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ePaper created 2016-03-24, 17:16:09 | version 1.38.0
research | 251 2016 implants Figs. 4a–c: Cross-sectional slice reveals tooth position in relationship to the bone (a) and the extension of the labial vestibule (red arrow) (b). The relationship to the maxillary sinus is essential for planning in the posterior region, where thin cortical plate can be clearly visualized (arrow) (c). Figs. 5a & b: Evaluating a potential receptor site within the cross-sectional view (Slice 63) (a). The positioning of the implant(s) need to fall within the envelope of the teeth (b). Figs. 6a–c: The cross-sectional image reveals a potential receptor site (a); the realistic implant and abutment simulation (b); the author’s preference places the implant within a defined zone of available bone defined as the “Triangle of Bone” (TOB) that also acts to relate implant position to the restorative outcome (c). mation that will be worn by the patient during the acquisition of the scan. In this manner, the desired tooth position can be evaluated in relation to the underlying bone and other important anatomic structures such as the maxillary sinus or the infe- rior alveolar nerve. Certain proprietary methods in- corporate the use of fiducial markers to help with the registration process for planning based directly upon the restorative needs for the patient. The use of interactive treatment planning has expanded dramatically in the past ten years as computing power has increased exponentially. As defined by the author, guided surgery can be divided into three distinct categories once a “virtual” plan has been established based on 3-D scan diagnosis (Ganz-Rinaldi Classification of Guided Implant Surgery Protocols). The first allows the information to be assessed, providing import- ant information to the clinician who will perform the surgical intervention free-hand based upon the software plan, termed “Diagnostic-Freehand”. The second category involves the fabrication of a surgical guide or template that is remotely constructed from the digital plan usually through rapid prototyping or stereolithography, CAD/CAM, or laboratory fabricated, termed CT-derived “Template-Assisted”. The drilling process is started and can be completed within the template helping to control trajectory and depth with the proper instrumentation. The third category requires a specific template design that allows for accurate drilling and osteotomy preparation, and with the proper manufacturer-specific carriers the implants can then be accurately delivered through the tem- plate, termed, “Full Template Guidance”. The use of advanced imaging modalities for pre-surgical prosthetic planning is essential for any type of im- plant surgical and restorative intervention, from the single tooth, multiple tooth restoration, full arch fixed and removable over-denture recon- struction. However, it is the correct use of three- dimensional tools that provides clinicians with the power to diagnose and treatment plan with the highest degree of acuity and accuracy. 3-D Planning Concepts: Full Arch Maxillary Overdenture Due to anatomical variations related to the max- illary sinus, the floor of the nose, the incisal canal, the facial trajectory of the anterior segment, thin cortical plates, and diminished overall bone density when compared to the mandible, the completely edentate maxilla offers additional diagnostic chal- lenges for clinicians. The axial view provides insight into the global topography of the maxilla (Fig. 1). The position of the incisal canal can be visualized, along with thin facial and palatal cortical plates. The volumetric rendering aids in the inspection of the bone, but does not offer any information regarding tooth or ultimate restorative position (Fig. 2). In order to achieve the concept of “true restoratively driven implant dentistry” pre-surgical Fig. 4a Fig. 5a Fig. 5b Fig. 6a Fig. 6b Fig. 6c Fig. 4b Fig. 4c 2512016