Ten patients with recurrent oral aphthous ulcers (canker sores) were randomly assigned, in double-blind fashion, to use one of two different toothpastes for three months, and then the alternate toothpaste for an additional three months. The toothpastes differed only in their content of sodium lauryl sulfate (SLS), a commonly used detergent. One of the toothpastes contained 1.2% SLS and the other contained none. The number of new aphthous ulcers that occurred was 64% less with the SLS-free toothpaste than with the SLS-containing toothpaste (p < 0.05).

Comment: Recurrent aphthous ulceration is a common, painful condition of the oral cavity. In many cases, recurrences can be prevented by identifying and avoiding allergenic foods, of which wheat appears to be the most frequent offender. Some patients with aphthous ulcers have deficiencies of iron, zinc, folic acid, or vitamin B12, and correction of these deficiencies may prevent recurrences.

SLS is added to most commercially available toothpastes as a cleaning agent. While it is effective for cleaning the teeth, it may also denature the mucin layer that coats and protects the tissues of the oral cavity, thereby exposing the underlying epithelium and rendering it more vulnerable to exogenous irritants and allergens. While SLS-free toothpastes are hard to find, most health food stores stock one or two acceptable products.

Herlofson BB, Barkvoll P. Sodium lauryl sulfate and recurrent aphthous ulcers. Acta Odontol Scand 1994;52:257-259.