Radioactive Dentin Abrasion

The term Radioactive Dentin Abrasion (RDA) (Ger. as: radioactive dentin abrasion ) means a method for measuring and also a measure of the abrading action ( abrasivity ) of substances to the dentin ( dentine ). In particular, the RDA - value refers to the erosive action of the abrasive particles contained in toothpastes, which is achieved with " standardized " brushing against a defined batch of a comparison material.

Since 1998, the RDA value is determined by the standard DIN EN ISO 11609.

Prior to the test, the entire dentin is radiolabeled. The RDA value is then determined by measuring the activity of that dentine, which was removed during the cleaning. The values ​​obtained depend on the size, quantity and surface structure of the abrasive particles that are mixed with the toothpaste.

The significance of the RDA value is controversial. The RDA value is namely determined to dentin, which is exposed only to already abraded surfaces or exposed root surfaces; usually it is surrounded by enamel. However, since this is harder than dentin, can not be closed to the abrasive action of healthy teeth readily from the RDA value.

History

As early as 1907 Willoughby D. Miller was concerned with the quantitative measurement of abrasion of teeth by various influences. Attempts to quantify the abrasion on the determination of the weight of abraded material failed due to changes in the fluid content of the teeth and abraded material during the test series.

1958 suggested grave Stetter et al before to measure the abrasiveness of the determination of the radioactivity of the abraded material. These teeth had to be previously radiolabeled by neutron radiation.

In the early 1970s, the American Dental Association formed a committee of experts (American Dentifrice abrasion Committee, dt as: American Commission for abrasion by dentifrices ), which should create a standardized method for comparing the abrasive effect of various dentifrices. Such was published in 1976, it was based on grave Stetter's method.

Method

The roots of previously extracted teeth are vital cleaned, cut to standard blocks, and radioactively labeled by mild neutron radiation, whereby a portion of the phosphorus atoms is converted into the hydroxylapatite in the 32P isotope (half-life 14.3 days). Then, a week will wait to make the percentage also emerging kurzlebigerer isotopes ( mainly 24Na ) subside. The pretreated teeth are partially embedded in plastic blocks and the remaining free surface in a standardized " Shine " successively brushed with a standard calcium diphosphate slurry and a slurry of the test substance. Both slurries then the radioactivity is determined and calculated as the ratio of the ablated by the two slurries of the dentine 32 P- isotope. Here, the Referenzaufschlämmung value of 100 is assigned.

Values

According to the German Dental Association RDA values ​​are indicated as follows:

  • Over 100 as a highly abrasive
  • 70 to 80 as medium abrasion
  • 30 as low abrasive.

Recommendations: Products with an RDA of ...

  • 70: only for specific applications
  • 30 to 70: for regular application
  • Less than 30: not recommended, as then the cleaning effect is considered to be too low.

The legal limit for the RDA value is in Germany 250

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