Dentin can be whitened with all forms of traditional teeth whitening albeit less effectively since it is situated beneath a thick layer of enamel. There are exceptions to the rule and also non-traditional ways to whiten teeth which can be more effective.
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Can dentin be whitened?
Yes, tooth dentin can be whitened and evidence of that can be seen in internal teeth whitening, which whitens the tooth from the inside out. The whitening gel is placed inside of the tooth and the dentin gets whitened first before the enamel does.
Below is a video showing what the procedure is like with before and after photos.
That should be enough evidence that the dentin can in fact get whiter.
Peroxide diffuses through tooth
Aside from internal whitening, traditional external whitening can still whiten the dentin but just less effectively. Peroxide that is placed on the enamel can diffuse through the dentin and even end up at the pulp.
Studies have shown that within 15 minutes of placing the gel on the enamel, you can find traces of it within the pulp chamber. That means it has diffused through all three layers of the tooth. Therefore, traditional bleaching still does have an effect on the dentin layer.
Traditional whitening is less effective on dentin
Traditional teeth whitening (external whitening) isn't very effective whitening dentin because there is a thick layer of enamel covering over the dentin meaning you can't whiten it directly. It will all make sense if you look at the anatomy of a tooth and how we apply whitening gel to the tooth.
The outermost layer of the tooth is the enamel which covers/insulates the dentin which is the second layer. What makes whitening less effective is the fact that we apply the bleaching gel to the enamel layer. This means the enamel gets whitened the most effectively since it is in direct contact with the gel.
Unfortunately since the dentin is beneath the enamel, it is not in direct contact with whitening gel. It is physically impossible to apply the bleaching gel directly to the dentin if it is not exposed. Obviously it will be more effective if you can apply the peroxide directly to the dentin.
Most effective way to whiten dentin
The most effective way to whiten the dentin is with internal bleaching, which places the whitening gel directly into contact with dentin. However, this form of whitening can only be performed on teeth that have been root canal treated.
Internal whitening: What to expect
Administer local anesthesia.
Drill a hole through the tooth until you reach dentin.
Place whitening gel directly into dentin.
This procedure is very invasive and is only reserved for root canal treated teeth which already have a hole drilled through it when the root canal was performed. It is most often done on discolored dead tooth.
Second best option
The next best option to whiten dentin is with professional teeth whitening, either in-office or with professional take home kits. All professional options will be more effective than OTC products which often come in lower concentrations.
Best way to whiten dentin: From most effective to least
Professional take home
Essentially all of these options are ranked based on efficacy which is correlated with peroxide gel concentration. Over the counter products will always come in a lower concentration than the professional ones.
While dentin can be whitened with OTC/professional products, it isn't the most effective way to do it since the gel isn't in direct contact with the dentin. Nonetheless, the dentin will still whiten but at a slower pace than the enamel which is in direct contact with the gel.
Of course, in terms of efficacy, the best option for most people to get the dentin whiter would be with professional teeth whitening since it has the highest concentration. If you're in Long Island City and interested in whitening, give our dentists a call.