There are many factors that influence the degree to which a person’s teeth whiten. Smoking, coffee, tea, red wine, tobacco, etc… all increase staining of a person’s teeth which can make them appear darker.The removal of staining through regular professional cleanings at a dental office along with periodic whitening can really make a big difference in the appearance of a person’s teeth.
Patients who have never whitened before will usually see more of a dramatic result than patients who regularly whiten their teeth. Also, younger patients will usually experience a more dramatic outcome than older patients.Some people who have developmental conditions where the enamel in their teeth are affected will not realize much of a benefit from whitening. Also, patients who have intrinsic stains within their teeth (which can occur from the use of Tetracycline, a form of antibiotic) will likely not see a difference after whitening their teeth.
Whitening is a reversible process. It is important for people to understand this because once you have achieved a certain tint of white on your teeth that you like, then you need to continue a maintenance process that involves reapplication of whitening gel throughout time. There are no specific guidelines as far as how often reapplication of whitening gel needs to be done. The process of continuing to achieve the whitening levels you would like to be at with your teeth are really dictated by the person themselves. As soon as a person notices that their teeth may not be as white as they once were and their desire is to get their teeth back to that previous level of "white", then the reapplication process should begin.
Typically, the easiest way for people to go through the reapplication process of whitening gel is to have custom trays made by a local dentist. This allows people to be in control of when they feel like they are in need of whitening. Many dental offices will usually sell tubes of whitening gel to patients with custom trays in order for them to be able to apply the gel when they see fit.