Orthodontists focus primarily on treating patients with skeletal and dental malocclusions. They aim to attain optimal occlusal and normal skeletal relationships and endeavour to maintain or enhance facial soft tissue balance during treatment. These objectives should be attained without disrupting and compromising the health of the temporomandibular joints (TMJs).

Orthodontists, like general dentists, will inevitably encounter patients exhibiting symptoms of temporomandibular disorders (TMDs). Dentists may refer such patients to an orthodontist for TMD treatment, while others may develop TMD problems during or after orthodontic treatment. TMD symptoms may exist before the start of orthodontic therapy or may develop or worsen during the treatment. It is important to note that not all these patients with TMD signs/symptoms would require definitive treatment. Therefore, it is crucial to thoroughly examine, document, diagnose, inform and manage these patients accordingly when necessary.

The topic of TMD management can be quite complex and multi-layered.

This chapter’s primary focus is to present an evidence-based approach to managing TMDs that can be a practical guide to orthodontic practice. Orthodontic specialists have historically been very close to the community of professionals when dealing with TMD.

Orthodontic students are significantly interested in issues related to occlusion and malocclusion, condyle position and orthodontics related to TMD. Functional occlusion following orthodontic treatment and current occlusal concepts are of direct concern. According to current scientific evidence, the main emphasis is on conservative treatment for most TMD conditions, especially during the early and acute stages.

For a thorough, detailed and highly referenced overview of every significant topic related to TMD and orthodontics, we recommend that readers look at our textbook on TMDs.

TMDs are an umbrella term for a group of conditions that affect the TMJ, muscles of mastication (MOM) and adjacent structures. TMDs can present as pain, restriction of jaw movement, joint noises and functional limitation. Pain may present locally, within the TMJ, MOM or associated structures, or can refer widely, presenting throughout the cervical and craniofacial regions.

A recent systematic review of TMD prevalence in the general population using Research Diagnostic Criteria for TMD (RDC/TMD) or Diagnostic Criteria for TMD (DC/TMD) reported a prevalence of 31.1% for TMJ disorders, 19.1% for disc displacement and 9.8% for degenerative joint diseases in the adult population. In children, the prevalence reported was 11.3% for TMJ disorders, 8.3% for disc displacement and 0.4% for degenerative joint disease. Only 3.6%–7% of individuals with signs and/or symptoms of TMD were estimated to require treatment.

The relationship between orthodontics and TMD has been controversial and debated for over half a century. Many believe that orthodontically changing the positions of the teeth and jaws will significantly affect the relationship of the condyles within the fossae either unfavourably or favourably. The main controversy is centred around whether achieving a particular occlusal outcome and an ideal condyle position via various elaborate technical and labour-intensive means will either resolve a pre-existing TMD or prevent TMD from occurring in the future.

The first discussion of a TMJ disorder in medical literature came from Dr. James Costen, an otolaryngologist. He described a syndrome with 11 symptoms related to the TMJs and the ears. ^, The cause was believed to be the over-closure of the mandible, which resulted from the loss of dental vertical dimension following tooth loss. The syndrome included TMJ sounds, pain in and around the jaw, limited mandibular opening, myofacial tenderness/pain and ear symptoms such as vertigo, tinnitus, pain and impaired hearing. The close anatomical proximity of the TMJ to the external auditory meatus and related structures was believed to contribute to the ear symptoms. This constellation of symptoms, called Costen’s syndrome, was later found to be fallacious from an anatomical viewpoint. ^, Although Costen’s aetiologic proposals were not fully proven with research, these observations formed an initial framework for various dental-based theories of TMD aetiology. The subject initiated great interest, awareness and involvement of dental professionals in assessing and treating these problems. Dental professionals were now TMJ-sensitised and stimulated to look more closely at occlusion as the primary causative factor in TMDs.

It was in the early 1970s that Dr. Ronald H Roth introduced gnathological concepts to orthodontics. Roth believed that orthodontic treatment was similar to prosthodontics/restorative dentistry, such as full-mouth rehabilitation, with the difference being that the orthodontists moved teeth instead of restoring them. Following the traditional gnathologic view, Roth believed that discrepancies in the occlusion and improper condyle position would cause TMD. He believed that orthodontists were obliged to attain gnathologically optimal functional, occlusal and condyle relationships.

A basic TMJ examination is integral to an initial evaluation of the orthodontic patient. The primary purpose of a TMJ evaluation is to ascertain the health condition of the joint and masticatory apparatus as a baseline and identify if there are any TMJ-related issues present prior to embarking on any orthodontic treatment. A similar protocol for TMJ examination can also be applied to the orthodontic patient during or after treatment. A basic screening questionnaire and a list of procedures for a clinical TMJ examination are summarised in Tables 92.2 and 92.3 .

