Page 49 - Craniomaxillofacial Implant Surgery - Jeroen P.J. Dings

Reliability and accuracy of surgical templates for craniofacial implant placement
INTRODUCTION
Reconstruction of cranio- and maxillofacial (CMF) defects is challenging due to
complex anatomy and proximity of vital structures1-3. Implant-supported prosthetic rehabilitation is nowadays regarded as a viable alternative to conventional reconstructive
surgery. The introduction of endosseous implants marked a revolutionary step in the
prosthetic rehabilitation of CMF defects with regard to improved retention, aesthetic
outcome, and ease of placement4-7. 3
Successful prosthetic driven rehabilitation depends on accurate diagnosis, preoperative planning, and subsequent placement of endosseous implants8-11.
The development of multiple detector computed tomography (MDCT) and cone beam computed tomography (CBCT) provides graphic and detailed three-dimensional (3D) information regarding bone volume, bone quality, and anatomical restrictions9,12. This 3D information allows accurate virtual planning using prosthetically oriented true- sized implants. As such, guided implant placement offers minimal invasive procedures, and reduces errors that are involved in standard implant surgery9,13,14.
CMF osseointegrated implants may be placed in a conventional manner or by stereolithographic (SLA) generated surgical guides11. Virtual planning software has enabled 3D computer-aided designing and also manufacturing (CAD-CAM) of surgical templates to allow guided implant placement. These surgical templates (drill guides) facilitate intraoperative correct positioning of implants at a predetermined depth and angle15-18. Surgical guides can be skeletal-, dental or mucosal supported19-21. Determination of the accuracy of surgical templates, by comparing deviations between virtually planned and actually placed implants, has been widely documented in different study designs, unfortunately, with compromised comparability and unfavorable results in terms of magnitude of error12-14, 21-28.
To our knowledge only few studies have reported on the accuracy of CMF implant placement with the aid of CAD/CAM-guided surgical templates19,20,29. The objective of this ex vivo study was to determine the accuracy of CMF implants placed in the orbital, nasal, and auricular region using skin-supported surgical templates. In addition, the influence of bone-fixation pins was measured. The hypothesis was that surgical templates allow proper implant placement, implicating that differences between virtually planned implant and the actual positions would be less than 1 millimeter.
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