Introduction
During orthodontic treatment, patients frequently encounter discomfort related to various orthodontic procedures. Typically, individuals describe these discomforts as sensations of pressure, tooth soreness and pain. It has been reported that orthodontic procedures can reduce patients’ proprioceptive and discriminating abilities for up to 4 days, lowering their pain threshold. This discomfort is attributed to pressure, ischaemia, inflammation and oedema in the periodontal ligament (PDL) space. The duration and intensity of pain vary across procedures and among patients of different ages and sexes.
This chapter is focused on the causes of pain of orthodontic origin, its pathophysiology, clinical manoeuvres that can make orthodontic procedures less traumatic and the philosophy of non-pharmacological and pharmacological management.
Definition of pain
International Association for the Study of Pain (IASP) has defined pain as ‘An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage’.
Pain is a subjective response, showing significant individual variations such as age, gender, pain threshold, emotional state, magnitude of force applied, cultural differences, type of malocclusion and previous pain experiences. Pain can be categorised based on pathophysiology as nociceptive, neuropathic or nociplastic pain. ,
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Nociceptive pain : It occurs as a result of direct stimulation of nociceptive nerve fibres through mechanical, chemical or thermal triggers or indirectly through the release of inflammatory mediators such as histamine, bradykinin, substance P, prostaglandins and serotonin.
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Neuropathic pain : It arises due to damage to the nerves or nervous system. It causes shooting and burning pain or numbness.
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Nociplastic pain : ‘The pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of the somatosensory system causing the pain’.
Pain pathway
There are three stages of pain pathway ( Fig. 101.1 ).
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First stage: Pain signal from the tissue is carried by the nociceptive fibre (afferent fibre), which is first order neuron to the spinal cord dorsal horn.
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Second stage: Signals from the dorsal horn are taken to the thalamus by second order neurons where the nucleus of that particular nerve is present.
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Third stage: From the thalamus, signals are then transmitted to the primary somatosensory cortex for further processing and pain perception.
Three stages in pain pathway.
First stage: Pain signal from the tissue is carried by the nociceptive fibre (afferent fibre), which is first order neuron to the spinal cord dorsal horn. Second stage: Signals from the dorsal horn are taken to the thalamus by second order neurons where the nucleus of that particular nerve is present. Third stage: From the thalamus, signals are then transmitted to the primary somatosensory cortex for further processing and pain perception.
Source: Based on the concept from https://upload.wikimedia.org/wikipedia/commons/f/fa/Afferents.png .
Theories of pain
Pain is a prevalent reason for medical consultations, yet we still need a comprehensive understanding of its causes and mechanisms. Despite extensive research, the specifics of pain remain elusive. There are four main theories of pain perception—specificity, intensity, pattern and gate control.
Specificity theory
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The specificity theory of pain was developed by Maximilian Von Frey in 1895. According to this theory, pain perception is processed entirely differently in the brain than in vision and hearing. According to Frey’s theory, separate epidermal nerve endings are responsible for transmitting pain. The ‘pain centre’ is a specialised area of the brain where pain signals are transmitted through specialised channels, wherein the information is processed to produce the pain experience. The specificity theory is no longer accepted.
Intensity theory
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This theory is based on Aristotle’s concept that pain results from excessive stimulation of the sense of touch. Critical factors affecting pain include central summation and stimulus intensity. It was suggested that the cells of the dorsal horn undergo summation.
Pattern theory
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The theory proposes that sensory information is encoded by specific patterns of neural activity in the peripheral nerves, which convey information about the type and intensity of the stimulus. This means that when we experience touch, warmth or other non-damaging or damaging stimuli, the peripheral sensory receptors respond by sending signals through the nervous system that create non-painful or painful experiences. Pain is said to occur when specific patterns of neural activity reach excessively high levels in the brain. In other words, the theory suggests that pain results from particular patterns of neural activity.
Gate control theory
Melzack’s pain theory has generated considerable interest and discussion regarding the understanding of pain. According to the theory, small, slow fibres are responsible for carrying pain stimulation, which enters the dorsal horn of the spinal cord. From there, other cells transmit these impulses from the spinal cord to the brain.
The spinal cord acts as a ‘gate’ that controls or restricts the transmission of pain signals to the brain or higher centres. When the gates are open wider, a greater number of pain messages are transmitted to the brain, leading to a higher level of pain. Conversely, fewer messages are transmitted when the gates are closed, resulting in lower pain levels.
Biopsychosocial model of pain
According to the biopsychosocial model, pain is a neurophysiological event influenced by social and psychological elements. It asserts that factors such as culture, family dynamics, environmental conditions and nociceptive stimuli collectively shape pain perception, impacting an individual’s emotions, behaviours and cognition.
Orthodontic pain pathway
Orthodontic pain is a type of nociceptive pain (inflammatory pain) initiated by mechanical force that induces vascular occlusion, pressure oedema and a cascade of inflammatory reactions around affected teeth. This cascade of events includes the inflammatory response of vascular alterations, the recruitment of inflammatory and immune cells and the release of neurogenic and pro-inflammatory mediators, which sensitises the nociceptors in the PDL and increases the pain sensitivity. Orthodontic pain is part of an inflammatory reaction that causes changes in blood flow following orthodontic force application ( Fig. 101.2 ). This results in the release of various chemical mediators, eliciting a hyperalgesic response. The neuropeptides are released, which are known to elicit a painful response.
Orthodontic pain pathway.
The neural circuits for transmission of orthodontic pain.
Source: Based on the concept by Long H, Wang Y, Jian F, Liao LN, Yang X, Lai WL. Current advances in orthodontic pain. Int J Oral Sci. 2016 Jun 30;8(2):67–75. doi:10.1038/ijos.2016.24. PMID: 27341389; PMCID: PMC4932774.
Various neuropeptides responsible for orthodontic pain are substance P (SP), calcitonin gene-related peptide (CGRP), neurofilament protein (NFP), vasoactive intestinal polypeptide (VIP), neuropeptides Y (NPY).
Substance P (SP) is a neuropeptide that plays a key role in pain signalling. According to Mangano et al., stimulation of periodontal nerve fibres by means of mechanical forces may induce the peripheral release of SP, the neurotransmitter in the pulp and periodontal ligament. SP leads to the release of messengers such as prostaglandins and cytokines, increasing intracellular second messengers. Although research supports its association with inflammatory periodontal disease, the role of this SP during orthodontic treatments has yet to be fully understood ( Fig. 101.3 ).
Role of neuropeptide: These neuropeptides released are known to elicit a painful response. Various neuropeptides responsible of orthodontic pain are substance P, calcitonin gene-related peptide (CGRP), neurofilament protein (NFP), vasoactive intestinal polypeptide (VIP), neuropeptides Y (NPY). Amongst all these neuropeptides, substance P has more correlation with the pain.
Clinicians’ approach to grouping pain of orthodontic origin
Burstone grouped the pain of orthodontic origin with intensity and time of onset. According to him :
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A.
Depending on the relationship of force application with pain, it can be groped as
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i.
first degree,
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ii.
second degree,
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iii.
third degree.
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i.
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B.
According to the time of onset:
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i.
immediate
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ii.
delayed.
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i.
