The colour of the tooth is determine by the dentine colour, it various from individual to individual and also different ethnic group. Chinese and Malays will tends to have slight yellowish tooth. The colour of the dentine getting more saturated with ageing.
The brightness (value) of the tooth is regulated by the thickness and translucency property of the enamel. The higher the brightness (value) of the enamel, the whiter the tooth. We have thicker enamel during young, and the enamel layer become thinner due to aging and wearing caused by mastication process.
The tooth colour also may affected by extrinsic staining due to coffee, tea and red wine. Tetracyclin (one type of antibiotic) may caused internal staining of the tooth in young child. There are two main methods of gel bleaching, one performed with high-concentration gel (37%-44%) and powered up the whitening process with a special blue light, this procedure known as “In-office bleaching”.
Another one with low-concentrated gel (10%-22%) and accomplished at home. Whitening is performed by applying oxidizing agent to the teeth with thin plastic trays for a short period of time. The application trays ideally should be well-fitted to retain the gel, ensuring even and full tooth exposure to the gel. This whitening process also known as “Home Bleaching”
The whitening gel contained oxidizing agents, Carbamide peroxide, which penetrates the porosities in the rod-like crystal structure of enamel and bleaches stain deposits in the dentine.
Below are step by step photos showing “In-Office Bleaching”
1. Isolation of teeth by retracting the cheek and the lip aways from the teeth. Record the original colour of teeth.
2. Protect the gum from the oxidizing gel with soft dam.
3. After applying the Carbamide Peroxide gel, the bleaching process is activated by using special blue light. Normal it need 4-5 cycle to bleach the teeth, 10 minute per cycle.
4. Compare the colour after bleaching with the original recorded colour. Usually is about 4-8 shade whiter with the shade guide (Tooth Colour Chart).
Some photos comparing before & after bleaching.
Dr Goon Yong Por
BDS, FICD, FADI, FICCDE