Are You a Good Candidate for Teeth Whitening?
Not everyone can start whitening immediately. Here are the criteria your dentist checks — and what to do if something needs addressing first.
The essential prerequisite: a healthy mouth
Professional whitening is not a procedure that can be started without a prior clinical assessment. Untreated cavities, active gum disease, or exposed root surfaces are absolute contraindications — not because whitening would make them worse in a spectacular way, but because peroxide in contact with these compromised areas causes acute sensitivity that makes the treatment unbearable. More seriously, a cavity creates a direct channel into the pulp: the peroxide then reaches the nerve and can cause irreversible pulpitis. Your dentist will systematically treat any active pathology before starting a whitening protocol. This is not a delaying tactic — it is the condition for a safe and effective treatment.
The stains that respond well to whitening
Teeth whitening works by oxidising chromophores — coloured molecules trapped in the organic matrix of enamel and dentine. Extrinsic staining (coffee, tea, red wine, tobacco, coloured foods) responds very well: these pigments are on the surface or in the superficial layers of enamel, accessible to peroxide. Age-related yellowing, which reflects a natural thickening of dentine (yellower and more visible through thinner enamel), responds well to professional whitening. Generalised intrinsic yellowing, present from birth or related to tetracycline intake during childhood, responds partially — the results are real but more modest and require a longer protocol. The dentist will tell you at the consultation whether your staining profile is favourable.
Stains that do not respond to whitening
Tetracycline staining (greyish or brownish bands across the tooth) is the most complex case: the chromophores are deeply incorporated into the dentine during tooth development, requiring very long whitening protocols (several months of nightly wear) with limited and variable results. White fluorosis spots (opaque white patches) do not whiten further — they are zones of hypomineralisation, not pigmentation. Whitening of surrounding enamel can actually make them more visible by creating a stronger contrast. Grey teeth caused by pulp necrosis (dead tooth) require internal whitening performed by the dentist from the inside, which is a completely different procedure from external whitening. In all these cases, the dentist will discuss realistic expectations with you.
Age: from what point can you whiten?
Whitening is contraindicated in children and adolescents whose teeth are still developing. The generally accepted threshold is age 16 to 18, when root development is complete and the dental pulp (nerve chamber) has retracted sufficiently to reduce sensitivity risk. In practice, most dentists do not start whitening before 18, and preferably once all wisdom teeth have erupted or their status has been assessed. In adults, there is no upper age limit — seniors respond just as well to whitening, though they often start with a lighter shade due to natural dentine exposure. Pregnancy and breastfeeding are relative contraindications: not because of documented toxicity, but through prudence, given the absence of clinical studies in this population.
The case of sensitive teeth
Dental sensitivity is not a contraindication to whitening — it is a parameter to manage. Patients who already experience hypersensitivity to cold before treatment are not excluded, but they require a specific protocol. The WhitenPro Home Sensitive protocol (10% carbamide peroxide, overnight wear) was designed for this profile: the lower concentration and longer diffusion time produce less acute sensitivity peaks than the Clinic protocol. Your dentist may also prescribe remineralising pre-treatment (fluoride gel applied in trays for 10 to 14 nights before whitening) to reduce enamel porosity. Potassium nitrate desensitisers, applied in the trays alternating with the whitening gel, are also an effective lever. The key is to tell your dentist about your sensitivity before treatment — not during.
What happens if you are not ready yet?
If the assessment reveals that your mouth is not yet ready for whitening, the dentist draws up a roadmap: treat the cavity, scale the tartar, stabilise the gum disease, wait for extraction healing. In most cases, this preparation takes 4 to 8 weeks. This is not a setback — it is the guarantee that the whitening, once started, will be effective and comfortable. Patients who are well prepared before treatment consistently report better experiences and better results than those treated without prior screening. At WhitenPro, the dentist always assesses your situation honestly and gives you a realistic timeline before starting any protocol.
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