Abstract
Temporomandibular disorders (TMDs) present a diverse group of musculoskeletal conditions affecting the temporomandibular joint, with symptoms ranging from pain to limited mandibular function. With growing interest in how orthodontic practices might influence or intersect these disorders, this review evaluates TMD from an orthodontic perspective. The paper outlines the multifactorial aetiology of TMD, incorporating biological, psychological, and biomechanical elements. Clinical evaluation and diagnosis are explored with emphasis on evidence-based assessment tools and imaging modalities. The review also considers the debated relationship between malocclusion, occlusal interferences, and TMD, revealing weak associations but no conclusive causal links. Orthodontic treatments, including extractions, orthognathic surgery, and appliance therapy, are critically examined, along with controversial concepts such as reverse orthodontics. Despite anecdotal claims, most current evidence indicates that well-executed orthodontics neither causes nor cures TMD. Management should prioritise reversible, conservative strategies, including patient education, behavioural modifications, splint therapy, and physical therapy. Surgery remains a last resort for non-responsive cases. The review advocates for a cautious, individualised approach to TMD in orthodontic patients, highlighting the need for more robust longitudinal data to inform future practice.
LEARNING OBJECTIVES
To understand the multifactorial aetiology of TMD from an orthodontic perspective
To evaluate the role of orthodontic treatment in TMD onset and management
To identify evidence-based strategies for the clinical assessment and management of TMD
Introduction
Temporomandibular disorders (TMD) encompass a spectrum of musculoskeletal and neuromuscular conditions affecting the temporomandibular joint (TMJ), masticatory muscles, and associated structures. These disorders manifest in various ways, including joint pain, clicking, crepitus, deviation during mandibular movements, and reduced range of motion. Historically, TMD has been a complex and often misunderstood diagnosis due to its multifactorial nature and overlapping symptoms with other orofacial pain syndromes. While TMD was traditionally considered a disorder of adults, emerging studies have reported an increasing incidence in children and adolescents. This has raised questions regarding the potential role of orthodontics in either the onset or management of TMD symptoms.1,2 Orthodontists must be equipped with the knowledge to distinguish TMD-related symptoms from those that are transient or caused by orthodontic adjustments.
This comprehensive review explores the incidence, aetiology, clinical assessment, and management of TMD in the context of orthodontic practice. It critically examines the relationship between orthodontic interventions – such as extractions, occlusal corrections, and orthognathic surgery – and TMD outcomes, with a strong focus on current literature and clinical evidence.
Epidemiology and aetiology of TMD
The prevalence of TMJ disorders is reported to be 5% to 35% in the general population, with a peak prevalence in females between the ages of 20 and 40 years. 3 Among adolescents aged 6 to 18 years, prevalence ranges from 12.2% to 35%, depending on the criteria and diagnostic tools used.4,5 It is important to note that a substantial number of young patients experience spontaneous remission, with approximately 25% reporting complete resolution of symptoms by their late twenties. 3
The aetiology of TMD is widely recognised as multifactorial, encompassing biological, psychological, behavioural, and biomechanical components. Occlusal discrepancies, trauma, systemic inflammatory disorders, and parafunctional habits such as bruxism and clenching have all been implicated. 6 The role of stress and anxiety is particularly well-established, with psychological stress contributing to increased muscle hyperactivity and pain sensitivity. 7
Hormonal influences may also account for the gender disparity, with estrogen believed to affect ligament laxity and joint structure, thereby increasing susceptibility in females. 8 Recent frameworks adopt a biopsychosocial model that integrates emotional, social, and behavioural factors into the understanding and management of TMD, suggesting that no single factor – such as occlusion – can be viewed in isolation. 9
Assessment of TMD in orthodontic patients
The assessment of TMD in orthodontic patients should begin with a thorough history. Important indicators include jaw pain, clicking or locking, headaches, reduced mouth opening, pain on mastication, and history of facial trauma. Patients should also be questioned about parafunctional habits, recent dental interventions, and emotional stress levels.10,11
Clinical examination includes palpation of the masticatory muscles and TMJ, assessment of mandibular movement (normal interincisal opening is 40–60mm), presence of joint sounds, and observation of mandibular deviations on opening or closing. Attention should be given to occlusal discrepancies such as slide from centric relation (CR) to maximum intercuspation (MI). A mandibular slide greater than 3mm may indicate dysfunction, whereas slides under 2mm are generally considered acceptable.12,13
Other clinical signs of interest include anterior open bite, excessive overjet, posterior crossbite, or deep bite. Additional tests like joint loading, muscle fatigue resistance, and mandibular tracking can further aid diagnosis. Imaging techniques such as magnetic resonance imaging (MRI) may be useful to confirm internal derangements or disc displacements, while cone beam computed tomography (CBCT) can assist in evaluating bony changes. For a standardised approach, tools such as the Diagnostic Criteria for TMD (DC/TMD) offer validated guidelines that are particularly useful in research and clinical settings. 13
Malocclusion and TMD
Malocclusion has long been suspected as a predisposing factor for TMD. Certain traits such as Class II malocclusion, posterior crossbite, deep bite, and increased overjet have been weakly associated with signs and symptoms of TMD.14,15 Egermark et al. noted that centric slides greater than 2mm, particularly in lateral directions, may contribute to the onset of TMD symptoms. 16
Nevertheless, large-scale population studies have failed to confirm a strong causal link. Pullinger and Seligman concluded that only a small percentage of TMD symptoms could be explained by occlusal variables. 17 Gesch et al. found no consistent association between functional occlusion and TMD signs, in a study involving over 7,000 adults. 18
Occlusal interferences have also been debated. Magnusson and Enbom showed that artificially induced non-working-side interferences could induce TMD symptoms in the short term. 19 However, these symptoms often resolve once the interference is removed. Additionally, Sadowsky and BeGole found that non-working side contacts were present in 91% of asymptomatic individuals, suggesting that such contacts alone are not predictive of pathology. 20
Further, Ramfjord et al. demonstrated that minor mandibular deviations and functional slides are common in the general population and should not be considered pathological unless accompanied by pain or dysfunction. 21
Overall, the current consensus supports the notion that malocclusion and occlusal interferences may act as contributing – but not causative – factors in TMD. Their role is likely to be significant only in the presence of additional risk factors such as parafunction, joint hypermobility, or emotional stress.
