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.