Final answer:
Dentures require periodic adjustments or replacements due to changes in the individual's oral structures to ensure they fit properly and maintain oral health.
Step-by-step explanation:
Dentures need to be rebased, relined, or remade at intervals primarily to ensure a proper fit and function. Over time, the gums and bone structure in the mouth can change, causing dentures to become loose or uncomfortable. Rebasing involves replacing the entire base of the denture while keeping the existing teeth, relining involves adding material to the tissue side of the denture to improve fit, and remaking involves creating an entirely new set of dentures. These procedures help maintain the effectiveness and comfort of dentures for the wearer. It is essential for dentures to fit properly to avoid discomfort, difficulty in eating, and oral lesions. Therefore, to ensure a proper fit and maintain oral health, these adjustments or replacements are necessary.