Knowing that normal constitutes a range is essential, so considerable variation among individuals should be expected. Painless TMJ clicking, crepitus, deviated opening, tenderness in certain areas or non-progressive limited jaw opening should be regarded as imperfections that do not reach the threshold of significant clinical problems. The patient’s self-report and description of his/her TMD complaint may be as important, if not more important, than the orthodontist’s clinical evaluation.

The key to an adequate screening examination is to identify situations where dysfunction and pain are associated with the TMJs. If there is pain, it is essential to resolve or manage it before embarking on orthodontic treatment. If the patient is in the midst of orthodontic treatment, it is usually necessary to stop certain aspects of active orthodontic treatment, such as inter-arch elastics or fixed functional appliances, and manage the pain.

According to evidence-based literature, orthodontic treatment generally has not been found to cause TMD. Therefore, proper orthodontic procedures can be described as TMD ‘neutral’ because, in general, they neither cause nor cure (or mitigate) TMD. Furthermore, orthodontic treatment does not prevent the development of TMD in patients who have malocclusions, so advocating orthodontic treatment to mitigate the risk of TMD developing in the future is unfounded. Studies have shown that using specific types of orthodontic treatment or appliances, such as headgear, inter-arch elastics or chin cups, and extraction treatment, does not increase the risk of developing TMJ disorder (TMD). ^,

The concept of CR has been an integral component of philosophy and theories of occlusion for more than a century. The term ‘centric relation’ refers to the relationship of the mandibular condyles to the glenoid fossae. Over the last six decades, the concept of CR has changed within the prosthodontic community from a retruded, posterior and, for the most part, superior condyle to an anterior-superior condyle position. Although the position of human condyles has not changed physiologically over the last six decades, these revised definitions always aim to describe CR as a biologically sound position.

Gnathologists believe centric occlusion (CO) or maximum inter-cuspation (MI) should coincide with a specific CR position. These clinicians also believe that a CR–MI discrepancy is the reason for patients developing signs and symptoms of TMDs. To identify a CR–MI discrepancy, orthodontic gnathologists use a specific CR bite registration known as the Roth power centric bite. Based on this information, they perform orthodontic or prosthodontic treatment to establish a coincidence between CO and an anterior-superior CR in the condyle position. However, Kandasamy et al. in 2013 demonstrated via an magnetic resonance imaging (MRI) study that irrespective of the centric bite registration used, including the Roth power bite registration, clinicians cannot accurately and predictably position condyles into specific locations in the glenoid fossae.

Further, the evidence suggests a range of acceptable condylar positions for the population at large. Each individual has his/her unique condylar position, more commonly located in the anterior to mid fossa regions than the retruded CR positions. However, individuals with healthy TMJs can even have a retruded condylar position. ^{, ,} There is no specific optimal three-dimensional (3D) position or location of the TMJ condyles in the glenoid fossa. However, a mid-to-anterior position may work best for most individuals. The original position of the condyles while the teeth are in CO should be used as a sound physiologic guide for deciding treatment. Any procedure that deviates or positions the condyles away from a position they naturally and physiologically occupy may be harmful to the patient in the long term.

Functional occlusion refers to the inter-arch contact relationship of the maxillary and mandibular teeth during various functional movements of the mandible. Two major types of functional occlusion have been proposed: canine protected occlusion (CPO) and group function occlusion (GFO). Canine protected occlusion (CPO) prevalence is more common in young adults and dynamically changes with age. Gnathologists and occlusion experts advocate the creation of CPO as the optimal functional occlusion after dental restorations and oral rehabilitation, including those undergoing orthodontic treatment. CPO refers to functional contacts between maxillary and mandibular canine teeth during lateral or side-to-side mandibular movements only on the working side, with no occlusal contact(s) on the non-working (balancing) side. This occurs when only the canine teeth are on the working side, discluding the entire dentition on laterotrusive movements out of CO. Some clinicians believe that failure to establish CPO during orthodontic treatment will predispose patients to TMD, as well as orthodontic relapse. ^{, ,}

However, the evidence does not support the concept that CPO is the only optimal functional occlusion for orthodontic patients. CPO as the goal of functional occlusion, ignores the importance of each person’s unique stomatognathic and neuromuscular functional status. People rarely function in the extreme lateral side-to-side border movements during functional activities, such as mastication and swallowing. Even during parafunction, a person would typically move the mandible forward or forward and to the side, not directly side-to-side. ^, The most important functional occlusal movements are those closest to CO.

