Light-activation through indirect ceramic restorations: does the overexposure compensate for the attenuation in light intensity during resin cement polymerization?
Abstract:ObjectivesThis study evaluated the effects of light exposure through simulated indirect
ceramic restorations (SICR) on hardness (KHN) of dual-cured resin cements (RCs),
immediately after light-activation and 24 h later.Material and Methods Three dual-cured RCs were evaluated: eco-Link (Ivoclar Vivadent), Rely X ARC (3M
eSPe), and Panavia F (Kuraray Medical Inc.). The RCs were manipulated in
accordance to the manufacturers’ instructions and were placed into cylindrical
acrylic matrixes (1-mm-thick and 4-mm diam… Show more
“…12,15,[19][20][21][22][23] However, there are no studies on the shade combinations of a resin inlay simulating the clinical situation including all the dentin, enamel, and translucent layers. In our previous study with the same indirect composite resin used in this study, we measured the power density of LCUs through resin overlays with various layer thickness combinations.…”
Reducing the dentin-layer thickness while increasing the translucent-layer thickness of resin inlays increases the photopolymerization of dual-cure resin cement, thereby increasing the early bond strength of resin inlays to dentin.
SUMMARYThe purpose of this study was to investigate whether dentin-layer thickness of resin overlays could affect the early hardness and shear bond strength of dual-cure resin cement (DCRC, RelyX ARC) after light curing with light curing units (LCUs) of various power densities: Optilux 360 (360), Elipar Freelight 2 (FL2), and Elipar S10 (S10). Resin overlays were fabricated using an indirect composite resin (Sinfony) with a dentin layer, an enamel layer, and a translucent layer of 0.5 mm thickness each (0.5-0.5-0.5) or of 0.2 mm, 0.5 mm, and 0.8 mm thickness (0.2-0.5-0.8), respectively. The DCRC was light cured for 40 seconds through the overlays, and surface hardness and shear bond strength to bovine dentin were tested 10 minutes after the start of light curing. Surface hardness was higher when the DCRC was light cured through the 0.2-0.5-0.8 combination than when the DCRC was light cured through the 0.5-0.5-0.5 combination with all LCUs. The ratio of upper surface hardness of DCRC light cured through resin overlays relative to the upper surface hardness of DCRC light cured directly was more than 90% only when the DCRC was light cured with S10 through the 0.2-0.5-0.8 combination. The shear bond strength value was higher when the DCRC was light cured with S10 through the 0.2-0.5-0.8 combination than when light cured with S10 through the 0.5-0.5-0.5 combination. This study indicates that reducing the dentin-layer thickness while increasing the translucent-layer thickness of
“…12,15,[19][20][21][22][23] However, there are no studies on the shade combinations of a resin inlay simulating the clinical situation including all the dentin, enamel, and translucent layers. In our previous study with the same indirect composite resin used in this study, we measured the power density of LCUs through resin overlays with various layer thickness combinations.…”
Reducing the dentin-layer thickness while increasing the translucent-layer thickness of resin inlays increases the photopolymerization of dual-cure resin cement, thereby increasing the early bond strength of resin inlays to dentin.
SUMMARYThe purpose of this study was to investigate whether dentin-layer thickness of resin overlays could affect the early hardness and shear bond strength of dual-cure resin cement (DCRC, RelyX ARC) after light curing with light curing units (LCUs) of various power densities: Optilux 360 (360), Elipar Freelight 2 (FL2), and Elipar S10 (S10). Resin overlays were fabricated using an indirect composite resin (Sinfony) with a dentin layer, an enamel layer, and a translucent layer of 0.5 mm thickness each (0.5-0.5-0.5) or of 0.2 mm, 0.5 mm, and 0.8 mm thickness (0.2-0.5-0.8), respectively. The DCRC was light cured for 40 seconds through the overlays, and surface hardness and shear bond strength to bovine dentin were tested 10 minutes after the start of light curing. Surface hardness was higher when the DCRC was light cured through the 0.2-0.5-0.8 combination than when the DCRC was light cured through the 0.5-0.5-0.5 combination with all LCUs. The ratio of upper surface hardness of DCRC light cured through resin overlays relative to the upper surface hardness of DCRC light cured directly was more than 90% only when the DCRC was light cured with S10 through the 0.2-0.5-0.8 combination. The shear bond strength value was higher when the DCRC was light cured with S10 through the 0.2-0.5-0.8 combination than when light cured with S10 through the 0.5-0.5-0.5 combination. This study indicates that reducing the dentin-layer thickness while increasing the translucent-layer thickness of
“…Poor monomer conversion of these materials might lead to low bond strength and high water sorption, compromising their physical properties. 8 The immediate light curing of dual-cured resin cements might cause a reduction in the degree of conversion. 9 The reason is that immediate light curing causes the rapid formation of cross-linked polymer chains, entrapping ª 2014 Wiley Publishing Asia Pty Ltd unreacted monomers and free radicals into the polymeric network, and thus jeopardizing the chemical curing.…”
A high-irradiance light-curing unit allows for a reduced irradiation exposure time with a short delay time, aimed at tooth restorations using a dual-cured resin cement.
“…Polymerization of resin cement is usually assessed by hardness tests, 12,13 and many studies on hardness measurements of DCRCs that were light cured through various indirect restorations were performed with one single shade. 14,15 However, in clinical situations, resin inlays are usually fabricated with a layering technique. Studies on the hardness of DCRCs light cured through resin overlays with a layering technique are difficult to find.…”
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 ΔE 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.
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