You can expect some adjustment for the first month after getting a partial, or full denture. If discomfort lasts longer than weeks, contact your denturist. Do not make your own adjustments.
Poor oral hygiene can be the reason for denture discomfort.
As we age, tissues become more sensitive to pressure and can cause sore spots. To ease discomfort, the mouth can be rinsed with baking soda and water or salt and water. If a sore mouth remains untreated, it can cause other problems. Contact a denturist if the soreness continues.
Lower dentures, over time, may not fit as well. Your denturist can add a soft liner. This is a permanent liner and it will stay soft.
The upper denture is the one that usually causes the least discomfort. The advantage for the upper denture is suction with the roof of the mouth.