Many dentists dispute the theory of abfraction, blaming this type of damage on what is commonly called "toothbrush abrasion".  This harks back to the early work of W.D. Miller in 1917, however it has been confirmed by more recent studies by T.C. Abrahamsen which have shown that toothpaste (not the toothbrush) is abrasive enough to cause this type of damage if the patient is too aggressive in brushing the teeth in a very hard and vigorous "sawing" motion.  Abrahamson suggests that the term "toothbrush abrasion" be replaced with the term "toothpaste abuse". 

His studies using mechanical "tooth brushing" machines have shown that the toothbrush alone does not cause the type of tooth damage shown here, but the addition of toothpaste to the bristles does!  (Toothbrushes without toothpaste do cause soft tissue damage and indeed, overly vigorous tooth brushing without toothpaste leads to gingival recession.)  The current support for the theory of abfraction, as opposed to theory of toothbrush abrasion may be due, at least in small measure to the considerable influence of toothpaste manufacturers who actually did much of the original work showing the damage that toothpaste could do to teeth, but suppressed the results for obvious reasons.

 

Dental Thermal Hypersensitivity Proponents of the theory of abfraction postulate that dental hypersensitivity to cold is due to abfractive removal of tooth structure at the cervix of the tooth due to bruxing.  Opponents would argue that most dental thermal hypersensitivity is due to erosion of tooth structure because of toothpaste abuse.

The evidence against the theory of abfraction is as follows:

• The theory of abfraction is based primarily on engineering analyses that demonstrate theoretical stress concentration at the cervical areas of teeth.  While there are a number of studies linking occlusal forces to tooth flexure, few controlled studies exist that demonstrate the relationship between occlusal loading and abfraction lesions.

• Most of the damage of this nature is to the buccal surfaces of the teeth, with little erosion to lingual surfaces.  If flexure of the teeth were causing this problem, it seems likely that we would see equal damage to both buccal and lingual surfaces.

• There is little or no evidence of these lesions in prehistoric skulls, even though the teeth show considerable occlusal (chewing surface) wear from mulling tough and fibrous foods.  All the cervical erosions found in historic skulls seem to begin after the invention of tooth powders and toothbrushes in the 16th century.

• The lesions tend to be much worse on the buccal surfaces of the premolars and the canines where patients are likely to place the most brushing force.  It becomes progressively worse as one proceeds from the posterior teeth to the anteriors.  Furthermore, the most affected teeth tend to be in buccal version. The teeth in which linguals are affected are mostly found mesial to an edentulous space (like the one shown in the image below).

• The damage seems to stop at the gingival crest instead of at the crest of the bone, which is where the theory of abfraction suggests the flexure should be the worst.  The gingiva heal daily protecting the root of the teeth from the toothbrush and toothpaste, and these lesions DO show a sharp delineation at the gingiva with a sloping finish in the coronal direction.

• Not all persons with cervical lesions demonstrate occlusal wear, which would indicate a bruxing habit, and not all persons with severe bruxing occlusal wear exhibit cervical non carious lesions.

• Frequently, the teeth in which  there is ongoing erosion of buccal tooth structure have no opponent in the opposite arch.  If it can be shown that the damage is ongoing, or that the damage began after the extraction of the opposing tooth, then bruxing cannot be a factor in producing it.

 

The theory of abfraction postulates that toothbrush abrasion works in combination with bruxing to create some fairly bizarre effects on teeth.  The  image on the right shows a tooth which has assumed the shape of a Coca Cola bottle. You are viewing the back of the tooth in a mirror.  Click the image to enlarge it.  The yellow arrow emphasizes the area of concern.  On the enlarged image, you can see that the damage stops at the gum line, leaving a shelf of unaffected root about even with the level of the gums.  On the other hand, the fact that this tooth is the last in the arch makes it more vulnerable to abrasion by the toothpaste on toothbrush bristles, as it does not have another tooth behind it to "protect" it.  Dentists who do not believe in the theory of abfraction argue that natural tooth structure is simply abraded away by overzealous tooth brushing.  The image below shows a similar 270 degree lesion surrounding both central incisors.  The lingual (tongue side) of the teeth are not affected as severely as the buccal (front) and interproximal (between the teeth) areas where vigorous brushing would most likely take place.