Development and pilot validation of a three-dimensional skeletal coordinate-based system for occlusal vertical dimension assessment in elderly Korean cadavers

Background: Establishing an accurate occlusal vertical dimension (OVD) remains fundamental for prosthetic rehabilitation. Historically, a 40 mm vertical reference has been widely cited; however, this value was derived from dentate adult populations using cast-based measurements. This pilot study aimed to re-evaluate anatomical OVD reference values in an elderly Korean population and to develop and preliminarily validate a three-dimensional skeletal coordinate-based measurement system for occlusal vertical dimension (OVD) using CT data. As a pilot investigation, the feasibility, reproducibility, and anatomical consistency of the proposed method were assessed in elderly Korean cadaveric specimens. These findings provide a methodological foundation for future in vivo clinical application. Methods: Twenty-five cadaveric specimens were initially screened, and 19 specimens with clearly identifiable vestibular landmarks were included in the final analysis. Virtual mandibular closure was performed by digitally rotating the mandible around a geometrically defined condylar axis until the first posterior occlusal contact was achieved. Vertical measurements were obtained perpendicular to the Frankfort Horizontal plane. Inter-observer reliability for maxillary and mandibular vertical components was assessed using a two-way random-effects model. Results: The mean maxillary vertical dimension was 20.3 ± 2.7 mm, and the mean mandibular vertical dimension was 15.8 ± 1.9 mm, yielding a mean OVD of 35.2 ± 3.7 mm. Inter-observer reliability was excellent (ICC = 0.986 for maxillary and 0.981 for mandibular components). Conclusions: Within the limitations of this pilot cadaveric study, CT-based three-dimensional skeletal analysis demonstrated an OVD lower than the historically cited 40 mm reference. These findings should be interpreted as a methodological refinement rather than a contradiction of previous reports and provide standardized skeletal baseline data for future clinical investigations in elderly populations.