Complete guide to teeth whitening: causes, methods & tips

Foods and drinks: Our diet is a major contributor to stained teeth. Beverages like coffee, tea, and red wine are notorious for yellowing teeth over time. They contain intense colour pigments called chromogens that attach to the enamel and darken its appearance². Other culprits include cola drinks, dark juices, and strongly pigmented foods such as berries, curry or turmeric-spiced dishes, soy sauce, and balsamic vinegar. Frequent consumption of these staining foods and drinks can lead to a dull or yellow hue on the teeth over time.

Tobacco use: This habitis one of the fastest ways to discolour teeth. Tobacco contains tar and nicotine, both of which cause stubborn stains. Tar is naturally dark, and nicotine, while colourless on its own, turns yellow when it combines with oxygen, creating yellowish deposits on tooth surfaces². These tobacco stains can be deep and very difficult to remove, often appearing brown or almost black in heavy smokers.

Poor oral hygiene: Not maintaining good oral hygiene can cause teeth to appear yellow or brownish. When you don’t brush and floss regularly, plaque builds up on teeth. Plaque itself is pale yellow. This tends to form especially around the gumline and between teeth, causing discolouration that can’t be brushed. If you skip professional cleanings, these deposits accumulate and teeth look dull and unhealthy.

Age: Getting older naturally changes the colour of your teeth. Over the years, the outer enamel layer gradually becomes thinner due to brushing and general wear, revealing more of the dentin layer underneath. Dentin is the hard tissue beneath enamel, and it has a yellowish or off-white tone. As enamel thins and more dentin shows through, teeth can start to look more yellow even if you have good habits².

Genetics: Some people are born with teeth that are slightly more yellow or dull, it can be genetic. The thickness and translucency of your enamel is inherited; if you have very thick opaque enamel, your teeth will appear whiter, whereas thinner or more translucent enamel allows the colour of dentin to show through more. Also, some individuals naturally have a more off-white or ivory shade to their teeth. Genetics also influence how susceptible your teeth are to staining.

Quick results. In-office whitening is the quickest way to whiten teeth – you’ll usually walk out in about an hour with a noticeably brighter smile.

Significant shade improvement. Professional teeth whitening services often help to achieve a change of several shades in one appointment.

Safe use of professional-grade products. Strong bleaching agents are applied under controlled conditions, minimising risks and ensuring effective results.

Effective for tough stains. Suitable for individuals with stubborn discolouration that requires intensive treatment.

High cost. It’s the most expensive whitening option and typically not covered by the NHS in the UK¹.

Potential for sensitivity. Strong whitening agents can cause temporary tooth sensitivity or gum irritation.

Flexible scheduling. You can whiten on your own schedule at home.

Controlled, gradual whitening. Some people prefer doing it gradually to control the level of whiteness and reduce sensitivity by taking breaks if needed.

Mid-range cost with excellent results. The cost is generally lower than in-office whitening while still giving excellent results—it’s a true middle-ground option.

Long-lasting effects. Results tend to last a good amount of time; many patients maintain their whiter teeth for a year or two before needing a touch-up, especially if they avoid heavily staining foods⁴.

Consistency matters. If you skip days or don’t wear them for the recommended time, you won’t achieve the full result.

Initial dental visits required. You need at least one visit for scan and impression and another to receive the kit, so it’s not as simple as buying something off the shelf.

Teeth whitening strips: Thin, flexible plastic strips coated with a layer of peroxide-based whitening gel. You press the strips onto your teeth and leave them on for typically 30 minutes a day for a period of about 1–2 weeks. They are generally easy to use and can lighten teeth a few shades with a course of treatment. Because the peroxide concentration in strips is lower than professional products, the results, while noticeable, are usually less dramatic than a dentist’s treatment².

Teeth whitening gel and one-size trays: Some kits come with pre-filled gel trays that you bite into, or with a syringe of gel and generic trays that you mold at home to fit over your teeth. You then wear the teeth whitening trays with the gel for a certain time daily, similar to strips in duration of treatment. If you choose a tray-based OTC kit, one thing to watch out for is tray fit – because they are not custom made, they might not fit tightly, which can lead to the gel oozing onto your gums or being uneven on teeth¹. This can cause gum irritation or inconsistent results.

Teeth whitening toothpaste: Unlike the above products, whitening toothpastes do not typically contain strong bleaches. Instead, they work by using mild abrasives and polishing agents to scrub away surface stains on the enamel². Some also have special chemicals like blue covarine, which deposits a subtle blue tint on the teeth that can make them appear slightly whiter by counteracting yellow tones⁴. Whitening toothpastes are good for maintenance and stain prevention, especially for stains from coffee/tea. They can help remove new stains before they settle in, and thus prevent yellowing. Teeth whitening with toothpaste usually lightens teeth by one shade over several weeks of use – they cannot change the inherent colour of your teeth deeply².

