There are thousands of toothpaste brands available worldwide. From gum care, teeth-strengthening, anti-hypersensitivity, teeth-whitening to herbal extracts. With this in mind, how do we know if we are choosing the right toothpaste? How do we trust the ingredients displayed on a toothpaste packaging?
I think the best way is to understand the function of each toothpaste ingredient in maintaining our oral health. This article will provide a detailed explanation to aid you in your next toothpaste purchase.
For your information , you can also watch the video I created on YouTube by clicking here.
History of Toothpaste
Around 3000-5000BC, Egyptians mixed powdered ashes from oxen hooves, myrrh, egg shells, pumice and water, into the first dental cream which was used to remove teeth debris. In the following 5000 years, the Greeks, Romans, Chinese and Indians then modified the paste into one that is more mouth-friendly. However, it was not uneconomical and highly abrasive.
It was not up till the dawn of the industrial age that its formulation started to improve along with an increase in demand for toothpaste. In 1873, Colgate & Company, which originally manufactured soap, was the first to mass produce toothpaste sold in jars. The first collapsible tube toothpaste was introduced by an American dental surgeon, Dr Washington Sheffield. The concept was then utilized by Colgate and Company after 20 years.
In 1914, fluoride was introduced into toothpaste, which was approved by the American Dental Association (ADA) in 1960 after decades of carrying out research projects. In the past century, manufacturers have gradually improved the formulations with various ingredients. They may be categorized into inactive ingredients (formulation excipients) and active ingredients.
Inactive Ingredients
1. Abrasive
Examples: hydrated silica, calcium carbonate, dicalcium phosphate dihydrate, calcium pyrophosphate, alumina, and sodium bicarbonate sodium metaphospate, perlite, nanohydroxyapatite.
Abrasives are tiny particles that rub against your teeth during toothbrushing to remove stains and to polish the surface of your teeth. Its abrasiveness depends on many factors such as:
- the abrasive particles hardness, shape, size and concentration
- the toothbrush’s filament shape and diameter
- the magnitude and direction of the applied force.
2. Surfactant
Example: sodium laurel sulfate (SLS).
The foam created in your mouth when you brush your teeth is formed in the same way as washing detergent does. This particular agent is called sodium laurel sulfate (SLS). It gives you the mere feeling of your teeth being cleaned. Besides the foaming effect, it also helps to distribute toothpaste in your mouth and it breaks up fatty or oily substances into smaller aggregates, just like your washing detergent.
However, SLS is an irritant to our oral tissues and may cause ulcers in some people.
3. Rheology Modifiers
Examples: carboxymethylcellulose, hydroxyethylcellulose, carrageenan, cellulose gum, xanthan gum.
Similar compounds in toothpaste tend to come together during prolonged storage. This is unideal as you would want them to be distributed homogenously so that your mouth receives all the ingredients during toothbrushing. Therefore, these modifiers act like a framework which holds the compounds in place. This backbone of the paste makes it gel-like so that you can squeeze it out of the tube and place it on your toothbrush.
4. Humectant
Examples: glycerin and sorbitol, polyethylene glycol and polypropylene glycol.
It is added to keep the paste moist and to prevent it from hardening, especially at the dispensing point. By maintaining the aqueous state, fluoride can work efficiently due to the presence of water.
5. Flavour and sweetener
Examples of flavours: mint, herbal, cinnamon and lemon.
Examples of sweeteners: sodium saccharin, sucralose and xylitol.
These are added for cosmetic or palatable reasons. Don’t worry they don’t usually cause cavity.
6. Coloring
Most toothpastes are white in colour, which is mostly contributed by titanium dioxide. Other artificial colours are added to create coloured stripes or a different colour altogether.
7. Preservative
Nowadays, preservatives are rarely used because some components like humectant and surfactants may be antimicrobial. Therefore, in older toothpastes that do not contain these ingredients, preservatives like sodium benzoate, ethylparaben or methylparaben are present.
Active Ingredients
1. Fluoride
Fluoride is a widely accepted “anti-decay” agent. There are at least 20 different fluoride compounds which are permissible in the European Union (EU). However, in most parts of the world, including the USA, only 3 fluoride compounds are approved for the use in toothpastes. They are sodium fluoride, sodium monofluorophosphate and stannous fluoride. The other types of fluoride compounds available in EU are aluminium fluoride, ammonium fluoride, calcium fluoride, potassium fluoride and sodium fluorosilicate.
