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

treatment planning based on CBCT cone beam supplement | 39 CAD/CAM 4 2016 dimensionsofthe alveolarridge appearedsufficient enough for implant placement (Fig. 10). The CBCT data confirmed the assumption, demonstrating a significant gain of bone volume in the interfo- raminal region of the mandible after augmentation. The horizontal thickness of the crestal alveolar bone was 5.53mm in region 44 and 4.43 in region 32. Theaugmentationprocedureresultedinahorizontal bone gain of about 3.9 mm in region 44 and 3.3mm in region 32 respectively, representing a mean bone gain of 3.6mm (Fig. 11). After elevating the flap, an apparently good osseointegration and stabilisa- tion of the autograft with the underlying pristine bone could be noticed (Fig. 12). Prior to implant placement, the fixation screws were removed. The four implants with a diameter of 3.75mm and a length of 11.5mm (BEGO Semados® RSX, BEGO Implant Systems) were inserted epicrestally in re- gions 33, 31, 41 and 43 using the freehand-method without a surgical guide (Fig. 13). The insertion torque of the implants was 35Ncm with good pri- mary stability. Pre-prosthetic surgery and prosthetic rehabilitation After three months of uneventful submerged healing, the panoramic X-ray showed a successful implant osseointegration without any signs of bone resorption (Fig. 14). Due to a lack of keratinised gin- giva, we decided for an enlargement of the ratio be- tween attached and free gingiva by performing mu- co-gingival surgery with the Edlan-Mejchar method (Figs. 15, 16 & 17). After an additional healing period of one month, the final bar retained, a removable acrylic overdenture was incorporated. The bar was constructed with bar abutments (PS TiBA, BEGO Im- plantSystems)andanon-preciousalloy(Wirobond®, BEGO Dental, Bremen) and was screw-retained on thefourimplants(Figs.18,19&20). Discussion In our case presentation, the patient suffered from an extremely horizontal bone resorption, re- sulting in a 1.0–3.0mm thin, and knife-edged alve- olar crest. Since standard diameter dental implants need a certain crestal bone volume for an adequate stabilisation and a good and predictable osseo- integration, augmentation procedures had to be performed prior to implant treatment.6 A recently published meta-analysis showed that dental implant survival has probably to be seen independently of the biomaterial used in augmen- tation procedures.7,8 Since this evidence is limited bythefact,thatdefectsize,augmentedvolume,and regenerative capacity are scarcely well described in literature,autogenousboneisstillrecommendedas the‘goldstandard’foraugmentationinthedeficient alveolar ridge. Simultaneous grafting and augmen- tationisthestandardprocedureinridgeaugmenta- tion, resulting in an extended operating time.3 Fortunately, as the vertical dimension of the an- teriormandiblewashighenoughinourclinicalcase, we were able to harvest an adequate autogenous bone block from the thin alveolar crest, in order to use it as an onlay graft for the horizontal augmen- tation of the anterior mandible. This procedure avoided donor site morbidity, and resulted in less operating time and a reduced patient discomfort. The dimensions of the graft were ideal for lateral augmentation, so that there was no need for any additional carving of the bone block. As mean bone gain after healing of the autogenous graft was Fig. 14: After three months of submerged healing, a successful implant osseointegration without bone resorption was visible on the panoramic X-ray. Fig. 15: Soft-tissue condition of the anterior alveolar crest at the time of implant-uncovering: lack of keratinised gingiva. Fig. 16: After uncovering the implants, an Edlan-Mejchar plastic surgery was performed to deepen the vestibulum. Fig. 17: Aspect after plastic surgery. Fig. 14 Fig. 15 Fig. 16 Fig. 17 42016

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