Ibrahim Salim Duqum1, Christian Brenes2, Gustavo Mendonca3, Thiago Almedia Prado Naves Carneiro4, Lyndon F Cooper5. 1. Division of Comprehensive Oral Health- Prosthodontics, Adams School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC. 2. Department of General Dentistry, Dental College of Georgia at Augusta University, Augusta, GA. 3. Biologic & Materials Sciences, Division of Prosthodontics, University of Michigan, Ann Arbor, MI. 4. Department of Occlusion, Fixed Prostheses, and Dental Materials, School of Dentistry, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil. 5. Associate Dean for Research, College of Dentistry, University of Illinois at Chicago.
Abstract
PURPOSE: To evaluate the marginal fit of CAD/CAM all ceramic crowns made from lithium disilicate and zirconia using two different fabrication protocols (model and model-less). MATERIALS AND METHODS: Forty anterior all ceramic restorations (20 lithium disilicate, 20 zirconia) were fabricated from digital impressions using a CEREC Bluecam scanner. Two different digital workflows were used: a fully digital model-less approach and a printed model digital approach. The crowns were cemented on the respective prepared typodont teeth and marginal gap was evaluated using Micro-CT. Each specimen was analyzed in sagittal and trans-axial orientations, allowing evaluation of the marginal fit (vertical and horizontal) on each surface. Logarithmic transformation was used with a significance of 0.05. After that a reliability analysis was performed by re-measuring four randomized selected images for each specimen and performing intraclass correlations to determine any systematic bias in the measurements. RESULTS: Vertical measurements in the lingual, distal and mesial views had an estimated marginal gap ranging from 101.9 to 133.9 µm for lithium disilicate crowns and 126.4 to 165.4 µm for zirconia. No significant differences were found between model and model-less techniques. CONCLUSIONS: Both workflows are valid protocols for the fabrication of monolithic ceramic restorations. The use of a printed model did not improve the marginal fit of lithium disilicate or zirconia crowns. Both materials are also clinically acceptable, no matter which workflow was used to obtain the restoration.
PURPOSE: To evaluate the marginal fit of CAD/CAM all ceramic crowns made from lithium disilicate and zirconia using two different fabrication protocols (model and model-less). MATERIALS AND METHODS: Forty anterior all ceramic restorations (20 lithium disilicate, 20 zirconia) were fabricated from digital impressions using a CEREC Bluecam scanner. Two different digital workflows were used: a fully digital model-less approach and a printed model digital approach. The crowns were cemented on the respective prepared typodont teeth and marginal gap was evaluated using Micro-CT. Each specimen was analyzed in sagittal and trans-axial orientations, allowing evaluation of the marginal fit (vertical and horizontal) on each surface. Logarithmic transformation was used with a significance of 0.05. After that a reliability analysis was performed by re-measuring four randomized selected images for each specimen and performing intraclass correlations to determine any systematic bias in the measurements. RESULTS: Vertical measurements in the lingual, distal and mesial views had an estimated marginal gap ranging from 101.9 to 133.9 µm for lithium disilicate crowns and 126.4 to 165.4 µm for zirconia. No significant differences were found between model and model-less techniques. CONCLUSIONS: Both workflows are valid protocols for the fabrication of monolithic ceramic restorations. The use of a printed model did not improve the marginal fit of lithium disilicate or zirconia crowns. Both materials are also clinically acceptable, no matter which workflow was used to obtain the restoration.
Authors: Andrés Sánchez-Monescillo; Carlos González-Serrano; José González-Serrano; João Malta Barbosa; Carlos López-Suárez; Sillas Duarte Journal: Materials (Basel) Date: 2021-12-18 Impact factor: 3.623