Teeth darken. Coffee, tea, red wine, smoking and simply getting older all contribute, and the result is a smile that looks duller than it used to. Whitening is the most common thing people ask us about in cosmetic dentistry, and it is also the treatment with the most confusion around it - partly because so many products claim to do it.
Here is how the real options compare, and a few things worth knowing before you start.
Two kinds of stain
Surface stains sit on the outside of the enamel and come from what you eat, drink and smoke. A professional clean removes a lot of these before any whitening is even needed - which is why a scale and polish is always the first step.
Deeper discolouration sits within the tooth. Age, certain medications taken in childhood, and past injury to a tooth all cause it. This is what whitening actually treats, and it is why a whitening toothpaste - which only works on the surface - never gets the result people hope for.
Professional in-chair whitening
A higher-strength whitening gel is applied to the teeth in the practice, with the gums protected, usually over about an hour. It gives the fastest and most noticeable change in a single visit, which suits a wedding or an event with a date on it.
The trade-off is that a stronger gel means more chance of temporary sensitivity, and the result tends to settle back slightly over the following week. We usually pair it with take-home trays to hold the shade.
Dentist take-home trays
We take impressions and make thin custom trays that fit your teeth exactly. You wear them with a lower-strength gel for a set time each day, usually for one to two weeks. The result builds gradually, sensitivity is easier to manage, and because the trays are yours you can top up in future without starting from scratch.
For most people this is the option we recommend. The shade change is very similar to in-chair over the course of the treatment, the sensitivity is gentler, and the cost is lower.
Chemist strips and kits
Over-the-counter strips and kits use a much weaker gel by regulation, and one-size trays that leak gel onto the gums and miss the edges of the teeth. They can lighten a little. They rarely get close to what a professional treatment does, and the money spent on repeated kits often ends up higher than one course of trays.
They are not dangerous if used as directed. They are just underpowered.
The home remedies to avoid
Charcoal powders, lemon juice, baking soda and the various things that go around social media work by abrasion or acid. They scrub or dissolve the surface of the enamel, which can look briefly brighter and then does not grow back. Over time they make teeth more sensitive and, because the softer layer underneath is yellower, eventually darker. Please do not.
What whitening cannot do
Whitening works on natural tooth. It does not change the colour of fillings, crowns, veneers or bonding. If you have a white filling or a crown on a front tooth, whitening the teeth around it will leave it looking darker by comparison.
That is the reason to whiten first and do any cosmetic work second. If a crown or veneer is planned, we whiten to the shade you want, then match the new work to it - not the other way round.
Sensitivity, and how long it lasts
Some sensitivity during whitening is common and temporary. It is managed by adjusting how long the gel is worn, spacing out the days, and using a sensitivity toothpaste through the treatment. It settles once you stop.
Results typically last a year or two before a top-up is needed, depending on coffee, wine and smoking. Custom trays make that top-up a few days rather than a new course.
Before you start
Whitening a mouth with untreated decay, gum disease or cracked teeth is uncomfortable and unwise, so it starts with a check-up. We look, clean, fix anything that needs fixing, and then whiten. We are at 12 Lake Esplanade in central Queenstown with free off-street parking - ring 03 441 8248 or send a message to book.
General information, not a diagnosis. Written and reviewed by Dr Adrian Paul, BDS (Otago), principal dentist at Lakeside Dental Practice, Queenstown. If something is worrying you, see a dentist.
