Occlusal comparison of hand-articulation versus digital articulation in orthognathic surgery

The aim of the present study was to develop measurement methods to evaluate occlusal differences in digitally-articulated and hand-articulated models in final occlusal planning for orthognathic surgery. A total of 10 (five class II and five class III) previously treated orthognathic cases were analysed by three oral and maxillofacial surgeon investigators, creating a total of thirty cases. Investigators used physical models to create a preferred hand-held final occlusion, which were then scanned and saved utilising a Trios 3® scanner (3Shape). Models were digitally disarticulated and sent back to investigators after a period of at least a month for digital articulation. Novel measurements of dental roll, pitch, and translational differences were performed by an independent engineer using Materialise 3-Matic® software. Statistical analysis was used to evaluate translational differences, the effect of deformity, and inter-investigator variation. A mean (SD) translational difference of 1.58 mm (1.14) mm was seen between the thirty digital and hard-articulated cases analysed. Minimal difference was seen in roll and pitch between hand articulation and digital articulation. A significant translational difference was seen in class III cases compared with class II (p = 0.0006) but not in roll or pitch. There was no significant difference seen between investigators related to translation (p = 0.18), roll (p = 0.09), or pitch (p = 0.17). Digital articulation yielded similar results to hand held in this pilot study. Using measurement techniques described in larger cohorts, its accuracy can be validated using currently available technology.