“Do upper dentures need adhesive?”

Adhesive can always be used to give the denture more stability. It's usually more of an issue with the lower denture.

Most dentures eventually need adhesive as the ridges shrink, which they do over time. For this reason , dentures need to be relied or rebased periodically. However, a new upper denture may not need adhesive for at least a year. Another contributing factor is the shape of the palate. A very flat palate typically will to have as much “suction” as one that has a high vault.

That depends on the patient. I have a number of patients that function exremely well with their denture with no adhesive. Then there some who desire some adhesive for more security with there denture. Variables such as bone volume, tissue volume and quality and contours, saliva quantity and quality, and patient ability all contribute to stability of a denture and its function with or with out adhesive.