When tetracycline was introduced over 60 years ago, people were thrilled to have another alternative antibiotic. While it was bad for bacteria, tetracycline also proved bad for the dentin in children’s teeth, causing a reaction that stained many patients’ teeth grey.
The first case of reported tooth discoloration in children occurred in 1956. Many, many other children had their teeth stained over the following decade before the connection was fully understood.
Teeth whitening can’t change this type of staining, as it is in the dentin of the teeth. At Gentle Dental, we use porcelain veneers to cover the effects of severe tetracycline staining.
Here’s some more information on how tetracycline caused staining.
Why did it turn teeth grey?
Tetracycline staining is tied to tooth mineralization. In teeth, mineralization is an ongoing process, where teeth continually lose (demineralization) and gain (remineralization) minerals such as calcium. When teeth lose more minerals than they regain, that is when decay sets in. Mineralization is especially active in young, growing teeth. Ingested fluoride has been proven to help in this process by strengthening the developing permanent teeth from within. Fluoride applied directly to the teeth helps to speed remineralization on the tooth surface.
Once it started showing discoloration, researchers looked into what tetracycline was doing to teeth. They found that if the teeth were exposed to tetracycline at a time of tooth mineralization or calcification, the tetracycline bound to the calcium ions in the teeth. If this happens before the teeth erupt, the tetracycline that has bound to the calcium will cause the teeth to come out with an initial fluorescent yellow discoloration. Once these teeth are exposed to light, however, the tetracycline will oxidize, and the discoloration will change from fluorescent yellow to non-fluorescent brown or grey over a period of a few months to years.
The location of the discoloration will correspond directly to the stage of tooth development at the time of the tetracycline exposure. Permanent teeth tend to show the discoloration with less color, but it is more widespread across the tooth.
Tetracycline is limited in its timeframe for use
Once the link and timeframe were established, the FDA changed the rules on the use of tetracycline. Now the antibiotic is not to be used by doctors during the second and third trimesters of pregnancy or in children up to 8 years of age. These ranges are the periods of calcification of the teeth.
Why can’t I whiten my stained teeth?
You’d think that whitening, such as our in-office teeth whitening at Gentle Dental, would be able to brighten teeth that have become grey due to tetracycline. But whitening only works on the tooth enamel, the outer layer of the teeth that is somewhat porous and can take stains from foods and drinks such as berries and coffee or red wine. Teeth whitening has no effect on the interior of the teeth, just on the enamel.
The interior of the tooth, called the dentin, is where tetracycline affects the color. When the dentin is stained, this is permanent. It’s also why our teeth become more yellow with age, as the enamel wears down and more of the dentin shows through. Although you may have heard claims of teeth bleaching fixing tetracycline discoloration, the dentin really can’t be whitened.
But it can be covered. That’s the idea behind porcelain veneers. A thin porcelain shell is placed over the visible front sides of the teeth to cover stains and imperfections. That’s how we can help with tetracycline-stained teeth at Gentle Dental.