Purpose of Detergents in Toothpaste
A major function of toothpastes is to clean teeth through the removal of food debris, dental plaque, and stains. Most toothpastes contain a detergent in addition to an abrasive to improve cleansing action by enhancing penetration into spaces between teeth and by facilitating plaque and stain removal.
Originally, toothpastes contained soap for this purpose. However, soap had many disadvantages, including its unpleasant taste and incompatibility with other ingredients, and since the 1930s detergents have replaced soap as the primary foaming agents in toothpastes. Ideally, a detergent must have appropriate foaming and cleansing properties, be compatible with other ingredients, and not affect flavor. Also, it must be non-toxic and non-irritating to the oral tissues at the concentration used.
Properties of Sodium Lauryl Sulfate (SLS)
Sodium lauryl sulfate (also known as sodium dodecyl sulfate) is currently the most widely used detergent in toothpastes because it satisfies almost all of these requirements. It is a foaming and solubilizing agent that is derived from coconut and palm kernel oils. SLS emulsifies fats, has a high affinity for proteins, and has mild antibacterial activity; all properties that help to disperse plaque deposits and prevent tooth stains from forming. Also, SLS emulsifies flavor oils in oral care products without altering their taste profiles or producing any aftertaste, unlike most other detergents. In addition to toothpastes, SLS is also used in countless shampoos, cosmetics and personal care products for its lathering and thickening properties.
Safety of SLS
Although unsubstantiated reports relating to harmful effects of SLS can be found on the internet, it has no serious toxicity issues and is not carcinogenic. Because of its affinity for proteins, SLS at higher concentrations (i.e. greater than 5%) is able to influence the barrier function of skin and can cause irritation (contact dermatitis) upon prolonged exposure. Similarly, SLS-containing products can cause irritation of the oral soft tissues in susceptible individuals as a side effect, but this is not a common problem since SLS levels in dental products are less than 2%. Some studies have reported that SLS in toothpaste may affect the recurrence of aphthous ulcers (i.e. canker sores), but other studies have shown no effect. The safety of SLS in toothpastes and mouthrinses has been demonstrated in hundreds of clinical trials and by the fact that these products have been used every day for more than 50 years without negative effects by billions of people around the world.
Many sulfate-free detergents exist, but they suffer drawbacks, such as poor foaming, instability, taste issues, and undesirable irritancy profiles. Because of its excellent foaming characteristics, stability, and lack of flavor problems, SLS is the best detergent for many toothpaste formulations. When combined with the unique dental properties of refined kaolin clay in Dentisse Natural Reflection Toothpaste, SLS helps to provide a product with very high cleaning ability that is gentle to the teeth and oral soft tissues.1
1 Schemehorn BR, Moore MH, Putt MS. Abrasion, Polishing, and Stain Removal Characteristics of Various Commercial Dentifrices In Vitro. J Clin Dent 22:11-18, 2011.
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