Visualization and Modelling in Dental Implantology

Introduction

In this chapter the author give his experiences gained developing visualization and graphical modelling tools in applications for computerized dental implantology. Intensive development efforts can be seen worldwide on the field of image-guided navigation systems applied in dental implantology. Several commercial products are available on European market (Simplant^®, www.sirona.de, Dental Planner, Albadent Inc.). Drawbacks and advantages of technology in dentistry and oral surgery for the last decade are surveyed by several laboratories (Siessegger et al, 2001, Ewers et al, 2005). The computerized implantology evolves into two directions: 1/ surgery support with prefabricated templates; 2/ active, image guided navigated drilling. In case of surgical template preparation of both the registration and drill calibration can be made outside of operation room in a stress-free environment. This improves accuracy; however, other problems like template fixing to patient’s jaw, complete absence of interactive control of drill’s orientation in space make the future of this method uncertain. In case of active, intraoperative navigation, the lack of experience, poor software support for synchronization of real and virtual environments sometimes overburden the surgeon. Future trend in computerized dentistry predicts less use of direct diagnostic imaging and more use of 3D visualization of anatomy (laser scanning of topography and various surface reconstruction techniques). Functional modelling is now possible with tooth surface database and simulation of occlusal properties (Pongracz and Bardosi, 2006). Modern visualization methods like resampling the slice sequence in CT and MR diagnostic volumes, combined views of surface topography and mesh surfaces support the modelling. These new approaches help in direct visualization of anatomy during surgery that revives wider use of active navigation in the future.

The accuracy of dental hand piece tracking in active navigation highly depends on the alignment method between diagnostic and surgical spaces (REGISTRATION) and the alignment procedure between tool’s own coordinate space and the coordinate space of attached sensor (CALIBRATION). Well designed computational approach is needed for calibration of dental hand piece with small and unique geometry (Bardosi and Pongracz, 2007, Pongracz et al, 2007).