Jaw Joint Problems

[drsushant]

The temporomandibular joint (TMJ / jaw joint) is located in

front of the ear where the skull and the lower jaw meet.

The joint allows the lower jaw (mandible) to move and

function for eating, talking etc.  The joint itself is made up of

two bones that are separated by a disc of cartilage (a

tough tissue).  Ligaments and muscles surround the joint.

Diagram Showing the Position & Anatomy

of the TMJ / Jaw Joint

Problems with the jaw joint are very common but typically

only last a few months before getting better.  In some

instances, only the muscles are affected (known as

myofacial pain dysfunction), whereas in others, the

cartilage and ligaments may also be a problem (known as

internal derangement of temporomandibular joint).

The most common symptoms are:

Joint noise – such as clicking, cracking, crunching,

grating or popping.

Pain – usually a dull ache in and around the ear.  The

pain may radiate, i.e. move forwards along the

cheekbone or downwards into the neck.

Headache.

Trismus – inability to open your mouth fully.

Most jaw joint problems are made worse by chewing and

are aggravated at times of stress.

What causes jaw joint problems?

Pain is caused by the muscles in and around the jaw joint

tightening up.  Joint noise occurs if the disc of cartilage

moves out of its normal position between the bones of the

jaw joint.  Most commonly, the disc slips forward and a

noise is made when it returns to its normal position in

between the bones.  The noise sounds louder to some

patients than others because the joint is just in front of the

ear.  The ligaments and muscles surrounding the joint can in

turn go into spasm, producing pain and a difficulty in

opening the mouth properly.

Why have I got jaw joint problems?

The cartilage in the jaw joint is thought to slip forwards

because of over-use of the muscles surrounding the jaw.

The over-use commonly produces tightening of the muscles

and may occur as a result of chewing habits, such as

grinding or clenching the teeth when under stress (usually

when asleep).  Nail biting or holding things between the

teeth can also cause jaw joint problems.  Less commonly,

missing back teeth, an uneven bite or an injury to the jaw

can lead to the problem.  Often, no obvious cause is found.

Are my problems anything to worry about?

Jaw joint problems are usually not serious and do not lead

on to other problems, e.g. arthritis of the jaw joint.

However, they are a nuisance.  Fortunately, jaw joint

problems usually respond well to simple treatments.

        

[drsushant]

Treatments vary depending on whether you are suffering

from myofacial pain dysfunction, internal derangement of

the temporomandibular joint or a combination of both.  On

the whole, treatment is aimed at trying to reduce the

workload of the muscles, so allowing the disc of cartilage to

return to a normal position in the joint.

 

This includes such advice as:

 

Eat a soft diet that requires little chewing – allowing the

over-worked muscles to rest.

 

Take painkillers – anti-inflammatory medication (e.g.

Ibuprofen) is good and can be taken as either tablets

or applied as a gel on the outside of the joint.

 

Use heat – e.g. wrap a hot water bottle filled with

warm water in a towel and apply it to the side of your

face.

 

Identify and stop any bad habits, such as clenching or

grinding.  Although, this may be difficult as they are

often ‘subconscious’, i.e. you may not be aware you

are doing them.

 

Use relaxation therapy and learn techniques to control

tension and stress.

 

Jaw joint exercises – your doctor will advise you on the

best kind of exercises for your problems.  Please

remember to follow them as instructed.

 

Rest the joint as much as possible, e.g. avoid yawning.

 

Wear a clear plastic splint that fits over the teeth and is

worn mainly at night (a Bite Raising Appliance).  This

helps support the joint and surrounding muscles.

 

Follow a physiotherapy programme.

 

Replace missing teeth to balance the bite (if

appropriate).

 

What happens if these methods do not help?

 

Surgery is only carried out in a small number of cases. 

This can involve manipulation of the joint whilst you are

asleep, or more rarely, surgery carried out with a mini

telescope.  In extreme cases, it may be necessary to open

the joint and operate on the bones, cartilage and ligaments.

 

Can jaw joint problems develop into anything worse?

