From whitening strips to in-office treatments — we break down the pros, cons, and results of different teeth whitening methods.
Why Teeth Discolour
Tooth colour changes for two reasons: extrinsic stains on the outer enamel surface (from coffee, tea, red wine, tobacco, and certain foods) and intrinsic discolouration deeper in the tooth structure (from ageing, certain antibiotics like tetracycline taken during childhood, or trauma). Whitening treatments work by bleaching discolouration — they are highly effective on extrinsic and mild intrinsic stains, but cannot change the colour of crowns, veneers, or composite fillings.
In-Office Professional Whitening
Professional in-clinic whitening uses a high-concentration hydrogen peroxide gel (typically 25–40%) applied directly to the teeth. The procedure takes about 60 to 90 minutes and can lighten teeth by six to eight shades in a single session. A protective barrier is placed on the gums before the gel is applied, and some systems use a light or laser to accelerate the process.
The results are immediate and dramatic. Touch-up visits once or twice a year maintain the effect. The main downsides are cost (higher than at-home options) and temporary post-treatment sensitivity in some patients, which usually resolves within 24 to 48 hours.
Custom Take-Home Whitening Trays
Custom whitening trays are fabricated from an impression or digital scan of your teeth. You fill them with a lower-concentration whitening gel (10–22% carbamide peroxide) and wear them for 1–2 hours daily, or overnight, for two to four weeks. The total whitening effect is comparable to in-office treatment — the difference is simply the pace.
This option is popular because it is more affordable than in-office treatment, the trays are reusable for future touch-ups, and you can whiten at your own convenience. Because the gel concentration is lower, sensitivity is usually milder.
Over-the-Counter Products: Strips and Kits
Whitening strips available in pharmacies contain a low concentration of hydrogen peroxide (around 3–10%). They can produce visible results after two weeks of consistent use, but the effect is generally more limited than professional options because the gel doesn't perfectly conform to tooth surfaces and the concentration is lower.
Over-the-counter products are a reasonable starting point for mild staining and for maintaining results after a professional treatment. They are not recommended as the sole whitening method for significant discolouration.
Who Should Avoid Whitening
Whitening is not appropriate for everyone. Patients with active gum disease, cavities, exposed root surfaces, or cracked enamel should resolve those issues first. Pregnant and breastfeeding women are advised to wait. Teeth that are heavily stained by tetracycline antibiotics often respond poorly to peroxide bleaching and may require alternative cosmetic solutions such as veneers.
If your front teeth include crowns or composite fillings, discuss this with us before whitening — those restorations will not change colour with the treatment, potentially creating a mismatch.
Managing Sensitivity and Maintaining Results
To minimise sensitivity, use a toothpaste formulated for sensitive teeth for two weeks before starting whitening. During treatment, avoid very hot or cold foods on the day you whiten. Anti-sensitivity gels can also be used in the whitening tray after a session.
After whitening, avoid strongly staining foods and drinks — particularly coffee, red wine, and tobacco — for at least 48 hours (the "white diet" period). Long-term maintenance means an annual or biannual touch-up and good oral hygiene habits.