Evaluating an Innovative Artifact-Resistant Marker-Based Registration Method for CBCT-Guided Implant Planning

Abstract

Objective:

Radiographic guides are instrumental for the digital design of surgical guides in image-guided dental implantology. These radiographic guides are used as part of the digital-workflow to couple dental anatomy and occlusion with the bony anatomy of the implant site, which is obtained using CBCT. A key step of the coupling process is called registration, which can be achieved using various methods. Unfortunately, all these methods present technical shortcomings that are specially exacerbated when CBCT images present metal or beam-hardening artifacts. The objective of this research was to evaluate a novel, artifact-resistant registration method using the principles of 2D orthogonal-imaging with fiducial markers for image-guided implant planning.

Study Design:

This in-vitro study included five scenarios with varying levels of image artifacts (absent, minimal, mild, moderate, and severe); where a radiographic guide was registered with (1) a widely used conventional registration method, and (2) the proposed marker-based orthogonal-imaging registration method. A paired student’s T test and one-way ANOVA were used for statistical analysis. Three evaluators (OMFR residents) performed both registration methods in order to evaluate inter-operator reliability using ICC scores.

Results:

Both the surface-based and proposed marker-based registration methods presented high reliability, with ICC scores of 0.88 and 0.99 respectively, and consistent results at all artifact levels. The accuracy of the proposed orthogonal-imaging marker-based method (0.00018 mm) was significantly better (p > 0.0001) compared to the surface-based registration method (0.175 mm).

Conclusion:

The use of orthogonal-imaging for radiographic guide registration in dental implantology has the potential to reduce registration error by an order of magnitude. This increased accuracy has the potential to improve implant placement; especially in complex cases. Furthermore, this novel method should be easy to implement clinically by utilizing the projection (i.e., basis) images that are routinely acquired for CBCT imaging.