journal of prosthodontic research 59 (2015) 210–212
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/jpor
Letter to the Editor Wear of tooth enamel against silver–palladium–gold alloy and two other restorative materials in vitro
Keywords: Wear
The purpose of the present study was to evaluate the wear of enamel against Ag–Pd–Au alloy, an indirect resin composite, a disilicate glass ceramic, and tooth enamel by means of a wear simulation.
Metal Alloy Resin composite
1.
Specimen preparation
Ceramic Enamel
Dear Editor, Silver–palladium–gold (Ag–Pd–Au) alloy has been widely used for fabricating inlays, crowns, and fixed partial dentures in Japan. Some tooth-colored restorative materials, such as ceramics and resin composites, have been also developed as alternative to Ag–Pd–Au alloy. When selecting a restorative material, abrasiveness of the material is one of the greatest concerns for clinicians. A number of wear simulations, including 10 methods (ACTA, Alabama [generalized, localized, sliding], Ivoclar [vertical, volumetric], Munich, OHSU [abrasion, attrition], and Zurich), have been performed to estimate the wear characteristics of restorative materials [1,2]. Wear of antagonistic enamel caused by a highly filled indirect resin composite was significantly higher than that caused by gold alloy in an Alabama localized wear test [3]. A few investigations have focused on the wear characteristics of Ag–Pd–Au alloy using two-body sliding tests. The wear loss of a highly filled indirect resin composite against Ag–Pd– Au alloy was not significantly different from that against enamel [4]. The mutual wear of a resin composite/tooth enamel pair was less than that of a resin composite/Ag–Pd–Au alloy pair [5]. However, limited information regarding the wear of antagonistic enamel against Ag–Pd–Au alloy and the alternative materials has been published, and direct wear behavior between enamel and Ag–Pd–Au alloy has been overlooked.
Hemispherical stylus heads 4.0 mm in diameter were fabricated with Ag–Pd–Au alloy (New Kinpalladium, Morita Corp., Tokyo, Japan; Lot No. 0707523), an indirect resin composite (Gradia, E3; GC Corp., Tokyo, Japan; Lot No. 1211272), a lithium disilicate glass (e.max Press, LT A3; Ivoclar Vivadent AG, Liechtenstein; Lot No. R78685), and bovine tooth enamel. The stylus heads cast with Ag–Pd–Au alloy were polished with silicone mounted polishing points (M2 and M3, Shofu Inc., Kyoto, Japan). The stylus heads of e.max Press and Gradia were made according to the manufacturers’ instructions and then polished with a polishing paste (Zircon-Brite, Dental Ventures of America Inc., Corona, CA, U.S.A.) on a felt wheel. Bovine anterior tooth was ground with custom-shaped rotary instruments (Carborundum Point, Shofu) to form the stylus head, and the enamel surface was polished with silicone mounted polishing points (M2 and M3, Shofu Inc., Kyoto, Japan). Additional bovine anterior tooth was ground flat with #600 silicon carbide paper and used for antagonist specimens.
2.
Two-body localized wear test
A wear simulator (Higuchi Corp., Nagasaki, Japan) was prepared according to a wear test developed at the University of Alabama [6,7]. As the stylus head vertically contacted the antagonist specimen in water, it rotated clockwise 15 degrees with an increasing load up to 75 N and then counter-rotated to the starting position. We applied 100,000 wear cycles at a frequency of 1.2 Hz. The worn surfaces of the antagonist specimens were observed by color laser three-dimensional profile microscopy (VK-8500, Keyence Corp., Osaka, Japan) at a
journal of prosthodontic research 59 (2015) 210–212
211
Table 1 – Volume loss of enamel antagonist after wear test.
Stylus
Mean (SD) (mm3)
Ag-Pd-Au alloy
0.06 (0.04)
Statistical comparisons for all pairs
p
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/jpor
Letter to the Editor Wear of tooth enamel against silver–palladium–gold alloy and two other restorative materials in vitro
Keywords: Wear
The purpose of the present study was to evaluate the wear of enamel against Ag–Pd–Au alloy, an indirect resin composite, a disilicate glass ceramic, and tooth enamel by means of a wear simulation.
Metal Alloy Resin composite
1.
Specimen preparation
Ceramic Enamel
Dear Editor, Silver–palladium–gold (Ag–Pd–Au) alloy has been widely used for fabricating inlays, crowns, and fixed partial dentures in Japan. Some tooth-colored restorative materials, such as ceramics and resin composites, have been also developed as alternative to Ag–Pd–Au alloy. When selecting a restorative material, abrasiveness of the material is one of the greatest concerns for clinicians. A number of wear simulations, including 10 methods (ACTA, Alabama [generalized, localized, sliding], Ivoclar [vertical, volumetric], Munich, OHSU [abrasion, attrition], and Zurich), have been performed to estimate the wear characteristics of restorative materials [1,2]. Wear of antagonistic enamel caused by a highly filled indirect resin composite was significantly higher than that caused by gold alloy in an Alabama localized wear test [3]. A few investigations have focused on the wear characteristics of Ag–Pd–Au alloy using two-body sliding tests. The wear loss of a highly filled indirect resin composite against Ag–Pd– Au alloy was not significantly different from that against enamel [4]. The mutual wear of a resin composite/tooth enamel pair was less than that of a resin composite/Ag–Pd–Au alloy pair [5]. However, limited information regarding the wear of antagonistic enamel against Ag–Pd–Au alloy and the alternative materials has been published, and direct wear behavior between enamel and Ag–Pd–Au alloy has been overlooked.
Hemispherical stylus heads 4.0 mm in diameter were fabricated with Ag–Pd–Au alloy (New Kinpalladium, Morita Corp., Tokyo, Japan; Lot No. 0707523), an indirect resin composite (Gradia, E3; GC Corp., Tokyo, Japan; Lot No. 1211272), a lithium disilicate glass (e.max Press, LT A3; Ivoclar Vivadent AG, Liechtenstein; Lot No. R78685), and bovine tooth enamel. The stylus heads cast with Ag–Pd–Au alloy were polished with silicone mounted polishing points (M2 and M3, Shofu Inc., Kyoto, Japan). The stylus heads of e.max Press and Gradia were made according to the manufacturers’ instructions and then polished with a polishing paste (Zircon-Brite, Dental Ventures of America Inc., Corona, CA, U.S.A.) on a felt wheel. Bovine anterior tooth was ground with custom-shaped rotary instruments (Carborundum Point, Shofu) to form the stylus head, and the enamel surface was polished with silicone mounted polishing points (M2 and M3, Shofu Inc., Kyoto, Japan). Additional bovine anterior tooth was ground flat with #600 silicon carbide paper and used for antagonist specimens.
2.
Two-body localized wear test
A wear simulator (Higuchi Corp., Nagasaki, Japan) was prepared according to a wear test developed at the University of Alabama [6,7]. As the stylus head vertically contacted the antagonist specimen in water, it rotated clockwise 15 degrees with an increasing load up to 75 N and then counter-rotated to the starting position. We applied 100,000 wear cycles at a frequency of 1.2 Hz. The worn surfaces of the antagonist specimens were observed by color laser three-dimensional profile microscopy (VK-8500, Keyence Corp., Osaka, Japan) at a
journal of prosthodontic research 59 (2015) 210–212
211
Table 1 – Volume loss of enamel antagonist after wear test.
Stylus
Mean (SD) (mm3)
Ag-Pd-Au alloy
0.06 (0.04)
Statistical comparisons for all pairs
p
