Why might occlusal disharmony occur following a functional reline?

The occurrence of occlusal disharmony following a functional reline can often be attributed to polymerization shrinkage of acrylic resin. During the reline procedure, the acrylic resin used to create a new impression may undergo dimensional changes as it cures. When this polymerization occurs, it can cause the material to shrink slightly, which may lead to alterations in the fit of the denture base relative to the underlying soft tissues and the opposing dentition. If the new base does not sufficiently match the required occlusal vertical dimension or interarch relationships, it can result in disharmony in occlusion, leading to discomfort for the patient and improper function during biting and chewing.

Other factors, such as inaccurate border molding techniques, overlapping of the impression material, and improper wax modeling, can contribute to issues in the retentive or support aspects of the denture, but the specific phenomenon of polymerization shrinkage directly impacts the occlusal relationships due to its effect on the dimensional integrity of the denture base itself. Thus, it is crucial to consider this factor when evaluating post-reline occlusal harmony.