Is the positioning guide mandatory for the virtual planning of orthognathic surgery? A randomized double-blind trial.

Objectives: The aim of this study is to verify the positioning of the condyles in computed tomography (CT) scans of skeletal Class II and Class III patients in virtual surgical planning before orthognathic surgery. The secondary aim is to determine whether occlusal devices are mandatory for performing a CT examination.

Materials and methods: In this retrospective randomized double-blind study, 42 CT scans were evaluated from patients who had undergone to orthognathic surgery at the University Hospital of the University of São Paulo. Male and female patients between the ages of 25 and 40 were included. The sample consisted of skeletal Class II and III patients. The CTs were randomly selected into centric relation (CR) and maximal intercuspal position (MI). Statistical analysis was performed with R Statistical Package and was considered significant in the case of p <0.0001.

Results: A total of 504 measurements were carried out in 42 patients. Three joint spaces on each side were used. No statistically significant difference between the inter- and intraobservers was found for CR and MI. Some scores were performed to avoid the risk of gender bias.

Conclusions: No statistically significant value was found between patients in CR and MI after mandibular manipulation. The use of a positioning guide to perform a CT scan prior to virtual planning is not absolutely necessary.