Mandibular size as a predictor of vertical dimension of occlusion based on cephalometric analysis.

There are multiple methods for determining Vertical Dimension of Occlusion (VDO), but most of them require scientific validation.

Aim: To study the correlation between mandibular cephalometric measurements and VDO in young Chilean adults with complete dentition and known inclusion criteria, by using modified Knebelman's technique.

Materials and method: The study population consisted of 96 young Chilean adults aged 18 to 35 years. Inclusion criteria were complete natural dentition, bilateral molar support, skeletal class I or mild class II, presence of anterior coupling, and asymptomatic temporomandibular joints. Exclusion criteria were prior or ongoing orthodontic treatment, having undergone orthognathic or other facial surgery, poor oral habits (mouth breathing, or lingual, labial or object interposition), severe dental crowding (IOTN score > 2), too much beard and/or soft tissue under the chin. Anthropometric measurements were taken with a modified digital vernier caliper. Mandibular cephalometric measurements were taken with the QuickCeph 2000 software on digital lateral cephalometric x-rays. All anthropometric and cephalometric measurements were taken by one operator. Based on the mandibular cephalometric measurements with the highest correlation, a mathematical model was proposed to predict the VDO [VDO' = (XAEO-STF)*0.3 + (R3R4 dist.)0.5 + (Go-Ar dist.)- 0.3 + (Ar-Po Mand.Depth.)*0.4 - 8], whose predictive capacity will be tested.

Results: The three cephalometric measurements with highest correlation with VDO were selected. The resulting predictive model correlated significantly with actual VDO (r= 0.77), in addition to having significant correlation values according to the Björk-Jarabak facial biotypes.

Conclusions: The proposed mathematical model demonstrated a strong correlation with the Vertical Dimension of Occlusion. It is a reliable method, uninfluenced by the patient's sex or biotype, and is useful for restoring the VDO within a physiological range close to its original state.