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statement of the problem: optical properties of the composite resins, concerning their translucency and thickness, are affected by discolored tooth structure or inherent darkness of the oral cavity. purpose: this study aimed to compare the translucency parameter (tp) of five different composite resins in different thicknesses and to evaluate their masking ability in black backgrounds. materials...

Objectives: Metal-ceramic restorations are the standard by which all esthetic restorations are measured. Fracture of dental restorations is a multifactorial problem, which is serious and costly. Debonding of porcelain from metal substructure and the bond strength depend on many factors. The purpose of this study was to determine whether or not the opaque porcelain thickness has a significant ef...

The metals for porcelain fusing used in this study were gold alloys and nickel-chromium alloys. Chromatic characteristics were compared between samples of 0.1, 0.2 and 0.3 mm thickness. The dentin porcelain was fused on the opaque surface. Chromatic analyses were then carried out at each stage of 0.1 mm-incremental reductions of the dentin thickness starting from 0.5 mm. In conclusion, the meta...

Opaque colony variants of two strains of group A streptococci have been compared with blue colonies of the same strains by electron microscopy. In opaque colonies, the cocci are joined into elongated chains by exaggerated intercellular septa that often occupy the major portion of each cell's circumference. The thickness and lamination of cell walls in opaque colony variants are identical to tho...

This study evaluated the masking ability of two opaques applied in different thicknesses. Eighty NiCr metal discs 16 mm in diameter and 1.0 mm thick were prepared. The disks were divided into 8 groups (n = 10). Ceramic opaque in paste (groups 1 to 4) or powder (groups 5 to 8) presentations were applied. They were machined with aluminum oxide burs to the following thicknesses: G1 and G5 = 0.10 m...

OBJECTIVES The aim of this study was to assess the influence of various ceramic thicknesses and luting agents on color variation in five ceramic systems. METHODS Fifteen disc-shaped ceramic specimens (11 mm diameter; shade A3) were fabricated with each of the six veneering ceramics tested, with 1, 1.5, or 2 mm thickness (n=5). Resin composite discs (Z-250, shade C4) were used as bases to simu...

The final color matching of porcelain crowns depends upon the accuracy of the original shade matching by the dentist and variables introduced during processing. Possible sources of processing variables include thickness and color of the opaque, thickness, color, and translucency of the body and enamel layers, firing temperature, and number of firings (Miller, 1987). These processing variables c...