79 Maxillary implant overdentures: two implants in atrophic jaws Surgical procedure All the implants were planned in the canine region using 3D Virtual Surgical Planning using computer software (Proplan CMF software; Materialise, Leuven, Belgium) to ensure an optimised implant location from both a surgical and prosthetic perspective. The implant positions were transferred to surgical template using computer software (3-Matic Medical 11.0; Materialise, Leuven, Belgium). All the participants were treated under local anaesthesia (Ultracain® D-S forte, Sanofi Aventis, Gouda, Netherlands) by the same oral and maxillofacial surgeon (GMR). The implants were placed using the surgical template and consecutive diameter drill sleeves, following the manufacturer’s instructions. After removal of the template, two implants (Nobel Active NP 3.5mm, Nobel Biocare®, Zurich, Switzerland) were placed with a minimum torque of 45 Ncm. Small bone dehiscences were covered with intra-orally harvested bone and a resorbable membrane (Bio-Gide®, Geistlich Pharma North America Inc., Princeton, USA). After the insertion of cover screws, the flap was repositioned and sutured. All participants received antibiotics (500mg Clamoxyl, GlaxoSmithKline, Utrecht, the Netherlands) for seven days, three times daily. The participants were instructed not to wear their conventional denture for two weeks and to rinse their mouth with 0.2% chlorhexidine twice daily (Corsodyl, GlaxoSmithKline, Utrecht, the Netherlands). After two weeks, the sutures were removed and the conventional denture was relined with a soft reline (Soft-Liner, GC, Leuven, Belgium). After three months of osseointegration the implants were provided with healing abutments during a second surgical procedure, which was followed by the prosthodontic procedure. Prosthodontic procedure Using a stock metal tray (Schreinemakers; Clan Dental Products, Maarheeze, the Netherlands), a preliminary alginate impression (Cavex CA 37; Cavex Holland BV, Haarlem, the Netherlands) was made to enable the dental technician to fabricate an individual impression tray of acrylic resin (Lightplast base plates; Dreve Dentamid GmbH, Unna, Germany). After relining the rims of the individual tray with a thermoplastic material (ISO Functional; GC Europe A.G., Leuven, Belgium) and placing screw-retained impression copings to the implants, the final impression was made with a polyether material (Impregum F; 3M ESPE, St. Paul, MN, USA). The vertical dimensions and intermaxillary relations were recorded with wax rims and a pin registration device. Acrylic resin teeth (Ivoclar SR Orthotyp DCL and Ivoclar VivodentPE, Ivoclar Vivadent AG, Schaan, Liechtenstein) were positioned for a trial arrangement following a bilateral balanced occlusion concept. For the implant superstructure two matrix copings (Locator® RTX, Zest Dental Solutions, Carlsbad, California, USA) were placed into the overdenture’s base. All copings were initially provided with medium force nylon attachment caps, enabling up- or down-grading the retentive force if needed. For additional support, all the overdenture were designed with full palatal coverage (Figure 5.1a-c). At overdenture placement, all the participants received hygiene instructions for their overdenture and mesostructure and were scheduled for routine maintenance recalls. All the prosthodontic procedures were performed by one prosthodontists (HJAM). 5
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