Methods for pain evaluation
Clinicians and scientists have attempted to quantify or grade the subjective perception of pain using various scales and instruments. Some of the commonly used scales are :
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i.
Patient interview/questionnaire
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ii.
Visual analogue scale (VAS)
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iii.
McGill’s pain questionnaire (MPQ)
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iv.
Verbal rating scale (VRS)
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v.
Algometers
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i.
Patient interview/questionnaire: This method consists of a set of specific questionnaires with relevant options that patients can choose according to their experience of pain during the procedure. For example, how will you describe your pain after the orthodontic appointment?
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Very intense, intense, less intense, very less intense.
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ii.
Visual analogue scale (VAS): Most frequently used scale. The visual analogue scale ranges from 1 to 10. Respondents are expected to mark a location on the line corresponding to the pain they have experienced. It provides the freedom to choose the exact intensity of pain ( Fig. 101.4 ).
Figure 101.4 Visual analogue scale (VAS): Most frequently used scale. VAS ranges from 1 to 10. Respondents are expected to mark a location on the line corresponding to the amount of experienced pain. It provides the freedom to choose the exact intensity of pain.
Source: Based on the concept from
Visual Analog Survey Scale — A Pain-ful Misnamed Scale
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iii.
McGill’s pain questionnaire (MPQ): This is a commonly used method in medical research but less explored in orthodontics. The main advantage of the MPQ is its provision for identifying quantitative measures of clinical pain. MPQ is also known as the pain rating index.
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iv.
Verbal rating scale (VRS): It consists of adjectives to describe different intensities of pain ( Fig. 101.5 ).
Figure 101.5 Verbal rating scale (VRS): It consists of adjectives to describe different intensities of pain.
Source: Based on the concept from Relvas JB, Bastos MM, Marques AA, Garrido AD, Sponchiado EC Jr. Assessment of postoperative pain after reciprocating or rotary NiTi instrumentation of root canals: a randomized, controlled clinical trial. Clin Oral Investig. 2016 Nov;20(8):1987–1993. doi:10.1007/s00784-015-1692-0. Erratum in: Clin Oral Investig. 2016 Nov;20(8):1995. doi:10.1007/s00784-016-1758-7. PMID: 26685850.
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v.
Algometer: In 1994, Simmons proposed the utilisation of an algometer to evaluate pain in patients seated in dental chairs and to record the force applied to the teeth during adjustments of fixed orthodontic appliances. Studies have confirmed the pressure algometer is an efficient and effective tool in screening and evaluating orofacial pain in patients.
Factors affecting pain intensity
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i.
Impulses from the brainstem:
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Nociceptive impulses may be altered in the spinal cord and brain cortex, which may cause sensations of no to low pain. If the patient has a history of painful dental experiences, the pain sensation would be felt as intense, being influenced by previous traumatic experiences even in the absence of pain stimuli.
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ii.
Emotional state
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The emotional state has been reported to be correlated to the pain experience. Greater emotional stress and anxiety reduce the pain threshold levels. In earlier phases of pain stimuli, the patient experiences the emotions of fear, which on prolongation, may convert to sadness. ,
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iii.
Age
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Different treatment mechanics are employed for patients based on their skeletal maturity levels. Thus, directly correlating age and pain perception is not feasible. Several studies have reported younger patients experiencing less pain than adults. However, a questionnaire study evaluating pain perception in patients aged 8–53 years has reported the highest pain frequency in 13- to 16-year-old patients. A systematic review could not establish a relation between the age of the patient and level of pain sensation.
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iv.
Gender
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Classic pain studies report differences in pain sensation based on gender, hormonal variations, cortisol-pain relationship, and pain threshold levels. Females are thought to be more sensitive to pain stimuli, however, recent literature reports no differences in pain perception based on gender. ,
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Pain and patient compliance
According to Jeffrey Chow et al., the primary causes of poor cooperation include pain besides functional and aesthetic impairment caused by the appliance. Almost 90% of orthodontic patients report pain during treatment, and 10%–20% of orthodontic patients discontinue therapy early because of the pain they experience. ,
A study found that 87% (48 out of 55 patients) reported pain the first evening after the appliance placement. The highest pain intensity was reached the day after the placement of separators. At day 7, 42% of the patients still reported pain. Girls made significantly higher pain ratings during the later phase (day 3–7) of the follow-up week. The experience of pain varied substantially among subjects. Pain intensity was gradually reduced, but still, more than 40% of the teenagers reported some pain after 1 week.
Orthodontic procedures causing pain
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A.
Removable appliance
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B.
Pain caused by orthodontist during instrumentation
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C.
Fixed appliance
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1.
Separator placement
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2.
Arch wire placement and activation
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3.
Arch wire characteristics
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4.
Maxillary expansion
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5.
Traction force to impacted tooth or tooth in unfavourable position
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6.
Intensity of force
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7.
Temporary anchorage device (TAD) insertion
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8.
Debonding
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1.
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D.
Fixed lingual appliances
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E.
Myofunctional and functional jaw orthopaedic appliance
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F.
Clear aligner therapy (CAT)
Removable appliance
The success of treatment with removable orthodontic appliances largely depends on patient compliance. Frequent removal and reinsertion of these appliances can cause discomfort and delay tooth movement. Overactivation or distortion of springs and bows may result in excessive force, leading to pain and potential tooth mobility issues. Additionally, activating the appliances without considering space for tooth movement, or neglecting necessary trimming (such as acrylic relief for tooth movement), can cause significant pain and may even render the tooth non-vital.
Pain caused by orthodontist during instrumentation
An inattentive and careless operator can inadvertently damage oral structures during clinical photography, the placement of bands, adjustments of arch wires, and during the bonding and debonding procedures.
Significant discomfort and pain can occur during intraoral clinical photography, particularly when using mouth mirrors. Arch wire ligation can also be uncomfortable, potentially resulting in ulcers or injuries caused by steel ligatures if not handled carefully, especially if sharp ends are left exposed. In some cases, this can even lead to bleeding. It is critical to address any sharp ends of arch wires that may protrude from the buccal tubes before the patient leaves the clinic.
Improper handling of instruments during the insertion of molar bands can lead to traumatic injuries to the gums and cheeks. Additionally, suction must be used cautiously during procedures like bonding to prevent irritation of the lingual frenulum and the floor of the mouth.
Fixed appliance
Fixed appliances can cause discomfort during several procedures, including the placement of separators, adaptation and insertion of bands, placement and removal of arch wires, insertion of temporary anchorage devices (TADs), applying traction to reposition a tooth or teeth in an unfavourable position, and during debonding procedures.
Separator placement
The placement of separators is the first step in fixed orthodontic treatment, as it creates space on the mesial and distal sides of the tooth or teeth that will be banded. Separators can be made from either metal or elastic materials. It is important to note that brass wire separators tend to cause more discomfort than elastic separators. When an elastic separator is placed between the contact points of the teeth to be separated, it may lead to a nagging pain.
