Whitening strips contain a peroxide gel that can lighten teeth by a shade or two when used as directed, while whitening toothpaste mainly removes surface stains rather than changing the tooth’s natural colour. Both can cause sensitivity, and some products are too abrasive or acidic. They do not whiten fillings, crowns or veneers, so a dental check before whitening is wise.
How teeth get darker
Tooth colour changes for two reasons:
- Surface stains (extrinsic): coffee, tea, smoking, red sauces and some mouthwashes leave pigments on the enamel. These respond to cleaning and polishing.
- Internal colour (intrinsic): the dentine underneath the enamel darkens with age, and some teeth are naturally darker, or discoloured by a dead nerve, old trauma or certain medicines in childhood. Only peroxide-based whitening, or restorations, can change this.
Our article on why teeth turn yellow explains the causes in more detail.
Whitening toothpaste: what it really does
Most whitening toothpastes work by polishing: they contain mild abrasives, sometimes with enzymes or ingredients that loosen stains. They can make teeth look cleaner and brighter by removing surface stains, but they do not change the internal shade in a meaningful way.
Points to keep in mind:
- Very abrasive pastes, used with a hard brush or heavy pressure, can wear exposed roots and increase sensitivity
- Charcoal toothpastes are often highly abrasive and usually contain little or no fluoride; there is no good evidence that they whiten teeth safely
- Choose a whitening toothpaste that also contains fluoride and use it with a soft brush
Whitening strips: how they work
Strips are thin plastic films coated with a hydrogen peroxide or carbamide peroxide gel. Placed on the teeth for a set time each day, the peroxide penetrates the enamel and breaks down coloured molecules in the dentine. With regular use they can produce a visible but modest change.
Limitations:
- Strips are one size, so they cover the front teeth unevenly and rarely reach crowded areas or back teeth
- Gel can touch the gums and irritate them
- Results fade over months, faster with coffee, tea and smoking
- Products sold online or abroad may contain concentrations that are not permitted in many countries, or ingredients such as chlorine dioxide that can damage enamel
Sensitivity and other side effects
The most common side effect of any peroxide whitening is temporary sensitivity to cold, and sometimes gum irritation. These usually settle after stopping. Whitening also does not change the colour of composite fillings, crowns or veneers, so after whitening natural teeth these may look darker than the teeth around them.
Whitening is not suitable on teeth with untreated decay, leaking fillings, exposed roots or active gum disease, and is usually avoided during pregnancy and breastfeeding. Our article on whether whitening damages enamel looks at the evidence.
Strips, toothpaste or dentist whitening: a comparison
| Whitening toothpaste | Whitening strips | Dentist-supervised whitening | |
|---|---|---|---|
| What it changes | Surface stains | Internal shade, modestly | Internal shade, more predictably |
| Fit | Not applicable | Standard, uneven | Custom trays or in-clinic application |
| Gum protection | Not applicable | Limited | Controlled |
| Checks before starting | None | None | Examination of decay, fillings, gums |
| Typical result | Cleaner, brighter look | One or two shades | Larger, more even change |
Our guide to in-clinic and at-home whitening explains the professional options.
Tips if you decide to use strips at home
- Have a check-up and cleaning first, so decay and gum problems are treated and surface stains removed.
- Buy products from a reliable pharmacy and follow the instructions exactly; do not leave strips on longer than indicated.
- Stop if sensitivity becomes strong, and use a toothpaste for sensitive teeth.
- Keep strips away from the gums as much as possible.
- Remember that fillings and crowns at the front will not change colour.
Whitening at Ajam Dental Clinic, Tripoli
At Ajam Dental Clinic, Fouad Chehab Boulevard, Al-Makateb Building, 1st floor, Tripoli, we check whether your teeth are suitable for whitening, remove surface stains with professional cleaning and discuss in-clinic or custom-tray whitening if you want a larger change. See our cosmetic dentistry and contact us by WhatsApp or phone to ask about whitening.
Frequently asked questions
Are whitening strips safe for enamel?
Strips from reliable brands, used as directed, are generally considered safe for enamel, although they can cause temporary sensitivity. Problems arise with overuse, with products of unknown origin or with acidic formulas. If you have exposed roots, decay or many front fillings, ask your dentist before using them.
How long do results from whitening strips last?
Results usually last several months, sometimes longer. They fade faster if you drink a lot of coffee or tea, eat strongly coloured foods or smoke. Good brushing, rinsing with water after staining drinks and regular professional cleaning help maintain the result.
Does whitening toothpaste whiten teeth?
It can make teeth look brighter by removing surface stains, but it does not significantly change their internal colour. For a real change in shade, a peroxide-based method is needed. Choose a whitening toothpaste that contains fluoride and avoid very abrasive or charcoal products.
Can I use whitening strips if I have crowns or veneers?
You can, but the crowns and veneers will not change colour. After whitening, they may look darker than the natural teeth next to them. If they are visible when you smile, discuss this with your dentist before whitening, as they may need to be replaced to match.
Why are my teeth sensitive after whitening strips?
Peroxide passes through the enamel and can temporarily irritate the nerve, causing sensitivity to cold. It usually disappears within a few days after stopping. Using the strips less often, choosing a lower concentration and using a toothpaste for sensitive teeth help. If sensitivity persists, see your dentist.
Have a question about your teeth?
Send a WhatsApp message to Dr. Abdel Rahman Ajam or Dr. Soumaya Ajam, or call the clinic to book a consultation.
This article provides general information for patients. It does not replace an examination by a dentist, who can advise you on your own situation.
