THEORIES OF PAIN
CLASSIFICATION OF PAIN
OPTIMAL FORCES FOR TOOTH MOVEMENT
MECHANISMS OF ORTHODONTIC PAIN
PATHOPHYSIOLOGY OF PAIN ASSOCIATED TO
THE MECHANISMS UNDERLYING ORTHODONTIC PAIN
3. NEURAL CIRCUITS AND REGULATION OF
THE INFLUENCE OF TYPE OF ORTHODONTIC FORCE
MODIFICATION IN ORTHODONTICS FOR LESS PAIN
PERCEPTION BY PATIENT
PAIN : An unpleasant sensory and emotional
experience associated with, or resembling that
associated with, actual or potential tissue damage
IASP Revised Definition of Pain (16TH JULY 2020)
5. The prevalence of pain and background factors such as
age, gender and culture/society, in addition to pain
physiology and the influence of concomitant emotional
and cognitive factors.
Since the orthodontic treatment may cause some degree of
suffering for the patients, it is important for orthodontists
to handle this situation in the best possible way.
6. Some ideas about the possibilities of avoiding,
reducing or alleviating pain in orthodontics are
It has been reported that nearly every tenth patient
interrupts his or her therapy due to early pain experiences.
Besides the actual experience of pain during orthodontic
treatment, fear of pain may also be a great problem, since it
contributes to patient’s failure to seek orthodontic treatment
7. Discomfort and pain caused in the initial stage of
fixed orthodontic treatment can be moderate to severe
and might last for more than 1 month. Generalized
dentogingival discomfort is more prevalent than
localized discomfort. Brushing teeth might cause mild
discomfort and consuming soft foods can
Pain and discomfort perceived during the initial stage of active fixed orthodontic treatment
Hamid Rakhshan 2014
9. SPECIFICITY THEORY
Seminal contributions to neural functioning were made at
the turn of the century by the English neurophysiologist
Charles Sherrington (1857–1952), who – among other
ideas – provided evidence for the existence of inhibition in
CNS functions (Foster and Sherrington, 1897).
Sherrington also provided a common ground for the
various stimuli capable of evoking pain.
10. Sherrington (1906) countered with the logic that a
common feature of events evoking pain is damage of
tissue. He suggested that all stimuli capable of
injuring tissue be labeled ‘‘noxious’’ and coined the
terms ‘‘nociception’’ and ‘‘noci-ceptor,’’ to describe
unique activity by selective afferents. Thus, he
defined a common ground for the concept of pain
11. Wilhelm Erb, while agreeing with the sensory
nature of pain, articulated what became known as
the intensive theory (Erb, 1874). Erb reasoned that
pain was the outcome of any type of strong sensory
stimulation, arguing that intense activation of any
sensory modality is unpleasant.
Arthur Goldscheider concluded that there must
be some form of summation that occurs for the sub
threshold stimuli to become unbearably painful.
12. GATE CONTROL THEORY
Melzack and Wall deconstructed theory of specificity
into 3 assumptions:
1)the anatomical assumption
2) the physiological assumption
3) the psychological assumption
13. Although they accepted the possibility that Individual
receptors might have a specific anatomy (the
anatomical assumption) correlated with sensitivity to a
specific physical stimulus (the physiological
assumption), they were skeptical that the
‘‘psychological dimension of the somesthetic
experience’’ could be identified with a specific skin
receptor type (the psychological assumption).
14. The "gate control" theory, which suggests that pain
can be reduced by simultaneous activation of nerve
fibers that conduct non-noxious stimuli.
16. CLASSIFICATION OF PAIN
Burstone (1962): classified a painful response to orthodontic
mechanics in two ways:
1)relationship of force application with pain
2)time of onset
• the patient is not aware of pain unless the orthodontist
manipulates the teeth to be moved by the appliance, e.g.
using instruments such as a band pusher or force gauge.
• pain or discomfort caused during clenching or heavy biting —
usually occurs within the first week of appliance placement. The
patient will be able to masticate a normal diet with this type of
• if this type of pain appears, the patient might be unable to
masticate food of normal consistency.
RELATIONSHIP OF FORCE APPLICATION
• which is associated with
sudden placement of heavy
forces on the tooth, e.g.
hard figure of eight tie
between the central incisors
to close a midline diastema.
• produced by variety of force
values from light to heavy and
representing hyperalgaesia of
the periodontal membrane.
This type of pain response
decreases with time i.e. the
pain reaction might start as
third degree but become
second or a first degree with
the passage of time
BASED ON TIME OF ONSET
19. PAIN ASSESSMENTS
The Visual Analogue Scale (VAS) is one of the
most commonly used tools for measuring pain
intensity. It’s a psychometric response scale that
can be used in questionnaries.