It is important to note that a specific functional occlusion achieved with treatment may not be sustained over the patient’s lifetime due to physiological changes. Regardless of the type of functional occlusion achieved, it often evolves into a group function type of balanced occlusion due to tooth wear, changes in the oral environment, demands on the dentition with growth and ageing, parafunction and occlusal settling. All these biological changes affect the vertical level and position of the canines and inter-arch relations.

In orthodontics, articulators have been primarily used with orthognathic surgical procedures to maintain the vertical reference dimensions of occlusion while laboratory procedures are being performed on the models. However, given the detail, visualisation, much greater diagnostic information, accuracy and efficiency that come with 3D imaging and virtual planning, mounting dental casts in cases involving orthodontics associated with orthognathic surgical procedures are no longer necessary to achieve the goals of that treatment protocol.

Dr. Ronald Roth, in the early 1970s, believed that the routine mounting of dental casts on articulators would aid the orthodontist in detecting CR–MI discrepancies and diagnosing 3D condylar CR discrepancies. By introducing his philosophy to the orthodontic profession with articulator mounting, Roth believed that he could produce superior outcomes by seating the condyles in an ideal position. Dr. Roth proposed that orthodontic treatments should be based around this condylar position of CR. He and other gnathologic orthodontists believed that this would either cure an existing TMD or prevent the development of TMD in the future. According to these clinicians, routine articulator mountings with the appropriate centric bite registration will improve the orthodontic diagnosis in 18.7%–40.9% of cases. ^,

When clinical examination and investigations lead to a presumptive diagnosis of TMD, the orthodontist may consider treating the patient in the office or referring to an appropriate oral medicine or orofacial pain colleague. Pain and dysfunction of TMJ are the primary reasons most people seek professional care. Dysfunction is usually a consequence of the pain rather than its cause; therefore, primary attention should be directed at managing pain and providing comfort to the patient. A clinician must follow current science, and evidence must support the clinical approach to managing pain and dysfunction.

In the past, treatment for TMDs focused on the relationship between the condyle and the fossa and on occlusion. However, there has been a significant change in management approaches, shifting towards a biopsychosocial model rather than the traditional dental-based model. This new approach represents a departure from conventional dentistry, which previously focused on adjusting occlusion and realigning jaw relationships and instead emphasises management based on the biomedical and psychosocial sciences.

The contemporary biopsychosocial model attempts to integrate the host of biological, clinical and behavioural factors that may account for the onset, maintenance and remission of TMD. The factors that are receiving the most attention and research in the understanding of TMD today are genetics (vulnerabilities related to pain), imaging of the pain-involved brain, endocrinology, behavioural risk factors, sexual dimorphism, psychosocial traits and states, and co-morbid pain conditions. ^,

There are conservative and reversible TMD treatments that orthodontists can provide for patients. In most cases, the specific cause of the TMD cannot be ascertained prior to treatment. Therefore, the treatments provided will be palliative pain-relieving measures. These methods and therapies include the following:

• •

  Patient self-directed care and education

• •

  Home physical therapies

• •

  Psychological approaches to treatment

• •

  Pharmacologic agents

• •

  Oral occlusal appliances

Patient self-directed care and education

Patients afflicted with TMJ disorder (TMD) frequently exhibit heightened sensitivity and anxiety. Following the initial diagnosis of TMD, it is imperative for the orthodontist to effectively address these concerns and communicate with the patient. It is worth emphasising that extensive research has demonstrated that 80%–90% of TMD patients can anticipate favourable short-term outcomes with minimal long-term implications subsequent to undergoing conservative physical therapy aimed at mitigating pain and restoring normal jaw functionality. ^,

In the management of TMJ disorder (TMD), it is imperative to effectively communicate to patients that favourable treatment outcomes can often be attained through the implementation of appropriate conservative measures. Several studies have indicated that patients who are apprised of this prognosis may exhibit improvement without professional intervention, primarily due to the relief provided by the explanation and the passage of time.

A very small proportion of patients require actual treatment procedures inside the joint.

These interventional procedures are more straightforward and less invasive measures such as arthrocentesis or arthroscopy. Traditional open-joint surgical operations are no more recommended.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

1. Limits of orthodontic treatment modalities: 3D perspective
2. Digital and computerised cephalometrics
3. Role of removable appliances in contemporary orthodontics
4. Dentofacial orthopaedics for class II malocclusion with vertical maxillary excess in growing children
5. Transposition of teeth
6. Contemporary approaches for the orthopaedic correction of class III malocclusion

Stay updated, free dental videos. Join our Telegram channel

Join