Bjørn Einar Dahl1, Hans Jacob Rønold2, Jon E Dahl3. 1. Doctoral student, Department of Prosthetic Dentistry, Institute of Clinical Dentistry, Dental Faculty, University of Oslo, Oslo, Norway. Electronic address: b.e.dahl@odont.uio.no. 2. Associate Professor, Department of Prosthetic Dentistry, Institute of Clinical Dentistry, Dental Faculty, University of Oslo, Oslo, Norway. 3. Professor, Institute of Clinical Dentistry, Dental Faculty, University of Oslo, Oslo, Norway; and CEO, Nordic Institute of Dental Materials, Oslo, Norway.
Abstract
STATEMENT OF PROBLEM: Whether single crowns produced by computer-aided design and computer-aided manufacturing (CAD-CAM) have an internal fit comparable to crowns made by lost-wax metal casting technique is unknown. PURPOSE: The purpose of this in vitro study was to compare the internal fit of single crowns produced with the lost-wax and metal casting technique with that of single crowns produced with the CAD-CAM technique. MATERIAL AND METHODS: The internal fit of 5 groups of single crowns produced with the CAD-CAM technique was compared with that of single crowns produced in cobalt-chromium with the conventional lost-wax and metal casting technique. Comparison was performed using the triple-scan protocol; scans of the master model, the crown on the master model, and the intaglio of the crown were superimposed and analyzed with computer software. The 5 groups were milled presintered zirconia, milled hot isostatic pressed zirconia, milled lithium disilicate, milled cobalt-chromium, and laser-sintered cobalt-chromium. RESULTS: The cement space in both the mesiodistal and buccopalatal directions was statistically smaller (P<.05) for crowns made by the conventional lost-wax and metal casting technique compared with that of crowns produced by the CAD-CAM technique. CONCLUSIONS: Single crowns made using the conventional lost-wax and metal casting technique have better internal fit than crowns produced using the CAD-CAM technique.
STATEMENT OF PROBLEM: Whether single crowns produced by computer-aided design and computer-aided manufacturing (CAD-CAM) have an internal fit comparable to crowns made by lost-wax metal casting technique is unknown. PURPOSE: The purpose of this in vitro study was to compare the internal fit of single crowns produced with the lost-wax and metal casting technique with that of single crowns produced with the CAD-CAM technique. MATERIAL AND METHODS: The internal fit of 5 groups of single crowns produced with the CAD-CAM technique was compared with that of single crowns produced in cobalt-chromium with the conventional lost-wax and metal casting technique. Comparison was performed using the triple-scan protocol; scans of the master model, the crown on the master model, and the intaglio of the crown were superimposed and analyzed with computer software. The 5 groups were milled presintered zirconia, milled hot isostatic pressed zirconia, milled lithium disilicate, milled cobalt-chromium, and laser-sintered cobalt-chromium. RESULTS: The cement space in both the mesiodistal and buccopalatal directions was statistically smaller (P<.05) for crowns made by the conventional lost-wax and metal casting technique compared with that of crowns produced by the CAD-CAM technique. CONCLUSIONS: Single crowns made using the conventional lost-wax and metal casting technique have better internal fit than crowns produced using the CAD-CAM technique.