Teeth whitening mouthwashes: Whitening mouthwashes contain a low percentage of hydrogen peroxide. By swishing daily, they can help a little with stain reduction, but because the contact time with teeth is brief, they are usually the least effective of the whitening products. Some people use whitening chewing gums or whitening “erasers”/swabs – these have minimal evidence of making a difference; they might freshen breath or clean some residue but won’t significantly whiten teeth. They can be seen as complementary products.

No dental visits required. You can purchase and use them at home without needing an appointment or professional oversight.

Affordable option. Over-the-counter products are generally much less expensive than dentist-supervised treatments.

Generally safe. When you follow the product’s directions, approved OTC whiteners are considered safe for teeth and gums³, with millions of users reporting no serious issues.

Good trial step. You can test an OTC product first—if you’re happy with the improvement, great. If not, you can then explore professional whitening⁴.

Lower whitening strength. Regulations limit peroxide concentrations in OTC kits, so they’re less effective at removing deeper or older stains.

Limited on intrinsic stains. If your teeth are heavily yellowed or have intrinsic discolouration, OTC products may not provide sufficient whitening.

Risky ingredients from dubious sources. Some online home kits may not fully disclose ingredients or could contain harmful substances⁴.

Potential for enamel or gum damage. Overusing products can harm your enamel or irritate your gums².

Baking soda. Baking soda is often mentioned as a natural way to brighten teeth. However, using abrasive substances on teeth, especially without professional oversight, can lead to enamel erosion and increased sensitivity over time. It is not a clinically recommended method for safe or long-term whitening. Dental professionals generally advise against using baking soda alone as a whitening solution.

Hydrogen peroxide (H₂O₂). Low concentrations of hydrogen peroxide are sometimes included in over-the-counter whitening products. However, using peroxide at home without professional guidance can lead to gum irritation, increased tooth sensitivity, and other side effects. High concentrations, in particular, pose serious safety risks and should never be used outside of professional treatments².

Coconut oil pulling. This traditional practice involves swishing oil in the mouth and is sometimes promoted as a whitening method. While it may help improve oral freshness or reduce plaque when used alongside standard hygiene practices, there is no reliable scientific evidence that oil pulling whitens teeth². It should not replace brushing, flossing, or professional care.

Activated charcoal. Charcoal-based products have become trendy for their supposed whitening effects. However, research has raised concerns about their abrasiveness and lack of proven benefits². Scrubbing teeth with highly abrasive substances can damage enamel and may even make teeth appear more yellow over time. Dental associations advise caution or avoidance of such products unless supported by clinical evidence.

Convenient integration. The system works with existing Invisalign aligners or Vivera™ retainers, so there is no need for separate whitening trays.

Professional-grade results. It delivers effective whitening both in-office and at home, using a formula powered by Opalescence™.

Customised treatment. The gel application and duration can be tailored by your dental provider to suit your specific whitening goals and sensitivity levels.

Cost-effective option. The Invisalign whitening system is generally more affordable than traditional in-office whitening treatments, making it an accessible choice for many patients.

Potential for sensitivity. Like other peroxide-based whitening agents, this system may cause temporary tooth sensitivity, especially during the early stages of treatment.

Limited suitability. It is not ideal for individuals who are not undergoing Invisalign treatment, unless they are provided with custom-fitted trays by a dental professional

Practice good oral hygiene daily: This is the foundation. Brush your teeth twice a day for two minutes each time using a fluoride toothpaste⁵. Proper brushing removes the film of plaque and any surface stains before they have a chance to set in. Use a gentle but thorough technique and consider an electric toothbrush if you don’t have one, as they can be more effective at plaque removal. Good oral hygiene not only keeps your teeth brighter but also healthy.

Watch your diet: Try to reduce your intake of the major staining culprits like coffee, black tea, red wine, cola, and strongly pigmented foods. Of course, you don’t have to cut these out entirely if you enjoy them, but moderation helps. When you do consume them, a few tricks can minimise their impact: rinse your mouth with water afterward or drink a bit of water or milk to help neutralize and wash away pigments. If possible, brush your teeth 30 minutes after consuming staining beverages or foods.

Quit smoking or using tobacco: There are countless reasons to quit tobacco for your health, and a cosmetic one is that not smoking will keep your teeth much whiter. Tobacco stains are very persistent; if you stop smoking, you’ll prevent those dark tar/nicotine deposits from continually layering onto your teeth. Non-smokers generally have much less yellowing over time than smokers².

Regular dental cleanings: No matter how well you brush, you won’t be able to prevent some plaque from hardening into tartar or reach every nook and cranny where stains can settle. That’s why seeing your dentist or hygienist for a professional cleaning at least twice a year is important. They will polish your teeth, removing surface stains and any calculus buildup, which instantly brightens your smile. You know that smooth, shiny feeling after a cleaning – teeth almost always look a bit lighter after that polish.