Tooth structure may be worn away in a few different ways. Enamel is the outermost covering of a tooth and the hardest structure in the human body (yes, harder than our bones!) When the outer covering of the tooth is worn away, a tooth can become sensitive and very susceptible to dental cavities. Imagine the tooth as an M&M candy, the outer portion is hard while the inner portion is softer, once you get through the hard part you are into a soft area.
An M&M is comparable in structure to a tooth
Attrition is the loss of enamel due to malocclusion (poor bite or alignment of teeth) or habits. A very small amount of attrition may be caused by normal everyday function but larger/deeper attrition is usually caused by malocclusion (the way the teeth fit together or are aligned can be poor) or parafunctional habits like nail biting, grinding, clenching, ice chewing, etc. Grinding and clenching of ones teeth, otherwise known as bruxism is one main cause of attrition, it typically occurs at night while the patient sleeps or during the day when a patient is under stress. Attrition appears as generalized wear across some or most teeth in the mouth. As the photo below shows, the inner portion of the tooth that is showing (yellow/orange colour) is dentin and beneath that is the nerve of the tooth. If soft dentin is exposed it is a poor insulator and can transmit different stimuli to the pulp of the tooth causing pain and irritation of the nerve.
Tooth in cross section due to bruxism/habits
Abrasion is the wearing away of tooth structure by a foreign object. Common causes of abrasion are:
-Brushing incorrectly or using a brush that is too firm
-Oral jewelry - Patients with pierced lips and/or tongue often wear away the enamel on adjacent teeth
Notice in this photo that the back teeth appear long and the exposed area is darker in colour, the exposed area is root which is very soft and can be sensitive to cold, hot or sweets. The root of the tooth should not be exposed as it is very soft and susceptible to being worn away.
Erosion is the chemical wearing down of tooth structure. Typically this kind of wear is caused by an acid. Citric acid is one of the most common agents. Citrus fruit (lemons, limes, oranges, grapefruit) and citrus juices contain citric acid which is highly acidic. Some candies also contain citric acid and many soft drinks contain additional harmful acids. Individuals who vomit frequently (such as people who are bulimic or with other conditions) also expose their teeth to very strong stomach acids.
Occasional exposure to most dietary acids is rarely a problem, but repeated exposure to high levels of these acids can cause premature wear. Some common habits to avoid are:
- Regularly sucking on lemons or limes
- Regularly eating or sucking on candies that contain citric acid
- Drinking several soft drinks daily, this includes diet pop as well!
- Drinking several glasses of lemonade or fuit juice daily
Even if you only occasionally eat or drink highly acidic foods, it's a good idea to at least rinse your mouth with fresh water when you are finished in order to reduce the amount of time the acids have to work on your teeth. If vomitting occurs it is recommended to rinse the mouth with water if possible, do not brush your teeth for atleast a 1/2 hour as this can move the acid around exposing all teeth.
Teeth that are eroded appear scooped out, it is like one side of the tooth is missing it's protective outer coating of enamel and the inner portion is exposed. Teeth can begin to appear more see through or translucent if enough structure is worn away.
Notice in this photos that the upper inside of these teeth appear yellowish, this is because the enamel has been eroded away exposing soft inner tooth structures, this was due to high acid levels.