Having unusual gray teeth? Having extremely yellow, gray or brownish teeth may be due to extended use of medication called tetracycline which is primarily given to children to treat infections. Tetracycline-caused stains are what is called the intrinsic stain. These intrinsic stains are in truth hard to whiten since the discoloration originates from the inside of the teeth and cannot be easily penetrated by bleaching agents. If the discoloration though is very minimal, teeth whitening kits may help solve this problem. But usually tetracycline-stained teeth are really huge problems. Some teeth whitening reviews said that home-based teeth whitening products can help whiten the teeth but the duration lasts for up to 6 months or more depending on the persistence of the person. This long treatment can really be a cause of frustration including its strain on the budget. Nevertheless the end result will never be a sparkling white set of teeth. Veneers are the usual solution for this kind of problem.