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ePaper created 2014-10-07, 09:31:41 | version 1.30.01
I special _ 3-D planning for implants tion, including single-tooth and multiple-tooth restoration, full-arch fixed and removable over- denture reconstruction. _3-D planning concepts for the mandible Regardless of the image acquisition process, there are four standard views that need to be fully appreciated in the diagnosis phase. These include thecross-sectional(A),theaxial(B),thepanoramic (C), and the 3-D reconstructed volume (D) as seen in Figure 1. The ability to interact within these images differs from software to software. It is the ability to visualise 3-D data with improved tools that empowers clinicians to assess individual patient anatomy. The cross-sectional slice is important for the assessment of the facial and lingual cortical bone plates, the intramedullary bone, and the positioning ofteethwithinthealveoli.Theaxialviewal- lowsinspectionoftheentireupperorlower jaw, the maxillary sinus volume, the posi- tion of the incisive canal in the maxillae, and the mental foramina in the mandible. The panoramic view is an overall scout image, and can be helpful in tracing the mandibular nerve, and assessment of the maxillary sinus floor near the nose region. The3-Dreconstructedvolumesareinvalu- able in the planning process and in com- municating information to the members of the implant team, including the patient and the dental laboratory technician who willfabricatethefinalprosthesis.Theseim- ages are especially useful, as they are most readily understood and appreciated. As represented in the flow chart, a patient may be sent to a radiology centre for a CBCT scan of the mandibular arch without a scanning appli- ance. The 3-D reconstructed volumes are easily understood and interpreted for the mandible (Figs. 2a–c). In the case demonstrated, there were several hopeless anterior teeth that were planned for extraction. The extent of the bone loss can be appreciated by the clinician and demonstrated to the patient as an excellent educational and com- munication tool. The virtual mandible can be ro- tated to reveal all views of the patient’s individual anatomical presentation (Figs. 3a & b). With inno- vative software tools, the teeth can be virtually extracted in the 3-D reconstructed volume, aiding the clinician in understanding the local anatomy to identify potential implant re- cipient sites (Figs. 4a & b). In this example, the alveolar ridge narrowed considerably at the crest. In order to facilitate implant placement, the ridge required an alveolec- tomy, reducing the ridge by approximately 8–10 mm. Advanced software applications allow for the bone to be sectioned based upon the desired plan. A bone reduction tem- plate pioneered by the author can be sim- ulatedbythesoftwareandthenfabricated to assist in the bone removal (Figs. 5a & b). The reduction template fits over the ridge, allowing complete visualisation of the residual bone to be sectioned from the alveolar ridge. The flattened ridge can also be simulated, greatly enhancing the clinician’s appreciation of the remaining 36 I cone beam3_2014 Fig. 8bFig. 8a Fig. 7bFig. 7a Fig. 9dFig. 9c Fig. 9bFig. 9a CBE0314_34-39_Ganz 30.09.14 14:17 Seite 3