Ting Sun1, Shanyu Zhou2, Renfa Lai1, Ruoyu Liu2, Shuyuan Ma1, Zhiying Zhou1, Shao Longquan3. 1. The Medical Centre of Stomatology, the 1st Affiliated Hospital of Jinan University, Guangzhou 510630, China. 2. Department of Stomatology, Nanfang Hospital, Southern Medical University, No.1838, North of Guangzhou Street, Guangzhou 510515, Guangdong, China. 3. Department of Stomatology, Nanfang Hospital, Southern Medical University, No.1838, North of Guangzhou Street, Guangzhou 510515, Guangdong, China. Electronic address: shaolongquan@smu.edu.cn.
Abstract
PURPOSE: The aim of this study was to evaluate the load bearing capacity and a reasonable thicknesss of dental monolithic zirconia crowns. MATERIALS AND METHODS: Polymethyl methacrylate (PMMA) abutment tooth specimens were made by CAD/CAM technic. Monolithic zirconia crowns (MZC), monolithic lithium disilicate crowns (MLC), layered zirconia crowns (LZC) and metal ceramic crowns(MCC), of which the occlusal thickness was 1.5mm were thereafter fabricated and cemented on the abutment tooth specimens. MCC with occlusal thicknesses of 0.6mm, 0.8mm, 1.00mm, 1.2mm were also made. All specimens underwent load-to-fracture test. Weibull parameters (σ0) and (m) were calculated. Fracture modes were also evaluated. RESULTS: The mean fracture load was 1863.16±116.81 for MLC, 2284.77±355.60 for MCC, 2308.0±510.94 for LZC, 4109.93±610.18 for MZC (1.5mm), 3068.31±233.88 for MZC (1.2mm), 2429.88±315.03 for MZC (1.0mm), 1814.60±68.21 for MZC (0.8mm) and 1308.38±111.38 for MZC (0.6mm). The fracture load of MZC was significantly higher than MCC, LZC and MLC (P<0.05). The fracture loads for MCC with different thickness were significantly different (P<0.05). Similar trend was observed for the characteristic strength (σ0) and Weibull modulus (m). For MZC and MLC, the fracture mode was catastrophic failure. The predominant fracture mode for LZC was catastrophic fracture. The fracture loads of MZC(1.0mm) and MCC were not statistically different (P>0.05). CONCLUSIONS: Monolithic zirconia crowns exhibit higher fracture loads than monolithic lithium disilicate crowns, layered zirconia crowns and metal ceramic crowns. The fracture resistance of monolithic zirconia crowns with a thickness of 1.0mm can be equal to metal ceramic crowns. Doubling the monolithic zirconia core from 0.6mm to 1.5mm increases the fracture resistance of this restorative system threefold.
PURPOSE: The aim of this study was to evaluate the load bearing capacity and a reasonable thicknesss of dental monolithic zirconia crowns. MATERIALS AND METHODS:Polymethyl methacrylate (PMMA) abutment tooth specimens were made by CAD/CAM technic. Monolithic zirconia crowns (MZC), monolithic lithium disilicate crowns (MLC), layered zirconia crowns (LZC) and metal ceramic crowns(MCC), of which the occlusal thickness was 1.5mm were thereafter fabricated and cemented on the abutment tooth specimens. MCC with occlusal thicknesses of 0.6mm, 0.8mm, 1.00mm, 1.2mm were also made. All specimens underwent load-to-fracture test. Weibull parameters (σ0) and (m) were calculated. Fracture modes were also evaluated. RESULTS: The mean fracture load was 1863.16±116.81 for MLC, 2284.77±355.60 for MCC, 2308.0±510.94 for LZC, 4109.93±610.18 for MZC (1.5mm), 3068.31±233.88 for MZC (1.2mm), 2429.88±315.03 for MZC (1.0mm), 1814.60±68.21 for MZC (0.8mm) and 1308.38±111.38 for MZC (0.6mm). The fracture load of MZC was significantly higher than MCC, LZC and MLC (P<0.05). The fracture loads for MCC with different thickness were significantly different (P<0.05). Similar trend was observed for the characteristic strength (σ0) and Weibull modulus (m). For MZC and MLC, the fracture mode was catastrophic failure. The predominant fracture mode for LZC was catastrophic fracture. The fracture loads of MZC(1.0mm) and MCC were not statistically different (P>0.05). CONCLUSIONS: Monolithic zirconia crowns exhibit higher fracture loads than monolithic lithium disilicate crowns, layered zirconia crowns and metal ceramic crowns. The fracture resistance of monolithic zirconia crowns with a thickness of 1.0mm can be equal to metal ceramic crowns. Doubling the monolithic zirconia core from 0.6mm to 1.5mm increases the fracture resistance of this restorative system threefold.
Authors: Regina Furbino Villefort; Marina Amaral; Gabriel Kalil Rocha Pereira; Tiago Moreira Bastos Campos; Yu Zhang; Marco Antonio Bottino; Luiz Felipe Valandro; Renata Marques de Melo Journal: Dent Mater Date: 2017-01-21 Impact factor: 5.304