Food dyes--natural or artificial-- nicotine and other substances can easily stain false teeth. These stains may be embarrassing, but you can remove them fairly quickly and easily. In addition to your usual cleaning regimen, which may include a standard denture cleaner, you have a few household items that, although you'd not use these on real teeth, are OK to use on false teeth stains.
Place your false teeth in an overnight denture-soaking solution. This will clean away food particles and may lighten some of the stains.
Brush your false teeth with a denture brush and then rinse them in clean running water (such as under your bathroom or kitchen faucet). Prepare a solution, as suggested by animated-teeth.com, of 1 tsp of bleach to 10 tsp of water in a bowl large enough to soak the teeth in.
Place the false teeth in the bleach and water solution and leave them there for 20 minutes. Check them when the time is up. If some staining remains, leave them in for another 10 minutes.
Rinse the false teeth well under cool, running water. You can now use them as usual.
Animated-teeth.com suggests adding 1 tsp of calcium chelating water softener to the bleach solution if tartar is a problem, in addition to staining. Brush away the loosened/softened tartar with a denture brush after using the solution. Prevent future stains by cleaning your false teeth daily (or more frequently if you smoke, drink coffee or eat staining foods) with a commercial denture cleaner.
Speak to your dentist before using any home products on your false teeth for stain removal--in most cases, these should not damage the false teeth, but according to animated-teeth.com, if the dental appliance contains metal there is a risk of corrosion.