title: Influence of photoactivation method and mold for restoration on the Knoop hardness of resin composite restorations.
abstract: The aim of this study was to evaluate in vitro the Knoop hardness in the top and bottom of composite photo activated by different methods when different mold materials were used. Z250 (3M ESPE) and XL2500 halogen unit (3M ESPE) were used. For hardness test, conical restorations were made in extracted bovine incisors (tooth mold) and also metal mold (approximately 2 mm top diameter × 1.5 mm bottom diameter × 2 mm in height). Different photoactivation methods were tested: high-intensity continuous (HIC), low-intensity continuous (LIC), soft-start, or pulse-delay (PD), with constant radiant exposure. Knoop readings were performed on top and bottom restoration surfaces. Data were submitted to two-way ANOVA and Tukey's test (p = 0.05). On the top, regardless of the mold used, no significant difference in the Knoop hardness (Knoop hardness number, in kilograms-force per square millimeter) was observed between the photoactivation methods. On the bottom surface, the photoactivation method HIC shows higher means of hardness than LIC when tooth and metal were used. Significant differences of hardness on the top and in the bottom were detected between tooth and metal. The photoactivation method LIC and the material mold can interfere in the hardness values of composite restorations.
authors.affiliation: Department of Dentistry, Implantology Area, University of Santo Amaro, Rua Prof. Eneas de Siqueira Neto, 340, 04829-300, São Paulo, SP, Brazil. williamcbrandt@yahoo.com.br
authors.forename: William Cunha
authors.initials: WC
authors.lastname: Brandt
authors.forename: Lais Regiane
authors.initials: LR
authors.lastname: Silva-Concilio
authors.forename: Ana Christina Claro
authors.initials: AC
authors.lastname: Neves
authors.forename: Eduardo Jose Carvalho
authors.initials: EJ
authors.lastname: de Souza-Junior
authors.forename: Mario Alexandre Coelho
authors.initials: MA
authors.lastname: Sinhoreti
mesh_terms: D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000528:radiation effects*; D003793:Dental Restoration, Permanent / Q000379:methods*; D006244:Hardness / Q000528:radiation effects; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D013499:Surface Properties
chemical_list: D003188:Composite Resins