Different staining foods react can darken a denture and its teeth. As with lower quality materials from which many cheap dentures are made from, cheap dentures often have a higher proabability to absorb food stains than with quality dentures. Usually quality dentures cost more, and last two to three times as long as cheap dentures. While many would agree they look the same when new. Using dentures overtime can show its wear and tear. One important aspect of where it can be helpful to know when to replace a denture is when the teeth no longer have the ridges in them that was used to chew food properly. Overtime, the ridges ontop of the denture teeth can be worn smooth. Chewing food with smooth dentures can make the body work overtime trying to digest food that should have been chewed a little longer.