title: Halogen and LED light curing of composite: temperature increase and Knoop hardness.
abstract: This study assessed the Knoop hardness and temperature increase provided by three light curing units when using (1) the manufacturers' recommended times of photo-activation and (2) standardizing total energy density. One halogen--XL2500 (3M/ESPE)--and two light-emitting diode (LED) curing units--Freelight (3M/ESPE) and Ultrablue IS (DMC)--were used. A type-K thermocouple registered the temperature change produced by the composite photo-activation in a mold. Twenty-four hours after the photo-activation procedures, the composite specimens were submitted to a hardness test. Both temperature increase and hardness data were submitted to ANOVA and Tukey's test (5% significance). Using the first set of photo-activation conditions, the halogen unit produced a statistically higher temperature increase than did both LED units, and the Freelight LED resulted in a lower hardness than did the other curing units. When applying the second set of photo-activation conditions, the two LED units produced statistically greater temperature increase than did the halogen unit, whereas there were no statistical differences in hardness among the curing units.
authors.affiliation: Area Materiais Dentários, Departamento de Odontologia Restauradora, Faculdade de Odontologia de Piracicaba, Universidade Estadual de Campinas, CEP-13414-903, Piracicaba, Sao Paulo, Brazil.
authors.forename: L F
authors.initials: LF
authors.lastname: Schneider
authors.forename: S
authors.initials: S
authors.lastname: Consani
authors.forename: L
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: A B
authors.initials: AB
authors.lastname: Correr
authors.forename: M A
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D003764:Dental Materials / Q000737:chemistry / Q000528:radiation effects*; D004867:Equipment Design; D006244:Hardness; D006801:Humans; D008029:Lighting / Q000295:instrumentation*; D008422:Materials Testing; D013696:Temperature; D013821:Thermometers; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials