title: Influence of visible-light exposure on colour stability of current dual-curable luting composites.
abstract: This study was conducted to evaluate influence of visible-light exposure on colour stability of dual-curable luting composite. Using six dual-curable luting composites [Bistite II (BI), Clapearl DC (CL), Dicor Light Activated Cement (DI), G-Cera Cosmotech II (GC), Lute-It (LU) and Variolink II (VA), disk specimens were prepared with the following two methods: (i) dual-cured specimens, exposure with visible-light from a photo-curing unit for 120 s and (ii) chemical-cured specimens, chemically cured without exposure. Five specimens were produced for each material and curing mode. After 24 h, all specimens were immersed in distilled water at 37 degrees C for 24 weeks, during which colour accuracy was measured with a dental colorimeter. The colours characterized in the Commission Internationale d'Eclairage (CIE) L*a*b* colour space were first determined 24 h after preparation (baseline colour evaluation), and again after 1, 2, 3, 4, 8, 12, 16 and 24 weeks. The colour difference (Delta E*) values between 24 h and the other immersion periods were calculated, and then analysed by repeated measure analysis of variance (ANOVA). In addition, the Delta E* values after 24 weeks for dual-cured specimens were compared with those for chemical-cured specimens by one-way ANOVA and by contrasts for each composite (P < 0.05). The Delta E* values were influenced by the material and curing mode as well as immersion period (P=0.0001). After 24 weeks the dual-cured specimens showed significantly lower Delta E* values than the chemical-cured specimens, except for the VA material. The CL material exhibited the least colour change (1.9 +/- 0.2) among the dual-cured specimens, and the VA material showed the least (4.5 +/- 0.9) among the chemical-cured specimens after 24 weeks. Dual-curable luting composites should be polymerized with the dual modes to ensure colour stability.
authors.affiliation: Department of Fixed Prosthodontics, Nagasaki University School of Dentistry, Nagasaki, Japan. t-naomi@net.nagasaki-u.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Koishi
authors.forename: N
authors.initials: N
authors.lastname: Tanoue
authors.forename: M
authors.initials: M
authors.lastname: Atsuta
authors.forename: H
authors.initials: H
authors.lastname: Matsumura
mesh_terms: D000180:Acrylic Resins / Q000528:radiation effects; D000704:Analysis of Variance; D003116:Color; D003188:Composite Resins / Q000528:radiation effects; D003776:Dental Porcelain; D008027:Light; D017646:Organosilicon Compounds / Q000528:radiation effects; D011140:Polyurethanes / Q000528:radiation effects; D019279:Resin Cements / Q000528:radiation effects*
chemical_list: D000180:Acrylic Resins; C096475:Bistite Resin Cement; D003188:Composite Resins; C464960:Cosmotech II; C433207:Lute-It; D017646:Organosilicon Compounds; D011140:Polyurethanes; D019279:Resin Cements; C109838:clapearl bonding agent; D003776:Dental Porcelain; C059495:dicor cement; C103502:Variolink