Arch wire placement and activation
Most patients experience pain when the arch wire is placed, although the severity and intensity can vary. Patients typically feel discomfort during the first week after placement, with a quick pain response occurring within 6 hours. This pain usually peaks around 24 hours after insertion and gradually decreases, reaching minimal levels by the sixth or seventh day. There are also variations in pain sensitivity depending on the time of day; patients often report more intense pain in the morning, which tends to diminish by the evening. This pattern may be attributed to the longer duration of time the arch wire has been in place. Additionally, pain during chewing is typically more pronounced in the posterior region compared to the anterior region. This could be related to the re-sensitisation of the inflamed periodontal ligament due to the compressive forces exerted during occlusion.
Various studies comparing pain perception during initial alignment and levelling have found no significant differences in pain intensity, prevalence or duration among different arch wires. A study by Erdinc et al. found that patients reported more pain in their anterior teeth compared to their posterior teeth. This can be attributed to differences in root surface area and the increased involvement of anterior teeth during levelling, as well as the greater tendency to use anterior teeth for biting. Goldreich et al. evaluated the effect of orthodontic arch wire activation on masseter muscle activity using electromyography (EMG) measurements. They observed a reduction in masseter muscle activity, which they attributed to noxious stimuli originating from the periodontal membrane. These stimuli caused inhibition of the jaw-closing muscles, often leading patients to avoid chewing hard foods.
Arch wire characteristics
Pain response is not reported to be affected by the arch wire characteristics such as type of material of the arch wire, the elasticity of the wire and wire dimensions.
Researchers comparing the pain response of different types of wires, including super elastic Nickel Titanium (NiTi) and conventional NiTi, found no significant differences among patients. Similarly, there was no notable difference between NiTi and stainless steel wires. , Super elastic NiTi wires, twisted wires and multi-stranded coaxial wires generate varying amounts of force. The different pain responses are observed with an increasing number of strands in the multi-strand, which makes the wire more flexible and, as a result, reduces the applied force. ,
On comparing the wires of two dimensions, 0.014.in NiTi and 0.016 in. NiTi, pain response was noted as similar in both cases, though the force levels increased by 50%.
Maxillary expansion
The forces exerted by the expansion appliance distribute itself into the craniofacial tissues in three planes of space, resulting in tissue remodelling and displacement of bones, which is perceived as pain by the patient, mainly in the initial 10 activations and peaks on the third and fourth days of activation. , Active phase of maxillary expansion varies in terms of protocol followed, type of appliance and the length of activation. Protocol with two turns/day results in a higher pain level than one turn/day. With the increase in age, the palatal sutures interdigitate, leading to increased resistance to maxillary separation. This causes force build-up and pain during expansion; hence, expansion is preferred before the closure of the mid palatal suture.
Cortisol pain relationship is positively associated with gender variation, with males having higher pain tolerance and females being more sensitive to pain. Hormonal variations, including estradiol and menstrual cycle variations, can be the influencing factors in the gender-based variation in pain perception during rapid maxillary expansion (RME).
Traction force to impacted tooth or tooth in unfavourable position
de Araujo et al. evaluated the complications after surgical exposure of impacted canines. They concluded that patients undergoing open surgical technique reported greater pain compared to the closed technique group, with a faster reduction in pain in the closed technique group.
Intensity of force
An earlier concept by Storey and Smith on light physiological forces for retraction and pain correlation has recently been debated. Histological studies suggest light forces produce physiologic tooth movements with minimal tissue damage and inflammatory response, while higher forces cause excellent periodontal compression and pain. , Spilt mouth study design comparing light and heavy forces on either side did not find any difference between the pain sensations by the patients. Another study comparing the light and heavy forces for 7 days reported higher pain levels on biting for the heavy forces group. This could be related to increase in interleukin 1 beta levels in the higher force group, which secretes pain producing pro-inflammatory mediators.
Temporary anchorage device (TAD) insertion
TADs used for anchorage purposes can cause pain both during insertion and afterwards. To minimise pain during insertion, a topical anaesthetic consisting of 2.5% lidocaine and 2.5% prilocaine is applied prior to the local infiltration. Local infiltration anaesthesia should be administered, while nerve blocks should be avoided, as the combination of topical anaesthetic and infiltration effectively reduces pain to a tolerable level.
Patients often feel anxious and anticipate more severe pain from the placement of miniscrews in the mouth; however, this perception is largely psychological. The actual pain experienced is generally less intense, and by 7 days after the insertion of TADs, most patients report no pain sensation.
A questionnaire study on the placement of miniscrews and related anatomical considerations indicates that palatal implants are associated with the most pain. This is followed by extra-alveolar implants, while inter-radicular implants are reported to cause the least pain. Factors such as bone density and the torque required for implant placement are considered responsible for the variations in pain experienced at different anatomical locations.
Debonding
In 1992, Williams and Bishara evaluated the threshold level for patient discomfort during debonding and concluded that tooth mobility and force application were two crucial influencing factors. Pain perception is higher in anterior teeth than in posterior teeth during debonding due to higher debonding force being distributed per unit area in the lower anterior teeth and lower tactile sensory threshold for the anterior teeth. ,
The type of debonding technique, as well as the material composition of brackets, are influencing factors in varying perceptions of pain levels during debonding techniques. Patients might experience sensitivity to thermal stimuli; however, that is transient and normal pain levels are restored within 7 days of debonding.
On comparing the lift-off debonding instrument with the ligature cutting pliers for debonding. Weak evidence was found that lift off debonding instrument reduced pain perception during debonding procedure. The patient experienced lower pain perception with adjunctive measures such as finger pressure, bite wafers and pre-operative analgaesia.
There are differences in pain perception with different techniques employed during debonding. Pre-emptive medication (paracetamol 1 hour before the procedure) was reported to be most effective, followed by finger pressure and stress relief group where patients were asked to open the mouth and not occlude to relieve the stresses.
Fixed lingual appliances
Lingual appliances induce pain sensations at different anatomic sites than labial appliances. Pain is experienced due to restricted tongue space and soreness due to lingual appliance. Greater eating difficulties are encountered, and it may take up to 3 months for the patient to adapt to lingual appliances.
A study reported that 57%–76% of patients complained of tongue soreness and related discomfort and the levels were significantly higher than those undergoing edgewise labial treatment. Twenty per cent to 44% of patients experienced high levels of the aforementioned discomfort. Although this discomfort decreased gradually with time, 20%–46% of patients felt discomfort until after removing the lingual appliances.
Myofunctional and functional jaw orthopaedic appliance
The correction of mandibular retrusion by myofunctional appliance involves a new pattern of muscle behaviour wherein the patient finds it challenging to retrude the mandible, which is termed ‘pterygoid response’. With an appliance’s constant forward posturing of the mandible, an area of enormous cellular activity above and behind the condyle develops, referred to as the ‘Tension Zone’ by Harvold. The ‘Tension Zone’ tissues are quickly invaded by proliferating blood vessels and connective tissue. After a few days, wearing the appliance becomes more comfortable than leaving it out.
The following protocol was developed by Dr. Kharbanda, who has over three decades of experience with functional appliances. He suggests the patient be examined within 24–48 hours after insertion of the appliance to evaluate for pain in and around the temporomandibular joint (TMJ) and muscles as the initial 2 days are critical for appliance adaptation, and the patient should be motivated to continue wearing the appliance. Within a week, another recall is scheduled, and it is seen that the patient becomes comfortable with the appliance and the advanced position of the mandible and does not report orthodontic pain. The adaptation of the muscles and mandible in the forward position is completed in about 8–12 weeks, as evidenced by the EMG patterns noted in the study. The masseter muscle elongates at the time of appliance insertion and vertical change in dimension, which returns to its original dimensions by 6 months, as evidenced by ultrasonography and MRI results ( Chapter 19 ).
