title: Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements.
abstract: This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements.
  
  
  
  A total of 80 ceramic veneer disks were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These disks were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into four subgroups, based on ceramic disk thickness (0.3, 0.6, 0.9, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm(2)) with respect to microhardness and degree of conversion was statistically evaluated by using analysis of variance (ANOVA).
  
  
  
  For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (p < 0.05). For the MH values between LC and DC resin cement groups, there was statistically significant difference (p < 0.05); overall, the MH values of LC resin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (p < 0.05). However, among the LC subgroups, there was no statistically significant difference among them (p > 0.05).
  
  
  
  The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup.
  
  
  
  While clinically adequate polymerization of LC resin cement can be achieved with a maximum 1.2 mm of porcelain veneer restoration, the increase of curing time or light intensity is clinically needed for DC resin cements at the thickness of more than 0.9 mm.
authors.affiliation: Assistant Professor and Director, Department of General Dental Sciences Predoctoral Prosthodontics and Biomaterials, Marquette University School of Dentistry, 1801 W Wisconsin, Ave, 53233 Milwaukee, Wisconsin, USA, Phone: (414)288-5411, e-mail: seokhwan.cho@marquette.edu.
authors.forename: Seok-Hwan
authors.initials: SH
authors.lastname: Cho
authors.affiliation: Marquette University School of Dentistry, Milwaukee Wisconsin, USA.
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Lopez
authors.affiliation: Department of General Dental Sciences, Graduate Dental Biomaterials, Marquette University School of Dentistry Milwaukee, Wisconsin, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Berzins
authors.affiliation: Department of General Dental Sciences, Marquette University School of Dentistry, Milwaukee, Wisconsin, USA.
authors.forename: Soni
authors.initials: S
authors.lastname: Prasad
authors.affiliation: Division of Biostatistics, Medical College of Wisconsin Milwaukee, Wisconsin, USA.
authors.forename: Kwang Woo
authors.initials: KW
authors.lastname: Ahn
mesh_terms: D055117:Curing Lights, Dental / Q000145:classification; D003776:Dental Porcelain / Q000737:chemistry*; D003801:Dental Veneers; D006244:Hardness; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D058105:Polymerization; D011829:Radiation Dosage; D019279:Resin Cements / Q000737:chemistry*; D055116:Self-Curing of Dental Resins / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: C508050:IPS e.max Press; D019279:Resin Cements; C493120:lithia disilicate; D003776:Dental Porcelain
keywords: Laboratory research; Resin cement; Thickness; Veneer.