At-Home Teeth Whitening: Methods, Effectiveness and Risks

Teeth whitening is among the most frequently asked about subjects in aesthetic dentistry. Searching online for "at-home teeth whitening" brings up very different kinds of content: custom trays prepared by a dentist, pharmacy and supermarket products, kits sold online and recipes using kitchen ingredients. Although they all fall under one heading, the way they work and the risks they carry are quite distinct. In this article we clarify that distinction and look at how each method works and what to watch for.

First a Distinction: Staining or Tooth Colour?

The result you can expect from whitening depends on the source of the colour. Extrinsic staining is the deposit left on the tooth surface by tea, coffee, tobacco and coloured foods, and some of it can be removed with professional cleaning. Intrinsic colour is the structural colour of the tooth, which naturally darkens with age. Whitening procedures are chiefly aimed at this second group. This is why the tartar cleaning carried out before whitening both reveals the true tooth colour and helps the procedure give an even result.

Some discoloration does not respond to whitening: darkening in a root-treated tooth, fluorosis-related marks, certain medication-related discoloration and restorations such as fillings or crowns fall into this group. Restorations are not affected by whitening agents, which can leave older fillings in the front region looking darker than the surrounding teeth after whitening.

What Is Home Whitening?

In dentistry, the term "home whitening" describes a method planned by a dentist but carried out at home. The process works as follows: the dentist first examines the mouth, assesses the source of the discoloration and addresses any decay or gum problems. An impression is then taken and custom clear trays are made. Whitening gel at a concentration determined by the dentist is applied to these trays, which are worn for a set period each day over the recommended number of days.

The custom tray does more than carry the gel: it ensures the gel is distributed evenly over the tooth surface and limits its contact with the gums. Home whitening takes longer than the method applied in a single session at the clinic, and in some cases the two are planned together. For how the in-clinic procedure works, see our article on in-office teeth whitening. For information about the methods and the general process, see our teeth whitening page.

Over-the-Counter and Online Products

Whitening Toothpastes

These toothpastes mostly contain abrasive particles or components aimed at dissolving surface deposits. They can bring some improvement in extrinsic surface staining, but they do not change the structural colour of the tooth. Long-term use of highly abrasive products can affect the enamel surface. Our article on what to consider when choosing a toothpaste may be a useful guide.

Whitening Strips and Ready-Made Trays

Because ready-made strips and standard trays are not produced for an individual mouth, they may not fit the tooth surface exactly. This can have two consequences: colour differences where the gel does not reach certain areas, and irritation where the gel contacts the gums. The concentration of active ingredient in these products varies from country to country and from product to product.

Kits and LED Devices Sold Online

The contents and active ingredient concentration of some kits sold online are not clearly stated, and the information on the packaging does not always match what is inside. The fundamental problem with these products is that no intraoral assessment has been made beforehand: if a whitening agent is applied without noticing existing decay, a fractured filling or a gum problem, complaints may increase.

Recipes Using Kitchen Ingredients

Applications using baking soda, lemon juice, vinegar, activated charcoal and similar materials are frequently recommended in online content. What these methods have in common is that they do not change the structural colour of the tooth but create a mechanical or chemical effect on the surface. Acidic materials can affect the mineral content of the enamel surface, while regular use of abrasive materials can increase surface roughness and make the tooth more prone to staining again. Enamel is not regenerated by the body once lost. For these reasons dentists do not recommend such applications.

Risks Worth Knowing About

Even when carried out under supervision, whitening can produce some temporary effects. With unsupervised use, both the likelihood and the severity of these effects increase:

• Tooth sensitivity: The most commonly reported effect during and after whitening; it is usually temporary. See our article on tooth sensitivity.
• Gum irritation: Contact between the gel and the gums can cause redness and a burning sensation. This is more likely with trays that are not custom-made.
• Uneven colour: Uneven distribution of the gel can leave colour differences between teeth or across a single tooth.
• Mismatch with restorations: Fillings and crowns do not lighten, so a colour mismatch may appear afterwards. Anyone with restorations in the front region would do well to discuss this with their dentist beforehand.
• Existing problems being overlooked: Decay or gum disease underlying the discoloration can be missed when the focus is on colour alone.
• Overuse: Exceeding the recommended duration and frequency can make sensitivity more pronounced and affect the enamel surface.

Who Is It Not Suitable For?

Whitening is not a procedure carried out in every situation. Where there is untreated decay, active gum disease or a fractured restoration, those problems need to be addressed first. During pregnancy and breastfeeding the procedure is generally postponed. In children and adolescents, dental development is expected to be complete. Where there is marked gum recession or widespread sensitivity, the form and concentration of the application are assessed separately.

Maintaining the Result

The colour achieved after whitening changes over time, and how quickly varies from person to person according to dietary habits and oral care. Staying away from darkly coloured drinks and foods in the first days, not smoking and maintaining regular oral care all help preserve the result. Our article on aftercare following teeth whitening contains detailed advice. If you are wondering about general approaches to a whiter smile, see our article on what to do for whiter teeth.

If Whitening Is Not Enough

When the source of the discoloration is structural, or where there are marks that do not respond to whitening, different approaches may come into consideration. Composite or porcelain-based restorations are then assessed; for details see our articles on laminate veneers and zirconia or porcelain laminate, and our porcelain crown page for treatment options. What sets these options apart from whitening is that they can involve an irreversible procedure on the tooth surface, so detailed assessment is needed before deciding.

Summary

The applications grouped under the heading of at-home whitening are not the same thing. Home whitening planned by a dentist and carried out with a custom tray is a supervised process because it rests on an intraoral assessment. With over-the-counter and online products no assessment is made beforehand, and poor tray fit and unknown ingredient concentrations can lead to unexpected results. Recipes using kitchen ingredients are not recommended because of the risk they pose to enamel.

This article is for general information. The source of your tooth colour and the approach that suits you are determined by clinical examination.