title: Effects of ceramic thickness and curing unit on light transmission through leucite-reinforced material and polymerization of dual-cured luting agent.
abstract: This study investigated the influence of ceramic thickness and curing unit on light transmission through leucite-reinforced material and polymerization of a dual-cured resin luting agent. Discs of Empress Esthetic (Ivoclar Vivadent) of 0.7-, 1.4- and 2-mm thickness were prepared. Variolink II (Ivoclar Vivadent) was placed in a 1-mm-thick cylindrical mold, and light-activated through ceramic for 40 s, using QTH or LED units. The samples were divided into dual, light, and chemically-polymerized control groups. Knoop hardness indentations were made on the top and bottom surfaces. Data were subjected to split-plot design three-way ANOVA and Tukey's test (P < 0.05). The light spectrum transmitted through ceramic was obtained using a spectrometer. Samples activated through 1.4-and 2-mm-thick discs showed lower hardness than all others groups, except for the chemical control group. Dual and light-polymerized control samples showed similar hardness to those activated through the 0.7-mm ceramic, whereas chemically polymerized control samples showed similar hardness to those activated through 1.4- and 2-mm ceramics. No significant differences in hardness were detected between the curing units or between the top and bottom layers. No significant alteration in the light spectrum profile was observed for both units, irrespective of the ceramic thickness.
authors.affiliation: Department of Restorative Dentistry, Dental Materials Division, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: Milena C
authors.initials: MC
authors.lastname: Pazin
authors.forename: Rafael R
authors.initials: RR
authors.lastname: Moraes
authors.forename: Luciano S
authors.initials: LS
authors.lastname: Gonçalves
authors.forename: Gilberto A
authors.initials: GA
authors.lastname: Borges
authors.forename: Mário A C
authors.initials: MA
authors.lastname: Sinhoreti
authors.forename: Lourenço
authors.initials: L
authors.lastname: Correr-Sobrinho
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D055095:Optics and Photonics; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; C075815:IPS-Empress ceramic; D011108:Polymers; D019279:Resin Cements; D003776:Dental Porcelain; C078519:leucite; C103502:Variolink