Degree of Conversion of a Resin Cement Light-Cured Through Ceramic Veneers of Different Thicknesses and Types

Abstract

During the cementation of ceramic veneers the polymerization of resin cements may be jeopardized if the ceramics attenuate the irradiance of the light-curing device. The aim of this study was to evaluate the effect of different types and thicknesses of ceramic veneers on the degree of conversion of a light-cured resin-based cement (RelyX Veneer). The cement was light-cured after interposing ceramic veneers [IPS InLine, IPS Empress Esthetic, IPS e.max LT (low translucency) and IPS e.max HT (high translucency) - Ivoclar Vivadent] of four thicknesses (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm). As control, the cement was light-cured without interposition of ceramics. The degree of conversion was evaluated by FTIR spectroscopy (n=5). Data were analyzed with one-way ANOVA and Tukey's test (α=0.05). Significant differences were observed among groups (p<0.001). The degree of conversion was similar to the control for all light-cured groups with interposition of ceramics of 0.5 mm and 1.0 mm (p>0.05). Among 1.5-mm-thick veneers, IPS e.max LT was the only one that showed different results from the control (p<0.05). At the thickness of 2.0 mm, only the IPS e.max LT and HT veneers were able to produce cements with degrees of conversion similar to the control (p>0.05). The degree of conversion of the evaluated light-cured resin cement depends on the thickness and type of ceramics employed when veneers thicker than 1.5 mm are cemented.

Polymerization shrinkage stress of composite resins and resin cements – What do we need to know?

“…2 When indirect restorations are recommended, esthetic onlays and crowns bonded with resin cement are the first option. 3 The optimal performance of all these direct and indirect restorations depend on proper polymerization of the resin component, which is characterized by transforming monomers into polymers, which is accompanied by volumetric reduction of the material. 4 A polymer occupies less volume than the monomers, the effect of which is well known as polymerization shrinkage.…”

Influence of Hemostatic Solution on Bond Strength and Physicochemical Properties of Resin Cement

“…The increasing demand for porcelain laminate veneers has led to the continuous development of dental ceramics with improved optical properties, translucency, and esthetics (1). It is well known that restorative ceramic materials require a clinical stage of bonding to tooth structures with adhesive resin cements (2).…”

“…The use of light-cured cements is based on the concept that the light emitted by curing units could pass through some indirect restorations, due to their translucency and reduced thickness (1). When bonding is effective, adhesive luting promotes increased fracture resistance of ceramic materials by cement penetration into the irregularities present at the internal surface of the restoration, leading to higher bond strength and lower crack propagation (4) Moreover, photoactivated resin cements (light-cured) have better color stability compared with that of chemically or dual-cured resin cements (5).…”

Degree of conversion of a flowable composite light-activated through ceramics of different shades and thicknesses

“…This clinical advantage, however, should not be the determinant factor for material choice in veneer cementation due to the possible attenuating effect provided by thickness, opacity and shades [11][12][13] . Additionally, the type and microstructure of the interposing ceramic material are significant factors in the properties of polymerized luting materials 14 .…”

“…In general, the use of these light-activated cements should be limited to some clinical situations such as inlays, veneers and onlays, in which the thickness and shade of restoration do not affect the ability of light to reach and activate the cement 15 . Considering the light-activated resin cements for veneers and onlays cementation, the polymerization quality is related to several factors such as photo-activation light source, irradiance, irradiation time, material composition and light attenuation caused by ceramic 11,[13][14][16][17][18] . It was observed that the transmittance of light through ceramic decreases as function of the material interposed between the light source and the resin cement 19 .…”