Literature shows that patients experience most discomfort and pain after 24 h of wearing orthopaedic appliances and thereafter there is a sharp decline after 3 days. , Pain associated with orthopaedic devices is caused by the acute inflammatory reaction in the sutural regions.
Clear aligner therapy
Studies indicate that adult patients treated with aligners experience less pain and fewer negative effects during the first week of orthodontic treatment compared to those treated with fixed appliances. The first 3 days of pain with aligners is less compared to fixed appliances. Aligner deformation often causes more pain and discomfort.
The controversy around pain levels during fixed appliance treatment versus clear aligner treatment was evaluated. Overall, clear aligner patients report better oral health and quality of life. However, only a noticeable difference in pain between the two treatments was reported on the third and fourth day of aligner adjustments, with no significant pain level difference at other time points.
Management of orthodontic pain
To date, numerous modalities have been invented and tested to reduce orthodontic pain as highlighted in flowchart given in Fig. 101.6 in clinical practice. They are as follows:
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Pharmacological
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Non-pharmacological
An overview of orthodontic pain, pathways, types, diagnosis and management.
Pharmacological
Pharmacological management of orthodontic pain during orthodontic treatment has been an important area of research. Current literature suggests the high efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) for pain management. However, a significant concern regarding NSAIDs is their potential interference with the inflammation linked to the tooth movement process.
A systematic review by Cheng et al. assessed the efficacy of analgesics in relieving pain during orthodontic treatment and found ibuprofen, acetaminophen and naproxen to be effective and commonly used analgesics for controlling orthodontic pain due to separator placement and arch wire activation. Ibuprofen and naproxen exhibit a consistent analgesic effect peaking at 6 hours, whereas acetaminophen’s analgesic effect gradually increases from 2 hours and extends to 24 hours. Compared to ibuprofen and acetaminophen, naproxen demonstrates a more robust analgesic effect at 2 hours, persisting up to 24 hours. Given the concern of potentially impeding tooth movement, administering low doses of analgesics for a brief duration is unlikely to significantly impact the process of tooth movement.
According to Eslamian et al., Naproxen 5% gel applied every 8 h for 3 days after the placement of separators is an effective method for reducing orthodontic pain following elastic separator placement.
A Cochrane systematic review evaluating the effectiveness of drug efficacy for orthodontic pain relief reported moderate quality evidence with no difference between NSAID and paracetamol at 2, 6 and 24 h post-orthodontic treatment. Pre-emptive ibuprofen taken 2 hours before was more beneficial than taken post-treatment; however, no difference was noted at 6 and 24 h post-treatment. The evidence was of very low quality. Pharmacological management of pain at various stages of orthodontic treatment is tabulated in Table 101.1 .
TABLE 101.1
Pharmacological management at different stages of orthodontic treatment
| Several authors have researched pharmacological interventions to reduce pain during separator placement and have concluded that paracetamol, ibuprofen and piroxicam are effective in managing pain. For greater efficiency, the recommended dosage schedule is 1 h before separator placement and 3 and 7 h after separator placement. |
| Several authors have researched using pharmacological drugs 1 h before the orthodontic intervention and reported high efficacy of naproxen sodium and paracetamol in managing pain by orthodontic intervention. |
Non-pharmacological
Mechanical approach
Literature evidence shows various mechanical approaches for relieving orthodontic pain, including vibration, chewing gum, biting wafers, transcutaneous electrical nerve stimulation (TENS), pulsed electromagnetic field (PEMF) and acupuncture.
Vibration.
Mechanical vibration, facilitated by various commercially available devices, helps alleviate orthodontic pain. Vibration aids in alleviating compression of the PDL, promoting blood circulation, and preventing the accumulation of inflammation by products. Another potential mechanism is the ‘gate control’ theory, wherein pain perception is diminished through the simultaneous activation of nerve fibres responsible for non-noxious stimuli. Lobre et al. utilised a micro pulse vibration device with a frequency of 30 Hz for 20 min daily over 4 months during the initial alignment and levelling phase. The device notably reduced pain scores for overall discomfort and biting pain throughout the 4-month observation period.
Chewing gum.
Chewing gum as a non-pharmacological approach for relieving orthodontic pain during initial arch wire placement and activation has been studied in the literature. Chewing rubbery materials increases blood flow to compressed areas of the periodontal ligament and prevents the formation of pain-inducing inflammatory metabolites, thereby reducing pain perception. According to Santos et al., chewing gum for 5 min after the initial arch wire placement and 5 min every 6 hours for the first week is effective for relieving orthodontic pain and can be a non-pharmacological alternative for managing orthodontic pain.
Biting wafers.
Biting wafers are used to relieve arch wire activation pain and to relieve debonding pain. In a study, Ibuprofen (400 mg), or a viscoelastic bite wafer, or chewing gum were used after initial arch wires. Bite wafers chewed for only 5 min every 8 hours as needed for 1 week were adequate and comparable to Ibuprofen after the initial activation of fixed orthodontic appliances. Mangnall et al. studied debonding pain and concluded that lower anterior teeth are the most painful during debonding, and biting on a soft acrylic wafer during debonding of the posterior teeth reduces the pain , ( Fig. 101.7 ).
(A) Soft acrylic wafer can be used during debond procedure to reduce the pain experience. (B) The patients reported the most painful sextant during debond to be the lower anterior teeth.
Source: Based on Mangnall LA, Dietrich T, Scholey JM. A randomized controlled trial to assess the pain associated with the debond of orthodontic fixed appliances. J Orthod. 2013 Sep;40(3):188–96. doi:10.1179/1465313313Y. 0000000045. PMID: 24009318; PMCID: PMC4161196.
Transcutaneous electrical nerve stimulation (TENS).
One widely utilised non-invasive pain management technique in medicine is TENS, a type of stimulation-induced analgesia. TENS involves the application of electrical stimulation through surface electrodes positioned over the painful area or along the distribution of nerves innervating the painful region. The electrical current typically ranges from 0 to 90 volts (60 mA), with a frequency range of 0 to 100 Hz. TENS delivers an electrical stimulus faster than the pain impulse, effectively closing pain gate impulses and reducing pain intensity. Additionally, TENS triggers the release of opiate-like peptides, including endorphins, further diminishing pain sensation. Roth assessed the efficacy of TENS in managing pain associated with orthodontic tooth movement. TENS was administered both externally and internally, bilaterally over the zygomatic arch and directly onto the teeth, by placing one probe electrode on the crown of each tooth and the other electrode on the palatal mucosa. The TENS unit delivered a frequency of 0.5 Hz with an intensity of 500 mA, each session lasting 20 min over 3 days. TENS proved an effective non-pharmacological method for managing tooth pain following separator placement. Zahid et al. investigated the effectiveness of TENS in alleviating periodontal pain resulting from canine retraction following orthodontic power chain placement. Their findings revealed that the application of TENS accelerated the pain reduction process, as evidenced by individuals’ pain score results.
