The importance of the postural evaluation in patients with temporomandibular joint dysfunction

Abstracts

O equilíbrio do corpo bem como os movimentos da cabeça são originados pelo posicionamento do crânio sobre a região cervical determinando assim a postura do indivíduo. Estando a articulação temporomandibular (ATM) diretamente relacionada com a região cervical e escapular através de um sistema neuromuscular comum, alterações posturais da coluna cervical podem acarretar em distúrbios na ATM e vice-versa. O número crescente de pacientes com disfunção da articulação temporomandibular (DTM) que apresentavam alterações posturais levou ao desenvolvimento de estudos que procuram demonstrar suas relações. Este trabalho propôs-se realizar uma revisão de literatura que demonstre a relação entre má postura e DTM. Salienta ainda a necessidade de uma equipe multidisciplinar, formada pelo médico ortopedista, o cirurgião dentista e o fisioterapeuta, para realizarem juntos o diagnóstico e o tratamento de tais alterações.

Postura; Disfunção temporomandibular; Coluna cervical; Ortopedia

ORIGINAL ARTICLE

The importance of the postural evaluation in patients with temporomandibular joint dysfunction

Daniela Vieira Amantéa^I; Ana Paula Novaes^II; Gabriel Denser Campolongo^III; Tarley Pessoa de Barros^IV

^IStudent of the Specialization Course in CTBMF of the Brazilian Association of Odontological Teaching - ABENO

^IIProfessor at the UNIBAN; Student of the Specialization Course in CTBMF of the Brazilian Association of Odontological Teaching - ABENO

^IIIProfessor at the UNIBAN, UNIP, ABENO; Coordinator of the CTBMF of the Orofacial Pain Unity - UNIDOR

^IVMaster in Health Sciences at the UNICID; professor at the UNIP, UNIBAN, ABENO; Coordinator of the Orofacial Pain Unity - UNIDOR; President of the Brazilian Society for the Study of Orofacial Injury - SOBRALOR

^{Correspondence}

SUMMARY

The position of the head over the neck determines the posture of the body and is responsible for the body balance and head movements. The temporomandibular joint (TMA) is directly related to the cervical and the scapular region by a common neuromuscular system. Changes in the cervical spine can cause lead to TMA disorders and contra wise.

The increasing number of patients with TMA disorders who also had postural disorders led to the development of studies to evaluate their interactions.

The present study aimed to review the papers that have shown a relationship between wrong posture and TMA disorders. It emphasizes the importance of a multidisciplinary team formed by an orthopedist, dental surgeon, and physiotherapist in the diagnosis and treatment of TMA disorders and wrong posture.

Key words: Posture; Temporomandibular disorders; Cervical spine; Orthopedics.

INTRODUCTION

The stomatognastic system is a functional unity of the organism characterized by several tissues of different origin and structure that act in harmony to perform different functional tasks. It consists of skeletal components (maxilla and mandible), dental arches, soft tissue (salivary glands, nervous and vascular supplies), TMA, and muscles. These structures are interconnected and interrelated; when activated, they aim to achieve the maximal efficiency with protection of all participating tissues⁽²³⁾.

The temporomandibular joint (TMA) takes part in this complex system. "A set of anatomical structures that, with the participation of special muscular groups, allow the mandible to make different movements during mastication⁽⁷⁾". It represents the articulate connection of the mandible to the base of the skull which, in turn, have muscle and ligament connections to the cervical region. They form a functional system called craniocervicomandibular system⁽¹⁹⁾.

Since head and cervical muscles are closely related to the stomatognastic system, studies were carried out to confirm that postural changes of the head and the body could have an adverse biomechanical effect upon the TMA and lead to temporomandibular disorders.

The present study aims to evaluate the effect of wrong posture in patients with TMA disorders and also to emphasize the importance of multidisciplinary teams formed by orthopedists, dental surgeons, and physiotherapists who can improve the diagnosis and treatment of patients with TMA disorders by working together.

LITERATURE REVIEW

Posture:

The ideal posture is defined as that characterized by a balance between the support structures requiring a minimal amount of effort and burden with a maximal efficiency of the body⁽⁶⁾.

