04.How whitening ingredients work
Peroxides (such as urea peroxide, carbamide peroxide) break down to hydrogen peroxide, which chemically bleaches both surface stains and the tooth itself. Peroxides, at a high enough concentration, can whiten teeth so that they’re lighter than your natural colour. Most of the non-toothpaste whitening products we looked at contain some form of peroxide (see Other ways to whiten), but it’s not an ingredient of any of the toothpastes in our Home Tester trial.
Abrasive agents (such as alumina, silica/hydrated silica, dicalcium phosphate) remove surface stains by physically rubbing them off the surface of the teeth.
Detergents (such as sodium lauryl sulphate) act as foaming agents and help to clean the tooth surface.
Enzymes (such as papain, derived from papaya) slow down the build-up of ‘pellicle’ — the protein-containing layer of saliva that forms on your teeth within a minute of brushing. Surface stains stick to the pellicle layer.
Polyvinylpyrrolidone (PVP) is another ingredient, found in some MACLEANS and NATURAL WHITE products. According to NATURAL WHITE, PVP “binds tightly to tannins and other types of potential tooth-staining compounds”, theoretically preventing stains from accumulating on the tooth surface. Interestingly, it was also the main ingredient in the first really successful hairsprays in the 1950s!
Triclosan is an antibacterial agent that can help reduce plaque levels and fight tooth decay. It’s also an anti-inflammatory agent, so can reduce the progress of gum diseases.
Others (such as tetrasodium pyrophosphate, pentasodium triphosphate, citric acid, sodium tripolyphosphate [Triclene®]) chemically alter the electrical charge on the stains so that they’re less able to stick to your teeth. One product’s mysteriously labelled ‘advanced whitening ingredient’ (or similar) may in fact just be the same as one found in other whitening brands. Compare the ingredients lists on the packaging to find out.
Bleaches and abrasives, the two whitening ingredients most commonly found in whitening products, are generally thought to be safe, but it’s useful to be aware of the following:
- Home bleaching is generally thought to be safe, but dental experts advise consulting your dentist before using them.
- Using home bleaching products well beyond the recommended level may result in damage to the protein component of tooth enamel, making the teeth appear more opaque (cloudy), so it’s important always to follow the product instructions carefully.
- Some people can also experience temporary tooth or gum sensitivity when using home bleaching products, and some products are designed specifically to reduce this transient problem.
- The levels of abrasives in toothpastes are generally low, so you shouldn’t need to worry about them wearing down the surfaces of your teeth.
- As a general rule, you shouldn’t over-clean your teeth or use excessive force when you brush. Twice a day for at least two minutes is what the Australian Dental Association recommends.
- Very abrasive toothpastes, such as those designed for removing tar from cigarette smoking, may not be suitable for children or people with sensitive teeth or receding gums.