20. The scale consists of a 100 mm horizontal or vertical line
with 2 endpoints labeled "no pain" and "worst ever pain"
for example. The patient places a mark on the line at a
point that corresponds to the level of pain intensity she
or he currently.
21. PAIN CHARACTERISTICS DURING
ORTHODONTIC TOOTH MOVEMENT
When a force is applied to a tooth, there is usually an
initial 1 or 2 days of discomfort/pain.
There is a great variety of findings concerning the
duration of pain. A number of patients describe
much longer periods of pain than the initial 1 or 2
days of discomfort/pain.
22. Scheurer reported
that, after insertion of
a fixed appliance in
170 patients (age 8 to
53 years), 25% of the
patients still reported
pain after 7 days. In a
few patients the
more than 4 weeks.
Scheurer P, Firestone A, Bttrgin
W. Perception of pain as a result
of orthodontic treatment with
fixed appliances. Eur J Orthod
Jones ML reported
moderate pain, the
worst was over by the
second day, peaking in
the evening and at
night. In those
continued for about a
and evenings, but little
Jones ML. An investigation into
the initial discomfort caused by
placement of an archwire. Eur J
23. OPTIMAL FORCES FOR TOOTH MOVEMENT
Light differential forces for tooth movement has been
recommended and are more efficient and more
biologic thus produces less pain and discomfort to
The term optimum orthodontic force is usually regarded as meaning
the force that moves teeth most rapidly, with the least discomfort to
the patient and least damage to the teeth and their investing tissues.
24. In 1932 Schwarz stated that biologically the most
favorable treatment is that which works with forces
not greater than the pressure in the blood capillaries.
Oppenheim (1944) and Reitan (1959) have also
reported the optimal force levels based on capillary
blood pressure in the periodontal membrane.
25. Burstone (1985) characterized optimal force by
maximal cellular response from the tooth supporting
tissues, including apposition and resorption of
alveolar bone, at the same time as the maintenance
of the vitality of these tissues is secured. Thus, the
amount of tooth movement is not the only indicator
of optimal force.
26. MECHANISMS OF ORTHODONTIC PAIN
Once orthodontic forces are applied on teeth,
marked responses occur at paradental tissues,
including periodontal tissues and the dental pulp.
A cascade of self-limiting inflammatory reactions,
including cellular, vascular, neural and
immunological reactions, act in an orchestrated way
to ultimately result in orthodontic pain and tooth
27. In effect, orthodontic pain and orthodontic tooth
movement are two interrelated and dependent
biological events with local inflammation being their
common mechanism. The products of local
inflammation (for example, prostaglandin and
bradykinin) act on sensory endings to incite painful
28. Therefore, the mechanisms underlying orthodontic
pain lie in periodontal inflammatory responses
induced by orthodontic forces.
The periodontal inflammation response includes
31. THE INFLUENCE OF TYPE OF
According to Reitan, pain is the result of
compression of the periodontal ligament
(PDL).It may indicate that hyalinized zones
are about to be formed in the periodontal
Andreasen et al. found no relationship
between reported pain and increased
forces.In their study, different forces
were applied between the canine and the
molars on each side using light force
(100 to 150 Gmm) on one side and
heavier force (400 to 500 Gm) on the
32. Williams OL, Bishara SE. Patient discomfort levels at
the time of debonding. Am J Orthod Dentofac
Orthop 1992; 101:313-7. Williams OL, Bishara SE.
Patient discomfort levels at the time of debonding. Am J Orthod Dentofac
Orthop 1992; 101:313-7.
At debonding, the patients may experience some
discomfort/pain. It appears that the discomfort threshold is
influenced by the mobility of the tooth and the direction of
force application. Patients withstand intrusive forces
significantly better than forces applied in a mesial, distal,
facial, lingual, or an extrusive direction.
33. Pathophysiology of Pain associated to orthodontics
Pain connected to orthodontic tooth movement originates from the
periodontal tissues due to mechanical injury causing pressure, ischaemia,
inflammation, and oedema in the PDL space producing inflammatory reaction.
Reduction of the proprioceptive and discriminating abilities occurs after
orthodontic force application for few days, which result in lowering of the pain
threshold and disruption of normal mechanisms associated with
proprioception input from nerve endings in the periodontal ligament
34. Due to diffusion of various inflammatory mediators intradental
nociceptive nerves get involved, the effects of periodontal tissue injury may
also be reflected.
