Danilo Gonzaga B de França1, Maria Helena S T Morais2, Flávio D das Neves3, Gustavo A S Barbosa4. 1. Assistant Professor, Department of Dentistry, School of Dentistry, State University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil. Electronic address: danillogonzaga@yahoo.com.br. 2. Graduate student, Department of Dentistry, School of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil. 3. Associate Professor, Department of Fixed Prosthodontics, Occlusion and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil. 4. Associate Professor, Department of Dentistry, School of Dentistry, Federal University of Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil.
Abstract
STATEMENT OF PROBLEM: Relatively little information is available on the accuracy of the abutment-implant interface in computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated zirconia and cobalt-chromium frameworks. PURPOSE: The purpose of this study was to compare the fit accuracy of CAD/CAM-fabricated zirconia and cobalt-chromium frameworks and conventionally fabricated cobalt-chromium frameworks. MATERIAL AND METHODS: Four groups of 3-unit, implant-supported, screw-retained frameworks were fabricated to fit an in vitro model with 3 implants. Eight frameworks were fabricated with the CAD/CAM system: 4 in zirconia and 4 in cobalt-chromium. Another 8 were cast in cobalt-chromium with conventional casting, including 4 with premachined abutments and 4 with castable abutments. The vertical misfit at the implant-framework interface was measured with scanning electron microscopy when only 1 screw was tightened and when all screws were tightened. Data were analyzed with the Kruskal-Wallis and Mann-Whitney tests (α=.05). RESULTS: The mean vertical misfit values when all screws were tightened was 5.9 ±3.6 μm for CAD/CAM-fabricated zirconia, 1.2 ±2.2 μm for CAD/CAM-fabricated cobalt-chromium frameworks, 11.8 ±9.8 μm for conventionally fabricated cobalt-chromium frameworks with premachined abutments, and 12.9 ±11.0 μm for the conventionally fabricated frameworks with castable abutments; the Mann-Whitney test found significant differences (P<.05) among all frameworks, except between the conventionally fabricated frameworks (P=.619). No significant differences were found among the groups for passive fit gap measurements (P>.05). CONCLUSIONS: When all of the screws were tightened, the CAD/CAM frameworks exhibited better fit accuracy compared with the conventionally fabricated frameworks. High levels of passive fit were achieved for the evaluated techniques.
STATEMENT OF PROBLEM: Relatively little information is available on the accuracy of the abutment-implant interface in computer-aided design and computer-aided manufacturing (CAD/CAM)-fabricated zirconia and cobalt-chromium frameworks. PURPOSE: The purpose of this study was to compare the fit accuracy of CAD/CAM-fabricated zirconia and cobalt-chromium frameworks and conventionally fabricated cobalt-chromium frameworks. MATERIAL AND METHODS: Four groups of 3-unit, implant-supported, screw-retained frameworks were fabricated to fit an in vitro model with 3 implants. Eight frameworks were fabricated with the CAD/CAM system: 4 in zirconia and 4 in cobalt-chromium. Another 8 were cast in cobalt-chromium with conventional casting, including 4 with premachined abutments and 4 with castable abutments. The vertical misfit at the implant-framework interface was measured with scanning electron microscopy when only 1 screw was tightened and when all screws were tightened. Data were analyzed with the Kruskal-Wallis and Mann-Whitney tests (α=.05). RESULTS: The mean vertical misfit values when all screws were tightened was 5.9 ±3.6 μm for CAD/CAM-fabricated zirconia, 1.2 ±2.2 μm for CAD/CAM-fabricated cobalt-chromium frameworks, 11.8 ±9.8 μm for conventionally fabricated cobalt-chromium frameworks with premachined abutments, and 12.9 ±11.0 μm for the conventionally fabricated frameworks with castable abutments; the Mann-Whitney test found significant differences (P<.05) among all frameworks, except between the conventionally fabricated frameworks (P=.619). No significant differences were found among the groups for passive fit gap measurements (P>.05). CONCLUSIONS: When all of the screws were tightened, the CAD/CAM frameworks exhibited better fit accuracy compared with the conventionally fabricated frameworks. High levels of passive fit were achieved for the evaluated techniques.
Authors: Pedro Molinero-Mourelle; Rocio Cascos-Sanchez; Burak Yilmaz; Walter Yu Hang Lam; Edmond Ho Nang Pow; Jaime Del Río Highsmith; Miguel Gómez-Polo Journal: Materials (Basel) Date: 2021-04-30 Impact factor: 3.623
Authors: Paulo Ribeiro; Mariano Herrero-Climent; Carmen Díaz-Castro; José Vicente Ríos-Santos; Roberto Padrós; Javier Gil Mur; Carlos Falcão Journal: Int J Environ Res Public Health Date: 2018-07-27 Impact factor: 3.390