Abrasion (dental)
| Abrasion (dental) | |
|---|---|
| Classification and external resources | |
| Specialty | dentistry |
| ICD-10 | K03.1 |
| MeSH | D014072 |
Abrasion is the loss of tooth structure by mechanical forces from a foreign element. If this force begins at the cementoenamel junction, then progression of tooth loss can be rapid since enamel is very thin in this region of the tooth. Once past the enamel, abrasion quickly destroys the softer dentin and cementum structures.
Possible sources of this wearing of tooth are toothbrushes, toothpicks, floss, and any dental appliance frequently set in and removed from the mouth. The appearance is commonly described as V-shaped when caused by excessive pressure during tooth brushing. Abrasion is seen at a cervical necks of the teeth, as a deep ridge on the buccal or labial surfaces. The surface is shiny rather than carious, and sometimes the ridge is deep enough to see the pulp chamber within the tooth itself.
The teeth most commonly affected are premolars and canines.
Relative dentin abrasivity (RDA) is a measurement of the abrasive effect that the components of the toothpaste have on the tooth, particularly on enamel and dentin. It involves using standardized abrasives compared against the test sample.
The determination of this value is done by determining the activity while cleaning worn dentin which is radioactively marked by mild neutron irradiation. The values obtained depend on the size, quantity and surface structure of abrasive used in toothpastes.
Since 1998, the RDA value is set by the standards DIN EN ISO 11609. Currently, the claim on products such as toothpaste are not regulated by law. The procedure was later adopted by ADA for measuring of Relative Dentin Abrasion Index. According to the ISO standard, every toothpaste with an RDA under 250 is safe for a lifetime of use.
The procedure is more precise and faster than former methods dependent upon the measurement of the depth of a groove cut into tooth structure. The results are obtained directly in terms of the amount of human tooth structure worn away by a toothbrush and dentifrice abrasive slurry operating at a known, constant brush pressure and a constant stroke speed. The coefficient of variation of the test is 6-7 when 8 replications are carried out, and 10-15 when only duplicates are run as in the usual routine testing. This is one half to one fourth of the variation involved in the depth-of-cut method and results can be obtained with an expenditure of one half to one third of the time of the former method.
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