Temporomandibular Joint Pain

*KadarkaraiKirupa, R. Rajashri, Kamali Raman, Aishwarya Balaji, Pavithra Elango, Swetha Karupaiah and Leelavathy Gopalakrishnan*

## **Abstract**

Temporomandibular joint (TMJ) is a synovial articulation between mandibular condyle and glenoid fossa in the temporal bone. Any structural and/or functional changes can affect the TMJ and related structures. Temporomandibular disorder (TMD) is a heterogeneous group of musculoskeletal disorders mainly characterised by regional pain in the facial and preauricular area and/or limitations/interference of jaw movement. TMD has multifactorial aetiology, which includes biology, and environmental social, emotional, and cognitive factors. TMD is more common orofacial pain condition and nondental origin. Factors associated with TMD include other pain condition, auto-immune disorder and psychiatric illness. The clinical conditions may present with limitation in opening and closing mouth, pain and articular noise. So this chapter mainly deals with the classification of TMJ disorder, diagnosis and management particularly TENS and ultrasound therapy for TMJ disorder.

**Keywords:** temporomandibular joint, TMJ disorders, TENS, pain, ultrasound therapy

## **1. Introduction**

The temporomandibular joint (TMJ) is a synovial joint. The joint is the articulation between the mandibular condyle and the glenoid fossa in the temporal bone. Temporomandibular joint disorders produce structural and functional changes of the joint. Temporalis, medial & lateral pterygoid, Masseter Maxilla/upper jaw Mandible/ lower jaw and the temporal. These disorders may present with specific clinical features such as pain, muscle tightness, limitation in opening and closing the mouth [1].

TMJ is the most complex joint. TMJ disorders occur when the muscles, ligament, joint capsule or any other structure surrounding the TMJ joint are affected. This consists of joint cavity, mandibular condyle, articular disc, muscle and nerve, which interacts with various structures such as cervical spine and orofacial region. When the physiological functions of some of these components are altered, functional and structural disorders result in clinical impact [2]. The unique feature of TMJ is that it acts as a fulcrum in which the movement is controlled by both morphology of joints and the dentition at the other end.

During life, the components of the joints including temporal, condylar and disc articular surfaces undergo continuous remodelling. The synovial fluid is responsible for nourishment and lubrication. The lateral pterygoid muscle is attached to the joint capsule. The function of the articular disc is to produce friction, stabilisation and viscoelastic properties. Mastication and speech are the main action of TMJ joint [3].

During mastication process, this joint supports a large number of forces. Excessive force on the joint can cause damage in its structure or alter normal function contact of condyles, discs and eminence. This damage and alteration can result in pain, dysfunction or both [3].

Temporomandibular disorders (TMDs) are group of heterogeneous musculoskeletal disorders mainly responsible for regional pain in the facial and preauricular, limitation and interference of the jaw movements. TMD has many causes, which includes biologic, environmental, social, emotional and cognitive factors. Factors associated with TMD include other pain condition (e.g. chronic headaches, fibromyalgia), autoimmune disorders, sleep apnoea and psychiatric illness. TMDs are the most common orofacial pain conditions other than dental origin [4].

Numerous risk factors have been implicated including joint and muscle trauma, anatomical factors (e.g. skeletal and occlusal relationship), pathophysiological factors (e.g. bone and connective tissue disorders, sensitization of peripheral and CNS pain processing pathways) and psychosocial factors (e.g. depression and anxiety, emotional and perceptual responses to psychological stressors).

### **2. Prevalences**

The prevalence of TMDs is around 12% of world population and 35 million people in US. TMDs affect both men and women but majority seeking care are women of age group 19–49 years. TMD is diagnosed in women 2–5 times more frequently than men. Studies suggest that women tend to have more severe symptoms and are nine times as likely to be diagnosed with majority limitations in jaw movements and unremitting pain.

There are various hypothesis put forward by several researchers to demonstrate the higher prevalence rate in women. Anatomical, hormonal, behavioural and genetic differences contribute to the disproportional ratio of women to men diagnosed [4].

**Anatomical differences** between males and females in jaw and skull affect the forces on TMJ. Maxillary bone is longer, wider and thicker in males than in females. The angle created by mandible is less obtuse in male than in female. Mandibular condyle is larger and temporal socket is deeper in males. All these anatomical factors create more stable environment for TMJ translation in males than in females.

**Hormonal differences** between men and women contribute to TMDs. Oestrogen and progesterone levels are higher in women during childbearing years. There is increased ligament laxity during preovulatory phase (oestrogen dominates). During follicular phase (days 1–9), relaxin hormone is secreted and it peaks during the luteal phase (days 15–28). These differences in the level of hormones released may contribute to greater laxity in some women. Increased ligament laxity increases joint play and it irritates the joints.

**Behavioural differences**—Men and women manage stress differently. Clenching, grinding and poor breathing habits can increase internalisation of stress and it may irritate TMJ [5].

Various studies revealed that at least one sign of articular dysfunction is seen in about 40–75% of cases in general adult population, and in 33% of cases, there is at least one symptom of dysfunction. Signs such as noise and asymmetric mouth

*Temporomandibular Joint Pain DOI: http://dx.doi.org/10.5772/intechopen.104842*

opening are prevalent in about 50% of the individuals and other symptoms such as difficulty in mouth opening are present in about 5% of cases [6]. Articular disorders are present in 19%, muscular forms of disorders in 23% and both in 27% of individuals in general population. In patients, these symptoms are more pronounced in 20–40 age group, and in general population, these symptoms are most commonly seen in 17–30 age groups.

Prevalence of moderate or severe TMDs was found to be 37.4% in children and adolescents between 6 and 14 years of age in Brazilian study.

Epidemiological surveys reported that 50–70% of population have signs of a disorder at some stage during their life, whereas an estimated 20–25% of the population have symptoms of TMD. The highest prevalence of TMD in relation to age has been estimated between the age of 20 and 40s. Among the post-menopausal women, those receiving hormone replacement therapy (HRT) were found to be at higher risk for TMD than those not receiving HRT. TMD is most prevalent in adolescents and women during the reproductive years and falls off sharply with advancing middle age [7].