The posture of each subject will be determined by muscular chains, fascias, ligaments, and bone structures that present continuity solution and are mutually dependent and encompass the whole organism⁽¹³⁾.

One method of postural evaluation was described by Kendall. It aimed to determine possible changes in body posture. Patients are positioned in the standing position in front of a crisscross space and, with the help of a plumb line, their posture is evaluated. The plumb line must lie in front of the lateral malleolus in the lateral view, between the medial malleoli in the anterior and the posterior view. The plumb line will cross the following structures⁽¹³⁾ in the normal subject:

Lateral View:

• Slightly anterior to the knee joint axis

• Bodies of the Lumbar Vertebrae

• Odontoid process of the axis

• External Acoustic Meatus

Anterior View:

• Between the knee joints

• Through the pubic symphysis

• Over the umbilicus

• Over the xiphoid process

• Over the tip of the nose

Posterior view:

• Between the knee joints

• Over the gluteal fold

• Vertebral Bodies

• C7 Spinous Process

Shifts in these positions indicate changes in body posture. The wholeness of human organism implies that even a small abnormality of the support structures results in postural disharmony. According to Souchard (1986), an initial tension in muscular chains is responsible for a series of associated tensions. Whenever a muscle shortens, its endings are made closer and bones to which they are attached are displaced, joints are blocked, and a body deformation develops. Therefore, the remaining muscles attached to the same bone will be affected by the displacement, which will spread to other bones and muscles and then successively⁽²⁴⁾

Temporomandibular Disorder

The term temporomandibular disorder is (TMD) is used to describe a group of diseases affecting the masticatory muscles, TMA, and surrounding structures. It is a debilitating disease that modifies the perfect performance of some essential functions, such as chewing food or appropriate pronunciation. The incidence of TMD has been increasing, specially in middle-age women (80% of patients⁽²⁵⁾. An imbalance of the TMA, alveolodental joint, and occlusion, together with the imbalanced action of masticatory muscles, leads to this myofascial dysfunction⁽²⁵⁾. Patients with TMD report as their main symptom the myofascial pain associated with mandibular dysfunction. Pain is usually over the preauricular region and spreads to the temporal, frontal, or occipital regions. It may present itself as a headache, earache, tinnitus, or even toothache⁽¹⁸⁾.

The spasm of masticatory muscles is believed to be the main cause of painful symptoms of the TMD and may be triggered by distension, contraction, or muscular fatigue⁽²⁵⁾. They, in turn, are usually caused by muscular hyperactivity that is responsible for 80% of TMD etiology⁽¹⁵⁾. Muscular hyperactivity is mainly caused by parafunctional habits (bruxism, onychophagia) that are aggravated and affected by emotional stress⁽¹⁹⁾.

Temporomandibular joint dysfunction and its relationship with posture:

When one evaluates the relationship between the skull and the cervical spine from the lateral view, one may observe that the greatest part of the skull weight, its gravity center, lies on the anterior region of the cervical spine and temporomandibular joints. As a result, its orthostatic position is maintained by a complex muscular mechanism involving the muscles of the head, nech, and shoulder girdle. Any change in one of these structures can lead to a postural imbalance not only locally, but also in other muscular chains of the organism because of the close relationships⁽²¹⁾.

The complex anatomical and biomechanical interactions between the stomatognastic system and the head and neck area are responsible for the relationship between the TMD and posture. Several studies have shown that patients with TMD present changes in the head and should positions, as well as an increased cervical lordosis.

Shifts in the head and shoulder positions can result from different changes, such as podalic anomalies or craniomandibular disorders. Disorders of the stomatognastic system, such as muscular hyperactivity, for example, lead to anterior cervicoscapular displacement^(3,16). The increased activity of the masticatory muscles affects the muscles responsible for countersupport (sternoicleidomastoid muscle, trapezius muscle), thus resulting in the shortening of the posterior muscles of the neck and lengthening of the anterior muscles, with an anterior projection of the body that exceeds the support quadrilateral⁽³⁾. The anterior position of the head will simultaneously lead to disorders of mandibular positioning and functioning, thus resulting in an increasing tension of the masticatory muscles and, as a result, TMD^(1,8,12,20).

