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CAD/CAM international magazine of digital dentistry No. 4, 2016

treatment planning based on CBCT cone beam supplement | 37 CAD/CAM 4 2016 Fig. 3: Pre-operative clinical aspect of the anterior alveolar ridge. Fig. 4: After elevation of the mucoperiostal flap, the sharp-edged alveolar ridge becomes visible. Fig. 5: Preparation of the osseous graft with the microsaw. Fig. 6: Detachment of the graft with a chisel. dibular and the interforaminal region of the chin are common sources for harvesting autogenous bone-grafts.Dependingfromthedonorsite,patient and surgeon should be aware of the possible con- frontation with various advantages but also dis- advantages when harvesting the bone. Harvesting bone from the iliac crest requires patient hospital- isation, and surgery under general anaesthesia, whereas intraoral bone harvesting can be per- formed ambulatory and under local anaesthesia.2,3 Themainproblemwithautogenousbonegraftingis represented by the high risk of patient morbidity, causing pain, swelling, and healing problems at the donor site.3 The aim of this case presentation is to demon- strate a predictable, two-stage operating protocol for the horizontal augmentation of the severely resorbed, edentulous anterior mandible with an autogenous bone graft, harvested from the crestal alveolarridgeatimplantsite,inordertocreateasuf- ficient bone volume for the later implant therapy, without donor morbidity for the patient. Patient data The47-year-oldmalepatientvisitedourdentalof- ficeinordertorenewhisoldandpoorfittingprosthe- ses in the lower and in the upper jaw. The remaining fiveteeth32–43inthefrontofthelowerjawhadbeen removed three months previously due to a chronic periodontitisinourdentalpractice.Nearlyallremain- ing teeth in the upper and the lower jaw showed sig- nificant signs of progredient chronical periodontitis, insufficient root treatments and prosthetic supra- structures as well (Fig. 1). The medical history of the patient was without any significant pathological findings. Diagnostic procedures In cases of long-term edentulism, the dental sur- geon is almost always confronted with a reduced bone volume, representing both a major challenge and a significant demand for the use of diagnostic imaging methods prior to augmentation and im- planttreatment.ConventionalX-rayimagescontain only a two-dimensional information concerning the vertical height of the alveolar bone. Therefore, they represent an insufficient method for the appreciation of the horizontal bony dimensions.4 In comparison, three-dimensional (3-D) diagnostic tools like cone beam computed tomography (CBCT) offer the advantage of the visualisation of the so called ‘z-axis’, representing the bone volume in the horizontal,i.e.bucco-lingualdimensionofthealve- olarcrestrespectively.Apropertreatmentplanning and the use of 3-D diagnosis are therefore crucial parameters for a predictable and sustainable final treatmentoutcomeinimplanttherapy,especiallyin patientcaseswithsevereresorptionofthejawbone, like in our presented patient case. The oral examination and the CBCT-Scan (SCANORA, SOREDEX, Schutterwald, Germany) re- vealed a distinct bone resorption in the lower jaw, showing a more pronounced horizontal atrophy in the anterior part of the mandible (Figs. 2 & 3). According to the clinical measurements and the values of the 3-D CBCT scan, the interforaminal vertical bone height was between 22.0–25.0mm. The horizontal bone volume amounted to between Fig. 3 Fig. 4 Fig. 5 Fig. 6 42016

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