This means that the colour of the teeth is lightened by placing a bleaching gel on the outer (external) surfaces of the teeth. Once again, using bleaching gels in this way may not work for certain types of discolouration, such as that caused by metal fillings or damaged blood vessels inside a tooth. There are two ways to do external bleaching.
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"Home" bleaching - this is similar to the OTC kit method, but with two main differences. Firstly, the dentist makes the rubber mouthguards so that they fit your teeth precisely, and secondly, the bleaching gel is stronger so it tends to be more effective. The dentist will give you tubes of bleaching gel and instructions on how to put the gel in the mouthguards. You will need to wear the mouthguards for a few hours each day. It may take a few weeks to achieve the colour that you want. The dentist will give you detailed instructions.
In the surgery - this is also known as "laser" or "power" bleaching. The dentist will put a rubber seal around your teeth to protect your gums. Then, the bleaching gel is painted onto your teeth and a special, bright light is pointed at them. This light speeds up the whitening process. The procedure takes one to two hours.
This means that the colour of a tooth is lightened by placing a bleaching product inside the tooth. Internal bleaching can only be done on teeth that have been successfully root treated. This means that the blood vessels and nerves inside the tooth have been replaced with a rubber filling.
To bleach a tooth in this way, the dentist will drill a hole (if it is a front tooth, the hole will be on the back so that you can't see it) and put the bleaching product into the hole. The hole will be sealed with a temporary filling, leaving the bleach inside the tooth. The procedure won't hurt because the tooth has no nerve inside it.