Papers by Keyword: Veneering Ceramic

Abstract: Zirconia ceramics are now widely used in dental restorations. The veneering porcelain chipping happens sometimes in zirconia-porcelain all-ceramic system. The objective of this study was to evaluate the bonding strength between the zirconia core and various commercial veneering ceramics. The shearing and bending methods were used to evaluate the bonding strengths of zirconia core and four veneering ceramics. Meanwhile, as surface treatment will play an important role for the bonding strength, the influence of 3 kinds of surface treatment was investigated. The results indicated that both the shearing and bonding strengths of Cercon ceram kiss is better. Moreover sand blasting is the most useful method of surface treatment.

Abstract: The dental community is using a variety of ceramic restorative materials such as porcelains (leucite or alumina based), glass-ceramics (leucite, mica, lithium disilicates), alumina-glass infiltrated, and CAD-CAM ceramics including pure alumina and zirconia (3Y-TZP) core materials. Polycrystalline ceramics such as alumina and zirconia serve as substructure materials (i.e., framework or core) upon which glassy ceramics are veneered for an improved appearance. Under masticatory loads, sudden fracture of the full-thickness restoration or of the veneering ceramic (chips) may occur. Stereomicroscope and scanning electron microscope analyses were used to perform qualitative (descriptive) fractography on clinically failed dental ceramic restorations. The most common features visible on the fracture surfaces of the glassy veneering ceramic of recovered broken parts were hackle, wake hackle, twist hackle, arrest lines, and compression curls. The observed features are indicators of the local direction of crack propagation and were used to trace the crack’s progression back to its initial starting zone (the origin). This paper presents the applicability of fractographic failure analyses for understanding fracture processes in brittle dental restorative materials and it draws conclusions as to possible design or processing inadequacies in failed restorations.

Abstract: This study investigated the effect of multiple firing on the wear behavior of dental all-ceramic veneering ceramic (Cercon). Samples were fabricated according to the manufacturer's requirement for different firing times. The wear test was operated under simulated oral environment. The results showed that multiple firing could influence wear behavior of all-ceramic Veneer. Significant difference was observed in wear scar width among different samples. All the groups except 7time-firing one showed good wear resistance with low wear rate, smooth surface and relatively constant frictional coefficient. With the increasing firing times the wear scar width became larger. The wear resistance of dental ceramic after seven times firing was significantly lower. SEM/DFM results showed the wear facets of veneering ceramic demonstrate grooves characteristic of abrasive wear. The significant change was that severe wear dominated by brittle fracture could be seen in the 7time-firing group. Multiple firing can decrease the wear resistance of dental all-ceramic Veneer, and the wear pattern has the tendency to severe wear. The possible explanation is that the microstructure and properties of all-ceramic Veneering changed during multiple firing.

Abstract: This in vitro study compared the wear behavior between the enamel/dentine, two types of dental veneering ceramics for all-ceramic restorations (Vita-alpha，Vintage -AL ). A variety of factors including hardness, fracture toughness, flexural strength, frictional coefficients, wear scar width, element concentrations were considered. The wear scars of the samples were characterized by dynamic atomic force microscopy (DFM). The element concentrations of the surface before/after the wear test were determined with energy dispersion spectrometry (EDS). In this study Enamel/dentine, Vita-alpha and Vintage-AL have showed good wear resistance. The results also showed that there were statistical significance in samples. The friction coefficient varied from time in each kind of materials. The analytical differences between materials were observed in wear width and properties of materials (p<0.05). The wear ability among four materials ranked from highest to lowest as follows, Vintage-AL, Vita-alpha, enamel and dentine. DFM results demonstrated the wear patterns of natural tooth detected as abrasive and denaturation of dental texture. Wear patterns of tested veneering ceramics consisted mainly of abrasive wear, adhesion and fatigue wear and the different pattern plays different roles in Vita-alpha and Vintage-AL. The EDS results showed the element concentration of Fe was obviously found on the samples. Resistance ability against wear of veneering ceramics is better than that of natural human teeth. And the ability may have some correlation with the ceramics mechanical properties.