How does it work?

Imagine that your teeth actually looks like a giant honeycomb.  Enamel is essentially a bunch of stacked tubes that form a giant wall.  Over time, these tubes can get clogged with pigment.  As these tubes get clogged, they block the transmission and reflection of light through your teeth.  This results in a darker or yellower appearance.

Food and drink which contain lots of dark pigment can accelerate this process.  The classic culprits here are things like coffee, tea, red wine, cola, and dark berry juices.

Oral bleaching products essentially act like chemical pipe-cleaners that help clear out the pigment from your enamel tubes.

They all work by the same mechanism of action;  it's just that the more expensive, prescription-only, and in-office productions have a much higher concentration of bleach.

In order of efficacy, least to most:

Over-the-counter (white strips/paint-on products) < bleaching trays < in-office

What about side effects?

The most common side effect is temperature sensitivity.  By cleaning out the clogged tubes, it's like unplugging a tooth's "ears";  sensations are no longer muffled and the nerves can become temporarily hyper-sensitized to changes in the surrounding environment.  

The flip side to the more effective bleaching products is that the power comes at a price;  they also tend to cause more sensitivity.

There was a time I tried a sample of take-home bleach from a dental convention.  The instructions said to line the trays and put them in while sleeping.  Around midnight, I woke up and felt like my teeth were on fire.  Just the slight breeze from breathing made them throb.  Not fun.

As a secondary side effect, there can also be localized irritation of the gums, especially if you already have gum disease or recession.

How do I counter the side effects?

If you have recession (exposed root surfaces), or gum disease, you'll want to talk with your dentist before starting any type of bleaching program.  It's best to make sure that your teeth and gums are safe for bleaching.  You might need to skip it entirely, or be very selective and careful about how you go about it.

As a general rule of thumb, I recommend starting with a short duration;  15-20 minutes when using over-the-counter strips or take-home trays.  If you're not sensitive, you can slowly increase the duration of your bleaching sessions.

If you are sensitive, then keep the sessions short.  You can also try taking days off to let the teeth rest in between.  For really sensitive teeth, using concentrated fluoride after bleaching sessions can help.  We give our patients a prescription fluoride gel and tell them to alternate bleaching versus fluoride days.  

Any other tips?

As I discussed before, there are certain types of food/drink that are more likely to stain your teeth.  For the best results, you'll want to try to avoid those while bleaching and for a week or two after you stop to let your teeth recover.  I had a patient once who started bleaching right after her braces came off…and we were all shocked when she came back with brown teeth.  Turns out that she was in the habit of drinking several large glasses of pomegranate juice each day.  The bleach opened up the tubes in her teeth - then she promptly filled them with pomegranate pigment and made them darker.  Fortunately, her teeth re-whitened as soon as she cut out the juice and resumed bleaching.

How long will bleaching last?

It depends on your diet and cleaning habits as well as what type of bleaching product you used.    On average, most whitening applications last between six months to two years.  If you're extremely careful about avoiding high-stain food/drink, you might get more mileage.