Any alcohol in the mouth, even a very small amount, can distort a breath test result and make it seem like a person had much more to drink than they actually did. It is unlikely that mouth alcohol would create a false positive breath test result for someone who did not drink any alcohol at all, but if a person did have some alcohol to drink, a little bit of alcohol in the mouth could skew a breath test result because it has a higher concentration of alcohol than the breath.
Dentures or denture adhesives can have this affect by holding leftover alcohol from drinking in the mouth in the dentures, adhesive material, or food stuck in the dentures or adhesive. The alcohol can then be released into the breath sample, even if a person took out their dentures before the test. Taking out the dentures can actually make the problem worse. Make sure to discuss your case with a DUI attorney if you use dentures or denture adhesives and you used them on the day of your arrest.