All these effects are perceived as pain by the patient.
35. DOES ORTHODONTIC PAIN HAVE ANY EFFECT ON
PATIENT COMPLIANCE AND DAILY ACTIVITIES?
• Brown and Moerenhout (1991) reported that pain from
orthodontic treatment has a definite influence on daily activities
of patients. The pain appearing within the first 48 hours is
considered to be so disturbing that it causes wakeful nights and
consumption of medication.
• The literature suggests that the patient’s initial attitude towards
orthodontics should be understood during the diagnostic phase
itself and should be discussed with the patients in all its reality.
This procedure, termed as ‘ rational restructuring’ in
psychology ( Todesco et al. , 1992 ) will prepare the patients to
encounter discomfort during treatment through their own
methods and also with the help of a specialist.
36. COMMON CAUSES OF ORTHODONTIC
Initial stages of treatment:Common causes of
Asiryet al conducted a study to evaluate the effect
of elastomeric separators on pain experienced by
patients and concluded that pain associated with
orthodontic separation starts and peaks within 4–
48 h from the placement of separators and starts to
decline to reach the lowest level on 5th day
37. INTERMAXILLARY ELASTICS
Intermaxillary elastics have been found to cause
pain in patients similar to wire placement, but the
pain due to elastics was not found to last as long as
the pain found after initial bonding.
Tuncer Z, Ozsoy FS, Polat-Ozsoy O. Self-reported pain associated with the
use of intermaxillary elastics compared to pain experienced after
initial archwire placement. Angle Orthod 2011
38. APPLIANCE ACTIVATION
Appliance activation causes disruption in the
periodontal ligament creating areas of pressure and
tension leading to discomfort to the patient. An
increase in pain 24 h after activation of appliance was
observed by Treinet al. in their patients.
Trein MP, Mundstock KS, Maciel L, Rachor J, Gameiro GH. Pain, masticatory
performance and swallowing threshold in orthodontic patients. Dental Press J Orthod
39. Luppanapornlarp et al. evaluated the effect of
force levels on the pain intensity and tooth
movement and thus concluded that lower forces
produced less pain as compared to higher forces with
equally effective tooth movement.
Ogura et al. compared the pain intensity among
subjects with light and heavy force application and
found that heavy forces cause greater biting pain few
hours after the force application.
40. DEBONDING OF ORTHODONTIC APPLIANCES
Mangnallet al. conducted a multicenter trial and
suggested that debonding of fixed appliances leads to
pain experience in the patients. Furthermore, lower
anteriors were reported to be most painful after
Mangnall LA, Dietrich T, Scholey JM. A randomized controlled trial to assess
the pain associated with the debond of orthodontic fixed appliances. J
41. INSERTION OF TEMPORARY ANCHORAGE
The study was conducted by Chen et al. to evaluate the
pain experienced by the patients during placement of
interdental implants and was compared to the baseline
value of discomfort during premolar extractions. They
concluded that the placement of interdental implants did
not cause pain greater than that during traditional
Chen CM, Chang CS, Tseng YC, Hsu KR, Lee KT, Lee HE. The perception of pain
following interdental microimplant treatment for skeletal anchorage: A
retrospective study. Odontology 2011
Rinchuse (1994) , in another report, described the
use of an occlusal rim wax for pain-free debonding.
Only few studies reported the literature reports,
which assessed discomfort levels during debonding.
43. Pain due to separator placement
banding of tooth
Nowadays bonding of buccal tubes are preferred than
banding of molars so separation of teeth, being most
painful step is not required.
44. Pain due to initial wire placement
-Jones M. An investigation into initial discomfort caused by placement of an archwire. Eur J Orthod. 1984
Initial wires used for alignment and leveling are thermal NiTi
and copper NiTi which have low load deflection and produces
very low level forces and thus result in less pain to the
patient. These wires become inactive on low temperatures so
after insertion if there is more discomfort, the patient is
asked to do mouth rinses with cold or icy water which
soothes the patient
45. Pain due to retraction mechanics
Previously retractions were done with sliding
mechanics and force was applied via head gears and J-
hooks. As the advancement happened these were
replaced by NiTi coil springs which give low
continuous forces. After introduction of loops made by
TMA wires like TLoop and KSIR arch wire optimum
tooth movements were done with less force and less
pain to the patient
46. Pain due to extra oral appliances
Scheurer PA, Firestone AR, Burgin WB. Perception of pain as a result of orthodontic treatment with fixed
appliances. Eur. J. Orthod. 1996
All extra oral appliances were used for anchorage
preservation, require patient compliance and exert
orthopedic forces. Now a day’s these are mostly substituted
by absolute anchorage devices like orthodontic implants.
