The Occlusal- TMJ- Cervical Connection

The Occlusal- TMJ- Cervical Connection

Orthodontics, Dentofacial Orthopedics and Temporomandibular Dysfunctions Exclusively
by S. Kent Lauson, D.D.S., M.S.

Presented at the Sixth Annual International Symposium on Clinical Management of Head, Neck, Facial Pain and TMJ Disorders
August 1990
Philadelphia, PA

Those of us involved in treating temporomandibular and myofacial pain dysfunctions are very aware that neckaches and backaches are very common as a complaint among these patients. The purpose of this presentation is to show how occlusion can play a major role in TMD/MPD and can play a strong role in cervical (neck) dysfunctions.

There are many etiologic factors which can produce craniomandibular dysfunctions. However, with the exception of trauma, most come as a result of occlusion. For occlusion itself to cause TMD/MPD, it must be incompatible with proper unrestrained TMJ function. Although this can happen in many ways, a common way is the presence of retrusive occlusal contacts. A retrusive contact is any contact which lessens or stops the growth of the mandible (for those still growing) and cause posterior displacement of the condyles.

It is well known that people with deep overbites are predisposed to TMD. Deep overbites can be due to lack of posterior vertical development and /or supereruption of anteriors causing premature anterior contacts on closure. If both, lack of vertical and anterior supereruption are present, the person will likely have the lower bicuspids at a lower level than the cuspids (due to lack of posterior vertical development) and more than normal attrition on all anteriors, cuspid to cuspid. When this is present, comprehensive neuromuscular orthodontics is highly indicated.

Class II malocclusions, even without deep overbites, may also predispose a person to TMD. This is because most Class II’s have some constriction in the maxilla, therefore, a constriction in the maxillary teeth contacts and the creation of buccal cusp retrusive contacts. A neuromuscular message is sent to the brain by the proprioceptive nerve endings in the periodontal ligaments of the teeth. The retrusion occurs through hyperactivity of mandibular retruders, (suprahyoids and posterior temporalis). Bruxing and clenching (hyperactivity of masseters, pterygoids and temporalis) can occur as the body’s response when the fit of the teeth does not match with proper unrestrained function of the temporomandibular joints. This hyperactivity of the masticatory muscles can be assessed by palpating these muscles for tenderness and size, or more accurately for evaluating them through electromyography (EMG).

The hyperactivity can lead to excessive attrition, more overclosure and subsequent shortening of masticatory muscles. The muscles can become painful due to lactic acid buildup from overuse. The TMJ disc can become displaced. The displacement is due to one or a combination of the following factors: (1) retrusive positioning of mandible resulting in posterior displacement of the condyles; (2) masticatory muscle overactivity and shortening causing superior position of the condyles and TMJ compression; (3) hyperactivity of superior head of the lateral pterygoids. This important muscle inserts on and pulls the disc anterior and medial to cause anterior-medial displacement of the disc. The posterior and/or superior position of the condyles can result in compression and mechanical entrapment of the critical neurovascular bundle within the retrodiscal tissue.

Because branches of the fithe and seventh cranial nerves and key arteries pass through this area, significant pain and dysfunction can occur which include, but are not limited to, the following symptoms:

1. Headaches, facial pain, difficulty chewing
2. Ears- ringing, fullness, pain and hearing loss
3. Eyes- blurring, pain, light sensitivity, watering

The TMJ internal derangement eventually leads to osteoarthritic, cartelageneous and soft tissue changes within the TMJ.

While all the changes with the teeth, masticatory muscles and TMJ have been occurring which I previously described, another phenomenon is also occurring. In order to have less straining on the mandibular retruder muscles (anterior digastric, posterior temporalis), the head accommodates by moving forward of normal ideal posture. This lessens the amount of pull necessary to retrude mandible.

The occlusal relationship of the forward head posture phenomenon can be demonstrated as follows:

1. Stand or sit upright with your head rotated back as far as comfortably possible. Let your lower jaw hang loose, unrestrained and gently tap your teeth together. Remember where the teeth touch.
2. Now rotate your head down toward your chest as far as comfortably possible. (Position head as if trying to make a double chin.) With your lower jaw hanging loose and unrestrained, tap your teeth together.

If your teeth fit comfortably in the first position, it is a good bet you have a forward head posture with resultant neckaches, headaches and backaches. During the day, your teeth have to close together many times (reported to be up to 2000 times a day just during swallowing). Because you can’t go walking around with your head tilted backward so your teeth fit together right, you instead compensate by bringing your head forward (which is the same basic neuromuscular relationship of the lower jaw to the cranium).

The forward head postural compensation places a heavy strain on the posterior cervical muscles and upper trapezius. This can lead to head, neck and back aches. Other symptoms include the numbing of fingers and hands from muscle entrapment (scalenes) of the brachial plexus. The constant muscular straining and forward head posturing can lead to loss of the normal lordotic curvature of the cervical spine. Normal movements of the head and neck are now somewhat restricted. Further progression of this cervical dysfunction can lead to kyphosis (reverse curvature), subluxations of cervical vertebrae and osteoarthritic degeneration.

Application of Principles

Postural observations should be made on all patients, especially those where changes in occlusion are contemplated, i.e., orthodontics, prosthodontics. Cervical spine x-rays (cephalometric x-rays showing cervical vertebrae) can be extremely valuable in determining occlusal positions that will help and never cause harm to our patients. When patients undergo restorative, orthodontic or TMJ treatment, postural evaluations should always be made. Consideration should be given to the question: are present occlusal relationships helping or hurting this person’s head posture? What can be done to improve or maintain the dynamic relationship of the teeth, lower jaw (and TMJ) and neck? Treatment should include the following:

1. Understand the relationship of occlusion, TMJ and posture.
2. Always move treatment in the direction of the better balance within the stomatognothic/cervical system. Do not equilibrate to lessen vertical dimension on vertically overclosed patients!
3. When working with dysfunctional patients or changing occlusion, do temporary, reversible procedures such as orthotics, temporary crowns and bridges or functional orthopedics.
4. When creating your temporary (or permanent) occlusion, always have patient upright (not lying down in the dental chair) in as good of a posture as possible. I have my patients in an exaggerated good posture when testing and developing temporary occlusion. This will allow them to move as fast as possible toward better posture, to help eliminate neck and back problems.
5. Use sophisticated scientific instrumentation such as computerized electromyography and computerized mandibular tracking to develop and document occlusal relationships.
6. Always have muscles relaxed as possible prior to establishing temporary occlusion. The myomonitor (TENS) is quite effective in relaxing muscles (reduce EMG readings to normal) and in allowing them to achieve normal resting length