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Introduction
During orthodontic treatment, patients frequently encounter discomfort related to various orthodontic procedures. Typically, individuals describe these discomforts as sensations of pressure, tooth soreness and pain. It has been reported that orthodontic procedures can reduce patients’ proprioceptive and discriminating abilities for up to 4 days, lowering their pain threshold. This discomfort is attributed to pressure, ischaemia, inflammation and oedema in the periodontal ligament (PDL) space. The duration and intensity of pain vary across procedures and among patients of different ages and sexes.
This chapter is focused on the causes of pain of orthodontic origin, its pathophysiology, clinical manoeuvres that can make orthodontic procedures less traumatic and the philosophy of non-pharmacological and pharmacological management.
Definition of pain
International Association for the Study of Pain (IASP) has defined pain as ‘An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage’.
Pain is a subjective response, showing significant individual variations such as age, gender, pain threshold, emotional state, magnitude of force applied, cultural differences, type of malocclusion and previous pain experiences. Pain can be categorised based on pathophysiology as nociceptive, neuropathic or nociplastic pain. ,
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Nociceptive pain : It occurs as a result of direct stimulation of nociceptive nerve fibres through mechanical, chemical or thermal triggers or indirectly through the release of inflammatory mediators such as histamine, bradykinin, substance P, prostaglandins and serotonin.
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Neuropathic pain : It arises due to damage to the nerves or nervous system. It causes shooting and burning pain or numbness.
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Nociplastic pain : ‘The pain that arises from altered nociception despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors or evidence for disease or lesion of the somatosensory system causing the pain’.
Pain pathway
There are three stages of pain pathway ( Fig. 101.1 ).
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First stage: Pain signal from the tissue is carried by the nociceptive fibre (afferent fibre), which is first order neuron to the spinal cord dorsal horn.
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Second stage: Signals from the dorsal horn are taken to the thalamus by second order neurons where the nucleus of that particular nerve is present.
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Third stage: From the thalamus, signals are then transmitted to the primary somatosensory cortex for further processing and pain perception.
Three stages in pain pathway.
First stage: Pain signal from the tissue is carried by the nociceptive fibre (afferent fibre), which is first order neuron to the spinal cord dorsal horn. Second stage: Signals from the dorsal horn are taken to the thalamus by second order neurons where the nucleus of that particular nerve is present. Third stage: From the thalamus, signals are then transmitted to the primary somatosensory cortex for further processing and pain perception.
Source: Based on the concept from https://upload.wikimedia.org/wikipedia/commons/f/fa/Afferents.png .
Theories of pain
Pain is a prevalent reason for medical consultations, yet we still need a comprehensive understanding of its causes and mechanisms. Despite extensive research, the specifics of pain remain elusive. There are four main theories of pain perception—specificity, intensity, pattern and gate control.
Specificity theory
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The specificity theory of pain was developed by Maximilian Von Frey in 1895. According to this theory, pain perception is processed entirely differently in the brain than in vision and hearing. According to Frey’s theory, separate epidermal nerve endings are responsible for transmitting pain. The ‘pain centre’ is a specialised area of the brain where pain signals are transmitted through specialised channels, wherein the information is processed to produce the pain experience. The specificity theory is no longer accepted.
Intensity theory
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This theory is based on Aristotle’s concept that pain results from excessive stimulation of the sense of touch. Critical factors affecting pain include central summation and stimulus intensity. It was suggested that the cells of the dorsal horn undergo summation.
Pattern theory
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The theory proposes that sensory information is encoded by specific patterns of neural activity in the peripheral nerves, which convey information about the type and intensity of the stimulus. This means that when we experience touch, warmth or other non-damaging or damaging stimuli, the peripheral sensory receptors respond by sending signals through the nervous system that create non-painful or painful experiences. Pain is said to occur when specific patterns of neural activity reach excessively high levels in the brain. In other words, the theory suggests that pain results from particular patterns of neural activity.
Gate control theory
Melzack’s pain theory has generated considerable interest and discussion regarding the understanding of pain. According to the theory, small, slow fibres are responsible for carrying pain stimulation, which enters the dorsal horn of the spinal cord. From there, other cells transmit these impulses from the spinal cord to the brain.
The spinal cord acts as a ‘gate’ that controls or restricts the transmission of pain signals to the brain or higher centres. When the gates are open wider, a greater number of pain messages are transmitted to the brain, leading to a higher level of pain. Conversely, fewer messages are transmitted when the gates are closed, resulting in lower pain levels.
Biopsychosocial model of pain
According to the biopsychosocial model, pain is a neurophysiological event influenced by social and psychological elements. It asserts that factors such as culture, family dynamics, environmental conditions and nociceptive stimuli collectively shape pain perception, impacting an individual’s emotions, behaviours and cognition.
Orthodontic pain pathway
Orthodontic pain is a type of nociceptive pain (inflammatory pain) initiated by mechanical force that induces vascular occlusion, pressure oedema and a cascade of inflammatory reactions around affected teeth. This cascade of events includes the inflammatory response of vascular alterations, the recruitment of inflammatory and immune cells and the release of neurogenic and pro-inflammatory mediators, which sensitises the nociceptors in the PDL and increases the pain sensitivity. Orthodontic pain is part of an inflammatory reaction that causes changes in blood flow following orthodontic force application ( Fig. 101.2 ). This results in the release of various chemical mediators, eliciting a hyperalgesic response. The neuropeptides are released, which are known to elicit a painful response.
Orthodontic pain pathway.
The neural circuits for transmission of orthodontic pain.
Source: Based on the concept by Long H, Wang Y, Jian F, Liao LN, Yang X, Lai WL. Current advances in orthodontic pain. Int J Oral Sci. 2016 Jun 30;8(2):67–75. doi:10.1038/ijos.2016.24. PMID: 27341389; PMCID: PMC4932774.
Various neuropeptides responsible for orthodontic pain are substance P (SP), calcitonin gene-related peptide (CGRP), neurofilament protein (NFP), vasoactive intestinal polypeptide (VIP), neuropeptides Y (NPY).
Substance P (SP) is a neuropeptide that plays a key role in pain signalling. According to Mangano et al., stimulation of periodontal nerve fibres by means of mechanical forces may induce the peripheral release of SP, the neurotransmitter in the pulp and periodontal ligament. SP leads to the release of messengers such as prostaglandins and cytokines, increasing intracellular second messengers. Although research supports its association with inflammatory periodontal disease, the role of this SP during orthodontic treatments has yet to be fully understood ( Fig. 101.3 ).
Role of neuropeptide: These neuropeptides released are known to elicit a painful response. Various neuropeptides responsible of orthodontic pain are substance P, calcitonin gene-related peptide (CGRP), neurofilament protein (NFP), vasoactive intestinal polypeptide (VIP), neuropeptides Y (NPY). Amongst all these neuropeptides, substance P has more correlation with the pain.
Clinicians’ approach to grouping pain of orthodontic origin
Burstone grouped the pain of orthodontic origin with intensity and time of onset. According to him :
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A.
Depending on the relationship of force application with pain, it can be groped as
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i.
first degree,
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ii.
second degree,
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iii.
third degree.
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i.
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B.
According to the time of onset:
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i.
immediate
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ii.
delayed.
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i.
