thumb|Clinical presentation of abfraction non-carious tooth tissue lesions on the cervical margins of upper left canine and premolar
Abfraction is a theoretical concept explaining a loss of tooth structure not caused by tooth decay (non-carious cervical lesions). It is suggested that these lesions are caused by forces placed on the teeth during biting, eating, chewing and grinding; the enamel, especially at the cementoenamel junction (CEJ), undergoes large amounts of stress, causing micro fractures and tooth tissue loss. Abfraction appears to be a modern condition, with examples of non-carious cervical lesions in the archaeological record typically caused by other factors.
Definition
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Abfraction is a form of non-carious tooth tissue loss that occurs along the gingival margin. In other words, abfraction is a mechanical loss of tooth structure that is not caused by tooth decay, located along the gum line. There is theoretical evidence to support the concept of abfraction, but little experimental evidence exists.
The term abfraction was first published in 1991 in a journal article dedicated to distinguishing the lesion. The article was titled "Abfractions: A New Classification of Hard Tissue Lesions of Teeth" by John O. Grippo. This article introduced the definition of abfraction as a "pathologic loss of hard tissue tooth substance caused by bio mechanical loading forces". This article was the first to establish abfraction as a new form of lesion, differing from abrasion, attrition, and erosion.
Signs and symptoms
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Abfraction lesions will generally occur in the region on the tooth where the greatest tensile stress is located. In statements such as these there is no comment on whether the lesions occur above or below the CEJ. One theory suggests that the abfraction lesions will only form above the CEJ. However, it is assumed that the abfraction lesions will occur anywhere in the cervical areas of affected teeth. Studies supporting this configuration of abfraction lesions also state that when there is more than one abnormally large tensile stress on a tooth two or more abfraction lesions can result on the one surface. The dentine and cementum are less dense than tooth enamel and therefore more susceptible to sensation from thermal/mechanical sources. Researchers have proposed that abfraction is caused by forces on the tooth from the teeth touching together, occlusal forces, when chewing and swallowing. These lead to a concentration of stress and flexion at the area where the enamel and cementum meet (CEJ). and flexion over time causes the bonds in the enamel of the tooth to break down and either fracture or be worn away from other stressors such as erosion or abrasion.