title: New-generation curing units and short irradiation time: the degree of conversion of microhybrid composite resin.
abstract: This in vitro study investigated the depth of cure of a microhybrid composite resin when cured with reduced times of exposure to three commercially available curing lights. Different sample thicknesses (1, 2, and 3 mm) were light cured in high intensity polymerization mode (2,400 mW/cm² for 5, 10, 15, and 20 seconds; 1,100 mW/cm² for 10, 20, 30, and 40 seconds; and 1,100 mW/cm² for 10, 20, 30, and 40 seconds, respectively). The degree of conversion (%) at the bottom of each sample was measured by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis after each polymerization step. Data were analyzed by ANOVA for repeated measures, showing the degree of conversion was not influenced by the curing light employed (P = .622) but was significantly influenced by the thickness of composite resin (P < .05). Variations in the degree of conversion vs the shorter irradiation time permitted (T1) were not significant among different lamps but were significant among different thicknesses. The depth of cure of microhybrid composite resin appears not to be influenced by the curing light employed. Increased irradiation time significantly increases the degree of conversion. Thickness strongly influences depth of cure.
authors.affiliation: Department of Cariology and Operative Dentistry, School of Dentistry, University of Turin, Turin, Italy. nicola.scotti@unito.it
authors.forename: Nicolla
authors.initials: N
authors.lastname: Scotti
authors.forename: Alberto
authors.initials: A
authors.lastname: Venturello
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Migliaretti
authors.forename: Francesco
authors.initials: F
authors.lastname: Pera
authors.forename: Damiano
authors.initials: D
authors.lastname: Pasqualini
authors.forename: Francesco
authors.initials: F
authors.lastname: Geobaldo
authors.forename: Elio
authors.initials: E
authors.lastname: Berutti
mesh_terms: D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D055117:Curing Lights, Dental; D006244:Hardness; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013997:Time Factors
chemical_list: D003188:Composite Resins; C470230:Gradia