title: The use of a head-mounted display in oral implantology: a feasibility study.
abstract: OBJECTIVE
  To compare the accuracy of a navigation system for oral implantology using either a head-mounted display (HMD) or a monitor as a device for visualization.
  
  
  METHODS
  Drilling experiments in plastic mandibles were performed by seven investigators supported by a navigation system using an HMD. A set of drilling experiments was carried out using a traditional monitor setup as standard of reference. Prior to the experiments, CT scans of the mandibles were performed. Positions of the boreholes were determined with the planning software Mimics[Formula: see text]. In order to find the correct positions of the boreholes, individuals had to match two pairs of crosshairs. By an infrared tracking device, the navigation system was able to spot the artificial jaw and the angular piece of the drill allowing for the navigation. After the experiments, a second CT scan was acquired: (i) to identify the beginning and the end of the boreholes, (ii) to compare the positions of the planned implant and the boreholes and (iii) to calculate the deviations.
  
  
  RESULTS
  Overall deviation of the starting point of the borehole was 1.24 ± 0.84 mm for the HMD and 1.12 ± 0.68 mm for the monitor, 2.68 ± 1.65 mm of the end point of the borehole for the HMD and 2.46 ± 1.34 mm for the monitor. The mean deviation of the axis was 4.68◦ ± 3.7◦ for the HMD and 4.53◦ ± 4.17◦ for the monitor.
  
  
  CONCLUSIONS
  As overall accuracies do not differ significantly, the two methods seem to be equal. Personal skills seem to be crucial as the results show remarkable differences among the test persons. The results of our study demonstrate that the use of an HMD has no major drawbacks compared to the monitor setting. The striking advantage is that the surgeon is no longer obliged to turn his head away from the operation site during navigation, as all data relevant for the procedure are superimposed on the image of the real world in his field of view.
authors.affiliation: Institute of Anatomy, Ludwig-Maximilians-Universität, Pettenkoferstraße 11, 80336 , Munich, Germany, balazs.vigh@gmail.com.
authors.forename: Balázs
authors.initials: B
authors.lastname: Vigh
authors.forename: Steffen
authors.initials: S
authors.lastname: Müller
authors.forename: Oliver
authors.initials: O
authors.lastname: Ristow
authors.forename: Herbert
authors.initials: H
authors.lastname: Deppe
authors.forename: Stuart
authors.initials: S
authors.lastname: Holdstock
authors.forename: Jürgen
authors.initials: J
authors.lastname: den Hollander
authors.forename: Nassir
authors.initials: N
authors.lastname: Navab
authors.forename: Timm
authors.initials: T
authors.lastname: Steiner
authors.forename: Bettina
authors.initials: B
authors.lastname: Hohlweg-Majert
mesh_terms: D003626:Data Display; D005240:Feasibility Studies; D006801:Humans; D008334:Mandible / Q000000981:diagnostic imaging / Q000601:surgery*; D019930:Mandibular Prosthesis Implantation / Q000379:methods*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*