The mouth, teeth and oral cavity are key structures of the body, as well as instruments of verbal communication, passages for breathing and essential routes for nutrition. Their balance is closely linked to the overall health of our organism. Over time, all characteristics of the oral cavity change significantly, especially as progressive aging makes physiological damage repair mechanisms less efficient. Cosmetic oral care products and correct hygiene are therefore valuable allies to keep lips, teeth, gums and the oral cavity general in a healthy condition.
The part of the teeth in direct contact with the oral cavity is the enamel, the most calcified and hardest biological tissue in humans, yet it exists in a precarious balance. It is constantly subject to mineral loss, mainly due to acids introduced through food or produced by bacteria in dental plaque through the metabolism of dietary sugars.
A bacterial film comprising a mixture of bacteria, starches, proteins and lipids forms on the tooth surface. In the presence of both bacteria and sugars, caries can develop. The consequences depend on individual susceptibility to corrosion, the type and quantity of bacteria, and the quality and amount of saliva secretion. When dental tissue is corroded by dietary acids in a process without bacterial involvement, the loss of materials, known as erosion, is progressive and hardly reversible.
While mechanical factors like tooth brushing have almost no or little effect on hard enamel, incorrect oral hygiene habits (e.g., the overbrushing of teeth) can result in abrasion and severe wear of the enamel. For these reasons, when developing oral hygiene products, the formulator must balance ingredients that are both gentle to teeth and effective for polishing.
This article describes the formulation of oral care products including toothpaste and mouthwash. It outlines key functional ingredients along with those for added benefits ranging from anti-tartar and desensitizing effects to strengtheners, whiteners and more. Prototype formulations also are presented.
Toothpaste and Mouthwash:
- A toothpaste in defined as a semi-solid material for removing naturally occurring deposits from teeth and is supposed to be used simultaneous with a toothbrush.
- A mouthwash is defined as a non-sterile aqueous solution, used mostly for its deodorant, refreshing or antiseptic effect. Mouthwashes or rinses are designed to reduce oral bacteria, remove food particles, temporary reduce bad breath and provide a pleasant taste.
Glycerin and Cocamidopropyl betaine in Toothpastes:
Humectant polyols (e.g. glycerin) ensure easy miscibility with saliva, wetting of abrasive solids, swelling of thickeners, maintenance of the formula water content and a basic sweet taste. A high concentration of humectants provides significant osmotic pressure on the bacterial cell walls and gingival mucosa. The use of osmo-protectors like betaine and ectoine has been proposed to reduce such effect. In a clinical trial, it was demonstrated that betaine reduces the irritating effects of sodium lauryl sulfate-containing products for oral hygiene in subjects with dry oral mucosa.
A crucial sensory element of toothpaste is the formation of voluminous foam that also must easily be rinsed off. This function is usually achieved using high-purity sodium lauryl sulfate at 1.0-1.5%, which is also needed to wet the solids. Alternatively, there are a few surfactants with acceptable taste; Cocamidopropyl betaine have proven efficient, with good taste and moderate foam production.
The characteristic foaming of toothpastes is enabled by surfactants (detergents), the most common being sodium lauryl sulfate (SLS) and Cocamidopropyl 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.
Why is glycerin a common toothpaste ingredient?
The purpose of glycerin in toothpaste ingredients is primarily to serve as a binder, humectant, and texture enhancer. Here’s a breakdown of these functions:
- Binder: Glycerin helps bind all the ingredients in toothpaste together, ensuring a consistent texture and preventing the components from separating. It contributes to the overall stability of the toothpaste formula.
- Humectant: Glycerin acts as a humectant, which means it helps retain moisture in the toothpaste. This property prevents the toothpaste from drying out and becoming difficult to use, maintaining its smooth consistency even after being exposed to air when the tube is opened.
- Texture enhancer: Glycerin contributes to the smooth and creamy texture of toothpaste, making it easier to spread on the toothbrush and apply to the teeth. It also helps create a pleasant mouthfeel during brushing.
- Sweetener: Sweeteners also improve the taste of toothpastes and mouthwashes and give them a mild and sweet taste. Glycerol is one of the most common sweeteners.
Glycerin is also a key ingredient in artificial saliva, which is a lifesaver for individuals suffering from dry mouth due to aging or cancer treatments like chemotherapy and radiation therapy. Without saliva, these individuals would be at a much higher risk of tooth decay and gum disease. Artificial saliva, primarily composed of glycerin, helps maintain a neutral pH in the mouth and provides a temporary substitute for natural saliva, protecting teeth from cavities and other oral health issues.
In addition to its use in artificial saliva, glycerin is also commonly found in toothpaste as a binder and humectant. It helps give toothpaste its smooth texture and prevents it from drying out. While there are alternative binders like silica that can be used in toothpaste, glycerin is not considered harmful, and its presence in toothpaste should not be a cause for concern.
Is Glycerin Better For Toothpaste Than Sorbitol?
Most natural toothpastes utilize sorbitol rather than glycerin seeing as sorbitol additionally plays the role of a sweetener and aids in preserving the toothpaste for drying out, though it doesn’t have the same preservation properties as glycerin.
The Safety of Glycerin in Oral Care Products
Ensuring the safety of oral care products is paramount, especially considering their direct contact with sensitive oral tissues. Let’s delve into the scientific studies, insights from dental professionals, and regulatory guidelines surrounding the use of glycerin in toothpaste formulations.
Scientific Studies Examining Glycerin’s Safety:
- Numerous studies have investigated glycerin’s impact on oral health, consistently concluding its safety for use in toothpaste.
- Research highlights glycerin’s biocompatibility with oral tissues, reinforcing its suitability for oral care products.
Insights from Dental Professionals on Glycerin’s Role in Oral Health:
- Dentists endorse glycerin as a valuable ingredient in toothpaste, citing its ability to enhance product stability and improve user experience.
- Oral health experts emphasize the importance of balanced formulations, including glycerin, for maintaining optimal oral hygiene.
Regulatory Approval and Guidelines for Glycerin Usage in Toothpaste:
- Regulatory bodies such as the FDA and ADA have approved glycerin for use in oral care products, affirming its safety and efficacy.
- Guidelines outline permissible concentrations of glycerin in toothpaste formulations, ensuring consumer safety and product quality.
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