 

It is important to realise that jaw joint problems, although a

nuisance, are not sinister and usually respond well to

relatively simple measures over a period of time.

 

Patients can manage most of the treatments themselves.

 

Occasionally, jaw joint problems may return after several

years.  It is very rare for jaw joint problems to progress to

anything serious, like arthritis.

        

[drmithila]

The temporomandibular joint (TMJ) is one of the most complicated joints in your body. You have one on each side of your face, just in front of your ears, where the temporal bone of the skull connects to the lower jaw (mandible). Your TMJs open and close like a hinge and slide forward, backward, and from side to side. When you bite and chew, they sustain an enormous amount of pressure.

As with other joints, the surfaces of your TMJs are covered with cartilage. Like the knee joint, the two parts of the joint are separated by a small disc, or meniscus, that prevents the bones from rubbing against each other. Muscles that enable you to open and close your mouth also serve to stabilize these joints, which are located about one-half inch (1.25 cm) in front of each ear canal.

A range of problems can affect the TMJs and the muscles surrounding them. These problems usually occur between the ages of 20 and 50. Most often, the cause of TMJ is a combination of muscle tension, anatomical problems, and injury. Sometimes, there may be a psychological component as well.

Like all of your joints, your TMJ may develop osteoarthritis, rheumatoid arthritis, and other inflammatory conditions. In rare instances, tumours may develop in this area. But for most people, pain in the area of the TMJ isn’t serious. Discomfort and pain may be temporary or chronic and often goes away with little or no treatment.

Causes of Temporomandibular Joint Dysfunction

In order for you to open your mouth and operate your jaw in the way that it should, your left and right TMJs must work in unison. If the movement of both of these joints isn’t coordinated, the disc that separates your lower jaw from your skull can slip out of position, and problems will result. Dislocation of your TMJ may take place if your mouth is forced to open rapidly or too widely.

In addition, muscle pain and tightness around the jaw can often come from muscle overuse as a result of clenching or grinding the teeth (bruxism) brought on by psychological stress or overuse. Extreme jaw clenching can also lead to pain over the temples. This occurs because the muscles that control jaw movement are also attached to a nearby bone of your skull. Excessive gum chewing or forceful biting, such as cracking nuts in your teeth, may also strain the TMJs and cause pain.

Some additional and less common ways of developing temporomandibular joint problems include:

ankylosis, which is loss of joint movement resulting from a fusion of bones within the joint or calcification of the ligaments around it
arthritis
certain inherited facial characteristics that produce misalignments
congenital abnormalities where the top of the jawbone doesn’t form or is smaller than normal
dental conditions such as a high filling, a tipped tooth, or teeth displaced due to earlier loss of other teeth
developmental abnormalities such as in some children where the top of the jawbone may grow faster or for a longer time than normal. Congenital and developmental abnormalities are rare, but can cause facial deformities and misalignment of the upper and lower sets of teeth.
hypermobility (looseness of the jaw), when the ligaments that hold the joint together become stretched
internal derangement, where the disc inside the joint lies in front of its normal position
structural abnormalities of the temporal joint
Symptoms and Complications of Temporomandibular Joint Dysfunction

There is an easy test you can do yourself to check whether you’re able to open your jaw as much as you should. Most people can place the tips of their index, middle, and ring fingers held vertically in the space between the upper and lower front teeth without forcing. If your space is smaller, or if you experience pain, or a clicking or grinding noise when you try to open your mouth this far, you probably have temporomandibular joint problems.

Common symptoms of TMJ problems include:

a clicking sound or grating sensation on opening the mouth or chewing
dull aching pain in front of the ear
headaches that don’t respond to the usual medical treatment
locking of the joint, making it difficult to open
tenderness of the jaw muscles
The pain will often occur only on one side of the face, and sometimes the pain may seem to occur near the joint rather than in it. Pain and muscle tightness may be present after waking up in the morning or during and after stressful periods. These symptoms result from muscle spasms brought on by repeated muscle or tooth clenching and tooth grinding. Many people grind their teeth during their sleep and aren’t even aware of it, and clenching and grinding is more forceful when a person is asleep than when they are awake.

