Fracture, roughness and phase transformation in CAD/CAM milling and subsequent surface treatments of lithium metasilicate/disilicate glass-ceramics

Alao, Abdur-Rasheed, Stoll, Richard, Song, Xiao-Fei, Abbott, John R., Zhang, Yu, Abduo, Jaafar, and Yin, Ling (2017) Fracture, roughness and phase transformation in CAD/CAM milling and subsequent surface treatments of lithium metasilicate/disilicate glass-ceramics. Journal of the Mechanical Behavior of Biomedical Materials, 74. pp. 251-260.

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Abstract

This paper studied surface fracture, roughness and morphology, phase transformations, and material removal mechanisms of lithium metasilicate/disilicate glass ceramics (LMGC/LDGC) in CAD/CAM-milling and subsequent surface treatments. LMGC (IPS e.max CAD) blocks were milled using a chairside dental CAD/CAM milling unit and then treated in sintering, polishing and glazing processes. X-ray diffraction was performed on all processed surfaces. Scanning electron microscopy (SEM) was applied to analyse surface fracture and morphology. Surface roughness was quantitatively characterized by the arithmetic average surface roughness Ra and the maximum roughness Rz using desktop SEM-assisted morphology analytical software. The CAD/CAM milling induced extensive brittle cracks and crystal pulverization on LMGC surfaces, which indicate that the dominant removal mechanism was the fracture mode. Polishing and sintering of the milled LMGC lowered the surface roughness (ANOVA, p < 0.05), respectively, while sintering also fully transformed the weak LMGC to the strong LDGC. However, polishing and glazing of LDGC did not significantly improve the roughness (ANOVA, p > 0.05). In comparison of all applied fabrication process routes, it is found that CAD/CAM milling followed by polishing and sintering produced the smoothest surface with Ra = 0.12 ± 0.08 µm and Rz = 0.89 ± 0.26 µm. Thus, it is proposed as the optimized process route for LMGC/LDGC in dental restorations. This route enables to manufacture LMGC/LDGC restorations with cost effectiveness, time efficiency, and improved surface quality for better occlusal functions and reduced bacterial plaque accumulation.

Item ID: 52781
Item Type: Article (Research - C1)
ISSN: 1878-0180
Keywords: CAD/CAM milling; fracture; lithium metasilicate/disilicate glass-ceramics; material removal mechanisms; roughness; surface treatments
Funders: James Cook University (JCU), Department of Industry, Innovation, Climate Change, Science, Research and Tertiary Education, Australia (DIICCSRTE), National Science Foundation of China (NSFC), National Institutes of Health (NIH), USA, National Institute of Dental and Craniofacial Research (NIDCR)
Projects and Grants: JCU IPRS, JCU Collaboration Grants Scheme, DIICCSRTE Grant no. ACSRF GMB 12029, NSFC Grant no. 51375335, NIH Grant no. R01DE017925, NIDCR Grant no. R01DE026772
Research Data: https://www.sciencedirect.com/science/article/pii/S1751616117302540
Date Deposited: 05 Mar 2018 01:21
FoR Codes: 09 ENGINEERING > 0912 Materials Engineering > 091201 Ceramics @ 60%
09 ENGINEERING > 0912 Materials Engineering > 091206 Glass @ 40%
SEO Codes: 92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920402 Dental Health @ 100%
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