Flexible dentures are not a new invention. In fact, they have been around since the early 1950s, but they were not taken up by dental practitioners with great enthusiasm as they were known to stain and deteriorate faster than other denture types.
There was a belief that more ridged-type dentures would spread the load better across remaining teeth. This staining problem was primarily caused by smoking tobacco. Nowadays, we have improved cleaning solutions and have far fewer people smoking. The attitude has considerably changed, and this type of material is now widely used.