 

        

[drmithila]

Researchers have identified a mechanism that may keep a well known signaling molecule from eroding bone and inflaming joints, according to an early study published online today in the Journal of Clinical Investigation.
Bone is continually recycled to maintain its strength through the competing action of osteoclasts, cells that break down aging bone, and osteoblasts, which build new bone. Osteoclasts also play a central role in common diseases that erode bone, where two signaling molecules, TNFα and RANKL, cause too much bone breakdown. Both are known to turn on the nuclear factor kappa B complex (NF-κB), which turns on genes that cause the stem cell precursors of osteoclasts to mature and start eating bone. While both TNFα and RANKL encourage bone loss, the current study argues that TNFα and RANKL have different effects on levels of a key inhibitory protein within the NF-κB pathway called NF-κB p100, with important consequences for drug design.
The NF-κB pathway as a whole signals for more active osteoclasts, but NF-κB p100 (p100) interferes with the ability of that same pathway to pass on the bone loss signal. While both TNFα and RANKL activate NF-κB signaling, RANKL efficiently converts p100 into a form that no longer blocks NF-κB pathway signaling and that leads to bone loss. In contrast, the current study is the first to show that TNFα lets p100 build up. Thus, TNFα both causes bone loss through NF-κB signaling and limits it via p100 accumulation.
Experiments found further that mice genetically engineered to lack NF-κB2p100 suffered more severe joint erosion and inflammation than their normal littermates in the face of TNFα. TNFα, but not RANKL, also increased levels of a protein in osteoclast precursors called TNF receptor-associated factor 3 (TRAF 3), which may help NF-κB p100 block osteoclast formation and inflammation.
“While further studies will be required to confirm and detail this mechanism, our results argue strongly that increasing levels of either TRAF3 or NF-κB p100 could represent a powerful new way to limit bone destruction and inflammation-induced bone loss seen in osteoporosis and rheumatoid arthritis,” said Brendan Boyce, M.D., professor within the Department of Pathology and Laboratory Medicine at the University of Rochester Medical Center, and the study’s corresponding author. “NF-κB p100 levels may vary with each person’s genes, making some more susceptible to TNFα-driven disease. Future solutions may be local delivery of p100 into diseased joints via gene therapy, or to target with a drug the enzyme, NIK, which otherwise limits the p100 supply.”
At the Center of Bone Loss and Inflammation
Drugs that block the function of TNFα are blockbusters (e.g. Enbrel, Humira and Remicade) because they effectively prevent bone loss and inflammation in most patients with rheumatoid arthritis. They have also been shown to reduce bone loss in women early after menopause.
Other studies, however, have suggested that TNFα cannot cause precursor cells to become osteoclasts unless RANKL first “primes” them. The debate has been spirited because it goes to which molecule should be targeted in near-future attempts to design more precise drugs.
The current results show that TNFα can signal for bone loss without RANKL, providing NF-κB p100 is also absent. By engineering mice with neither RANKL nor NF-κB p100, Boyce and colleagues found that TNFα had greatly increased ability to signal for osteoclast maturation and bone loss in this scenario.
Another unexpected result was measured in changes in gene expression, the process by which information encoded in DNA chains is used to build proteins that make up the body’s structures and carry it messages. The team found that mice engineered to over-express TNFα, but also to lack NF-κB p100, had significantly increased inflammation in their joints when compared to mice with high TNFα levels, but with p100 present to counter it.
Along with Boyce, the study was led by Zhenqiang Yao and Lianping Xing in the Department of Pathology and Laboratory Medicine at the University of Rochester Medical Center. The study was funded in part by the National Institutes of Health.
“We believe NF-κB p100 limits not only osteoclast maturation, but also the number of inflammatory cells attracted to the joints in response to TNFα,” Boyce said. “If confirmed, it would mean that p100 has more than one role in more than one major bone disease, and thus would create new opportunities to reverse disease by manipulating p100 levels

        

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