Methods for pain evaluation
Clinicians and scientists have attempted to quantify or grade the subjective perception of pain using various scales and instruments. Some of the commonly used scales are :
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i.
Patient interview/questionnaire
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ii.
Visual analogue scale (VAS)
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iii.
McGill’s pain questionnaire (MPQ)
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iv.
Verbal rating scale (VRS)
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v.
Algometers
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i.
Patient interview/questionnaire: This method consists of a set of specific questionnaires with relevant options that patients can choose according to their experience of pain during the procedure. For example, how will you describe your pain after the orthodontic appointment?
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Very intense, intense, less intense, very less intense.
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ii.
Visual analogue scale (VAS): Most frequently used scale. The visual analogue scale ranges from 1 to 10. Respondents are expected to mark a location on the line corresponding to the pain they have experienced. It provides the freedom to choose the exact intensity of pain ( Fig. 101.4 ).
Figure 101.4 Visual analogue scale (VAS): Most frequently used scale. VAS ranges from 1 to 10. Respondents are expected to mark a location on the line corresponding to the amount of experienced pain. It provides the freedom to choose the exact intensity of pain.
Source: Based on the concept from
Visual Analog Survey Scale — A Pain-ful Misnamed Scale
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iii.
McGill’s pain questionnaire (MPQ): This is a commonly used method in medical research but less explored in orthodontics. The main advantage of the MPQ is its provision for identifying quantitative measures of clinical pain. MPQ is also known as the pain rating index.
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iv.
Verbal rating scale (VRS): It consists of adjectives to describe different intensities of pain ( Fig. 101.5 ).
Figure 101.5 Verbal rating scale (VRS): It consists of adjectives to describe different intensities of pain.
Source: Based on the concept from Relvas JB, Bastos MM, Marques AA, Garrido AD, Sponchiado EC Jr. Assessment of postoperative pain after reciprocating or rotary NiTi instrumentation of root canals: a randomized, controlled clinical trial. Clin Oral Investig. 2016 Nov;20(8):1987–1993. doi:10.1007/s00784-015-1692-0. Erratum in: Clin Oral Investig. 2016 Nov;20(8):1995. doi:10.1007/s00784-016-1758-7. PMID: 26685850.
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v.
Algometer: In 1994, Simmons proposed the utilisation of an algometer to evaluate pain in patients seated in dental chairs and to record the force applied to the teeth during adjustments of fixed orthodontic appliances. Studies have confirmed the pressure algometer is an efficient and effective tool in screening and evaluating orofacial pain in patients.
Factors affecting pain intensity
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i.
Impulses from the brainstem:
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Nociceptive impulses may be altered in the spinal cord and brain cortex, which may cause sensations of no to low pain. If the patient has a history of painful dental experiences, the pain sensation would be felt as intense, being influenced by previous traumatic experiences even in the absence of pain stimuli.
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ii.
Emotional state
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The emotional state has been reported to be correlated to the pain experience. Greater emotional stress and anxiety reduce the pain threshold levels. In earlier phases of pain stimuli, the patient experiences the emotions of fear, which on prolongation, may convert to sadness. ,
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iii.
Age
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Different treatment mechanics are employed for patients based on their skeletal maturity levels. Thus, directly correlating age and pain perception is not feasible. Several studies have reported younger patients experiencing less pain than adults. However, a questionnaire study evaluating pain perception in patients aged 8–53 years has reported the highest pain frequency in 13- to 16-year-old patients. A systematic review could not establish a relation between the age of the patient and level of pain sensation.
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iv.
Gender
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Classic pain studies report differences in pain sensation based on gender, hormonal variations, cortisol-pain relationship, and pain threshold levels. Females are thought to be more sensitive to pain stimuli, however, recent literature reports no differences in pain perception based on gender. ,
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Pain and patient compliance
According to Jeffrey Chow et al., the primary causes of poor cooperation include pain besides functional and aesthetic impairment caused by the appliance. Almost 90% of orthodontic patients report pain during treatment, and 10%–20% of orthodontic patients discontinue therapy early because of the pain they experience. ,
A study found that 87% (48 out of 55 patients) reported pain the first evening after the appliance placement. The highest pain intensity was reached the day after the placement of separators. At day 7, 42% of the patients still reported pain. Girls made significantly higher pain ratings during the later phase (day 3–7) of the follow-up week. The experience of pain varied substantially among subjects. Pain intensity was gradually reduced, but still, more than 40% of the teenagers reported some pain after 1 week.
Orthodontic procedures causing pain
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A.
Removable appliance
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B.
Pain caused by orthodontist during instrumentation
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C.
Fixed appliance
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1.
Separator placement
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2.
Arch wire placement and activation
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3.
Arch wire characteristics
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4.
Maxillary expansion
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5.
Traction force to impacted tooth or tooth in unfavourable position
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6.
Intensity of force
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7.
Temporary anchorage device (TAD) insertion
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8.
Debonding
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1.
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D.
Fixed lingual appliances
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E.
Myofunctional and functional jaw orthopaedic appliance
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F.
Clear aligner therapy (CAT)
Removable appliance
The success of treatment with removable orthodontic appliances largely depends on patient compliance. Frequent removal and reinsertion of these appliances can cause discomfort and delay tooth movement. Overactivation or distortion of springs and bows may result in excessive force, leading to pain and potential tooth mobility issues. Additionally, activating the appliances without considering space for tooth movement, or neglecting necessary trimming (such as acrylic relief for tooth movement), can cause significant pain and may even render the tooth non-vital.
Pain caused by orthodontist during instrumentation
An inattentive and careless operator can inadvertently damage oral structures during clinical photography, the placement of bands, adjustments of arch wires, and during the bonding and debonding procedures.
Significant discomfort and pain can occur during intraoral clinical photography, particularly when using mouth mirrors. Arch wire ligation can also be uncomfortable, potentially resulting in ulcers or injuries caused by steel ligatures if not handled carefully, especially if sharp ends are left exposed. In some cases, this can even lead to bleeding. It is critical to address any sharp ends of arch wires that may protrude from the buccal tubes before the patient leaves the clinic.
Improper handling of instruments during the insertion of molar bands can lead to traumatic injuries to the gums and cheeks. Additionally, suction must be used cautiously during procedures like bonding to prevent irritation of the lingual frenulum and the floor of the mouth.
Fixed appliance
Fixed appliances can cause discomfort during several procedures, including the placement of separators, adaptation and insertion of bands, placement and removal of arch wires, insertion of temporary anchorage devices (TADs), applying traction to reposition a tooth or teeth in an unfavourable position, and during debonding procedures.
Separator placement
The placement of separators is the first step in fixed orthodontic treatment, as it creates space on the mesial and distal sides of the tooth or teeth that will be banded. Separators can be made from either metal or elastic materials. It is important to note that brass wire separators tend to cause more discomfort than elastic separators. When an elastic separator is placed between the contact points of the teeth to be separated, it may lead to a nagging pain.
