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ePaper created 2017-05-10, 16:12:25 | version 1.38.0
| case report restoration of the edentulous maxilla Fig. 12: Atlantis Conus Abutments seated. Note the “margins” of the abutment, and the point where the parallel preparation begins, is supra-gingivally positioned. Fig. 12 poured in vacuum-mixed die stone. After setting, the impression coping screws were removed and the im- pressions were separated from the hardened casts; standard laboratory procedures were followed in cleaning and trimming the working casts. Base plate and wax rims were made for continuation of the den- ture fabrication. The impression materials were re- moved from the duplicate denture and it was posi- tioned back onto the mandibular cast to be scanned. An online order was completed including identifica- tion of the implants involved and the case was shipped to Dentsply Sirona for the design and manu- facture of the Atlantis Conus Abutments. The working cast, implant analogue connections and the denture duplicate were scanned at the Atlantis production site and the abutments were individually designed using Atlantis VAD (Virtual Abutment Design) software to ensure that all abut- ments were parallel to each other. The restorative margin of each abutment were placed close to the soft tissue height surrounding each implant, but always supragingival to guarantee unobstructed seating of the finished restoration. Each abutment was milled to a 5-degree taper to match the SynCone caps ensuring an intimate fric- tion-fit. Upon design completion, the images of the abutment designs were made available for review and approval before manufacturing (Fig. 7). Once the de- sign presented was found to be satisfactory, approval for production of the patient-specific abutments was granted. It is important to note that no fees are in- curred by the dentist or dental laboratory during this process until design is agreed upon and authorisation to proceed is given. The abutments are custom-de- signed to fit specifically to the denture set-up or du- plicate denture provided; there are no sizes, heights, angles or collars to select from a catalogue and, there- fore, no risk of choosing incorrectly. When received, the Atlantis Conus Abutments were secured to the working cast with abutment screws, along with four prefabricated SynCone caps (Figs. 8 & 9). The caps were seated onto the abutments and sent to the dental laboratory to be impressed. The impression was poured twice, one in improved dental stone and one in refractory material for fabrication of a cast metal frame. While waiting for the frame to be completed, final try-in appointments for the denture set-up were completed, and the patient approved fabrication of the dentures. The denture set-up with a final bite record were returned to the dental lab, the cast metal frame was seated on the improved dental stone cast and areas around the stone copy of the SynCone caps were blocked out prior to processing. The SynCone caps will be captured intraorally, rather than having them pro- cessed in the dental laboratory. All work was com- pleted on the duplicate stone cast rather than the original working cast. The cast metal frame was opaqued to prevent grey show-through. The set-up was transferred to the cast with the metal frame and the dentures were processed (Figs. 10 & 11). Because the Atlantis Conus concept results in a fully implant-supported prosthesis, the peripheral borders of the finished structure were greatly reduced and the occlusal table was abbreviated at the first molar. The length of functional arch follows the iden- tical AP spread principles used for hybrid prosthetics to avoid excessively long cantilevers. At this point, the structure is a bridge and not an overdenture. To facilitate seating of the abutments in the patient, a clear matrix was made with the abut- Fig. 13: SynCone caps are fitted to the abutments to verify unobstructed and complete seating. Fig. 14: Rubber dam is placed over the abutments to prevent pick-up material from locking into undercut areas below the prepared margin. SynCone caps are seated and ready to be captured into the prosthesis. Fig. 13 Fig. 14 14 CAD/CAM 2 2017