Studies of changes in occlusion after the insertion of complete dentures (part II).

The aim of this clinical experimental study was to investigate whether, and what, changes in occlusion occur between 3 weeks and 1 year after insertion of complete dentures. Twenty-six edentulous patients, who already had their jaw relation registered for part I of this study some 357 days before, were re-examined. The same special non-arcon measuring articulator was used for determination of any positional differences between the presently recorded central condylar position with inter-occlusal gap and the equilibrated intercuspal position, from approximately 1 year previous. Differences were recorded electronically in the condylar area in three dimensions. The position of the condylar balls of the measuring articulator in maximum intercuspation had shifted, since the previous recording, by about 0.62 +/- 0.04 mm (0.04-1.76 mm) in the sagittal and 0.89 +/- 0.72 mm (0.01-3.06 mm) in the vertical direction. Whereas the differences measured in maximum intercuspation scattered in the sagittal plane uniformly around the centric condylar position, in the vertical plane they were shifted cranially about an average of 0.77 +/- 0.85 mm (1.06 mm caudally to 3.06 mm cranially). The results indicate that in half of the patients from the present sample the occlusion did not remain stable, which is assumed to be mainly caused by resorption of alveolar bone and abrasion of the acrylic teeth. Therefore, at each check-up visit not only the health of the denture-bearing tissues and the fit of the dentures, but also the mandibular posture and the occlusion should be examined carefully.