Arch wire placement and activation
Most patients experience pain when the arch wire is placed, although the severity and intensity can vary. Patients typically feel discomfort during the first week after placement, with a quick pain response occurring within 6 hours. This pain usually peaks around 24 hours after insertion and gradually decreases, reaching minimal levels by the sixth or seventh day. There are also variations in pain sensitivity depending on the time of day; patients often report more intense pain in the morning, which tends to diminish by the evening. This pattern may be attributed to the longer duration of time the arch wire has been in place. Additionally, pain during chewing is typically more pronounced in the posterior region compared to the anterior region. This could be related to the re-sensitisation of the inflamed periodontal ligament due to the compressive forces exerted during occlusion.
Various studies comparing pain perception during initial alignment and levelling have found no significant differences in pain intensity, prevalence or duration among different arch wires. A study by Erdinc et al. found that patients reported more pain in their anterior teeth compared to their posterior teeth. This can be attributed to differences in root surface area and the increased involvement of anterior teeth during levelling, as well as the greater tendency to use anterior teeth for biting. Goldreich et al. evaluated the effect of orthodontic arch wire activation on masseter muscle activity using electromyography (EMG) measurements. They observed a reduction in masseter muscle activity, which they attributed to noxious stimuli originating from the periodontal membrane. These stimuli caused inhibition of the jaw-closing muscles, often leading patients to avoid chewing hard foods.
Arch wire characteristics
Pain response is not reported to be affected by the arch wire characteristics such as type of material of the arch wire, the elasticity of the wire and wire dimensions.
Researchers comparing the pain response of different types of wires, including super elastic Nickel Titanium (NiTi) and conventional NiTi, found no significant differences among patients. Similarly, there was no notable difference between NiTi and stainless steel wires. , Super elastic NiTi wires, twisted wires and multi-stranded coaxial wires generate varying amounts of force. The different pain responses are observed with an increasing number of strands in the multi-strand, which makes the wire more flexible and, as a result, reduces the applied force. ,
On comparing the wires of two dimensions, 0.014.in NiTi and 0.016 in. NiTi, pain response was noted as similar in both cases, though the force levels increased by 50%.
Maxillary expansion
The forces exerted by the expansion appliance distribute itself into the craniofacial tissues in three planes of space, resulting in tissue remodelling and displacement of bones, which is perceived as pain by the patient, mainly in the initial 10 activations and peaks on the third and fourth days of activation. , Active phase of maxillary expansion varies in terms of protocol followed, type of appliance and the length of activation. Protocol with two turns/day results in a higher pain level than one turn/day. With the increase in age, the palatal sutures interdigitate, leading to increased resistance to maxillary separation. This causes force build-up and pain during expansion; hence, expansion is preferred before the closure of the mid palatal suture.
Cortisol pain relationship is positively associated with gender variation, with males having higher pain tolerance and females being more sensitive to pain. Hormonal variations, including estradiol and menstrual cycle variations, can be the influencing factors in the gender-based variation in pain perception during rapid maxillary expansion (RME).
Traction force to impacted tooth or tooth in unfavourable position
de Araujo et al. evaluated the complications after surgical exposure of impacted canines. They concluded that patients undergoing open surgical technique reported greater pain compared to the closed technique group, with a faster reduction in pain in the closed technique group.
Intensity of force
An earlier concept by Storey and Smith on light physiological forces for retraction and pain correlation has recently been debated. Histological studies suggest light forces produce physiologic tooth movements with minimal tissue damage and inflammatory response, while higher forces cause excellent periodontal compression and pain. , Spilt mouth study design comparing light and heavy forces on either side did not find any difference between the pain sensations by the patients. Another study comparing the light and heavy forces for 7 days reported higher pain levels on biting for the heavy forces group. This could be related to increase in interleukin 1 beta levels in the higher force group, which secretes pain producing pro-inflammatory mediators.
Temporary anchorage device (TAD) insertion
TADs used for anchorage purposes can cause pain both during insertion and afterwards. To minimise pain during insertion, a topical anaesthetic consisting of 2.5% lidocaine and 2.5% prilocaine is applied prior to the local infiltration. Local infiltration anaesthesia should be administered, while nerve blocks should be avoided, as the combination of topical anaesthetic and infiltration effectively reduces pain to a tolerable level.
Patients often feel anxious and anticipate more severe pain from the placement of miniscrews in the mouth; however, this perception is largely psychological. The actual pain experienced is generally less intense, and by 7 days after the insertion of TADs, most patients report no pain sensation.
A questionnaire study on the placement of miniscrews and related anatomical considerations indicates that palatal implants are associated with the most pain. This is followed by extra-alveolar implants, while inter-radicular implants are reported to cause the least pain. Factors such as bone density and the torque required for implant placement are considered responsible for the variations in pain experienced at different anatomical locations.
Debonding
In 1992, Williams and Bishara evaluated the threshold level for patient discomfort during debonding and concluded that tooth mobility and force application were two crucial influencing factors. Pain perception is higher in anterior teeth than in posterior teeth during debonding due to higher debonding force being distributed per unit area in the lower anterior teeth and lower tactile sensory threshold for the anterior teeth. ,
The type of debonding technique, as well as the material composition of brackets, are influencing factors in varying perceptions of pain levels during debonding techniques. Patients might experience sensitivity to thermal stimuli; however, that is transient and normal pain levels are restored within 7 days of debonding.
On comparing the lift-off debonding instrument with the ligature cutting pliers for debonding. Weak evidence was found that lift off debonding instrument reduced pain perception during debonding procedure. The patient experienced lower pain perception with adjunctive measures such as finger pressure, bite wafers and pre-operative analgaesia.
There are differences in pain perception with different techniques employed during debonding. Pre-emptive medication (paracetamol 1 hour before the procedure) was reported to be most effective, followed by finger pressure and stress relief group where patients were asked to open the mouth and not occlude to relieve the stresses.
Fixed lingual appliances
Lingual appliances induce pain sensations at different anatomic sites than labial appliances. Pain is experienced due to restricted tongue space and soreness due to lingual appliance. Greater eating difficulties are encountered, and it may take up to 3 months for the patient to adapt to lingual appliances.
A study reported that 57%–76% of patients complained of tongue soreness and related discomfort and the levels were significantly higher than those undergoing edgewise labial treatment. Twenty per cent to 44% of patients experienced high levels of the aforementioned discomfort. Although this discomfort decreased gradually with time, 20%–46% of patients felt discomfort until after removing the lingual appliances.
Myofunctional and functional jaw orthopaedic appliance
The correction of mandibular retrusion by myofunctional appliance involves a new pattern of muscle behaviour wherein the patient finds it challenging to retrude the mandible, which is termed ‘pterygoid response’. With an appliance’s constant forward posturing of the mandible, an area of enormous cellular activity above and behind the condyle develops, referred to as the ‘Tension Zone’ by Harvold. The ‘Tension Zone’ tissues are quickly invaded by proliferating blood vessels and connective tissue. After a few days, wearing the appliance becomes more comfortable than leaving it out.
The following protocol was developed by Dr. Kharbanda, who has over three decades of experience with functional appliances. He suggests the patient be examined within 24–48 hours after insertion of the appliance to evaluate for pain in and around the temporomandibular joint (TMJ) and muscles as the initial 2 days are critical for appliance adaptation, and the patient should be motivated to continue wearing the appliance. Within a week, another recall is scheduled, and it is seen that the patient becomes comfortable with the appliance and the advanced position of the mandible and does not report orthodontic pain. The adaptation of the muscles and mandible in the forward position is completed in about 8–12 weeks, as evidenced by the EMG patterns noted in the study. The masseter muscle elongates at the time of appliance insertion and vertical change in dimension, which returns to its original dimensions by 6 months, as evidenced by ultrasonography and MRI results ( Chapter 19 ).
