Interview: “It is often not possible to achieve perfectly white teeth”
Many people have their teeth whitened to achieve a brighter smile and to improve their self-confidence, yet they are often insufficiently informed about the potential side effects of certain tooth whitening treatments or products. Dental Tribune International spoke with three German researchers, Prof. Matthias Epple and Drs Frederic Meyer and Joachim Enax, about their recent critical review of modern concepts for tooth whitening. They shared their findings with DTI.
Prof. Epple and Drs Meyer and Enax, what are some of the current tooth whitening methods and products?
Tooth whitening can be performed by both dental professionals in their office and patients at home. Commercially used whitening products such as toothpaste, gels and mouthwashes are mainly based on either peroxides or abrasives.
Peroxides oxidise organic chromophores, that is, the coloured compounds found in coffee, tea, red wine or tobacco. These are referred to as extrinsic stains. After tooth bleaching, organic chromophores will become non-coloured. However, the bleaching action is not limited to unwanted coloured compounds. Organic molecules in dentine could also be damaged, which may lead to tooth sensitivity and the mechanical weakening of the tooth.
Toothpaste formulations are highly complex and consist of many different ingredients, including abrasives for efficient plaque removal. Some types of toothpaste may also contain abrasives that help to remove extrinsic stains. Examples include perlite, which is a silicate, and alumina. However, using agents with high abrasiveness, for example those found in toothpaste for smokers, may damage exposed dentine and gingivae and lead to harmful abrasion and the weakening of the tooth.
In addition to peroxides and abrasives, various other whitening agents are used in toothpaste and mouthwashes. Studies have demonstrated that agents such as colourants, surfactants and hydroxyapatite can also contribute to tooth whitening.
Who should avoid tooth whitening?
Using whitening techniques based on peroxides and highly abrasive toothpaste for stain removal may result in unwanted side effects. Individuals with exposed dentine, for example, owing to erosion or gingival recession, should avoid tooth whitening. They should especially avoid toothpaste with high radioactive dentine abrasion (RDA) values as this may attack the soft dentine and the gingivae. Furthermore, bleaching with peroxides often leads to tooth sensitivity, which is called “bleaching sensitivity”. The organic matrix of the tooth may be damaged by peroxides, especially in the dentine, which contains approximately 20% of the organic matrix, mainly collagen. Those who want to use tooth whitening products should know that they may be harmful to the teeth and the gingivae.
Which chemical agents should be avoided in tooth whiteners?
As stated, toothpaste with high RDA values may damage the soft dentine. Peroxides should be used only after consulting a dentist. Antibacterial agents such as chlorhexidine and stannous salts such as stannous fluoride and stannous chloride stain the tooth surface. It is also important to note that the low concentration of peroxide used in different kinds of toothpaste does not contribute to tooth whitening.
What is the safest and the most effective way to whiten your teeth?
Many people prefer white teeth and a bright smile because this affects their appearance and quality of life positively. Tooth colour, however, is mainly determined by the dentine and by certain lifestyle habits. Dentine becomes more visible with increasing age due to continuous chemical and mechanical abrasion of enamel. Thus, it is often not possible to achieve perfectly white teeth. However, brushing your teeth twice a day and avoiding harmful habits such as drinking red wine, tea or coffee and smoking will help improve the appearance of the teeth.
Editorial note: The study, titled “A critical review of modern concepts for teeth whitening”, was published in the September 2019 issue of Dentistry Journal.