and
to Dr. Anneke Bush for her statistical support. This research
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study was supported by funds from the Air Force Surgeon
General Research Program.
13. Burstone CJ. Rationale of the segmented arch. Am J Orthod 1962;
48:805-822.
Author contributions
14. Polat O, Karaman AI. Pain control during fixed orthodontic
appliance therapy. Angle Orthod 2005; 75:214-219.
WD: analyzed and interpreted the data and drafted the
manuscript. WL: was responsible for the design and
manuscript primary draft of the original study from which
this research highlight was written.
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