The end results of an at-home teeth whitening kit can vary quite a lot. Sometimes these results might exceed your expectations, and other times the whitening effect might be barely noticeable. And then there's the possibility that the results are very much mixed, to the point that some teeth whiten, while others do not. What causes this mixed result, and what can be done to overcome it?
Focused on Your Enamel
Teeth whitening doesn't penetrate the entire tooth to whiten it as a whole. Whitening treatments in fact tackle staining and discoloration on your dental enamel, which coats your teeth. This enamel is made of extremely strong mineralized compounds (primarily carbonate substituted hydroxyapatite crystallites). Beneath that enamel is a substance called dentin, which makes up most of the overall structure of a tooth.
Enamel responds well to whitening, but the extent of this response depends on the enamel's thickness. Enamel tends to become thinner with age, and this can be accelerated by enamel erosion. This erosion occurs when the microorganisms in your mouth (oral bacteria) interact with food and drink (especially those high in sugars and carbohydrates). This interaction creates an acid that can cause enamel erosion.
Thinning dental enamel caused by age and/or erosion means that the dentin becomes visible. This dentin tends to have a yellow hue, and cannot be whitened to the same degree as enamel. If your teeth whitening efforts have had minimal effects on certain teeth, it might be that you're seeing dentin, with teeth that still have a sufficient enamel coating responding more favorably to the treatment. This can create a curious effect, with some teeth remaining yellow while others whiten.
Overcoming a Mixed Result
These mixed results can mean that an at-home whitening kit is unlikely to achieve the anticipated results. Consider seeing your dentist. Teeth with deficient enamel can benefit from a cosmetic solution, such as a dental veneer to cover the outward-facing side of the tooth. Dental bonding, in which a thin layer of dental resin is applied to the tooth, can also cover any teeth with deficient enamel. Your other teeth can then be whitened to the same level as the veneer or bonded tooth, eliminating your previous mixed result.
In many ways, the ultimate success of your whitening attempts will depend on the state of your dental enamel. Specific teeth with deficient enamel will need an alternative solution, allowing your other teeth to then be whitened to match the cosmetic dental restoration.
For more information, ask your dentist about their teeth whitening services.