Orthodontics and TMD
The relationship between orthodontic treatment and TMD has been debated for decades. Early advocates of occlusion-based orthodontics, such as Roth, 22 argued that correcting malocclusion and establishing a centric condylar position could alleviate TMD symptoms. However, most studies suggest that orthodontic treatment does not significantly influence the development or resolution of TMD.16,23
Orthodontics as a potential treatment for TMD
It has been proposed that orthodontic appliances may relieve TMD by reducing bruxism through temporary periodontal discomfort, which lessens loading on the TMJ. 24 Some studies found a reduction in TMD symptoms in patients with fixed appliances, although results were not statistically significant.20,25
Still, long-term research does not support the idea that orthodontic treatment in childhood prevents TMD development in adulthood.16,26 A Cochrane review also concluded that current evidence is insufficient to establish any definitive link between orthodontic therapy and TMD management. 23
Tooth extractions and TMD
Some functional orthodontists believe that extractions lead to posterior displacement of the condyles, thereby contributing to TMD. 27 However, empirical studies comparing extraction and non-extraction groups have failed to reveal differences in TMD symptom frequency.28-30 Moreover, no increase in TMD prevalence was observed among patients treated with premolar extractions and inter-maxillary Class II elastics, 31 and some improvement in TMD symptoms has been reported in both extraction and non-extraction cases. 25
A critical limitation of many of these studies, however, is that they often include only well-managed cases with ideal outcomes. As a result, they may fail to capture dysfunction caused by poorly executed treatment. This raises an important methodological concern – that the wrong question may have been asked. Rather than simply comparing extraction versus non-extraction cases, future research should assess the impact of compromised outcomes, such as over-retracted incisors, narrowed dental arches, or posterior bite collapse.
Some clinicians have adopted a “reverse orthodontics” approach, aiming to reopen extraction spaces, restore arch width, or decompress the TMJ through orthopedic expansion. While anecdotal success has been reported, these methods currently lack robust scientific validation. At this stage, reverse orthodontics should not be considered a standard or evidence-based practice, and its promotion without strong longitudinal data is not clinically justified.
Orthognathic surgery and TMD
Orthognathic surgery does not consistently improve or worsen TMD symptoms. A five-year follow-up study indicated that while some patients experienced symptomatic relief, others showed no significant change. 32
Impact of orthodontics on disc position
There is limited evidence that orthodontic interventions affect disc position. In one study, nearly half of patients diagnosed with disc displacement on arthrography had no TMJ sounds, casting doubt on the reliability of clicks as diagnostic markers. 33 To date, no changes in disc position have been documented following orthodontic treatment using imaging techniques such as arthrography or MRI. 34
Some functional orthodontists and Roth proponents argue for a specific condylar alignment to avoid occlusal interferences.22,27 However, these positions have not been validated by scientific data. 30 Repositioning splints have not reliably changed condylar positions, 35 and a significant percentage of asymptomatic individuals exhibit posterior condylar positioning. 36 Large-scale studies have similarly found no association between occlusal function and TMD. 18
Management of TMD in orthodontic patients
Management of TMD in orthodontic settings should always begin with conservative and reversible approaches. These include:
patient education on posture, oral habits, and avoiding trauma
behavioural therapy, including stress management, habit awareness, and biofeedback
soft diet and limiting wide jaw movements or prolonged function
pharmacologic therapy such as NSAIDs, low-dose tricyclic antidepressants, and muscle relaxants 37
physical therapy including electromyography (EMG) biofeedback, ultrasound, or low-level laser therapy38,39
Occlusal splints, particularly stabilisation splints, may provide symptom relief by reducing muscle activity and protecting the TMJ. Anterior repositioning splints may be considered in cases involving disc displacement with reduction. Santacatterina et al. found that repositioning splints offered superior results compared to flat-plane splints for joint clicking and pain. 40 However, long-term benefits remain uncertain. A Cochrane review by Al-Ani et al. found insufficient evidence to strongly support any one splint type over another. 41
Surgical intervention, such as arthrocentesis, arthroscopy, or open joint surgery, should be reserved for patients with persistent symptoms unresponsive to conservative care. 42
Conclusion
Temporomandibular disorders are multifactorial, involving biological, psychosocial, and biomechanical factors that interact uniquely. Evidence does not support a direct link between malocclusion, orthodontic treatment, and TMD, nor that orthodontics offers a cure. Occlusal issues may influence some patients but mainly act as modifiers within a biopsychosocial context. Orthodontists should cautiously screen for TMD, avoid irreversible interventions initially, and use conservative treatments like education and physiotherapy, with referrals when needed. Future research should focus on long-term, detailed studies to identify which patient groups, if any, benefit or are harmed by treatments.