title: Effect of different light-curing devices and aging procedures on composite knoop microhardness.
abstract: The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC) and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S) on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s) on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.
authors.affiliation: Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, SP, Brazil. fervoltarelli@hotmail.com
authors.forename: Fernanda Regina
authors.initials: FR
authors.lastname: Voltarelli
authors.forename: Claudia Batitucci
authors.initials: CB
authors.lastname: dos Santos-Daroz
authors.forename: Marcelo Corrêa
authors.initials: MC
authors.lastname: Alves
authors.forename: Alessandra Rezende
authors.initials: AR
authors.lastname: Peris
authors.forename: Giselle Maria
authors.initials: GM
authors.lastname: Marchi
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D055117:Curing Lights, Dental; D003799:Dental Stress Analysis; D006245:Hardness Tests; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008029:Lighting / Q000295:instrumentation; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; D011108:Polymers