Fluoride concentration is usually measured in parts per million (ppm), and most toothpastes have around 1000ppm to 1500ppm, that is approximately 0.1% to 0.15% of fluoride. Toothpastes with higher fluoride concentration (2800ppm, 5000ppm) may be prescribed by dentists to patients who have high risk of having decay.
2. Anti-plaque or anti-gingivitis agent
Triclosan
Triclosan is a broad-spectrum antibacterial agent (can kill a wide range of bacteria) which also has anti-inflammatory properties. Although it can reduce plaque and gingivitis, it has a few drawbacks such as potentially causing hormone disruption, alteration in gut microflora (as shown in animal studies), as well as being labelled as ‘very toxic to aquatic life with long lasting effects’ by the Globally Harmonized System of Classification and Labelling of Chemicals. Thus, it has been removed from most toothpaste brands.
Stannous fluoride
The addition of Stannous fluoride in toothpastes started around 1940, after which it was revived again in the last decade. It has antimicrobial properties and showed to cause a reduction in gingival inflammation to a certain degree, although it was claimed to cause extrinsic staining.
Zinc citrate or zinc chloride
Aside from being an antimicrobial, its antiplaque and antigingivitis effects are limited if it is not combined with other active agents such as triclosan and stannous salts.
3. Anti-malodour agent
Example: zinc chloride
Odour is generally generated by volatile sulphur compounds such as hydrogen sulphide and methyl mercaptan which vaporize easily and smell like rotten eggs. Zinc salts such as zinc chloride is particularly useful in combating odour as it reacts with sulphide to form zinc sulphide, which is very insoluble and non-volatile, therefore leading to the removal of odour.
4. Anti-tartar or anti-calculus agent
Examples: sodium pyrophosphate, potassium pyrophosphate or zinc salt
Tartar (or calculus) is formed when minerals that accumulate in dental plaque form crystals and aggregates which harden the dental plaque (crystallization). Anti-tartar agent works by inhibiting crystallization. Thus, they are also known as crystal growth inhibitors.
5. Whitening agent
There are 2 types of stains which make your teeth looks dark/yellow:
- Extrinsic stain: Coloured compounds accumulate on the surface of the tooth.
- Intrinsic stain: Coloured compounds get trapped inside the tooth substance during the tooth’s growth stage. It is normally due to certain drugs or genetic inheritance.
For removal or prevention of extrinsic stain, it can be accomplished by:
- Mechanical methods such as using abrasives.
- Chemical methods such as using sodium pyrophosphate or potassium pyrophosphate which removes pellicle proteins on tooth surfaces. These proteins aid in the attachment of stains.
- Optical whitening agent which alters the optical properties of the tooth, causing observers to perceive the tooth as being whiter colour. An example of an optical whitening agent is blue covarine.
Intrinsic stain removal requires agents like hydrogen peroxide which can penetrate the tooth to oxidize the intrinsic stain molecules, turning them into lighter coloured compounds. However, it is very hard to stabilize hydrogen peroxide in toothpastes. Thus, it is not proven to be effective.
6. Agent for relieving hypersensitivity
When the gingiva recedes, it exposes the root surface which has many tiny openings (dentinal tubules). The dentinal tubules contain fluids in them, and the movement of these fluids is sensitive to thermal change. The fluid movement caused by thermal changes is what stimulates the pulpal nerve, resulting in the individual experiencing a sharp pain.
There are two ways to reduce its stimulation:
- Blocking or occluding the tubules using compounds like strontium salts, stannous fluoride, calcium sodium phosphosilicate and arginine bicarbonate.
- “Numbing” the nerve by using desensitizing agents such as potassium nitrate or potassium citrate. Despite their uncertain efficacy, they are still being used in high concentration and they contribute to the bitterness in toothpastes.
7. Other active ingredients
Several other anti-decay agents which have been utilized in toothpastes are calcium glycerophosphate (CaGP), xylitol, nano-hydroxyapatite, sodium trimetaphosphate and remineralizing agents (CPP-ACP, enamelon technology)
Reference
- van Loreven C., 2013. Toothpaste. Karger Medical and Scientific Publishers.
