Reliability of 3D Face-Scans for Measuring Vertical Dimension of Occlusion

Objectives: This study evaluated the accuracy of obtaining the vertical dimension of occlusion (VDO) measurements on 3D face by comparing it manual VDO measurements.
Methods: The ethics committee ruled that this study did not require a formal approval (BASEC_Nr.Req-2023-00163). Dentate volunteers (n=20; mean-age=30.0±10.7 years) were recruited. VDO was measured for each participant clinically using a veneer calipers with the jaws positioned in maximal intercuspation (MI), and at different jaw separations of 2mm, 4mm, and 6mm. VDO was measured for each participant using two sets of facial anatomical landmarks, PN-STP: pronasale to soft-tissue pogonion (STP), and SN-STP: subnasale and STP, for all planned separations. The participants’ faces were scanned for all the dimensions. The resulting scans were imported into a 3D mesh-processing software; the VDOs were measured digitally. Bland-Altman plots assessed the agreement between the methods. Coefficient of variation (CoV) was employed to ascertain the precision and repeatability of the digital method.
Results: Eighty VDO measurements (clinical=40, digital=40) were recorded. VDO between PN-STG, revealed a Bland-Altman bias of 0.203mm with 95% Limits of Agreement (LoA) ranging from -0.0587 mm to 0.465mm, and the digital method had an average CoV of 0.356% (95%CI: 0.245%, 0.468%). VDO between SN-STG, revealed a lower bias of 0.104mm with 95% LoA ranging from 0.091mm to 0.299mm, and the digital method had an average CoV of 0.469% (95%CI: 0.379%, 0.560%).
Conclusions: The findings of this study demonstrate that VDO can be measured accurately from face scans using 3D mesh-processing softwares. This pilot study demonstrated that small changes in the VDO could also be detected using the digital methods, suggesting that this method may be clinically acceptable. The clinical application of the study findings must be focused towards incorporating this method of VDO acquisition into clinical workflows for fabricating CAD-CAM complete dentures.