Abstract
The plaster cast model (PCM) needs to precisely reproduce the patient’s dentition to ensure optimal fit of the surgical splint; However, transporting physical models entails a risk of fracture of cusps, brackets or entire models. This study evaluated whether clinically significant differences (>1 mm) exist between the patient’s dentition and the PCM, and whether additional fractures occur from transportation from Odense, Denmark, to Rockhill, USA. This prospective study enrolled 10 orthognathic surgical patients. Three digital models were produced per patient: A direct intraoral scan, a scan of the PCM in Odense, Denmark, and a scan of the PCM at 3D Systems, Rockhill, USA. Primary outcome was distance between 2 sets of digital models. Primary predictor was transportation. The study found only 2 patients with no differences above 1 mm. Fractures occurred more often on brackets compared with teeth (Odds ratio: 5.4; P < .001). Fractures of brackets occurred twice as often on maxillary models (P = .045). Fractures occurred equally often during the 2 transportations. In conclusion, surgical splints produced from PCM could incorporate inaccuracies primarily related to the orthodontic appliances. Therefore, it is recommended to minimize model transportation before digitization and preferably use intraoral scanning to minimize errors. Key words: Orthognathic surgery, Surgical splints, dental models, digital occlusion, intraoral scanner, plaster cast model.
Highlights
Plaster cast models (PCM) and intraoral scans (IOS) are considered accurate for clinical use and are used in a variety of dental clinical settings
6 patients had a model with at least 1 clinical difference above 1 mm when comparing the PCM with the IOS and 5 patients had at least 1 model with differences above 1 mm when comparing the PCM with 3DS
There was no significant difference in the amount of difference whether the models where transported from the orthodontist to the department or from the department to 3D Systems
Summary
Plaster cast models (PCM) and intraoral scans (IOS) are considered accurate for clinical use and are used in a variety of dental clinical settings (e.g. fixed partial prosthesis, orthodontic treatment, etc.). Under ideal circumstances, both IOS and PCM produce precise results[1, 2, 7, 9–11]. Errors in the PCM could result in inaccurate fit of the surgical splint. This inaccuracy will increase the interdental distance or rotate the moving jaw-segment during intermaxillary positioning
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