Teeth are the hardest structures in the body. They are composed of an inner layer made of a substance called dentin and a hard outer layer made of enamel. Enamel is similar in hardness to steel. As long as the hard enamel layer of a tooth is intact, the tooth is resistant to wear. If the enamel is lost or damaged due to decay, chemical erosion or abrasion, the softer dentin is exposed and the teeth wear rapidly.
In third world countries a lot of the food is unprocessed and contains dirt and other abrasives which can cause wear while chewing. Most wear on teeth in the United States and other developed countries, however, occurs due to clenching. Normally the teeth only contact during chewing and swallowing. If you find your teeth contacting at any other time, you are clenching.
Research indicates most people clench to some extent during sleep. Others clench more frequently or have habits such as biting the fingernails, pipe smoking or gum chewing that contributes to wear. Occupational environment can also influence the amount of wear in someone who clenches. Those who work in dusty environments (constuction, farming, cement factories, mining , etc.) or places with acidic atmospheres have accelerarted rates of wear. Wear of the teeth can easily be distinguished from erosion because tooth structure is only missing where the teeth contact each other. Below are some examples of severe wear.
Wear of maxillary (upper) lingual (tongue side) tooth surfaces. (arrows).
Note the wear at the arrows on the back side of these upper front teeth. A close look shows the wear pattern mimics the edges of the lower teeth which have worn into these surfaces half way through the teeth.
Severe wear on the lower anterior teeth.
Wear can occur in selected areas of the mouth or be spread evenly over all the teeth. When wear is localized to one spot it is usually seen in the front teeth. This can occur even though the back teeth show very little wear. This is usually caused by the patient clenching on the front teeth by jutting the lower jaw slightly forward. The wear on the lower teeth is accelerated if the patient has had crowns placed on the upper front teeth which have porcelain on the back surfaces of the teeth where the lower teeth contact the uppers (porcelain is harder than enamel and causes more wear).
Wear of the front teeth can also occur if many or all of the back teeth are missing.
Wear of front teeth caused by clenching and loss of back teeth. Front teeth are designed for biting into food. The back teeth are designed for chewing. With the back teeth missing, the front teeth take all the force of closing and chewing and quickly wear out. This is one reason it is important to replace back teeth when they must be removed.
Even wear of all teeth in the mouth in a tobacco chewer. Wear which occurs evenly throughout the mouth comes from eating course or dirty food, clenching in a dusty environment, side to side clenching or habits such as tobacco chewing. Note that the patient has worn through the porcelain covering some of the crowns on the teeth ( white arrow) as well as having worn into the front teeth (red arows).
Lower teeth of same patient as above.
Note the wear on the lower front teeth (blue arrows), the places where the porcelain has been worn through on the crowns (white arrows) and the worn surfaces on the gold crowns (red arrows).
Click here to see how this condition can be treated.
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