Unlike enamel, for which teeth whitening is designed, dentin is yellow and even brown in some cases. Because of that, people with more dentin tend to have darker teeth. Moreover, as people age, their enamel thins due to erosion and general wear and tear. When this happens, teeth lose their natural whiteness as the dentin layer underneath becomes more exposed.
But is it possible to whiten dentin?
Whitening is Designed for Enamel
Whitening uses hydrogen peroxide to remove staining molecules from the surface of and within enamel. In teeth that still have a good layer of intact enamel; whitening would have very little effect on the dentin layer. The bleaching agent in whitening would first have to penetrate the enamel layer, which would mean multiple whitening sessions.
Too much whitening, however, is bad for your gums and teeth so that rules out the possibility of frequent whitening treatments in a short space of time. However, a study found that 35% hydrogen peroxide could change the colour of dentin, but in terms of lightness, only enamel was affected. A dark layer of enamel then would still be visible even after whitening.
Whitening Dentin is Painful
Since dentin is filled with tubules that are connected to the nerve in a tooth, trying to whiten teeth that have suffered from substantial enamel erosion would be painful. The hydrogen peroxide would likely penetrate the dentin layer and irritate the nerve. Not only could this damage the nerve and possibly kill it, but it would also be extremely painful for a patient.
Veneers and Whitening Together
A safer alternative to whitening dentin would be to opt for veneers for teeth that have little enamel. Although in the past it was difficult for the veneer bonding agent to adhere to dentin, advances in cosmetic dentistry have made the process easier. If several of your teeth are yellow due to enamel loss, then veneers would be a safer option.
Whitening can also be combined with veneers. For example, it is quite common for patients to first whiten their teeth before having their veneers placed. This allows the dentist to match the shade of the veneers to the newly whitened teeth. Teeth that are badly eroded then can benefit from veneers while the surrounding teeth with more enamel can be safely whitened.
If your finances are tight, discuss the situation with your dentist. Together, you can decide which teeth to veneer and which teeth can be whitened safely.