The global teeth whitening market is worth billions of dollars and growing — fuelled by social media aesthetics and an enormous range of products making bold claims. Here is an evidence-based look at what actually works, what is a waste of money, and what can actually damage your teeth.
How Whitening Works (and Doesn't)
There are two ways to whiten teeth: bleaching and abrasion. Bleaching uses peroxide (hydrogen peroxide or carbamide peroxide) to chemically oxidise the pigmented molecules within the tooth enamel and dentin, lifting colour from inside the tooth. Abrasion uses mildly abrasive particles to mechanically remove surface stains from the outside of the enamel.
Bleaching is the only method that changes the actual colour of the tooth — it works on intrinsic (internal) discolouration. Abrasion only removes extrinsic (surface) stains from coffee, tea, and tobacco. Both effects can look similar on a moderately stained tooth, but bleaching produces significantly more dramatic results.
Professional Whitening (The Most Effective Option)
In-office whitening (Zoom, Opalescence Boost, KöR, etc.) uses 25–40% hydrogen peroxide gel, often activated with a special light. A single 60–90 minute appointment can lighten teeth by several shades. Cost: $300–$1,000.
Custom at-home trays from your dentist use 10–22% carbamide peroxide or 3–10% hydrogen peroxide gel in custom-fitted trays worn for 1–2 hours daily or overnight for 1–2 weeks. Results are comparable to in-office treatment, achieved more gradually. Cost: $150–$400, and trays can be reused for future touch-ups.
Over-the-Counter Options
Whitening strips (Crest Whitestrips, etc.) are the most effective OTC option. They use 6–10% hydrogen peroxide and produce noticeable results over 1–2 weeks. Not as dramatic as professional treatment, but the evidence base is solid. Cost: $30–$60.
Whitening toothpastes work primarily through mild abrasion. Some contain low concentrations of peroxide. Good for maintaining whiteness and removing surface stains, but do not expect dramatic colour change. Worth using as a maintenance step.
Whitening mouthwashes have very limited evidence of effectiveness — the contact time with teeth is too short for peroxide to meaningfully bleach enamel.
The Products That Don't Work (or Cause Harm)
Activated charcoal toothpaste has been heavily marketed but has no credible evidence of whitening effectiveness. Worse, charcoal is highly abrasive and can damage enamel with regular use. The American Dental Association has not given it a seal of acceptance. Avoid it.
Oil pulling (swishing oil in the mouth) has proponents but no reliable clinical evidence of whitening effect beyond what normal saliva provides.
Baking soda (sodium bicarbonate) has mild, gentle abrasive properties and some evidence of surface stain removal. It is too mild to cause significant enamel damage at typical use levels and is an ingredient in some dentist-recommended toothpastes. It does not bleach.
Lemon juice / apple cider vinegar are highly acidic and can permanently erode enamel. Do not use them for whitening. The acid damage is real and irreversible.
What Whitening Cannot Fix
Whitening does not work on crowns, veneers, fillings, or bridges — only natural tooth enamel. Teeth discoloured by tetracycline antibiotics or dental fluorosis (from excessive fluoride during development) respond poorly to bleaching and typically require veneers. Ask your dentist whether your specific discolouration is likely to respond to bleaching before investing in treatment.
Is Whitening Safe?
Professional and OTC peroxide whitening is safe for most adults when used as directed. The main side effect is temporary sensitivity — the teeth and gums may be sensitive to temperature during and shortly after treatment. This typically resolves within days of completing treatment. Using a sensitivity toothpaste for two weeks before starting treatment can help. People with existing gum recession, severely worn enamel, or untreated cavities should address those issues before whitening.