title: Effect of Lithium Disilicate Veneers of Different Thickness on the Degree of Conversion and Microhardness of a Light-Curing and a Dual-Curing Cement.
abstract: OBJECTIVE
  Various materials and systems for bonding lithium disilicate to the tooth substrate are available to clinicians, who can adapt the materials to each clinical situation to maximize the performance of indirect esthetic restorations. This study aimed to evaluate the degree of conversion (DC) and the microhardness (MH) of a dual-curing and a light-curing cement under lithium disilicate discs of different thicknesses.
  
  
  METHODS
  A total of 48 lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) samples were prepared and divided into three groups (n = 16) according to the thickness (group A was 0.6 mm; group B was 1.0 mm; group C was 1.5 mm). Each group was further divided into two subgroups (n = 8) according to the resin cement employed, NX3 (Kerr) or Choice 2 (Bisco). A standardized quantity of cement was placed on the sample, and DC was evaluated with an attenuated total reflectance Fourier transformed infrared spectrophotometer (Nicolet IS10, Thermo Scientific). Twenty-four hours after DC was established, Vickers test was performed on the cement with a microindentometer (Leica Microsystems). Results were statistically analyzed with analysis of variance test and significance set at P < .05.
  
  
  RESULTS
  Statistical analysis showed cement type had a significant influence (P = .005) on DC. MH results were influenced by thicknesses only between 0.6 and 1.5 mm when light-cured cement was employed.
  
  
  CONCLUSIONS
  The light-curing and the dual-curing cements reached comparable DCs between 0.6 and 1.5 mm. However, the light-curing resin showed a higher DC and MH.
authors.forename: Nicola
authors.initials: N
authors.lastname: Scotti
authors.forename: Allegra
authors.initials: A
authors.lastname: Comba
authors.forename: Milena
authors.initials: M
authors.lastname: Cadenaro
authors.forename: Luca
authors.initials: L
authors.lastname: Fontanive
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Breschi
authors.forename: Carlo
authors.initials: C
authors.lastname: Monaco
authors.forename: Roberto
authors.initials: R
authors.lastname: Scotti
mesh_terms: D003738:Dental Cements / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D008422:Materials Testing
chemical_list: D003738:Dental Cements; C493120:lithia disilicate; D003776:Dental Porcelain