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ePaper created 2017-08-25, 17:58:13 | version 1.38.0
pleased, lost confidence in the clinician, and sought another opinion. The initial review of the CBCT data was remarkable in the depiction of the thin, sharp, knife-edged alve- olar ridge (Fig. 7). The 3-D volumetric reconstruction also reveals the position of the bilateral mental fo- ramina and inferior alveolar nerves (seen in orange). Contrary to the 2-D view of the panoramic radio- graph, 3-D imaging and interactive treatment plan- ning software allow clinicians to truly understand the patient's existing anatomy. For the example of the fully edentulous mandible, the CBCT scan revealed that the underlying bony ridge was quite sharp and uneven at the crest. This presentation would certainly not be favourable to place implants with a flapless surgical approach. In fact, to facilitate the placement of implants, and facilitate the restorative phase, it would be beneficial to flatten the irregular ridge to gain the appropriate and desired width at the alveolar crest (Fig. 8). The CBCT data provides us with much more infor- mation and clinicians should consider ALL of the views afforded by the CBCT scan data and use the tools of the planning software to simulate the posi- tioning of the implants, such as the axial and cross-sectional views. The right and left inferior alve- olar nerves (IAN) were traced to determine the avail- able width in the anterior symphysis for implant placement. It was determined that four standard diameter implants could be positioned to support an overdenture as desired by the patient (Fig. 9). In the planning phases, clinicians should be consid- ered the engineers and architects of the oral cavity, providing a ‘blueprint for success’ based upon the data provided by the 3-D imaging, and the ability to simulate the implant position to avoid adjacent vital guided implant reconstruction case report | anatomy. The CBCT data can often yield significant surprises that cannot be determined with 2-D imag- ing. The initial assessment of the CBCT data revealed that the patient was not positioned properly during the scan acquisition. The inferior border of the man- dible was not imaged. It is very important that pa- tients be positioned properly to assure that all perti- nent diagnostic information is available for review. Fortunately it did not impact the diagnostic phase for the purposes of implant placement. The cross-sectional images revealed the presence of a thick facial buccal plate of bone in some areas, thinner in others, and a thick lingual plate of bone generally. The surprise was in the symphysis, a hollow area in the anterior central area exactly where im- plants would be placed! Other hollow areas and intra- osseous vessels were noted (see arrows, Fig. 10). The ‘hollow’ areas in the anterior symphysis are as illus- trated in the 3-D reconstructed volumes with four simulated implants in an occlusal view. The hollows in the anterior symphysis area of the mandible are seen in a ‘clipping’ view with simulated implants, slicing through the 3-D volumetric recon- struction (Figs. 11a & b). This anatomical variation could not be determined with 2-D imaging modali- ties. Once this was known, the planning of implants could proceed with the knowledge of the individual patient’s anatomical presentation. The patient was informed of the issues related to the anatomy as shown on the 3-D simulation from the CBCT scan. These images are invaluable to educate the patient and improve case acceptance, and extremely invalu- able for the diagnostic process in determining the best surgical approach. Proper diagnosis and treat- ment planning through 3-D imaging and simulation software revealed that the narrow ridge would have been a significant obstacle using a flapless approach, and the hollows in the bone may have caused signifi- Fig. 17: Each of the four implants was measured for implant stability with the implant specific SmartPeg. Figs. 18a & b: A resorbable calcium apatite bone grafting material was used to fill voids and cover the implant—followed by applications of platelet-rich fibrin (PRF). Figs. 19a–c: Healed site at three months (a). Uncovering of the integrated implants, healing collars and SmartPeg to measure ISQ values postoperatively (b). SmartPeg measuring ISQ values at uncovering (c). Fig. 20: Four overdenture attachments to support a complete mandibular denture. Fig. 17 Fig. 18a Fig. 18b Fig. 19a Fig. 19b Fig. 19c Fig. 20 CAD/CAM 3 2017 29