Perhaps it`s really toothpaste abrasion and not toothbrush abrasion after all!
Trisha E. O`Hehir, RDH, BS
When you see a patient with obvious "toothbrush abrasion," do you caution him or her about using a hard-bristle toothbrush? Do you suggest that the patient stick with a soft brush and use shorter, gentler strokes? This seems logical, since we`ve traditionally been told that hard brushes lead to abrasion of dentin.
But, is that really the case? What research do we have to support these traditional views? Perhaps it`s really toothpaste abrasion and not toothbrush abrasion after all!
In the 1940s, studies linked brushing with toothpaste to the high incidence of cervical abrasion. Over the years, many variables have been suggested to explain this, such as brushing technique, brushing force, brushing frequency, brushing time, type of brush, and bristle stiffness. Only a couple of studies linked hard bristles to abrasion. These studies were conducted 40 to 50 years ago and compared natural and artificial bristles on flat-trimmed, multi-tufted brushes.
In the majority of other studies conducted in the past on this subject, hard bristles were not linked to cementum and/or dentin wear. In laboratory tests, no reduction in test acrylic was seen after 20,000 brush strokes when soft, medium, or hard brushes were used with water. Wear on the test surface occurred when toothpaste was added to the model.
This is similar to using a cloth or a brush to clean a sink. Without cleanser, the cloth or brush does not abrade the surface, but is merely the vehicle to carry the abrasive cleanser. The same is true with toothbrushes. Toothpaste is the abrasive in this case, not the brush. It`s the toothpaste on the toothbrush - and not the bristles themselves - that cause "toothbrush abrasion."
Recently, Drs. Dyer, Addy, and Newcombe from the dental school in Bristol, England, published a laboratory study on this subject. The goal of their study was to measure the effects of toothpaste in combination with several, different toothbrushes. They used a laboratory brushing machine to test 12 toothbrushes of varying stiffness - three hard, three medium, and six soft - with Colgate Ultra Cavity Protection(r) as the standard toothpaste. The brushing machine produced the equivalent of six years of brushing, or 20,000 brush strokes. Wear measurements were taken at 5,000, 10,000, and 15,000 strokes on the pieces of acrylic used to simulate dentin.
Quite surprisingly, the soft brushes resulted in more acrylic wear than the hard brushes. This is likely due to the ability of the soft brushes to hold the toothpaste in contact with the surface longer. Soft bristles also have the ability to flex more than hard bristles, delivering toothpaste to more surface area. Since it is actually the toothpaste that causes the wear, brushhead configuration appears more important than bristle stiffness.
Although measuring wear on acrylic is a good substitute for dentin, the researchers pointed out that there are many more factors to be considered in the mouth. Not measured in this laboratory study were the synergistic effects between abrasion and erosion, which may lead to loss of tooth structure and tissue. This study isn`t conclusive in condemning soft toothbrushes as a major factor in "toothbrush abrasion," but the findings do provide important information that we can use in analyzing cases of abrasion and when counseling patients. In cases of cervical abrasion, it might be best to recommend brushing without toothpaste to avoid further loss of root structure, and then applying a fluoride gel or fluoride toothpaste.
Trying to place the blame for toothbrush abrasion
On April 1, 1999, a lawsuit was filed by an Illinois resident, alleging that the ADA and eight toothbrush manufacturers were negligent for failing to warn consumers about a "disease known as toothbrush abrasion."
Since that time, the plaintiff and his attorneys have been unable to substantiate their case. They have been given several opportunities to put forth an appropriate theory connecting toothbrushes to "toothbrush abrasion," but have failed to do so. According to the ADA News, "... attorneys had been seeking class-action status, alleging that toothbrushes are `unsafe and unreasonably dangerous` and should carry package warning on the `risks of toothbrush abrasion,` as well as instructions on how to use the brushes to avoid abrasion."
The lawsuit has been amended three times, and dismissed by the judge each time. It`s clear that the research in this area will not substantiate a claim that toothbrushes are the primary cause of "toothbrush abrasion."
Trisha E. O`Hehir, RDH, BS, is a senior consulting editor of RDH. She also is editor of Perio Reports, a newsletter for dental professionals that addresses periodontics. The Web site for Perio Reports is www.perioreports.com. She can be reached by phone at (800) 374-4290 and by e-mail at trisha@