Optical characteristics of resin composite before and after polymerization / 대한치과보존학회지

OBJECTIVES: The aim of this study was to evaluate the optical characteristics such as color and translucency changes before and after light curing, to quantify the CQ and to measure refractive indices of body and opaque shade of resin composites materials. MATERIALS AND METHODS: Resin composites used in this study were A2 body and A2 opaque shade of Esthet-X, Filtek supreme, Gradia Direct, Clearfil Majesty and Beautifil?? Color and translucency changes before and after light curing were evaluated by colorimeter, the CQ was quantified by GC-MS and refractive index changes were measured by spectroscopic ellipsometer. RESULTS: Translucency parameter (TP) was significantly increased after curing. The CQ content of body shades are higher than that of opaque shades in all resin composites. Refractive index increased after polymerization in all materials and significant difference in Deltarefractive index was found between body and opaque shade (significance level 0.05). CONCLUSIONS: For an accurate shade match, direct shade matching of resin composite should be performed by using the cured material.

The effect of reinforcing methods on fracture strength of composite inlay bridge / 대한치과보존학회지

The purpose of this study is to evaluate the effects of surface treatment and composition of reinforcement material on fracture strength of fiber reinforced composite inlay bridges. The materials used for this study were I-beam, U-beam TESCERA ATL system and ONE STEP(Bisco, IL, USA). Two kinds of surface treatments were used; the silane and the sandblast. The specimens were divided into 11 groups through the composition of reinforcing materials and the surface treatments. On the dentiform, supposing the missing of Maxillary second pre-molar and indirect composite inlay bridge cavities on adjacent first pre-molar disto-occlusal cavity, first molar mesio-occlusal cavity was prepared with conventional high-speed inlay bur.The reinforcing materials were placed on the proximal box space and build up the composite inlay bridge consequently. After the curing, specimen was set on the testing die with ZPC. Flexural force was applied with universal testing machine (EZ-tester; Shimadzu, Japan). at a cross-head speed of 1 mm/min until initial crack occurred. The data wasanalyzed using one-way ANOVA/Scheffes' post-hoc test at 95% significance level. Groups using I-beam showed the highest fracture strengths (p 0.05). Most of the specimens in groups that used reinforcing material showed delamination. 1. The use of I-beam represented highest fracture strengths (p 0.05). 3. The reinforcing materials affect the fracture strength and pattern of composites inlay bridge. 4. The holes at the U-beam did not increase the fracture strength of composites inlay bridge.