Radioactive Dentin Abrasion ( RDA )

Most people are aware of the importance toothpaste plays in an oral hygiene routine. An effective toothpaste can keep your teeth clean and help deter a number of dental disorders and diseases. While the importance of toothpaste is not debatable, there are certain toothpastes which can have both negative and positive qualities and it is important to know about these toothpastes to avoid future dental issues.

It is important to use a toothpaste which is not too abrasive. Abrasives generally are used to remove plaque and keep teeth clean, but using a toothpaste that is too abrasive can do damage to your teeth. If used over time the abrasion can damage the tooth enamel, which helps protect your teeth from cavities. It is highly recommended to use a toothpaste with a low-level of abrasion.

The term radioactive dentin abrasion (or RDA) is a method of measuring abrasivity and the degenerative effects it has on tooth dentin. The effect will vary depending on quantity, surface structure and particle size of the abrasive additives in the toothpaste. The measurement incorporates a large selection of test samples compared to standardized abrasives and is recorded as an RDA value ranging from 30 to 200. The exact value is determined by an intricate process that involves testing the effect of the materials by brushing over and comparing radioactively marked dentin samples. For a toothpaste to be approved by the FDA it first must have an RDA value.   

The ADA (American Dental Association) introduced their own improvements to the RDA abrasion test. It involves taking extracted human teeth, stripping them of enamel and irradiating it with neutrons. A brushing machine is then used on the extracted teeth and are they are brushed at a consistent pressure and stroke speed. The produced rinse water is measured for radioactivity and a score of abrasivity is given to the toothpaste. Unlike the FDA whose scale reaches 200, the ADA's scale reaches 250 and any score over 100 is considered to be abrasive.

Below is the scale ADA uses to measure abrasivity of toothpastes:

RDA Scale of Abrasivity

0-70	Low abrasive levels
70-100	Medium abrasive levels
100-150	Highly abrasive levels
150-250	Extremely high levels and could be hazardous

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