Please activate JavaScript!
Please install Adobe Flash Player, click here for download
ePaper created 2015-05-29, 13:18:43 | version 1.38.0
I technique _ virtual planning trajectory of the maxillary alveolus (a), and the re- verse is true after rotating the maxillary volumetric reconstructiontoviewtheleftside(b).Finally,when considering the mechanical forces of mastication and movement of the prosthesis, a line can be drawn between the two most anterior implants that establishes the potential for rotation in the occlusal plane (Fig. 11). A second line can be drawn at the most anterior aspect of the maxillary teeth. The distance between the two anterior implants and the maxillary incisor teeth (red arrows) repre- sents a cantilever that could result in tipping of the denture when the patient bites into an apple. The ball-abutment is only one potential stock abutment choice for an over-denture application. Another widely used abutment is the Locator attachment (Zest Anchors). The use of realistic Lo- catorattachmentsallowsforapreciseunderstand- ing of the implant-to-implant relationship, and spacing around the arch which is necessary to gain maximum retention of the prosthesis to resist dislodgment during mastication (Figs. 12a & b). Inaddition,theutilizationofvirtualabutmentsaids in determining the correct tissue cuff heights of the abutments above the bone, and through the soft tissue (Fig. 13). The vertical distance can be evaluated within the framework of the prosthetic design(Fig.14a).Thenewdigitaltoolsallowfornew paradigmstobeestablishedassessingtherelation- ship of the implant position, abutment position, andprosthesispriortothescalpelevertouchingthe patient. Crown-to-root ratios and the trajectory of the implant-abutment complex can be visualized within the virtual plan, providing valuable surgical and restorative information during the planning phase (Fig. 14b). In addition to the axial, panoramic, and three- dimensional reconstructed volume, the impor- tanceofthecross-sectionalimageiscriticaltofully appreciate the relationship between the implant position within the bone, and the emergence through the tooth. One area that has not been emphasizedhowever,istheabilitytodeterminethe prosthetic space required for the abutment as it relates to the thickness of soft tissue supporting the overdenture (Fig. 15a). The realistic ball abut- ment can be clearly visualized sitting on the coro- nal aspect of the implant (red line), and the tissue cuff height of the abutment (green line). One com- ponent that is not easy to determine is the metal housing that will be processed within the denture. This component part is not yet available within the software libraries to the author’s present knowl- edge. Therefore an approximation was digitally represented (gold), so that the extra height can be visualized (yellow line), revealing the thin palatal aspect of the overdenture (Fig. 15b). Once the vir- tual plan has been established a surgical template can be designed by the software and then fabri- catedthrough3-Dprinting,stereolithography,ora CAD/CAM process to assist in the placement of the implants within the anticipated restorative needs of the patient (Fig. 16). _3-D Planning Concepts: Full Arch Maxillary Fixed Prosthesis Therearefewdifferencesbetween3-Dplanning concepts for an overdenture prosthetic design, or a fixed prosthetic rehabilitation supported by implants. All aspects of the patient’s bone and soft tissue anatomy must be carefully evaluated. After a proper assessment of the available bone, key im- plantpositionsareidentified,andsimulatedwithin the3-DreconstructedvolumeasseeninFigure17a. However, it is important to once again evaluate the potentialimplantreceptorsitesbasedupontheen- velope of the occlusion (Fig. 17b). Using “selective transparency” helps to provide an enhanced per- spective of how the implant abutment projections (yellow) are spaced within the desired restoration (Fig. 17c). The frontal view clearly illustrates the importance of the implant abutment projections, revealing for this example a nearly parallel place- ment of the implants (Figs. 18a & b). “Selective Transparency” can be applied to multiple struc- tures,tohelpvisualizetheentirecomplexoftheim- plant, abutment projection, radiopaque template, and the underlying bone (Fig. 18c). By rotating the 3-D reconstructed volumes, it is apparent how powerful these interactive software tools can be (Figs. 19a & b). Once the final positions of the im- Figs. 15a & b_The top of the implant (red line) serves as the foundation for the abutment at a specific tissue cuff height (green line) (a); the metal housing represented in gold also has a vertical component (yellow line) (b). Fig. 16_Once the implant position has been confirmed, the software will generate the virtual design of the template. Figs. 17a–c_Eight implants positioned to support a fixed restoration (a) to fit within the framework of the desired tooth position (b); using “selective transparency” the underlying bone can be visualized (c). Figs. 18a–c_Frontal view of the scanning template with yellow abutment projections seen above the occlusal plane (a); semi-transparent scanning template (b); and all three objects translucent to visualize the position of the implants within the bone (c). Fig. 19a & b_Another 3-D view showing the emergence of the abutment projections through the scanning template. 10 I cone beam2_2015 Fig. 19a Fig. 19b