Temporomandibular disorders. Part 2: non-surgical management

In Part 1 of this series, the aetiology and diagnosis of temporomandibular disorders (TMD) were discussed.¹ Owing to the complexity of TMD, its management can present challenges. Although general evidence-based non-surgical guidelines exist for TMD, it is important to highlight that there is not one approach for all, and specific patient factors need to be considered.² Therapeutic interventions should be patient-centred and monitored over time for change.³ The aims of this article are to discuss the non-surgical management options that are available, other than appliance therapy, for patients with TMD, to present the evidence base to support their use and to provide some practical suggestions for primary care dental practitioners to adopt.

Physiotherapy

Physiotherapy is frequently chosen for the management of TMD due to its reversibility and relative low cost compared to other treatment modalities. The therapeutic goals are to decrease pain, aid muscle relaxation, reduce muscular hyperactivity, improve function and to improve quality of life.⁴ Physiotherapists provide bespoke rehabilitation programmes for each patient depending on the outcome of a comprehensive biopsychosocial assessment.⁵

These programmes involve a combination of the strategies outlined in this article. The interdisciplinary relationship between dentistry and physiotherapy is important in TMD management. It is recommended that referring clinicians communicate clearly and refer only to physiotherapists who have postgraduate training in the management of musculoskeletal disorders of the head and neck.⁶ A thorough referral letter detailing clinical findings, diagnosis and discussions to date, can help to improve a patient's onward journey by enabling a cohesive and consistent therapeutic dialogue.

Self-management

There can be significant crossover between acute and chronic TMD signs and symptoms, therefore, even though it is important to try and differentiate between them clinically, many of the non-surgical treatment options are still applicable to both situations. The signs and symptoms of TMD can be transient and self-limiting, and early adoption of invasive treatments, such as occlusal adjustment or surgery, ought to be avoided.²

There is now consensus in the literature that the initial management strategy for patients with TMD should involve reversible self-management protocols.⁷ The importance of patient engagement with self-management strategies should be emphasized. Verbal advice should be supported with written information and reinforced at subsequent visits.⁷ Despite self-management being widely discussed in TMD literature, the supporting evidence remains unclear due to heterogeneity and the limited number of well-designed experimental studies.⁸

Patient education

Individualized patient education is considered to be a key aspect of TMD management; the aims being to allow the patients to have some control over their diagnosis, prevent further injury and to alleviate symptoms.^3,9 It is important to explain to patients that despite self-management strategies, some symptoms may persist, such as clicking.

It is thought that psychosocial factors and parafunctional activity can play a role in the pathogenesis and/or persistence of musculoskeletal pain.⁴ Therefore, dental practitioners should be able to provide reassurance, a clear explanation of the diagnosis, tailored advice to raise awareness of parafunctional activity and sensitively identify any potential psychological factors.¹⁰

Patient education should be delivered using simple and understandable language and should include the following: the nature of the condition; predisposing, precipitating and prolonging factors; anatomy of the TMJ; management strategies and goals of therapy.¹¹ There is good evidence that educating patients about their condition can in itself be effective in reducing pain.¹²

TMD can significantly affect quality of life, therefore it is very important to reassure patients of the condition's benign nature.¹³ Evidence suggests that the language selected by clinicians can influence musculoskeletal rehabilitation.¹⁴ For example, the words ‘degenerative’ and ‘damage’ can be alarming for patients and have the potential to exacerbate symptoms, particularly for those patients who are anxious about their condition.¹⁴ Using less evocative words like ‘irritation’ can be helpful. The overall aim of education is to provide patients with the knowledge and confidence to self-manage their condition during exacerbations.²

For many, normal daily functions such as mastication and yawning can exacerbate symptoms. More masticatory effort is required to eat hard and chewy foods. Therefore, patients should be advised to tailor their diet to one which is pain-free, but not necessarily completely restricted to soft foods.³ There is no consensus on diet modification duration; however, it is sensible to conduct a 2-week review to determine its success and whether firmer/chewier foods can be gradually reintroduced.⁷ Those patients with temporomandibular hypermobility (subluxation) should be advised to avoid ‘end of range’ mouth-opening positions, for example during yawning. Placing the tongue on the palate during yawning will limit movement during this action.

