Surface quality of yttria-stabilized tetragonal zirconia polycrystal in CAD/CAM milling, sintering, polishing and sandblasting processes

Alao, Abdur-Rasheed, Stoll, Richard, Song, Xiao-Fei, Miyazaki, Takashi, Hotta, Yasuhiro, Shibata, Yo, and Yin, Ling (2017) Surface quality of yttria-stabilized tetragonal zirconia polycrystal in CAD/CAM milling, sintering, polishing and sandblasting processes. Journal of the Mechanical Behavior of Biomedical Materials, 65. pp. 102-116.

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Abstract

This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (Rₐ) and maximum roughness (R(z)) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software. X-ray diffraction patterns prove the sintering-induced monoclinic-tetragonal phase transformation while the sandblasting-induced phase transformation was not detected. The CAD/CAM milling of pre-sintered Y-TZP produced very rough surfaces with extensive fractures and cracks. Simply polishing or sintering of milled pre-sintered surfaces did not significantly improve their surface roughness (ANOVA, p>0.05). Neither sintering-polishing of the milled surfaces could effectively improve the surface roughness (ANOVA, p>0.05). The best surface morphology was produced in the milling-polishing-sintering process, achieving Rₐ=0.21±0.03 µm and R(z)=1.73±0.04 µm, which meets the threshold for bacterial retention. Sandblasting of intaglios with smaller abrasives was recommended as larger abrasive produced visible surface defects. This study provides technical insights into process selection for Y-TZP to achieve the improved restorative quality.

Item ID: 46595
Item Type: Article (Refereed Research - C1)
Keywords: CAD/CAM milling; material removal mechanisms; phase transformation; surface damage; surface morphology; surface treatments; yttria-stabilized tetragonal zirconia polycrystal
ISSN: 1878-0180
Funders: James Cook University (JCU), Australia-China Science and Research Fund (ACSRF), Department of Industry, Innovation, Climate Change, Science, Research and Tertiary Education, Australia (DIICCSRTE), National Natural Science Foundation of China (NNSFC)
Projects and Grants: JCU Collaboration Grants Scheme (2013-14), DIICCSRTE/ACSRF Grant no. ACSRF GMB 12029, NNSFC Grant no. 51375335
Date Deposited: 08 Dec 2016 01:03
FoR Codes: 09 ENGINEERING > 0912 Materials Engineering > 091201 Ceramics @ 60%
11 MEDICAL AND HEALTH SCIENCES > 1105 Dentistry > 110599 Dentistry not elsewhere classified @ 40%
SEO Codes: 86 MANUFACTURING > 8610 Ceramics, Glass and Industrial Mineral Products > 861002 Ceramics @ 50%
92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920402 Dental Health @ 50%
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