Teeth whitening is the most requested cosmetic treatment in the office. With the proliferation of kits sold at pharmacies, grocery stores and even on Instagram, confusion is widespread. Here is what I tell patients who ask me: "Doctor, is it worth paying more for professional whitening?"
How does teeth whitening work?
The active ingredient in all whitening products is peroxide — either hydrogen peroxide or carbamide peroxide which breaks down into hydrogen peroxide. This molecule penetrates tooth enamel and breaks down colored pigments embedded in the dentinal tubules. The concentration of peroxide and the application time determine effectiveness.
- Professional products: 25 to 40% hydrogen peroxide
- Pharmacy kits: 6 to 10% peroxide (EU/Canada regulatory limit)
- Over-the-counter products (strips, pens): 1 to 3% — very limited effectiveness
- Activated charcoal, baking soda: abrasive, do not chemically whiten
In-office whitening: what to expect
At the office, we offer two complementary approaches. In-chair whitening (Zoom or Beyond type) uses a high concentration of gel activated by LED light for 60 to 90 minutes. Take-home whitening uses custom trays with a lower concentration gel worn 2 to 4 hours per day for 2 to 3 weeks. Both methods can be combined for maximum results.
- In-chair whitening: visible results from the first session (3 to 8 shades)
- Custom trays: gradual and lasting results
- Protective gel on gums to prevent irritation
- Included follow-up: before and after assessment with Vita shade comparison
Pharmacy at-home kits: honestly
Pharmacy kits (Crest, Colgate Optic White, etc.) are safe and can produce mild results on surface stains. But their concentration is limited by Canadian regulation, and universal trays don't fit your dentition perfectly — which reduces gel contact with teeth and increases the risk of gum irritation. Expect a maximum of 1 to 2 shade changes.
- Limited effectiveness (1 to 2 shades vs 3 to 8 in office)
- Non-custom trays (less effective)
- Risk of gingival irritation if poorly fitting
- Less lasting results (6 to 12 months vs 18 to 36 months in office)
Who can have their teeth whitened?
Whitening is safe for healthy tooth enamel. It is contraindicated during pregnancy and breastfeeding, on teeth with untreated active cavities, and on restorations (crowns, veneers, fillings) which do not whiten. A prior assessment is essential to ensure your teeth and gums are in good health before starting.
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Learn moreFrequently asked questions
Does teeth whitening damage enamel?
No, when done correctly with appropriate concentrations. Twenty years of clinical studies show that peroxide whitening, used as directed, causes no lasting damage to enamel. Temporary post-treatment sensitivity (24 to 48 hours) is normal and reversible.
How long do the results last?
Professional whitening typically lasts 1 to 3 years depending on your consumption of coffee, tea, red wine and tobacco. Annual touch-ups with custom trays make it very easy to maintain results.
Does whitening work on crowns or veneers?
No. Porcelain, composite or zirconia restorations do not respond to whitening agents. If you want to harmonize the color of your natural teeth with your restorations, this should be discussed with your dentist before treatment.
What does professional whitening cost on the Plateau Mont-Royal?
In-office whitening typically costs between $400 and $700 depending on the type of treatment (single session or custom trays). This price includes the pre-treatment assessment, follow-up and maintenance trays. Most insurance plans do not cover cosmetic treatments.
Ready to take care of your smile?
Our team on Plateau Mont-Royal is available Monday through Friday.