In the acute phase, for example when there is short-term restricted movement due to a displaced disc or inflamed muscle, vigorous exercise should be avoided to prevent further irritation.¹⁵ Resting the mandible and avoiding aggravation of awake parafunctional activity, while offering reassurance that it is safe to use the mandible as normally as possible within their own tolerance, is also beneficial. In these situations, giving reassurance and using positive language throughout discussions is important.¹⁴

Awareness of parafunctional behaviour

Successful management is more likely to be achieved when contributing factors, such as stress and oral parafunctional habits, are addressed, particularly when a suspected causative factor for the TMD is overactivity through clenching or grinding.¹⁰ Patients should be informed of any potential parafunctional behaviours, and recommended to monitor and avoid any behaviours that exacerbate their symptoms.⁷ Avoiding habits, such as unilateral chewing (where possible), chewing pens, nails and gum, can minimize stresses on the masticatory system.¹⁶

The Oral Behaviour Checklist was designed to identify and quantify the frequencies of oral behaviours during both sleep and during waking hours.¹⁷ This self-reporting instrument consists of 21 questions, which are graded from 0 to 4 according to frequency. This tool can highlight the frequency of oral behaviours and can help to raise a patient's awareness of their parafunctional activity.¹⁸ It is important that patients learn to keep their masticatory muscles relaxed by keeping their teeth apart, rather than in occlusion.⁴ Therefore, to help break parafunctional habits, frequent reminders throughout the day can be beneficial to symptomatic patients. Regular reminders to return to a resting jaw position at predetermined intervals in the day via phone alarms, use of apps (eg ‘No clenching’) or sticky notes around the house/at work can be recommended.

Thermal therapy

Localized thermal therapy can be effective in relieving pain and relaxing muscles in myalgia patients, by encouraging vasodilation, which increases blood flow to the area.¹⁹ A variety of protocols has been presented in the literature; however, there is no evidence for the use of one over another. Anecdotally, when symptomatic, the application of hot compresses to the painful muscle for at least 5 minutes, three times a day is useful. It is often beneficial for hot compresses to be applied prior to performing any prescribed exercises, massage or before eating, particularly during acute exacerbations.

Massage

Self-massage, in the form of kneading, friction and stretching should be limited to the area of discomfort or the tense masticatory muscle.^7,16 Following demonstration, patients are mainly advised to self-massage the masseter and temporalis muscles, as these are the most easily accessible. Self-massage can improve blood circulation and reduce tension in the masticatory muscles.²⁰

Relaxation techniques

Chronic pain can affect emotional wellbeing and, conversely, emotional wellbeing can influence pain.²¹ Increased understanding of ascending and descending neural pathways has legitimized the use of more holistic strategies.²² Positive emotional states, self-confidence, relaxation and beliefs that pain is manageable, may improve a patient's pain experience. The following strategies may therefore be helpful: mindfulness techniques, diaphragmatic breathing to aid relaxation and lifestyle changes to reduce stress.²³

Psychological interventions

It is widely acknowledged that oral health can impact upon an individual's physical and psychological health.²⁴ Furthermore, those with chronic pain associated with other comorbidities are more at risk of developing chronic TMD pain. There is no expectation for a dental practitioner to diagnose, discuss or manage a psychological comorbidity, yet recognizing when a patient may be having particular difficulty with coping is appropriate. Furthermore, if a patient discloses any underlying or associated mental health problems, it is important to ensure that they are already receiving appropriate support or that a referral to their general medical practitioner is made. As mentioned in the first article in the series,¹ many screening tools are available to help initiate communication, for example the Patient Health Questionnaire-4 (PHQ-4). This is an ultra-brief, reliable and valid screening instrument that can be used by clinicians for identifying potential cases of anxiety and depression (Figure 1).²⁵

The biopsychosocial model proposes that pain arises as a result of biological, psychological and social factors. Individuals will experience unique pain variations depending on the interplay between these factors. This can explain why individuals can have very different pain experiences despite the same level of nociception.²⁶ Reluctance to address psychosocial issues has been related to inadequate training, time, insufficient monetary incentive and cultural ethos favouring a ‘quick fix’.³¹ It is important that a patient's feelings are not dismissed because they play an integral part in the pain experience and simple reassurance can be helpful in influencing some of the mechanisms that can inhibit pain.

Cognitive behavioural therapy

Cognitive behavioural therapy (CBT) aims to challenge and break down negative thoughts, and provide management strategies to improve state of mind.²⁷ The literature shows that patients with chronic pain related to TMD may benefit from CBT.²⁸ CBT alone is not better than other non-surgical interventions; however, it can complement management of TMD.²⁹ To make a referral to a CBT practitioner for pain, a dentist will need to collaborate with the patient's general medical practitioner.

Physical therapies

It is suggested that physical therapies provide short-term symptomatic relief for TMD patients; however, due to limited evidence, there is uncertainty as to whether these benefits are sustained long term.² The use of physical therapies as part of a multimodal approach, may reduce the need for further treatment and, potentially, other more invasive therapies, as patients are more likely to be able to self-manage their condition should it return.

Therapeutic exercises

Therapeutic exercises are widely prescribed to patients with TMD who present with limited and abnormal TMJ movement patterns. These exercises aim to restore function by reducing inflammation, pain and muscular activity, and promoting repair and regeneration.³⁰ In order for patients to accurately and safely perform any home physiotherapy regimen, a physiotherapist or dentist competent to do so needs to provide thorough instructions and motivation.³⁰ There appears to be a distinct lack of consensus on the optimal exercise prescription, in particular the recommended frequencies, durations and intensities. Table 1 illustrates some examples of frequently recommended (but not exhaustive) exercises. The exercises selected for a patient will depend upon the presenting symptoms. It is the responsibility of an experienced clinician to know how to progress or regress each exercise to align with the patient's stage of recovery and capability.

