Well-fitted dentures should feel comfortable in your mouth and not cause gum soreness or ulcers. If you’re experiencing any gum soreness, it may be due to the constant rubbing of the denture base against your gums, which may indicate an improper fit. Your dentures should enable you to speak, chew, and smile with stability, without shifting around in your mouth. Properly fitting upper and lower dentures should not cause difficulty in chewing, even for harder or chewy foods.