Influence of fiducial markers and imaging methods on registration accuracy in edentulous arches.

Statement Of Problem: Virtual implant positioning allows greater predictability in oral rehabilitation. Edentulous arch images can be matched in a planning software program by aligning fiducial markers, a procedure known as image registration. Among the steps involved in guided implant surgery, registration may contribute to deviations, leading to the mispositioning of implants and further adverse clinical outcomes.

Purpose: The aim of this in vitro study was to evaluate the registration accuracy of edentulous arch images with fiducial markers obtained using different imaging methods.

Material And Methods: Fiducial markers made of gutta percha (G), flowable composite resin (R), metallic spheres (S), and impression material (I) were installed on 4 tomographic guides, which were scanned by tomography to produce Digital Imaging and Communications in Medicine (DICOM) files and 2 intraoral scanners (VIRTUO and TRIOS) following the dual-scan protocol. The images were registered in the Blue Sky Plan software program (n=12) for each group. Zeiss INSPECT was used to assess registration accuracy through 3-dimensional deviations between groups and references models. Data were analyzed with 2-way ANOVA and the Tukey test (α=.05).

Results: No significant difference was found in registration deviation for all DICOM file groups. In the VIRTUO and TRIOS groups, markers G and R exhibited significantly larger deviations than DICOM G (P<.05). The automatic alignment provided an acceptable image registration only for DICOM G and DICOM R.

Conclusions: Fiducial markers and imaging methods are capable of influencing the registration accuracy of edentulous arch images in a planning software program. The deviations of the DICOM file groups were statistically similar for all markers, while TRIOS and VIRTUO showed greater deviations for markers G and R. The registration method may add inaccuracies to the digital flow before guided implant surgery.