THE THEORY OF ABFRACTION BELIEVE IT OR NOT THE

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The Theory of Abfraction

Believe it or not, the theory of abfraction is not proven. Dentists began noticing eroded or notched areas (erosions) on teeth close to the gum line (the cervix of the tooth) as early as the early 1700’s. The origin of these tooth defects remained a mystery for 150 years until a dentist named W.D. Miller did some research and published a paper in 1907 titled: Experiments and observations on the wasting of tooth tissue variously designated as erosion, abrasion, chemical abrasion, denudation, etc.

His conclusions were based on both observation and experiment. He concluded that these notch-like cervical erosions were caused by vigorous tooth brushing in combination with abrasive tooth powders.

Interestingly, GV Black, who is widely considered the father of modern dentistry disagreed with Miller, and even traveled to England to see his work. Black had to agree that many of Millers experimentally produced lesions looked like the erosions he had been studying, but remained skeptical. Black eventually published a paper, based on observation alone refuting Miller’s conclusions. Unfortunately, Miller died before he could respond to Black’s paper, and the origin of cervical erosions has remained controversial ever since.

In the early 1990’s, a dentist named J.O. Grippo concluded that cervical erosions were the result of flexing of the teeth at the gum line due to heavy bruxing (grinding). This flexure resulted in damage to the enamel rods at the gum line resulting in their loosening and consequent flaking away of the tooth structure.

THE THEORY OF ABFRACTION BELIEVE IT OR NOT THE

He named this type of damage abfraction in a paper published in 1991 (Grippo JO.Abfractions:a new classification of hard tissue lesions of teeth. J EsthetDent 1991:3:14-19)

Nearly all the research on the relationship of occlusal forces (bruxing) to cervical lesions shows that teeth do, indeed flex in the cervical region under bruxing loads, but none seems to cite actual damage caused by this deformation without an abrasive or erosive component applied as well. Nevertheless, the abfraction theory argues that bruxing forces alone can cause the erosion of the tooth structure on buccal surface, especially in the cervical region, that every dentist and hygienist is familiar with. It is postulated that abfraction is responsible for chronic sensitivity of the teeth to cold foods and liquids. This biomechanical theory implies that damage like that seen in the images below would be difficult to repair with bonded fillings because the repair would tend to pop off after a while due to the constant deformation of the tooth caused by bruxing.

THE THEORY OF ABFRACTION BELIEVE IT OR NOT THE

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 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 toothpaste 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.

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