Page 17 - Craniomaxillofacial Implant Surgery - Jeroen P.J. Dings

Virtual preoperative planning is essential for evaluation of the available bone quantity and density to improve reliable treatment planning of CMF implants32,33. Besides evaluating the available bone dimensions and characteristics, planning is also critical in determining the spatial proximity of anatomical locations and avoiding vital structures34,35. Although osseointegration of CMF implants is predictable, its success rate is mainly determined by sufficient primary implant stability. It is crucial in virtual preoperative planning to respect a zone of at least 2 mm of peri-implant bone to ensure primary implant stability and a predictable restorative outcome36-38.
Translation of the virtual treatment plan to the surgery is essential for predictable clinical- and prosthetic outcomes39. Virtual planning software enables 3D-computer- aided designing (CAD) and also computer-aided manufacturing (CAM) of surgical templates31. The use of surgical templates facilitates correct intra-operative positioning of extra-oral implants in predetermined areas with sufficient bone volume, thereby shortening operation time39-41. The accuracy of surgical templates, that compare deviations between virtually planned and actually placed implants, has been widely documented in different study designs that show variable results and unfavorable outcomes in terms of magnitude of error42,43. However, few studies have reported on the accuracy of CMF implant placement in a conventional manner versus installation with the aid of digitally designed surgical templates29,40,41. Advances in manufacturing technology and material science has led to various clinical applications of surgical templates1. Surgical guides can be skeletal-, dental- or mucosal supported42. The use of soft tissue supported surgical templates offers the opportunity for flapless implant placement, thereby maintaining an intact periosteum and blood supply38,44. This is beneficial, especially with regard to maxillofacial defects of oncologic origin, which often have compromised healing ability due to scar tissue and irradiation2. Furthermore, minimally invasive surgery reduces the morbidity and surgery duration, while preserving the soft tissue architecture and hard tissue volume45-47. On the other hand, minimally invasive surgery also has disadvantages, such as limited surgical overview due to a lack of visibility of anatomical landmarks and vital structures. Furthermore, absence of tactile control may lead to an increased risk for mispositioning and malalignment of implants48,49.
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General introduction and outline of this thesis
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