Literature shows that patients experience most discomfort and pain after 24 h of wearing orthopaedic appliances and thereafter there is a sharp decline after 3 days. , Pain associated with orthopaedic devices is caused by the acute inflammatory reaction in the sutural regions.
Clear aligner therapy
Studies indicate that adult patients treated with aligners experience less pain and fewer negative effects during the first week of orthodontic treatment compared to those treated with fixed appliances. The first 3 days of pain with aligners is less compared to fixed appliances. Aligner deformation often causes more pain and discomfort.
The controversy around pain levels during fixed appliance treatment versus clear aligner treatment was evaluated. Overall, clear aligner patients report better oral health and quality of life. However, only a noticeable difference in pain between the two treatments was reported on the third and fourth day of aligner adjustments, with no significant pain level difference at other time points.
Management of orthodontic pain
To date, numerous modalities have been invented and tested to reduce orthodontic pain as highlighted in flowchart given in Fig. 101.6 in clinical practice. They are as follows:
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Pharmacological
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Non-pharmacological
An overview of orthodontic pain, pathways, types, diagnosis and management.
Pharmacological
Pharmacological management of orthodontic pain during orthodontic treatment has been an important area of research. Current literature suggests the high efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) for pain management. However, a significant concern regarding NSAIDs is their potential interference with the inflammation linked to the tooth movement process.
A systematic review by Cheng et al. assessed the efficacy of analgesics in relieving pain during orthodontic treatment and found ibuprofen, acetaminophen and naproxen to be effective and commonly used analgesics for controlling orthodontic pain due to separator placement and arch wire activation. Ibuprofen and naproxen exhibit a consistent analgesic effect peaking at 6 hours, whereas acetaminophen’s analgesic effect gradually increases from 2 hours and extends to 24 hours. Compared to ibuprofen and acetaminophen, naproxen demonstrates a more robust analgesic effect at 2 hours, persisting up to 24 hours. Given the concern of potentially impeding tooth movement, administering low doses of analgesics for a brief duration is unlikely to significantly impact the process of tooth movement.
According to Eslamian et al., Naproxen 5% gel applied every 8 h for 3 days after the placement of separators is an effective method for reducing orthodontic pain following elastic separator placement.
A Cochrane systematic review evaluating the effectiveness of drug efficacy for orthodontic pain relief reported moderate quality evidence with no difference between NSAID and paracetamol at 2, 6 and 24 h post-orthodontic treatment. Pre-emptive ibuprofen taken 2 hours before was more beneficial than taken post-treatment; however, no difference was noted at 6 and 24 h post-treatment. The evidence was of very low quality. Pharmacological management of pain at various stages of orthodontic treatment is tabulated in Table 101.1 .
TABLE 101.1
Pharmacological management at different stages of orthodontic treatment
| Several authors have researched pharmacological interventions to reduce pain during separator placement and have concluded that paracetamol, ibuprofen and piroxicam are effective in managing pain. For greater efficiency, the recommended dosage schedule is 1 h before separator placement and 3 and 7 h after separator placement. |
| Several authors have researched using pharmacological drugs 1 h before the orthodontic intervention and reported high efficacy of naproxen sodium and paracetamol in managing pain by orthodontic intervention. |
Non-pharmacological
Mechanical approach
Literature evidence shows various mechanical approaches for relieving orthodontic pain, including vibration, chewing gum, biting wafers, transcutaneous electrical nerve stimulation (TENS), pulsed electromagnetic field (PEMF) and acupuncture.
Vibration.
Mechanical vibration, facilitated by various commercially available devices, helps alleviate orthodontic pain. Vibration aids in alleviating compression of the PDL, promoting blood circulation, and preventing the accumulation of inflammation by products. Another potential mechanism is the ‘gate control’ theory, wherein pain perception is diminished through the simultaneous activation of nerve fibres responsible for non-noxious stimuli. Lobre et al. utilised a micro pulse vibration device with a frequency of 30 Hz for 20 min daily over 4 months during the initial alignment and levelling phase. The device notably reduced pain scores for overall discomfort and biting pain throughout the 4-month observation period.
Chewing gum.
Chewing gum as a non-pharmacological approach for relieving orthodontic pain during initial arch wire placement and activation has been studied in the literature. Chewing rubbery materials increases blood flow to compressed areas of the periodontal ligament and prevents the formation of pain-inducing inflammatory metabolites, thereby reducing pain perception. According to Santos et al., chewing gum for 5 min after the initial arch wire placement and 5 min every 6 hours for the first week is effective for relieving orthodontic pain and can be a non-pharmacological alternative for managing orthodontic pain.
Biting wafers.
Biting wafers are used to relieve arch wire activation pain and to relieve debonding pain. In a study, Ibuprofen (400 mg), or a viscoelastic bite wafer, or chewing gum were used after initial arch wires. Bite wafers chewed for only 5 min every 8 hours as needed for 1 week were adequate and comparable to Ibuprofen after the initial activation of fixed orthodontic appliances. Mangnall et al. studied debonding pain and concluded that lower anterior teeth are the most painful during debonding, and biting on a soft acrylic wafer during debonding of the posterior teeth reduces the pain , ( Fig. 101.7 ).
(A) Soft acrylic wafer can be used during debond procedure to reduce the pain experience. (B) The patients reported the most painful sextant during debond to be the lower anterior teeth.
Source: Based on Mangnall LA, Dietrich T, Scholey JM. A randomized controlled trial to assess the pain associated with the debond of orthodontic fixed appliances. J Orthod. 2013 Sep;40(3):188–96. doi:10.1179/1465313313Y. 0000000045. PMID: 24009318; PMCID: PMC4161196.
Transcutaneous electrical nerve stimulation (TENS).
One widely utilised non-invasive pain management technique in medicine is TENS, a type of stimulation-induced analgesia. TENS involves the application of electrical stimulation through surface electrodes positioned over the painful area or along the distribution of nerves innervating the painful region. The electrical current typically ranges from 0 to 90 volts (60 mA), with a frequency range of 0 to 100 Hz. TENS delivers an electrical stimulus faster than the pain impulse, effectively closing pain gate impulses and reducing pain intensity. Additionally, TENS triggers the release of opiate-like peptides, including endorphins, further diminishing pain sensation. Roth assessed the efficacy of TENS in managing pain associated with orthodontic tooth movement. TENS was administered both externally and internally, bilaterally over the zygomatic arch and directly onto the teeth, by placing one probe electrode on the crown of each tooth and the other electrode on the palatal mucosa. The TENS unit delivered a frequency of 0.5 Hz with an intensity of 500 mA, each session lasting 20 min over 3 days. TENS proved an effective non-pharmacological method for managing tooth pain following separator placement. Zahid et al. investigated the effectiveness of TENS in alleviating periodontal pain resulting from canine retraction following orthodontic power chain placement. Their findings revealed that the application of TENS accelerated the pain reduction process, as evidenced by individuals’ pain score results.
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