Increased cervical lordosis is an important sign of TMD as well^{(4,5,10,14,15,17)}. The reason for such postural abnormality has been addressed in several studies. Some papers state that, with the anterior displacement of the head, the vision field is lowered and cervical lordosis increases in the attempt to level the vision field so as to make it functional⁽¹¹⁾. Other authors state that, since masticatory and cervical muscles are synergic, an imbalance between then gives rise to retrusive forces acting upon the mandible; the latter leads to a change in their rest position and muscular hyperactivity⁽⁵⁾. In 1990, Gillespie showed that increased cervical lordosis results from an increase in the masticatory muscles due to a change in the tension of the associated structures (muscles, fascias, and ligaments)⁽¹⁰⁾.

In addition, as for the head position, other studies have shown that the head have a tendency to be leaned or rotated towards the painful TMA⁽²⁰⁾.

The shoulder position can also be altered by increased masticatory muscle activity^(4,9,15,22). Lack of shoulder levelling^(4,9,15,22) may be present, with protrusion or elevation of the shoulder on the same side as the affected TMA⁽²⁰⁾. Changes in shoulder position develops because the masticatory muscle hyperactivity leads to cervical muscle hyperactivity, with contraction of the muscles responsible for shoulder elevation and protrusion⁽¹⁶⁾. In contrast, other authors have not found a significant relationship between the lack of shoulder levelling and muscular activity⁽²⁶⁾.

DISCUSSION

Patients with temporomandibular joint disorders have significant changes in the body posture. Because of these findings and the complex anatomical and biomechanical interaction between the stomatognastic system and the head and neck region, several studies were carried out to discuss such relationships^{(4,5,9,10,14,15,16,17,20,22)}.

The anterior displacement of the head in patients with TMD has been addressed in several studies^{(1,3,8,12,16,20)}. The anterior position of the head beyong the gravity center has been found in all studies, thus confirming the interrelationship between body posture and joint disorders.

There are different theories to explain the increased cervical lordosis found in patients with TMD^(5,10). However, there is a consensus that this abnormality is an important sign and very frequently found in patients with joint dysfunction^{(4,5,10,14,15,17)}. As for the leaned or rotated head towards to the affected TMA⁽²⁰⁾, we did not find other papers reporting this sign.

As for the shoulder position, lack of levelling was found in several studies^(4,9,15,22), thus confirming that the hyperactivity of masticatory muscles can lead to the contraction of cervical muscles, thus affecting the position of the shoulder girdle⁽¹⁶⁾. Despite the fact that the studies carried out by Zonnenberg⁽²⁶⁾ did not show any relationship between the increased activity of the masticatory muscles and the lack of shoulder levelling, other studies, such as that carried out by Bienfat⁽²⁾, have reported that the lack of shoulder levelling results from a late process of adaptation of body structures and is referred to the hyperactivity of masticatory muscles and increased cervical lordosis.

CONCLUSION

The present study reviewed the literature studies showing the relationship between wrong posture and TMA disorders and confirmed the close relationship between TMD and changes in body posture. Patients with TMD are expected to present postural shifts, such as the anterior displacement of the head, increased cervical lordosis, and lack of shoulder levelling (see ^{Picture 1}).

In addition, one must emphasize the need to consider the patient with TMA disorders as a whole. The stomatognastic system must be evaluated by the dental surgeon, and body posture must be assessed by the orthopedist in order that, by working together, they define a therapeutic plan for the individual patient.

REFERÊNCIAS BIBLIOGRÁFICAS:

Trabalho recebido em 02/02/2004.

Aprovado em 24/06/2004.

Work performed at the Brazilian Association of Odontological Teaching

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Publication Dates

• Publication in this collection
  16 Nov 2004
• Date of issue
  Sept 2004

History

• Received
  02 Feb 2004
• Accepted
  24 June 2004