If you find that your dentures develop an unpleasant smell, the most common reason for this is the development of bacteria on your prosthetic. These bacteria can become entrenched in the small nooks and crannies of your dentures, or even underneath them along the gum line. This is compounded by the fact that dentures tend to stymie the production of saliva, which contributes to the buildup of plaque.
Thankfully, there are plenty of measures you can take if you want to keep your dentures in good condition. After you finish eating with them, you can rinse them off to remove any residual food. You should then brush both your prosthetic and your gums twice a day, just like you used to with your natural teeth. Finally, leave your dentures to soak in a cleaning solution each night to break up any residual bacteria on the prosthetic.