What Is RDA in Toothpaste? A Dentist Explains
RDA stands for Relative Dentin Abrasivity. It is a standardized laboratory measure used to compare how much a toothpaste abrades dentin—the layer beneath enamel—under controlled test conditions.
That definition is useful, but it is also easy to oversimplify. An RDA number does not tell you how white a toothpaste will make your teeth, and it should not be treated as a complete safety grade. As a dentist, I look at RDA as one piece of a larger picture that includes the full formula, the type of stain, brushing technique, gum recession, sensitivity, and how often the product is used.
How is toothpaste RDA measured?
RDA testing compares a toothpaste with a reference abrasive assigned a value of 100. The toothpaste is tested on dentin specimens using a controlled brushing procedure, and its result is expressed relative to that reference.
The American Dental Association’s toothpaste review describes RDA as a standardized scale developed by the ADA, government agencies, and other stakeholders. The current ISO 11609 standard for dentifrices includes requirements and methods for evaluating toothpaste abrasivity.
It is important to remember that this is a laboratory comparison. RDA does not recreate every variable in your mouth, such as saliva, brushing pressure, toothbrush stiffness, acid exposure, frequency, and exposed root surfaces.
What does an RDA number actually tell you?
In general, a higher RDA result means the toothpaste produced more dentin abrasion in that standardized test. A lower result means less abrasion relative to the reference material.
But RDA is not a direct measurement of enamel loss, and small numerical differences should not be interpreted as precise predictions of clinical wear. The ADA states that toothpastes at or below an RDA of 250 are considered safe and effective when used properly. It also cautions that values below 250 should not be used by themselves to rank the clinical safety of toothpastes.
That nuance matters. An RDA of 70 is lower than 100 in a lab test, but that does not mean the first toothpaste is automatically “30% safer” in the mouth. The number is comparative—not a percentage and not a diagnosis.
Why does RDA measure dentin instead of enamel?
Enamel is the hard outer surface of the crown of a tooth. Dentin lies beneath it and is also present under the cementum covering the root. Dentin can become exposed when gums recede, root cementum is lost, or tooth wear progresses.
Because exposed dentin is softer than enamel, abrasivity becomes especially relevant for people with recession, root exposure, or established wear. There are separate laboratory approaches for enamel abrasivity, sometimes described as Relative Enamel Abrasivity or REA. An RDA score should not be relabeled as an enamel-abrasion score.
Does a higher RDA mean better stain removal?
Not necessarily. Abrasive particles help toothpaste remove plaque and extrinsic stains, but cleaning performance depends on more than the RDA number. Particle type, shape, size, concentration, chemical stain-control ingredients, and the rest of the formulation all influence performance.
A published study comparing cleaning power and dentin abrasivity found that the relationship was not one-to-one; toothpastes with different formulations could clean differently without following a simple “more abrasion equals more whitening” rule. That is one reason shoppers should be skeptical of unverified charts that reduce every toothpaste to a single number.
Whitening toothpaste works best on surface stains from sources such as coffee, tea, wine, and tobacco. For a deeper explanation of stain type and realistic expectations, see our guide to how whitening toothpaste addresses coffee stains.
Who should pay closer attention to toothpaste abrasivity?
RDA may deserve more attention if you have:
- gum recession or exposed root surfaces;
- dentin sensitivity;
- visible tooth wear or cervical notches near the gumline;
- a habit of brushing hard or using a firm-bristled brush;
- frequent dietary acid exposure; or
- a whitening routine that combines multiple stain-removal products.
Technique still matters. Use a soft-bristled toothbrush, light pressure, and controlled strokes. If you experience persistent sensitivity, new wear, pain, or recession, ask your dentist to identify the cause rather than simply switching products. Our article on whitening toothpaste for sensitive teeth covers that decision in more detail.
How to compare whitening toothpastes using RDA
Use RDA as a useful data point—not as the entire buying decision. A practical comparison should include:
- Source: Is the number supplied by the manufacturer from a recognized test method, or copied from an unattributed online chart?
- Stain goal: Are you trying to remove external stains or change deeper tooth color?
- Formula: What other polishing, oxidizing, or stain-control ingredients are present?
- Daily-use fit: Does the product suit your sensitivity, recession, cavity risk, and dentist’s recommendations?
- Technique: Are you using a soft brush and avoiding excessive pressure?
For category context, our dentist guide to charcoal toothpaste and enamel safety explains why the finished formulation and verified testing matter more than a broad ingredient label.
What is the RDA of White Birch Whitening Toothpaste?
White Birch Whitening Toothpaste has a published RDA of 45. That is a low relative dentin-abrasivity result, but the number should still be interpreted with the same scientific care described above—not as a percentage or a stand-alone guarantee.
Made from Japanese White Birch trees through the binchotan method. After that process is established, Binchotan is combined in a white, creamy toothpaste formula with calcium peroxide and hydrated silica. The toothpaste contains no hydrogen peroxide or sodium lauryl sulfate (SLS) and is made in the USA.
You can review the formula and linked testing on the White Birch Whitening Toothpaste page. For more on the whitening system, read how calcium peroxide toothpaste works. Our Japanese whitening toothpaste guide also explains the difference between an ingredient’s Japanese origin and the country where the finished toothpaste is made.
RDA questions patients often ask
Is RDA the same as “grit”?
No. Texture can affect how a toothpaste feels, but your fingers or tongue cannot reliably determine its laboratory abrasivity. A smooth paste can contain polishing particles, and a gritty sensation does not provide a verified RDA value.
Is the lowest possible RDA always best?
No. Toothpaste has to clean effectively as part of a complete oral-care routine. The goal is a well-designed formula used with proper technique—not simply chasing the smallest number.
Can RDA predict sensitivity?
Not by itself. Sensitivity can come from recession, exposed dentin, enamel wear, cavities, cracks, recent dental treatment, bleaching agents, or other causes. RDA is relevant context, but it cannot diagnose why a tooth hurts.
Should I stop using a toothpaste because of an online RDA chart?
Not without checking the source and speaking with your dentist if you have concerns. Product formulas change, many charts repeat unsourced numbers, and the ADA advises against using sub-250 RDA values alone to rank clinical safety.
A dentist’s bottom line
RDA is a standardized laboratory measure of relative dentin abrasivity. It can help you understand one part of a toothpaste formula, especially when comparing daily whitening products or managing exposed dentin. It cannot tell you everything about cleaning, whitening, enamel wear, or sensitivity.
Look for a transparent, sourced RDA result; evaluate the entire formula; brush gently with a soft-bristled brush; and involve your dentist when you have recession, wear, or persistent sensitivity. That is a more useful approach than treating one number as a complete report card.
By Dr. Andrew Frangella, DDS
This article is for general education and is not a substitute for an examination, diagnosis, or personalized advice from your dentist.
