Effects of layering technique on the shade of resin overlays and the microhardness of dual cure resin cement.
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The purpose of this study was to assess the color of layered resin overlays and to test the early microhardness of dual cure resin cement (DCRC) light cured through the layered resin overlays. Resin overlays of 1.5 mm thickness were fabricated with the A3 shade of Z350 (Group 1L), the A3B and A3E shades of Supreme XT (Group 2L), and the A3, E3, and T1 shades of Sinfony (Group 3L) using one, two, and three layers, respectively (n=7). Each layer of the resin overlays was set in equal thickness. The color of the resin overlays was measured with a colorimeter and compared with an A3 shade resin denture tooth. DCRC was light cured through the resin overlays, and the early microhardness of the DCRC was measured. The DeltaE value between the denture tooth and the resin overlays and the Vickers hardness number (VHN) of the DCRC were analyzed with one-way ANOVA and Tukey's HSD test. The color differences were 8.9+/-0.5, 5.3+/-1.0, and 7.3+/-0.5 and the VHNs were 19.4+/-1.1, 21.1+/-0.9, and 29.3+/-0.6 for Groups 1L, 2L, and 3L, respectively. Therefore, to match the designated tooth color of resin inlays and to increase the early microhardness of DCRC, layered resin inlays are more appropriate than single-dentin-layer resin inlays. However, the translucent layer should be used cautiously because the color difference of resin inlays with a translucent layer was affected more than those without a translucent layer. (+info)
Characterization of enamel and dentin surfaces after removal of temporary cement--effect of temporary cement on tensile bond strength of resin luting cement.
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This study was performed to investigate the effect of temporary sealing with cement on the tensile bond strength of resin luting cement to tooth substrate. Five temporary cements and five resin luting cements were used. Six hundred bovine incisor teeth were randomly divided between each group. Effect of temporary sealing on the tensile bond strength of resin luting cement varied in accordance with the temporary cement used. Temporary sealing with both the eugenol-containing and the eugenol-free temporary cements decreased the tensile bond strength of resin luting cement. The tensile bond strength with one of the resin luting cements was most stable on both enamel and dentin pretreated with all temporary cements tested. (+info)
The extent of polymerization of Class II light-cured composite resin restorations; effects of incremental placement technique, exposure time and heating for resin inlays.
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The extent of polymerization of light-cured composite resins cured in relatively large class II cavities was estimated by measuring Knoop hardness on sectioned surfaces of resin restorations. The influences of the incremental placement technique, exposure time, and post-curing of resin inlay on the extent of polymerization of two different resin materials were examined. For both MFR type (HE) and hybrid type (P50) materials, the 3-step incremental placement technique was superior when the cavity was restored by the direct filling method. For resin inlays, the post-heating improved the conversion of resin restorations. However, because the final degree of conversion of resin attained by heating was influenced by the initial conversion of the resin at the stage of light-curing, the 2-step incremental placement technique was recommended at the light-curing stage for even resin inlays. As the exposure time is influenced by the transmittance of material and the intensity of activator light, it should be optimized in accordance with manufacturers' directions. (+info)
Glazing and finishing dental porcelain: a literature review.
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BACKGROUND: Dental porcelain has found an increased number of applications in recent years with the development of new methods for the construction of porcelain veneers and intracoronal restorations. In addition, it is used in metal-ceramic and all-porcelain crowns and bridges for the restoration of anterior and posterior teeth. METHODS: This paper presents a review of a number of studies that have examined the visual and microscopic appearance and roughness of glazed, unglazed and polished porcelain surfaces using techniques such as, scanning electron microscopy and surface profilometry. FINDINGS: All have agreed that glazed porcelain provides a smooth and dense surface. Many have shown that polishing can produce an equally smooth surface, which may even be esthetically better. Some studies supported the use of polishing as an alternative to glazing. However, reports have shown that unglazed porcelain is more abrasive than glazed. CLINICAL SIGNIFICANCE: This paper aims to guide general practitioners in the proper polishing of adjusted porcelain in the dental office. The recommendations of various authors are summarized in Table I. (+info)