Question: I’ve heard that tooth whitening isn’t a permanent treatment, that your teeth will get darker again after you quit whitening. What is the truth about this?
Answer: The answer here is not straightforward, and I hope I don’t confuse you. There are three separate points to make, and two of them depend on which professional whitening treatment you have.
First, you need to understand that there are two very different professional tooth whitening treatments. There is the dentist-supervised at-home tooth whitening system, where the dental assistant takes impressions of your teeth which are used to make clear plastic custom trays that you take home and put a bleaching gel in them at home.
The other system is typified by Zoom whitening, where the treatment is completely administered in the dentist’s office, under a bleaching light.
When you bleach your teeth, there is an immediate tooth whitening relapse which is more intense when a bleaching light is used. What happens is that during the treatment, your teeth absorb peroxide. The peroxide releases oxygen inside your teeth structure, and the oxygen oxidizes the discolorations and eliminates them. Right at the end of the appointment, you still have tiny bubbles of oxygen inside your teeth. The bubbles will make your teeth appear a little bit whiter. They will dissipate over a period of two or three weeks, and then you will have a stable color, which will be dramatically whiter than before you started treatment.
With Zoom whitening or other systems using a light, you also have a tooth desiccation factor. The heat from the light tends to dry out your teeth, making them appear whiter than usual. It takes your teeth a couple of days to re-hydrate and go to a more normal color.
So, in summary, with a bleaching light, you will have very white teeth right at the end of the appointment. The whiteness will fade quickly over the first couple of days and then will fade more slowly, getting to a stable color in two or three weeks. With the tray bleaching systems, you don’t have the desiccation factor, only the oxygen bubble factor. So the fading will be less dramatic, and will occur over two or three weeks.
The final point is about long-term relapse. Yes, your teeth will darken some over time after any tooth whitening treatment. But they will always be lighter than they would have been. You could make an analogy with painting the walls of a room. The walls might be dirty and smudged and look a little gray. So you paint them a nice white color, which makes them permanently whiter. But then let’s say that you have toddlers in the house and they continue to touch your walls with their dirty hands, and there is dust and grease in the air. Over a period of years, those nice white walls will darken again and you may need to re-paint. That’s similar to what happens with your teeth. Teeth continue to absorb stains. Foods from blueberries to red wine to cola drinks have dark pigments that are absorbed by your teeth. So even after whitening treatments, your teeth will absorb these stains and you will need touch-up treatments every year or two to maintain them at their brightest white.
—Dr. David Hall
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