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ePaper created 2015-05-29, 13:18:43 | version 1.38.0
I technique _ virtual planning stereolithography, CAD/CAM, or laboratory fabri- cated, termed CT-derived “Template-Assisted”. The drilling process is started and can be completed within the template helping to control trajectory anddepthwiththeproperinstrumentation.Thethird category requires a specific template design that allows for accurate drilling and osteotomy prepa- ration, and with the proper manufacturer-specific carriers the implants can then be accurately deliv- ered through the template, termed, "Full Template Guidance."Theuseofadvancedimagingmodalities for pre-surgical prosthetic planning is essential for any type of implant surgical and restorative inter- vention, from the single tooth, multiple tooth restoration, full arch fixed and removable over- denture reconstruction. However, it is the correct use of three-dimensional tools that provides clini- cianswiththepowertodiagnoseandtreatmentplan with the highest degree of acuity and accuracy. _3-D Planning Concepts: Full Arch Maxillary Overdenture Duetoanatomicalvariationsrelatedtothemax- illary sinus, the floor of the nose, the incisal canal, the facial trajectory of the anterior segment, thin corticalplates,anddiminishedoverallbonedensity when compared to the mandible, the completely edentate maxilla offers additional diagnostic chal- lengesforclinicians.Theaxialviewprovidesinsight 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 restorativelydrivenimplantdentistry”pre-surgical prosthetic planning should start prior to any scan being taken. A scanning appliance can be fabricated from a duplicate of a patient’s existing well-fitting denture, or a new diag- nostic set-up which positions the teeth at the ideal vertical dimension of occlusion, centric relation, and functional/aesthetic components (Fig. 3a). The patient wears the scannographic appliance during the scan, ideally held in place with a pre-determined bite registration to minimize movement. The scan reconstruction will then contain both the tooth position and the underlying bone (Fig. 3b). The combination of the anatomical scan data with the radiopaque template allows unprecedented diagnostic potential. The template reveals the tooth position (red arrows) in relationship to the underlying 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 positiontotherestorativeoutcome(c). Figs. 7a & b_The occlusal view of the volumetric rendering aids in the implant-to-implant positioning within the bone (a). Superimposing a translucent scannographic template over the maxilla provides the information to position implants within the restorative envelope (b). Figs. 8a & b_Use of “selective transparency” with abutment 08 I cone beam2_2015 Fig. 10a Fig. 10b Fig. 11 Fig. 12a Fig. 12b Fig. 13 Fig. 14a Fig. 14b Fig. 15a Fig. 15b Fig. 16