What is TMD (Temporomandibular Joint Disorder)?

Temporomandibular disorder, or TMD, describes a range of issues arising from in and around the temporomandibular joint (TMJ). These involve: night-time grinding or clenching; tooth wear and cracks in teeth; clicking or pain when opening and closing the lower jaw; pain resulting from long periods of mouth opening; or limited capacity for mouth opening. The causes of these symptoms usually have many factors involved.

So where do we start? Firstly, your general dentist will assess your symptoms and possible causes of TMD, then will tailor your treatment accordingly.

The temporomandibular joints (TMJ) provide the pivot points for the lower jaw’s range of movement. This joint can suffer damage over time from disc displacement (clicking or locking), arthritic wear, or other pathological issues.
The masseters are the main muscles of mastication involved in chewing. If these become overworked they can become hypertrophic (enlarged), may become tender, and lead to further grinding and clenching.
Wear tends to occur on the chewing surfaces of teeth over time due to excessive grinding. The small lower incisors shows the most wear but wear will also be occurring on all the teeth. In severe cases, the wear can be quite significant and lead to shorter teeth and reducing the vertical dimension of your bite.
The necks of teeth can also suffer abfraction, which is wear that leads to concavities here and exposes dentine. The exposed dentine can be quite sensitive and since this part of the tooth is less dense, further wear or decay is likely to develop here.
A major muscle of mastication that stretches out laterally here is called the temporalis. If increased tension is experienced here, headaches are commonly experienced.
Those who suffer TMD may find that their jaws fatigue quickly after holding there mouths open for a short period of time. This is generally because of the overworked muscles of mastication that work in the opposite direction to close the jaw.
Congestion in the nasal sinuses may lead to increased mouth breathing and this can increase the likelihood of congestive sleep apnoea. It is important to search for any issues that be contributing to TMD when selecting a treatment protocol.

Causes of TMD

Congestive sleep apnoea: occurs as a result of your tongue rolling back in your mouth at night, blocking your airways. Grinding and clenching may occur as an attempt to wake yourself up at night. Specialised splints or C-PAP machines can be useful in treating this condition.

Crooked teeth have been occasionally associated with TMD, though usually when there are more significant bite problems. Teeth straightening, at times with jaw repositioning surgery, may help to reset your bite into a more harmonious position.

Anxiety, stress, and personality quirks may just lead some people to grind without any other clearly defined cause.

What are the treatment options?

Splints

If sleep apnoea and bite discrepancies don’t seem to play a large role we usually start with a splint. This is a clear plastic mouthguard you wear on your top teeth at night. These are specially fitted for your teeth so they don’t fall out easily and provide an even bite with a free range of movement. These will not stop your grinding or clenching, but it will help to reduce it and ease forces. The plastic material acts as a buffer between your teeth and protects them from wear and cracks. The splint can look bulky at first, but after a couple of weeks most people adapt fairly well. For our splints, we use a hard firm material on the outside and a gel layer on the inside fitting surface. These are generally reported as far more comfortable than the standard plain hard splint design.

Splints are specially moulded to your teeth to ensure they will stay on all night snugly.
At Smile Design Dental we use a gel internal layer to ensure comfort.
Hard plastic outer layer will keep the splint’s stability and absorb the wear from nocturnal grinding. The bite will be fairly even to ensure forces are well distributed and avoiding any locking from the joints.

Muscle Relaxant Injectables

Muscle relaxant injectables provide an alternative to those who find a splint still too bulky. These can be injected into the overworked, enlarged chewing muscles. The masseters, bands of thick muscle at the back of your jaws, are usually injected first and reviewed 4-6 weeks later. The muscles will lose some strength so that they will naturally release when clenched, easing tightness. The temporalis, a band over the temple and stretching laterally across the skull, may also require injecting. The injectables typically last 4-6 months and can be seen to slim the jawline giving a nice aesthetic side effect.

Injectables into the masseter muscles will reduce strength and bulk. Allowing the jaw to open with less resistance and will reduce capacity to clench tightly for long periods. Reducing the bulk can help to slim the jawline.
A thin wide band of muscle over the temporals is the temporalis. When these muscles are overworked there is an increased tendency for headaches. Muscle relaxant injectables may be added here along with the masseters may be warranted in some cases.

Other treatments

Physiotherapy can also be used as an adjunct to the prior treatment methods. This will f on improving range of motion and decreasing tension. If your TMD is a little more complicated you may require a more specialised splint, anti-inflammatory or anti-anxiety medications. If there are physiological changes to the joints then surgery may be required. Arthritis or other changes can occur when TMD has been present for a long time without adequate intervention. These can be difficult to treat and may only provide a small improvement, therefore early management of TMD is critical.

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