November 07, 2015
There are other processes involved in damaging our teeth that have nothing to do with tooth decay, infection or bacteria. These are attrition, abrasion, erosion and abfraction. Let’s take a close look at what these conditions are and how they differ.
Attrition is a normal process that occurs in every person, wherein, the opposing teeth rub against each other while chewing. In a long term this leads to gradual wearing down of the occlusal surface of the teeth. However, some people exhibit an accelerated rate of wear which is often attributed to bruxing. Clenching and grinding bring the opposing teeth in contact with a greater than normal force and for a longer period of time. It is typical for attrition that no outside or foreign object is involved. The effect is visible only on the biting surfaces of the back teeth and incisal edges of the front teeth which generally become flat over time.
On the other hand, teeth abrasion is also caused by friction, but from a different source. Abrasion occurs when one uses a hard toothbrush or abrasive toothpaste to brush vigorously. Other external objects that are likely culprits are lip piercings, cracking nuts, chewing on pencils, fingernails, tobacco and so on. It is therefore likely to occur on the outer or buccal side of the teeth where the objects come into constant contact. In other words, it is caused by harmful habits and is not a natural occurring process.
Another process of tooth wear is abfraction in which the abnormal load created by bruxing is the main causative factor. But this is unlike attrition which is also attributed to bruxing, where direct friction or rubbing leads to loss of tooth structure at the occlusal level. The main impact of the loading in abfraction is at a different location from the point of contact. Here, the pressure causes tooth flexure which in turn leads to flaking of the enamel at the neck of the tooth instead of the biting surface. It is normally observed at the buccal side of the teeth near the gum line, where the enamel is at its weakest. Though this is also a mechanical process, no external object is involved like abrasion. Abfraction lesions are V-shaped while the abrasion and attrition lesions are flat.
A chemical process is involved in erosion, unlike the other three which are mechanical in nature. When the acid level in the saliva rises, it begins to dissolve the enamel. These changes in the acid levels in the mouth occur due to external as well as internal reasons. External factors are generally foods and drinks that are acidic in nature or contain carbohydrates which are converted to acid by bacteria. Internal factors would be GERD or vomiting where the acidic contents of the stomach come into the mouth. Low saliva production can also be the cause of teeth erosion. When the buffering capacity of the saliva is eliminated the pH in the mouth drops significantly and promotes the demineralization of the enamel structures.
If you compare each of these conditions, accelerated attrition and abfraction are mainly caused by bruxing, but the damage occurs at different points of the teeth. On the other hand, abrasion is caused by rubbing against foreign objects and erosion is caused by chemical components.
Each of these processes may affect the tooth structure at the same time in varying degrees. Enamel that has been damaged by abfraction is more likely to be affected by erosion or abrasion. Similarly, tooth surface that has been softened by erosion or an acid attack is more susceptible to abrasion and abfraction.