Teeth Whitening

The colour of teeth is the most important expression of oral health and beauty. Porcelain white teeth do not exist in nature; just like skin, their colour is subjective. The "natural teeth whiteness" includes varying shades of yellow, grey, brown, and red.
Contrary to popular belief, it is not the enamel that determines tooth colour. In fact, enamel is translucent and colourless and only reveals the colour of the dentine underneath. Over the years however, the enamel may become stained by food and drink pigments (causing so-called external or extrinsic colouring), while the dentine tends to thicken in the internal crown chamber of the teeth. Consequently, with age teeth darken and lose their original brilliance.
There are numerous other causes of tooth staining. The most widely known intrinsic agent is tetracycline, found in a large group of broad-spectrum antibiotic drugs, introduced into medicine in 1948. The first reports that it induced tooth staining date to 1956. The tetracycline molecules are incorporated in hydroxyapatite crystals (forming long molecules of calcium tetracycline-orthophosphate) during the mineralisation phase which is part of tooth development. This process mainly affects the dentine but sometimes the enamel is also involved. Hypoplasia of the enamel may also be observed, with yellow, yellowish-brown, grey, and blue staining as well as the possible formation of stripes. The colour is often bilateral and may involve numerous teeth on both arches.
Another cause of staining is fluorosis, deriving from an excess of fluoride during the natural formation of the enamel matrix and calcification. This leads to hypoplasia of the enamel and the formation of "white spots". Darker colouration is caused by extrinsic factors after dental eruption, and pronounced fissures may even be observed in the enamel.
There are various others causes of teeth colouration such as chromogenic bacteria, found in the saliva, phenylketonuria, foetal erythroblastosis, Mediterranean anaemia, or amelogenesis and dentinogenesis imperfecta, etc.
The majority of patients who want their teeth whitened have staining problems due mainly to extrinsic or natural causes. Depending on the method chosen, this type of treatment usually requires one or at most two sessions. Intrinsic stains may call for more sessions, depending on the severity and degree of the staining. In these cases the best possible results are obtained only by using the Smartbleach^® method illustrated below.
Teeth whitening exploits a series of products, processes or procedures that make the teeth appear whiter in colour.
The quest for the most effective treatment of teeth stains is not new. Over the centuries there has been an increasing interest in making teeth whiter. The ancient Egyptians and Phoenicians bleached the teeth by combining an alkaline treatment with potassium carbonate and sunlight. The Romans washed their teeth with natural substances. In the 14th century, teeth whitening was the treatment most in demand after extraction, performed via the combined use of metal wires and nitric acid. During the late 19th century, a combination of hydrogen peroxide (H₂O₂), ether and electricity was used, followed by use of the same ingredients but with heat instead of electricity.
Hydrochloric acid (HCl) was used from 1916 onwards and then mixed with H₂O₂ in 1966. In 1970 hydrogen peroxide was confirmed as the most efficacious decolouring agent.