Power density of various light curing units through resin inlays with modified layer thickness

Abstract

ObjectivesThe purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers.Materials and MethodsTo investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr). The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured.ResultsPower density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p < 0.05). Power density through 1.5 mm resin inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units.ConclusionsTo enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays.

Early Hardness and Shear Bond Strength of Dual-cure Resin Cement Light Cured Through Resin Overlays With Different Dentin-layer Thicknesses

“…Two layer combinations of resin overlays were fabricated according to our previous study: 17 resin overlays with dentin-layer thickness of 0.5 mm, enamel-layer thickness of 0.5 mm, and translucent-layer thickness of 0.5 mm (0.5-0.5-0.5 combination); and resin overlays with dentinlayer thickness of 0.2 mm, enamel-layer thickness of 0.5 mm, and translucent-layer thickness of 0.8 mm (0.2-0.5-0.8 combination).…”

“…Furthermore, resin inlays are fabricated with more than one layer; the dentin layer, the enamel layer, and the translucent layer are used simultaneously. Unfortunately, there are no studies evaluating how the thickness of each layer affects indirect composite resins, although the thickness of each layer affects the curing light penetration through resin inlays 17,18 and thereby the photopolymerization of DCRCs under resin inlays.…”

“…Higher-power density was measured through resin overlays with dentin-layer thickness of less than 0.2 mm and increased translucent-layer thickness in all LCUs. 17 Therefore the purpose of this study was to investigate whether 1.5-mm-thick resin overlays with dentin-, enamel-, and translucent-layer thicknesses of 0.5 mm each, or 0.2, 0.5, and 0.8 mm could affect the photopolymerization of the DCRC. At first, the DCRC was light cured through two layer thickness combinations of the resin overlays and microhardness was measured.…”

Effects of layering technique on the shade of resin overlays and the microhardness of dual cure resin cement

“…22 The power density of the LCU through resin overlays could be enhanced using enamel and translucent layers because these layers were less effective than the dentin layer in attenuation of the curing light. 11,22 Therefore, the relatively higher translucency of the enamel and translucent layers, compared to that of the dentin layer, enhanced the curing light penetration through the resin overlays and thus increased the photopolymerization of the DCRC. Consequently, the null hypothesis could be rejected.…”

“…7,10 On the other hand, incorporation of enamel and translucent layers on resin overlays increased curing light penetration through layered resin overlays. 11 Higher curing light penetration could enhance the light curing of DCRC beneath the resin overlays. 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.…”