Toothpaste Formulation Basics

Source: Merriam Webster.

A quick internet search returns some articles asserting that a toothpaste is a toothpaste. It is true that most marketed dentifrices are composed of a core set of base ingredients that are combined to make dentifrice the entity we recognize today. These inactive (non-therapeutic) additives function as cleaners, stabilizers, or give esthetic benefits, and typically include:

• Abrasives Why? Cleaning. To aid the toothbrush in mechanically removing food debris, surface stains and dental plaque, an abrasive system is utilized. Commonly used abrasives are hydrated silicas, calcium carbonate, sodium bicarbonate, alumina, phosphate salts, and others.¹⁹As opposed to the extremely harsh abrasives in use prior to the mid-1900s which have been abandoned for safety reasons, modern day dentifrice abrasives are mild and safe for frequent, long-term use, and ADA-accepted toothpastes must meet the International Standards Organization (ISO) requirement of having an RDA (relative dentin abrasivity) score of 250 or less.

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• Water Why? Solvent. The humectants (see below) and water collectively make up around three-quarters of a toothpaste’s formulation and contributes to the paste’s ‘flowability’. ¹⁹ The other excipients in toothpaste are dissolved in water for mixing.¹⁹

• Humectants Why? Prevent drying. To keep the solvent (usually water) in the toothpaste from drying out, humectants like sorbitol, glycerin, and propylene glycol are added to bind it. They additionally aid in keeping a smooth consistency and flow from the tube and can serve as preservatives. ¹⁹

• Binders/thickening agents Why? Add body, prevent separation.Natural gums like xanthan, carboxylmethyl cellulose carbomers, or synthetic celluloses are added, which swell when they contact water to give bulk and texture, and to stabilize the formulation by stopping the solid and liquid phases of the paste from separating. ¹⁹ They contribute to the familiar consistency of dentifrice in appearance and mouthfeel, and facilitate its easy flow onto the toothbrush.

• Surfactants Why? Foaming. The characteristic foaming of toothpastes is enabled by surfactants (detergents), the most common being sodium lauryl sulfate (SLS) and cocamidapropyl betaine . These multi-factorial excipients also assist in cleaning, as well as the stability of the emulsion via preventing flavor oil separation with the dentifrice.^19,29

• Buffers Why? pH. To ensure a toothpaste remains stable and is performing as intended (e.g., for fluoride bioavailability), buffers are added for pH constancy. Pyrophosphates, sodium citrate, and trisodium phosphate are examples.

• Flavoring, sweeteners, colors Why? Taste and esthetics. Peppermint, menthol, xylitol, sorbitol, and sodium saccharin are all examples of flavors and sweetening agents that are incorporated to give fresher breath and a desirable taste and brushing experience. Sweeteners are non-caries promoting. Added pigments/dyes give visual interest, and ingredients such as titanium dioxide lends opacity.^19,29

• Specialty ingredients Why? Natural products interest. Recently, specialty ingredients that may appeal to those interested in products viewed as natural-friendly have been incorporated into some toothpastes. Some examples include hemp/CBD, coconut oil, and tea tree oil.