I have seen dentures that look very realistic, mostly because the teeth aren't perfectly straight or impossibly white. The main thing that gives them away, however, is the fit. I have talked to some denture wearers and notice their teeth won't move naturally with the words. Their teeth will either remained clenched or else slip around in their mouths. I'd say if a person wants more natural looking dentures, he or she may need to shop around for the best adhesives available.