The first time you get dentures is always the most difficult. As an experienced denture wearer, you've already learned the basics about speaking and eating with dentures. There will always be an adjustment period, but it will be shorter and easier than the first time. If you replace your denture regularly then the adjustment period is much shorter, since the changes in your new dentures would be relatively small.

Prolonged use of an ill-fitting dentures can irritate the gums, tongue and cheek, and may cause the ridges of your mouth to shrink to the point where it will be almost impossible to fit you with normal dentures.

Generally, the more dramatic the changes that are necessary to restore proper appearance and function, the longer the adaptation period. When you look at the consequences of an ill-fitting denture, the short adjustment period is not so bad.