Evaluation of relative deviations in virtual articulators for simulating occlusal contacts at increased vertical...

Accurate planning for occlusal vertical dimension (OVD) increase is crucial for prosthodontic success. This study evaluates the effects of different OVD increase amounts (2 mm or 5 mm), methods (articulator-based or intraoral) and virtual facebow use on occlusal contacts.

Twenty-one individuals were initially recruited; three dropped out, leaving 18 participants. Digital impressions, bite records in maximum intercuspal position (MIP) and facial scans were obtained. Each participant received eight occlusal splints, varying by OVD increase method, amount and facebow use. Centric relation contacts and MIP were recorded using articulator paper and a scannable bite material. These scans were superimposed with Group D (2 mm intraoral increase without facebow) serving as the reference baseline. Deviations in the X (lateral), Y (anteroposterior) and Z (superoinferior) directions were analyzed using non-parametric tests with Bonferroni correction for pairwise comparisons.

No significant deviations were observed in the X-direction. However, significant deviations occurred in the Y and Z-directions in certain groups, particularly with a 5 mm intraoral increase. Effect size analysis indicated that most Y-direction differences were minor, whereas Z-direction deviations at higher OVD increases were more clinically relevant.

Regardless of the method, increasing the OVD by 2 or 5 mm and using a virtual facebow did not significantly affect the number of occlusal contacts. However, spatial deviations of contacts were detected, with articulator-based 5 mm increase producing fewer deviations than intraoral methods. Within the limitations of this study, the virtual facebow did not substantially reduce deviations.