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KMID : 1035320170440020107
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Korean Society for Dental Materials
2017 Volume.44 No. 2 p.107 ~ p.117
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Mechanical Properties of Ceramic/Polymer Blocks for CAD/CAM Dental Restoration
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Ku Seung-Won
Park Jong-Hwan
Ko Yeong-Mu
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Abstract
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The goal for restorative dentistry is to replace lost tooth substance by a restorative material whose properties are similar to a natural tooth. The increasing demand for esthetics, combined with health and environmental concerns about some metallic restorations, has stimulated research in metal-free restorations. For this purpose, CAD/CAM technology has been introduced in dentistry 3 decades ago and is rapidly becoming popular. It reduces the number of clinical sessions and increased quality in a shorter period of time. Furthermore, allows to extend the use of ceramics with life-like appearance, color stability, chemical stability, have good mechanical and optical properties, as well as excellent biocompatibility. Although ceramics has been widely used for dental CAD/CAM blocks, still experience a relatively high f ailure r ate due to the brittlene ss. Another potential hazard i s e xce ssive we ar o f the opposing t ee th due to the high hardness. Ceramic/polymer composite blocks, so called resin nanoceramics or hybrid ceramics have recently been introduced to the market. They improved the machinability and edge stability with suppressing the brittleness. They are easier to operate and repair if necessary. The mechanical p rope rties of two c ommercially a vailable de ntal C AD/CAM b locks, P olyglass (Ve ricom, K orea) a nd Enamic (Vita, Germany), were investigated in this study. Commercial blocks were cut into (4.0×1.2×17.0) mm to determine the flexural strength with a three-point bending test. The surface microhardness and fracture toughness were also measured. Weibull characteristics and elastic modulus were calculated. Polyglass consists of irregular-shaped ceramics in an organic resin matrix, while Enamic composes ceramic network infiltrated with cured polymers. Polyglass showed higher values in flexural strength (132.30±7.04 MPa), Weibull modulus (22.46) and fracture toughness (1.47±0.73 MPa√m) than those of Enamic (113.73±10.93 MPa, 12.72, and 1.21±0.51 MPa√m). In contrast, Enamic exhibited higher values in elastic modulus (7.0±0.4 GPa) and hardness (2.18±0.52 GPa) than those of Polyglass (5.1±0.8 GPa and 0.86±0.09 GPa).
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KEYWORD
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Dental, Aesthetic restoration, CAD/CAM, Block, Composite resin, Ceramic, Strength, Weibull analysis, Fracture toughness, Hardness
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