Australasian Dentist Magazine March April 2021

Category 80 Australasian Dentist Whitening toothpastes The concept of whitening toothpastes has been around for over 50 years. However, these original toothpastes were excessively abrasive and worked by removing stain and enamel layers. Modern versions of whitening toothpastes are much more tooth friendly and, if used regularly, can help to maintain whiter teeth. The key word here is maintain – they rarely whiten to any great degree. Whitening toothpastes contain detergents and a very mild abrasive to gently scrub staining from the surface of the enamel. Silica is the most commonly used abrasive, although some products also contain alumina and dicalcium phosphate. Additional chemical or polishing agents such as peroxide, titanium dioxide and baking soda are also used. In the concentrations used, none of these products actually alter the shade of the tooth itself. Whitening provided by dental professionals Hydrogen Peroxide Vs Carbamide Peroxide carbamide peroxide u These products can only be used for in-chair whitening procedures – not take-home whitening. The chemical formula for Carbamide Peroxide is CH6 N2 O3 on the pulp, hydrogen peroxide produces more sensitivity than carbamide peroxide of a comparable concentration. In office tooth whitening Whitening lamps or ‘laser’ toothwhitening options are often perceived by the public to be superior to home whitening because they can ‘see’ the procedure being performed. Is the light necessary and is there any clinical benefit? This raises some controversy and polarises opinion. The theory is that the light ‘activates’ the gel in some way, increasing the rate of free radical release. There are numerous studies showing the lights to be effective, however, these are usually done by the companies that manufacture the lights themselves. These should therefore be approached with an open mind! So, although there is questionable evidence to prove the effectiveness of lamps, if your patients are happy with the results, and they enjoy the experience then the choice is up to you. There is however, an over whelming body of evidence to show that dentist supervised home whitening is very effective and produces consistently superior results. u Tooth whitening options The chemical formula for hydrogen peroxide is H2o2 Louis Jacques Thenard discovered it in 1818. Hydrogen peroxide is a potent oxidizing agent. The whitening action is a result of oxygen free radicals that oxidize larger pigment molecules into smaller, less visible molecules. Carbamide peroxide is hydrogen peroxide compounded with urea. Urea helps stabilise the formula giving carbamide peroxide a more predictable and longer shelf life than hydrogen peroxide alone. Under Australian law and Dental Board of Australia regulations: u Only dental clinicians can use teeth whitening products containing more than 6% hydrogen peroxide or 18% Dental board factsheet link www.dentalboard.gov.au/codes-guidelines/faq/use-of-teeth-whitening-products.aspx Australian consumer law link www.accc.gov.au/business/advertising-promoting-your-business/false-or-misleading-statements In the presence of water, carbamide peroxide degrades into urea and hydrogen peroxide. Any given volume of carbamide peroxide will yield 35% volume of hydrogen peroxide when it breaks down. A notable difference between hydrogen peroxide and carbamide peroxide is the rate of breakdown, and therefore, the rate of release of oxygen ions. Carbamide peroxide is a more stable molecule and breaks down more slowly than hydrogen peroxide. Carbamide releases about 50% of its peroxide in the first 2 to 4 hours, then the remainder over the next 2 to 6 hours. Hydrogen peroxide breaks down almost immediately, releasing its peroxides entirely within the first hour. It is thought that due to this relatively concentrated bombardment of peroxides clinical