Opalescence 40
Opalescence 40 is a high-concentration carbamide peroxide whitening gel used with careful tooth, gum and restoration assessment.
The short answer
Opalescence 40 is a high-concentration carbamide peroxide whitening gel; its use should follow the product instructions and a dental assessment of teeth, gums and restorations.
What does the number 40 mean in this whitening gel?
The number refers to the gel concentration, not a guarantee of a particular shade. Whitening changes natural tooth structure, while fillings, crowns and veneers do not lighten in the same way.
What should be checked before choosing a whitening plan?
A clinician checks for decay, cracks, gum inflammation, exposed dentine and mismatched restorations before selecting a whitening plan. They protect soft tissues, control where gel is placed and review sensitivity or irritation after use.
When should you delay whitening and see a dentist?
Arrange an examination before whitening if you have tooth pain, untreated cavities, gum disease, ulcers, marked sensitivity or a restoration in the visible smile. Stop use and contact a dental professional if burning, persistent pain or swelling develops.
What should you ask about whitening gel and restorations?
Ask whether the colour is caused by surface stain, enamel or dentine, whether existing restorations will match, and which application method suits your mouth. Ask how sensitivity will be managed and what to do if the gums become irritated.
Frequently asked questions
Can this gel whiten a crown?
No. Whitening affects natural tooth structure, so a crown may need separate colour planning or replacement for a match.
Why can whitening cause sensitivity?
Peroxide can temporarily affect fluid movement through dentine, which may stimulate the tooth nerve.
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Who wrote this page
This library is published by Dental Nation, a licensed dental group practising in the United Arab Emirates. Pages are written and overseen by the same clinical team that treats patients in our clinics, and are held to a fixed editorial standard for safety and accuracy.
This page is patient education, not medical advice, and cannot replace an examination. Anything urgent — facial swelling, trauma, uncontrolled bleeding or severe pain — needs a dentist or emergency care now.