title: Microstructure and nanoindentation analyses of low-temperature aging on the zirconia-porcelain interface.
abstract: The aim of the present study was to investigate the effects of low-temperature aging on the micro-mechanical and micro-structural properties of zirconia-porcelain interface. In total, thirty-three Y-TZP zirconia blocks were fabricated by using CAD/CAM technology, veneered with porcelains. Specimens were submitted to low-temperature aging in an autoclave at 134°C, additional 0.2MPa pressure for 0h, 5h, or 10h. Flexural strength was obtained by using three-point bending test. Micro-mechanical properties (nano-hardness (H) and reduced modulus (Er)) were investigated by nanoindentation tests. Scanning electron microscopy and X-ray diffraction analyses were performed to identify the micro-structure and fracture behavior. The flexure strength, modulus and hardness of zirconia increased after 5h aging and decreased after 10h aging. No significant alterations of the reduced modulus or hardness of porcelain were detected in the whole aging duration. Width of the zirconia-porcelain interface was extended towards the bulk of zirconia. The detachment and cracks could be observed in zirconia, and the crystal alignment was disorganized in porcelain after 5h aging and 10h aging. Mechanical properties of the veneering porcelain are not affected by low-temperature aging. However, the expansion and the alterations of micro-mechanical and micro-structural properties of zirconia-porcelain interface were detected.
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237# Luo Yu Road, Wuhan, China.
authors.forename: M D
authors.initials: MD
authors.lastname: Peng
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237# Luo Yu Road, Wuhan, China.
authors.forename: J Q
authors.initials: JQ
authors.lastname: Wei
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237# Luo Yu Road, Wuhan, China. Electronic address: wang.yn@whu.edu.cn.
authors.forename: Y N
authors.initials: YN
authors.lastname: Wang
authors.affiliation: The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237# Luo Yu Road, Wuhan, China. Electronic address: li.q@whu.edu.cn.
authors.forename: Q
authors.initials: Q
authors.lastname: Li
mesh_terms: D003776:Dental Porcelain; D003801:Dental Veneers; D008422:Materials Testing; D013499:Surface Properties; D013696:Temperature; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
keywords: Flexural strength; Low-temperature aging; Nanoindentation; Zirconia-based restorations; Zirconia-porcelain interface