Dental Tribune Pakistan Edition

Editor - Online Haseeb Uddin CLINICAL PRACTICE4 DENTAL TRIBUNE Pakistan Edition November 2014 n dental implantology, the optimal and truly passive fit of the framework is essential for the longterm success of a restoration owing to the physiology of bone tissue around implants. For a multiple-unit implant-supported restoration, the traditional pouring technique is rather complex and challenging. The difficulty of achieving a passive fit is directly correlated to the number of components used and the volume of the framework. CAD/CAM technology provides such a high level of accuracy that it has revolutionised the field of restorative dentistry. Today, many implant manufacturers collaborate with industrial companies to develop state-of-the- art machining solutions for their implant-supported frameworks. In that regard, the concept developed by Simeda (Anthogyr) is innovative and supported by many years of proven success in the fabrication of CAD/CAM dental restorations. The major advantage of CAD/CAM technology is that it guarantees a highly accurate and predictable fit (< 10 m). This clinical case report demonstrates the high potential of this novel digital solution. Patient presentation The male patient was a former smoker and 51 years old when the treatment was initiated. He presented with high blood pressure and took Tahor (pFizer) on a daily basis. In addition, he had been on Kardegic (Sanofi) therapy since a heart attack in 2005. For functional and aesthetic reasons, he wanted a fixed prosthesis in his maxillary arch (Figs. 1a & b). Debridement and pre-implant surgery Owing to the periodontal condition of his remaining maxillary teeth, all of them were atraumatically removed. Then, mechanical debridement was performed through alveolar curettage and copious irrigation with Betadine. A maxillary complete overdenture was fabricated and placed on the same day of the extractions. After a healing period of four months, DentaScan images (GE Healthcare) were obtained to evaluate the bone height. The scans showed significant bone resorption in the posterior sections of the maxillae (Figs. 2a–c): SA-4, according to Misch’s classification, since the residual ridge height was less than 5 mm. Sinus grafting was deemed necessary and implant placement had to be delayed by five to six months, until complete healing and good initial stability had been achieved. Bilateral sinus lift was performed under local anaesthesia from a lateral approach using the technique described by Tatum. The Schneiderian membrane was lifted gently. As there were no perforations, platelet-rich fibrin was used for coverage of the sinus floor. Maxgraft (botiss biomaterials) allografts were placed to elevate the maxillary sinus floor, and then covered with a Bio-Gide (Geistlich) collagen membrane and platelet-rich fibrin. After a healing period of five months, the patient underwent a CT scan wearing a scan prosthesis of acrylic resin and commercially available teeth for visibility of the desired tooth location in the CT images. The CT examination showed adequate bone volume in the grafted posterior regions and an even sinus floor with homogeneous allografted areas. The dome-like shape of the vestibulo-lingual crosssections was indicative of the absence of material leakage into the maxillary sinuses (Fig. 5a). Osteogenic activation I performed osteogenic activation of the processed maxgraft bone used for sinus lift using the technique described by Scortecci. A trans-parietal approach was used for insertion of the Bone Matrix Osteotensor (Victory) after a minimally invasive flapless protocol. Endosteal stimulation results in osteogenic activation and allows evaluation of the mechanical strength of the grafted areas by probing. Owing to this simple and minimally invasive technique, the initial quality of the future recipient bone site is easily assessed. These techniques have been successfully used in orthopaedics for ten years. In view of the excellent response to osteogenic activation, it was decided that implants would be placed 45 days later. Treatment planning The case was planned in the SIMPLANT (DENTSPLY Implants) treatment planning software. The scan prosthesis is critical for determination of the correct position and axial alignment of the implants; visualisation of the emergence profile; and determination of the size, position and axial alignment of the abutments. Furthermore, it allows optimal use of the available bone height. At this stage, special attention should be paid to 3-D positioning of the implants and particularly to the emergence profile in order to facilitate the fabrication process of the final restoration. Straight or angled conical abutments are now clearly visible on the vestibulo-lingual cross-sections. Ten Axiom PX implants (Anthogyr) were planned for a maxillary screw-retained bridge restoration (Figs.5a-c). Implant placement Implant placement was performed under local anaesthesia using the case-specific surgical guide. For this patient, I used a specific implant design (Axiom PX, Anthogyr) with symmetrical double- lead threads (selfdrilling and self-tapping) and a reverse conical neck. Its unique design, combined with a special drilling protocol, promotes bone conden sation even in soft bone, ensuring excellent initial fixation. The BCP (biphasiccalcium phosphate) sandblasting technique yields an implant surface with superior osteoconductive properties that positively influence the development of osteoblastic cells in the early stage of osseointegration. A flapless technique was used for implant placement. The flapless technique has definite advantages: preservation of the subperiosteal blood vessels, and improved patient comfort owing to a shorter operating time and simple post-operative care. Temporary bridge and immediate loading It was agreed with the patient that the implants would be immediately loaded, provided that good initial stability was obtained. The temporary removable prosthesis would be worn for a limited period. Fortunately, adequate stability was achieved, allowing for immediate loading. Each implant (except #27) was torqued to 35 Ncm or more. On the same day, an impression was made using the pick-up technique, with a previously prepared impression tray. First, the final straight conical abutments were hand tightened into the implants using a torque of 15 Ncm. They were intended to accommodate the screwretained provisional and then the final screwretained prosthesis. The Axiom PX implant system offers two major Author Dr Richard Marcelat, France I Fig. 1a Initial status. Fig. 1b Pre-op panoramic radiograph. Figs. 2a–c DentaScan images. Fig. 5a Implant placement planning in SIMPLANT (DENTSPLY Implants) software. Fig. 5b Implant placement planning in SIMPLANT (DENTSPLY Implants) software. Figs. 5c–d CT cross-sections. Fig. 7a Panoramic radiograph showing the temporary bridge placed 48 hours earlier. Figs. 7b The high-rigidity temporary bridge made of cobalt–chromium and resin. Fig. 8 Healing status at six months post-op. Fig. 9a The impression. Fig. 9b The interconnected pick-up transfer copings. Fig. 9c The wax bite block. Fig. 9d The master model. Fig. 1a Fig. 1b Fig. 2a Fig. 2cFig. 2b Fig. 5b Fig. 5c Fig. 5d Fig. 7a Fig. 7b Fig. 8 Fig. 9a Fig. 9b Fig. 9c Fig. 9d Use of a full-arch bridge in the maxillae: A case report Contribution of CAD/CAM technology to implant-supported screw-retained restorations Fig. 5a

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