Is Your Toothpaste Being Too Hard on You?

In my last article, I discussed how many tooth-whitening products on the market have very low pH’s, possibly causing erosion or more pronounced toothbrush abrasion for consumers who attempt to whiten on a regular basis. As the enamel is softened from the acid exposure, it becomes more prone to abrasion when patients attempt to brush the sticky gel residue and bitter taste off their teeth.¹

Repeated acid exposure (whether dietary or due to dental products), combined with abrasive and flexural forces on the tooth, may lead to dentin exposure and the formation of non-carious cervical lesions.^2, 3, 4

Having looked at the acidic component of some dental products, I’d like to next look at the range of abrasiveness of some toothpastes and their effects on tooth structure. But before delving in, let’s look at how toothpaste abrasiveness is measured.

History of RDA Values

In 1970, the American Dental Association (ADA) began creating a standardized system for measuring the abrasiveness of toothpastes that were on the market relative to a standardized control sample. They assigned their control paste, calcium pyrophosphate, a value of 100 on their Relative Dentin Abrasivity (RDA) scale.⁵

The FDA supported these studies and deemed that no toothpaste should exceed 2.5 times the abrasiveness of the control standard, or an RDA of 250. Since studies at the time showed that 80 to 90 percent of extrinsic stains could be removed with a toothpaste of an RDA between 100 and 200, this seemed reasonable.⁶

Their upper limit of an RDA of 250 was based on research that showed that lab-simulated brushing with such a dentifrice would cause 1mm of dentin wear after 100,000 strokes - what they deemed a lifetime of a brushing, and an acceptable loss of tooth structure.⁷

While the ADA webpage on toothpastes states that the RDA scale “should not be used to rank the safety of dentifrices with RDA values below 250” and that “these values do not correspond to potential clinical effects, like abrasion,” some studies have shown that there is a direct correlation between the RDA value of a toothpaste and the amount of abraded dentin.^8, 9

Given that there are many other variables to consider when it comes to toothbrush abrasion, such as brushing force and time, bristle stiffness, technique, effects of electric brushes and pre-exposure to acid, I would recommend using the softest toothpaste that allows patients to manage their stain levels over six-month periods between cleanings. For most people, that may mean an RDA value around 100 would be reasonable. With so many great options on the list that meet that criteria, I just don’t see a reason to stray much higher.

Dr. Imahn Moin, DDS. http://www.oaktreedentalcare.com/

References