Manual therapy

Manual therapy (MT) incorporates professionally applied joint mobilization, manipulation and soft tissue techniques. Trained physiotherapists use MT techniques in conjunction with therapeutic exercises to improve strength, co-ordination, mobility and importantly, to reduce pain.³¹ It has been proposed that these techniques trigger neurophysiological mechanisms that are responsible for reducing muscle activity and relieving pain.²⁹ The use of MT alone, or in combination with exercise, has shown promising treatment results for all TMD; however, there is a lack of substantial high-quality evidence to support its effectiveness.³¹ Ultimately, the choice of MT techniques used will depend on clinical findings, the irritability of the tissues and the patient's preferences.

There are an array of mobilization and manipulation interventions, graded from I to V, which can be performed on the upper cervical spine and TMJs by appropriately trained clinicians (such as physiotherapists). Evidence has shown that mobilization of the cervical spine can reduce pain in those with myofascial pain.³¹ Examples of TMJ mobilization include mandibular distraction, anterior–posterior translation and recapture techniques for displaced discs. Although these techniques are beyond the remit of this article, it is important to stress that grade V manipulation techniques, which involve a thrusting movement, are contraindicated in the management of TMD.³²

Electrotherapy

Electrotherapy has been advocated for the management of TMD, although the supporting evidence is limited. The two main modalities are transcutaneous electrical nerve stimulation (TENS) and low-level laser therapy (LLLT).

Transcutaneous electrical nerve stimulation (TENS)

TENS, which is considered to be safe and non-invasive, is now regularly used due to its analgesic and muscle relaxing effects.³³ Surface electrodes attached to a battery-operated device are placed on the skin surface to deliver small electrical pulses to painful areas. This action is thought to block the transmission of pain signals and potentially stimulate the production of endorphins.³⁴ The results from studies evaluating the effectiveness of TENS as an adjunctive therapy for pain management in masticatory muscles are positive; however, due to the low number of studies, small sample sizes and the lack of follow up, TENS cannot yet be considered as a standard treatment for patients with TMD.^33,34

Low-level laser therapy

LLLT is thought to provide both localized analgesic and anti-inflammatory effects through direct light irradiation, without causing a thermal response.³⁵ Despite there being no universally accepted consensus on the mechanism of action of LLLT, it has been proposed that this therapy has multiple actions, including improvement of local blood circulation and reduction of oedema.³⁶ It is not possible to determine the efficacy of LLLT in the management of TMD due to the variation of its use across the literature. Specifically, the site of application, the frequency of applications and the beam characteristics studied.³⁶ For the aforementioned reasons, it would be wise to consider this therapy as an adjunct, rather than an isolated intervention.

Acupuncture

Acupuncture comes under the umbrella of complementary or alternative medicines. It is derived from ancient Chinese medicine and involves the insertion of small gauge needles into defined anatomical points along a meridian – a pathway along which vital energy (Qi) is said to flow.³⁷ Acupuncture and dry needling are often confused. Although these practices both aim to provide relief from pain, dry needling differs in that it involves the insertion of needles into trigger points.

Although limited, there is evidence to support that acupuncture provides a short-term analgesic effect in those with myofascial pain without restricted mouth opening.³⁸ The exact mechanism for its analgesic effect is currently unknown; however, it is theorized that it promotes downregulation of pain signal transmission and the release of natural endogenous opioids.³⁹ The success of this adjunct could be due to its ability to temporarily improve symptoms, allowing self-management strategies to take effect.² Importantly, adverse events and side effects of acupuncture in TMD patients are infrequently reported in systematic reviews.⁴⁰ There may be some limitations to accessing this intervention in some regions, due to limited numbers of sufficiently trained clinicians.³

Conclusion

A structured approach should be taken in the management of TMD, one that is determined by an individual's diagnosis and symptoms, and escalated appropriately in line with the patient's response to reversible interventions. Evidence supports the cumulative effect of multiple reversible interventions with a biopsychosocial approach. A combination of relaxation exercises with diaphragmatic breathing, self-massage to the masticatory muscles, thermal therapy, active and passive stretching and proprioceptive exercises are suggested for those patients with myogenic pain and/or restricted mouth opening.^7,30,41 The close interrelationship between muscle activity and pathogenesis of degenerative or displacement disorders theoretically allows the extrapolation of the conservative measures to be beneficial for pain not classically defined as myogenic.

When the reversible interventions detailed in this paper are adopted at an appropriate time, success rates of 68-95% across the subtypes of TMD (see ‘classifications’ in the first article of the series¹) have been reported.⁴² Success is more likely to be achieved with a team approach when factors such as stress, depression, anxiety and parafunctional activities are addressed. Furthermore, an optimal result is more likely to be achieved if appropriately trained health professionals are involved in a patient's care.