Dental Abfraction
Dental Abfraction
Dental Abfraction
Dealing with hypersensitivity of teeth with non-carious cervical lesions is a difficult task. These were thought to be erosion- abrasion lesions. It was Grippo, who originated the term abfraction', in 1991 to describe the pathologic loss of tooth enamel and dentin caused by biomechanical loading of forces.
Up until now, research into the causes of abfractions seems to be divided into two camps- those who argue for tooth brushes and other artificial forces as the cause and those researchers who point to internal physiological sources as the culprit. The latter argument, though not providing a complete explanation, does offer a significant clue to the real cause of this troubling phenomenon.
The earliest review in English, of the erosion abrasion issue as it relates to tooth brushing and dentifrices seem to be the original works of WD Miller in the late 1880s and early 1900s. He believed that erosion was caused by weak acids or gritty tooth powders, or by both, assisted by the toothbrush.
In 1950, SC Miller suggested that traumatic and lateral forces by the tongue, lips and cheeks were contributors to gingival recession. Glickman, in 1965 proposed that susceptibility to recession was influenced by many factors such as the position of teeth in the arch, the angle of the root in the bone, and the mesio-distal curvature of the tooth surfaces.
Yettram et al found that abfraction could occur even gingival to the margin of crowns and that the amount of load placed on the teeth was the key factor. Finally, in 1984, Lee and Eakle described lateral forces as the cause of the tooth structure breakdown. Grippo had stated that the forces could be static, such as those produced by swallowing and clenching, or cyclic, as in those generated during chewing action.
The abfractive lesions are caused by flexure and ultimate material fatigue of susceptible teeth at locations away from the point of loading. The breakdown is dependent on the magnitude, duration, frequency and location of the forces.
Clinical Implications
A dentist who restores an abfraction lesion to relieve hypersensitivity of the patient's tooth should be aware that to prevent this restoration from falling out, one needs to treat the cause of the abfraction before restoring it.
If a tooth has an abfraction, the occlusal loading on the tooth can be tested in centric occlusion and in excursive movements with occlusal marking paper. There is a good chance that the tooth with abfraction will have a heavy marking on one of the inclines of a cusp. This damaging lateral force produces stress lines in the tooth and results in tooth break down.
If the patient does not have heavy markings on the inclines, then he may have abnormal activity of the tongue. A normal swallow' is a swallow that is initiated with the tip of the tongue starting in the area of the maxillary anterior papilla, that continues with a peristaltic like action, pressing up against the roof of the maxilla, forcing the bolus posteriorly and finally down the throat. The tip of the tongue remains in the area of the anterior papilla during the entire swallow. Any other swallow is considered to be the result of abnormal tongue activity. The tongue should not press with any force into, against or between any teeth during the swallow.
Examine the area of abfraction with the patient's teeth together and lips slightly parted. Check whether the tongue is pushing into the tooth, or if salivary bubbles are visible coming between the interproximal spaces. Tongue thrusting can be the result of large tongues or obstructed airways.
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