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Teeth whitening works through a single chemistry: peroxide breaks down into free radicals that oxidise chromogenic molecules (the coloured compounds) within the enamel and dentinal tubules. Whether you are using a home tray, strips, or the Zoom chairside system, this is what is happening. The meaningful difference between home and professional whitening is the concentration of the active agent, how long it contacts the tooth, and how that translates into clinical outcome.
How Peroxide Concentration Determines Results
Home whitening products in India are typically formulated at 3–10% carbamide peroxide (CP) or 3–6% hydrogen peroxide (HP). Carbamide peroxide breaks down in the mouth to release approximately one-third its concentration as active hydrogen peroxide, so a 10% CP gel delivers approximately 3.3% HP. At this concentration, whitening is gradual — treatment over 10–14 consecutive nights produces a measurable shade change of approximately 2–4 Vita shade guide steps.
Professional in-chair systems (including Zoom, which Dazzle uses) apply 25–40% HP directly to the tooth surface under gum barrier protection. At this concentration, the oxidation reaction proceeds much faster. A single 60–90 minute Zoom appointment (3–4 light-activation cycles of 15 minutes each) produces a shade change of 6–8 steps in most patients. The speed difference is proportional to the concentration difference.
Custom Tray vs Over-the-Counter Home Products
Within home whitening, there is an important distinction between over-the-counter products and dentist-dispensed custom tray kits:
OTC whitening strips: Pre-loaded strips with fixed concentration. No custom fit — coverage of the gum margin and interproximal areas is imprecise. Effective for surface stains on anterior teeth within the strip’s contact area. Results are real but limited.
Dentist-dispensed custom tray kits: Custom trays are fabricated from a digital or alginate impression of your teeth. They fit precisely to the gum margin, ensuring the gel contacts the tooth surface uniformly without contacting the gingival tissue. Higher concentration gels (10–16% CP) can be used safely with custom trays because the precise fit minimises gum contact. These produce more consistent results than OTC products and allow the patient to top up results at home after initial professional whitening.
What Home Whitening Cannot Do
Home whitening is ineffective for intrinsic staining that is structural rather than chromogenic: tetracycline staining (antibiotic taken during tooth development creates a grey-brown banding within dentin that peroxide cannot oxidise away), fluorosis white spots (hypomineralised enamel areas that are already lighter than the surrounding tooth but have different optical properties), and discolouration from devitalised teeth (the dark grey-brown of a dead tooth comes from haemoglobin breakdown products within the pulp chamber — external peroxide does not reach this).
For these cases, the options are microabrasion (for surface fluorosis), composite resin masking, veneers, or (for devitalised teeth) internal bleaching — a procedure performed through the access cavity of the root canal-treated tooth. The choice between treatments is covered in detail in our cosmetic dentistry overview.
When Home Whitening Is the Right Choice
Home whitening is appropriate for: extrinsic staining from tea, coffee, red wine, and tobacco on a tooth structure that is otherwise healthy and without restorations in the smile zone; patients who want gradual, controlled whitening over a few weeks rather than an in-chair appointment; and patients maintaining results after Zoom whitening (a dentist-dispensed custom tray kit used monthly is the standard maintenance protocol after professional whitening at Dazzle).
Home whitening is not appropriate for: patients with active gum disease or untreated cavities (peroxide on diseased tissue causes significant sensitivity and pain); patients with porcelain or composite restorations on the front teeth (these will not whiten with peroxide — the whitened natural teeth will no longer match the fixed shade of the restoration); or patients with dentinal hypersensitivity that has not been assessed and managed. See our veneer comparison guide for when whitening is best sequenced before veneers.
FAQs
Q1: How long do whitening results last?
Zoom whitening results: 12–24 months before noticeable fade with normal dietary habits. The fade rate is highly individual — tea and coffee consumption, smoking, and red wine are the primary determinants. Monthly or as-needed use of the dentist-dispensed home tray maintains results indefinitely. Home whitening alone: 6–12 months before visible re-staining in most patients.
Q2: Will whitening damage my enamel?
Published evidence does not show permanent enamel damage from correctly used peroxide whitening at standard concentrations. Temporary demineralisation occurs during treatment and remineralises within hours after gel removal. The risk of enamel damage from misuse — leaving gel on beyond recommended time, using inappropriately high concentrations without supervision — is real but preventable.
Q3: My front teeth have crowns. Can I still whiten?
The natural teeth can be whitened; the crowns will not change shade. If the crowns were matched to your pre-whitening shade, they will appear yellower than the whitened natural teeth. This is manageable: whiten first to the desired shade, then replace the crowns colour-matched to the new shade. The sequence matters — do not replace crowns before whitening if you plan to whiten.
Q4: Can I whiten if I have sensitive teeth?
Sensitivity is a common side effect, not a contraindication. Using potassium nitrate toothpaste for 2 weeks before whitening reduces tubular fluid movement and pre-conditions the pulp. Alternating whitening nights with off nights reduces cumulative sensitivity. Low-concentration gels with longer contact time produce equivalent results with less sensitivity than higher concentration gels. At Dazzle, whitening cases with pre-existing sensitivity are managed with modified protocols, not simply declined.
