Acute pain or discomfort during orthodontic treatment is commonly reported. A study done
in 2002 found that 87% of patients experienced pain after orthodontic visits.
Additionally, "feeling pain" has been identified as the primary treatment concern for
many patients prior to orthodontic treatment. More so, it can negatively affect patient
compliance and attitude toward treatment.
Numerous studies have shown that pain varies in intensity and duration among orthodontic
patients. The placement of orthodontic separators is a standard procedure to facilitate
placement of orthodontic bands by creating a small amount of space between posterior
teeth. Separator placement reliably produces acute discomfort to patients. Pain generated
from orthodontic separator placement originates in the periodontal ligament (PDL) as
compression forces are applied to the PDL unequally to open a small space (less than 0.5
mm) between the teeth. This compression triggers sterile necrosis or hyalinization in
some areas of the PDL, leading to acute pain. The course of pain generated from
orthodontic separators typically begins 4 hours after placement, reaching highest pain
intensity approximately 24 hours after placement, and continuing to decrease in intensity
until returning to pre-placement baseline after seven days.
Variation in reported pain intensity across orthodontic patients is of interest to any
practitioner who desires to improve patient outcomes. In an attempt to enhance the
orthodontist ability to understand pain and its predicting factors, researchers have
examined pain from orthodontic treatment relative to patient demographics, personality
traits, psychological factors, perceived need and attitude toward treatment, among
others. Okeson asserts that pain is not directly related to the extent of tissue injury.
Noxious stimuli originating in peripheral neurons (such is the case with separators) are
subject to modulation at multiple levels through a complex central inhibitory system,
where many other factors participate in decreasing or increasing the pain experience.
Hence, an individual's emotional state, pain expectation and perception of control, as
well as activities or distractions that will differ brain attention (Gate Control) can
significantly influence the pain experience. Perceived stress, or the degree to which
situations in an individual's life exceed their ability to cope, could be a good
predictor of experienced pain. The Perceived Stress Scale is the most widely used
screening form to evaluate perceived stress and asks subjects to recall the frequency of
feeling overloaded and overwhelmed in the past month.
Recently, more attention has been given to the role of physical activity (PA) in reducing
pain in patients that undergo orthodontic treatment. Physical activity has been shown to
be an effective mediator of acute pain tolerance and pain sensitivity, an effect known as
Exercise Induced Hypoalgesia (EIH). One study reported that a 1-mile run decreased pain
intensity evoked from a weight being placed on the index finger. A similar decrease in
pain response to pressure applied to the finger was found in subjects in another study
who performed 30 minutes of aerobic exercise. It has also been demonstrated that exercise
increased dental pain thresholds in response to electrical stimulation of the pulp. The
exact mechanism involved in EIH remains elusive. Still, several pathways have been
implicated including activation of the endogenous opioid pathway, increased
Adrenocorticotropic Hormone release, and a conditioned pain the pain perceived in another
area of the body.
Researchers have demonstrated that higher self-reported physical activity reduced the
pain levels generated by placement of orthodontic separators when compared to patients
with low physical activity. Self-reported measurements of physical activity carry
limitations. The Physical Activity Questionnaire (PAQ) used in previous studies have
demonstrated an only moderate correlation with direct activity observation (r=0.45), and
with an activity monitoring device (r=0.57). The PAQ asks participants to report pain in
the last seven days, and if given before treatment was performed, provides no data on
physical activity during the week when subjects are experiencing pain. To further explore
the correlation between physical activity and acute pain during orthodontic treatment, a
more reliable measure of physical activity is warranted.
Actigraphy sensors provide an objective measure of physical activity. Actigraphy sensors
include pedometers, which count steps over a defined time interval, and accelerometers,
which measure acceleration in "activity counts" that are then extrapolated to the
Metabolic Equivalent of Task (METS) to measure energy expenditure. No other paper has
evaluated the effect of physical activity measured with pedometers on acute pain
following separators placement during orthodontic treatment. Because not all patients
experience pain at the same level, it would be beneficial for clinicians to identify
which patients are likely to experience more intense pain before beginning treatment. To
this end, the purpose of this study is to test the effect of physical activity measured
by pedometer on acute pain produced by the placement of separators.
Protocol amended to include minors aged 15-17.