On occasion a customer will have one tooth that does not whiten and there are only a few possible explanations for this:
Blunt trauma can cause the veins and arteries located in the pulp of the tooth to rupture causing bleeding into the surrounding hard tooth tissue, thus creating a brown/gray stain. As a result of the bleeding the body will acknowledge that the tooth is dead, send large amounts of immune system cells to the area while excluding the dead tooth. Over time the root and surrounding bone will decay.
Another possibility is you had dental work (cap, crown, or veneer) placed on the tooth that is a different color. Prior to such treatment’s it is in your best interest to have the surrounding teeth whitened because the dentist will make the new dental work the same shade as your teeth at the present time.
None of the above seem to fit? There’s one more possibility. Take a look at the tooth; do you see any dents on its surface? If so you may have damaged tooth enamel caused by impact? If that’s the case you may need to pay a visit to your dentist because your dentin may be exposed.
If none of the above apply to you have you tried using custom fitted teeth whitening trays? They are far better than over the counter whitening strips and are identical to what dentist create for their patients. When custom teeth whitening trays are purchased online they are a mere fraction of the cost dentist charge.