Setting expectations

There is a ceiling and it is genetic

Teeth whiten to their own natural whiteness and no further. A client will never be whiter than their inherent baseline colour. If they never had paper white teeth, this will not give them paper white teeth.

Find out what they are expecting before you start. Most people are delighted. The ones who are not usually arrived expecting something that was never possible.

What causes the staining

Age

Teeth darken with wear and accumulated stain. Teenagers see dramatic results. By the forties yellow gives way to brown and it takes more work.

Translucency

Thin transparent teeth, most often the front ones, have less pigment to bleach. Transparency is the one thing whitening cannot correct.

Food and drink

Red wine, coffee, tea, cola, carrots, oranges. Acidic foods erode enamel and let the yellow dentin show through.

Smoking

Nicotine leaves brown deposits that soak into the tooth.

Drugs

Tetracycline during tooth formation. Too much fluoride causes fluorosis.

Grinding and trauma

Micro cracks that darken the biting edges, and larger cracks that collect stain.

White spots

Some clients have chalky white patches or streaks on their teeth before you touch them. That is usually mild fluorosis, from too much fluoride while the teeth were forming. Mild cases often look better after whitening because the tooth around the patch catches up.

Spots can also stand out more part way through a treatment. The tooth is dehydrated at that moment and the drier patches show whiter than the rest. It settles as the tooth takes water back from saliva over the next 72 hours.

Two kinds of stain

Extrinsic stains sit on the surface from food, drink and tobacco. Light ones brush off. Stubborn ones need bleaching. Left long enough they work into the dentin.

Intrinsic stains form inside the tooth from trauma, age, or drugs during formation. Some clients still benefit, but you cannot guarantee it.