Placements of implants are done under local anesthesia so is
less painful to patient and it gives ease of retraction without
47. Pain due to expansion of maxilla
Proffit W R. Contemporary Orthodontics. St. Louis. C. Mosby CO
Rapid maxillary expanders are orthopedic devices and
produces separation between the two halves of the maxilla.
Since the process is very rapid, over the period of 15-20
days, and is a painful procedure. NiTi palatal expanders are
the newer advances, exerting low level forces over the
period of 3-6 months and less painful.
Non-steroidal anti-inflammatory drugs
(NSAIDs) are often recommended by orthodontists
to their patients to alleviate the pain caused during
orthodontic tooth movement.
Usually, analgesics are advised after the procedure is
performed, but preemptive administration of
analgesics has been found to be useful before
procedures like separator placement
51. VIBRATORY FORCES
Based on their clinical study, Marie et al. have
advised the use a vibratory apparatus by the patients
to ameliorate the pain caused by orthodontic
52. Vibratory forces are effective when used before the
development of pain as they improve and re-
establish the blood supply in the pain-causing
Vibration may help relieve compression of the PDL,
promoting normal circulation to prevent the
proliferation of inflammatory by-products.
53. BITE WAFERS
Mangnallet al. conducted a randomized clinical trial
the results of which showed a reduction in pain
during debonding procedures when the patients
were made to bite on soft acrylic wafers. Hwang et al.
suggested the use of thera bite wafers in relieving
pain after orthodontic procedures.
55. ANESTHETIC GELS
Keim described an anesthetic gel “oraqix” containing
a combination of lidocaine and prilocaine in 1:1 ratio
by weight. Such gels can be used when performing
routine orthodontic procedures to relieve the
56. CHEWING GUMS
Farzanegan et al. conducted a randomized clinical
trial on 50 patients to evaluate the efficacy of various
measures to reduce pain after placement of initial
They suggested that efficacy of chewing gums as a
method to relieve pain caused due to such
orthodontic procedures was comparable to that of
57. MEDICATED WAX
Kluemper et al. conducted a comparative study on
subjects using wax to relieve the discomfort caused
by fixed orthodontic appliances with those using wax
containing slow releasing benzocaine.
The patients using medicated wax reported of less
pain as compared to the other group showing the
analgesic properties of benzocaine containing wax.
58. BEHAVIORAL THERAPY
Wang et al. provided cognitive behavioral therapy to
150 patients and compared the effects with the use of
analgesics. They concluded that the behavioral
therapy was effective in pain control during initial
stages of orthodontic treatment.
59. VIBRATING NEEDLE (VIBRAJECT)
In orthodontic treatment sometimes we have to
remove teeth for gaining space and other surgical
procedure and that definitely need administration of
local anesthesia. Various advancements have been
made in anesthetic agents and techniques to get a
pain free and comfortable anesthesia.
60. The VibraJect LLC (USA) was first introduced in
1995 and was developed under the hypothesis that a
vibrating needle would stimulate large diameter
nerve fibers and thereby close the gate to smaller
nerves carrying the pain signal from the injection
61. LOW LASER THERAPY
A recent systematic review demonstrated that LLLT might
improve orthodontic treatment by accelerating tooth
movements and modulating acute pain, as well as
The quality of scientific evidence that supported LLLT
use in modulating acute pain was low.
62. Bayani and colleagues designed a study evaluating the
efficacy of ibuprofen, bite wafer and low power red and
infrared lasers in orthodontic pain management. The
authors concluded that a single session from a low power
infrared laser was the most effective and suitable
methodology for pain relief in orthodontic patients
following archwire placement.
63. GENE THERAPY
Gene therapy is defined as a method that delivers genes or
DNA sequences to target cells that can transiently or
stably express those genes or DNA sequences to alter the
biological functions of those cells. Pain relief could be
achieved through delivering endogenous opioid genes into
64. At present, the application of gene therapy in clinical
practice is limited by its biosafety concerns.Nevertheless,
its potential biosafety concerns may be addressed in the
near future, and it may become a viable and mainstream
treatment strategy for orthodontic pain relief.
Orthodontic pain, an inflammatory pain, shares many
similar features with common inflammation, but it has
specific hallmarks. The exact molecular mechanisms of
the pathogenesis of orthodontic pain are still poorly
Orthodontists must be aware of the various factors that
might cause discomfort to the patients and should be
able to manage such episodes to improve the
compliance of patients with the orthodontic therapy.
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