Radioactive Dentine Abrasion
The term Radioactive Dentine Abrasion ( RDA ; German about Abrasion of radioactive dentine ) describes a method for measuring and also a measure of the abrasive effect (abrasiveness) of substances on the dentine (dentin). In particular, the RDA value relates to the abrasive effect of the cleaning bodies contained in toothpastes , which is achieved with "standardized" cleaning against a defined batch of a reference substance .
The RDA value has been defined by the DIN EN ISO 11609 standard since 1998.
Before the test, the entire dentin is radiolabelled. The RDA value is then determined by measuring the activity of the dentin that was removed during cleaning. The values achieved depend on the size, amount and surface structure of the cleaning particles that are added to the toothpaste.
The significance of the RDA value is controversial. The RDA value is determined on the dentine, which is only exposed on already abraded surfaces or on exposed tooth necks ; it is usually surrounded by tooth enamel . However, since this is harder than dentine, the RDA value cannot simply be used to infer the abrasive effect on healthy teeth.
history
As early as 1907 Willoughby D. Miller was concerned with the quantitative measurement of the abrasion of teeth by various influences. Attempts to quantify the abrasion by determining the weight of the abraded material failed due to changes in the fluid content of the teeth and the abraded material during the test series.
In 1958, Grabenstetter et al suggested measuring the abrasiveness by determining the radioactivity of the abraded material. To do this, the teeth had to be radioactively marked beforehand using neutron radiation .
At the beginning of the 1970s, the American Dental Association formed a commission of experts ( American Dentifrice Abrasion Committee , dt. About: American Commission on abrasion by dentifrices ), which should create a standardized procedure for comparing the abrasive effects of different dentifrices. One such was published in 1976, based on Grabenstetter's method.
Procedure
The roots of previously vital extracted teeth are cleaned, cut into standardized blocks and whereby part of the radioactively labeled by mild neutron radiation, phosphorus - atoms in the hydroxyapatite in the isotope 32 is converted P ( half life 14.3 days). A week is then taken to allow the proportion of short-lived isotopes (mainly 24 Na) that are also formed to subside. The thus pretreated teeth are partially in plastics blocks embedded and the remaining free surface in a standardized "Shine" successively with a standard calcium diphosphate - slurry and a slurry brushed of the test substance. The radioactivity of both suspensions is then determined and the ratio of the 32 P isotopes removed from the dentin by the two suspensions is thus determined. The reference slurry is assigned the value 100.
values
RDA values are denoted as follows:
- over 100 as highly abrasive
- 70 to 80 as medium abrasive
- 30 as slightly abrasive.
Recommendations: Products with an RDA value of ...
- over 70: only for specific applications
- 30 to 70: for regular use
- below 30: not recommended, as the cleaning effect is then assessed to be too low.
The legal upper limit for the RDA value in Germany is 250.
Individual evidence
- ↑ WD Miller: Experiments and Observations on the Wasting of Tooth Tissue Variously Designated as Erosion, Abrasion, Chemical Abrasion, Denudation , D. Cosmos XLIX, 1, 109, 225, 1907
- ↑ RJ Grabenstetter, RW Broge, FL Jackson, AW Radike: The Measurement Of The Abrasion Of Human Teeth By Dentifrice Abrasives: A Test Utilizing Radioactive Teeth J Dent Res 1958; 37 (6): 1060-1068. PMID 13611120
- ↑ a b Hefferren JJ: A laboratory method for assessment of dentrifrice abrasivity. J Dent Res 1976; 55 (4): 563-573 PMID 1064599