A short history of teeth-whitening
4,000 years ago, the Egyptians created a whitening paste using ground pumice stone and wine vinegar. The method was effective but it also damaged the teeth as the stone would cut abrasions in the enamel and the vinegar’s acid would leak in and rot the teeth from the inside. The Romans found a way to whiten teeth without stone. They used their urine. They would rub pee on their teeth as the ammonia was an effective bleaching agent. In the Middle Ages people visited their barbers who, at the time, were hair and teeth experts. Barbers would file teeth down and then apply a whitening acid. It was effective method as well but it eroded the enamel and led to tooth decay. Nowadays teeth are whitened using hydrogen or carbamide peroxide gel and this method was discovered very much by accident. The chemical had been used as an oral antiseptic for gums, and when dentists turned it into a gel to keep it on people’s teeth for longer periods of time, they noticed that teeth got whiter as a result.
Why people have different teeth colour?
The colour of natural teeth is created by the reflection and scattering of light off the enamel, combined with the colour of the dentin under it. Human genes affect the thickness and smoothness of the enamel. Thinner enamel allows more of the colour of the dentin to show through. Daily, a thin coating forms on the enamel and picks up stains. Tooth enamel also contains pores that can hold stains. Aging makes teeth less bright as the enamel gets thinner and the dentin becomes darker. It is also possible to have stains inside the tooth. These are called intrinsic stains and can be caused, for example, by exposure to too much fluoride in childhood while teeth were developing. Trauma may also darken a tooth. Receded gums, exposed roots of teeth may appear yellow or discoloured.
What does tooth whitening involve?
The enamel layer is porous, made up of hydroxyapatite crystals, which means staining agents can work their way down into the tooth, where you can’t simply scour them away. The whiteners use bleaching chemicals to get down into the tooth enamel and set off a chemical reaction that breaks apart the staining compounds. Most tooth whiteners use one of two chemical agents: carbamide peroxide or hydrogen peroxide.
Is Teeth Whitening Dangerous?
No. As long as you use whitening provided and supervised by your dentist and in the manner it is intended, there is no actual danger to your mouth. Dental Cavities need to be treated before teeth are whitened because the whitening solution can pass through decayed areas and reach the inner parts of the tooth.
Is Teeth Whitening Safe For Teeth With Fillings or Bonding?
Yes, it is. You will not damage any other restorations you have had done to your mouth. That means existing fillings, bondings, bridges, veneers, and crowns will be unharmed by any whitening you have done. However, keep in mind that whitening your teeth may make them different colours than these other restorations. You cannot whiten a filling or crown or other restoration; that will remain the same colour it was before you whitened.
Does it Harm Enamel of Teeth?
No. There has been no evidence that the enamel of the tooth is harmed. It does not make the teeth any softer nor does it change the surface of the tooth.
How long does this take?
The total treatment can usually be done within 2 to 4 weeks. To begin the at-home procedure, the dentist takes impressions of your mouth, and then has soft, custom mouth trays made. To administer the treatment, you put a small amount of the gel into the tray and wears it for 1-2 hours during the day, or while sleeping. In difficult cases, trays may need to be worn for up to six weeks.
What to expect
You may experience some sensitivity for a short time during your treatment but this is normal. There are desensitising products available to minimise or prevent sensitivity during whitening.
How long will my teeth stay whiter?
The effects of whitening are for life. The results can be maintained with whitening tray wear every 1 to 2 or even 6 months as a top up routine.
What about whitening toothpastes?
There are several whitening toothpastes on the market. Although they do not affect the natural colour of your teeth, they may be effective at removing some enamel staining. Whitening toothpastes may also help the effect to last, once your teeth have been professionally whitened.
Can a single tooth which has been root filled be whitened?
Yes. Sometimes dead teeth go discoloured after a root filling. If the tooth has been root treated, the canal (which contained the nerve) may be reopened. The whitening product is applied from the inside to whiten the tooth.