title: Effect of light-activation with different light-curing units and time intervals on resin cement bond strength to intraradicular dentin.
abstract: The aim of this study was to assess the bond strength of a resin cement to intraradicular dentin varying the light-curing unit and the moment at which the light was applied. Post spaces of endodontically treated canines were prepared. The roots were distributed into 6 groups (n=10) according to the light-curing unit and the moment of light exposure: I) Quartz tungsten halogen-600 mW/cm² (QTH) + immediate light activation (t0); II) QTH + light activation after 10 min (t10); III) Light-emitting diodes (LED)-800 mW/cm² (LED-800)+ t0; IV) LED-800 + t10; V) LED-1,500 mW/cm² (LED-1500)+ t0; VI) LED-1500 + t10. After post cementation, slices from coronal, middle and apical post/root regions were submitted to the push-out test and failure evaluation. It was verified that LED-800 (4.40 ± 3.00 MPa) and LED-1500 (4.67 ± 3.04 MPa) provided bond strength statistically superior to QTH (3.13 ± 1.76 MPa) (p<0.05), and did not differ from each other (p>0.05). There was no significant difference between t0 and t10 (p>0.05). Coronal post/root region (4.75 ± 3.10 MPa) presented significantly higher bond strength than the apical (3.32 ± 2.30 MPa) (p<0.05) and middle regions (4.14 ± 2.99 MPa) showed intermediate values. Adhesive failures were predominant when using QTH. Adhesive and mixed failures occurred more frequently in the apical region. Higher adhesion of the resin cement to intraradicular dentin was observed in the coronal region with LED light-activation, regardless of the moment of light exposure.
authors.affiliation: Dental School, University of Ribeirão Preto, Ribeirão Preto, SP, Brazil.
authors.forename: Maria Eleonora
authors.initials: ME
authors.lastname: Miguel-Almeida
authors.forename: Mario Lucio da Costa
authors.initials: ML
authors.lastname: Azevedo
authors.forename: Fuad Abi
authors.initials: FA
authors.lastname: Rached-Júnior
authors.forename: Camila Favero
authors.initials: CF
authors.lastname: Oliveira
authors.forename: Ricardo Gariba
authors.initials: RG
authors.lastname: Silva
authors.forename: Danielle Cristine
authors.initials: DC
authors.lastname: Messias
mesh_terms: D000268:Adhesiveness; D002484:Cementation / Q000379:methods; D003188:Composite Resins / Q000737:chemistry; D055117:Curing Lights, Dental / Q000145:classification*; D003481:Cuspid / Q000648:ultrastructure; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure*; D005898:Glass / Q000737:chemistry; D006801:Humans; D006813:Humidity; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation / Q000379:methods*; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D011176:Post and Core Technique / Q000295:instrumentation; D019279:Resin Cements / Q000737:chemistry* / Q000528:radiation effects; D018915:Root Canal Preparation / Q000379:methods; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D019227:Tooth Apex / Q000648:ultrastructure; D019553:Tooth, Nonvital / Q000628:therapy
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C500742:ED Primer II; D008689:Methacrylates; C438843:Panavia-Fluoro; D019279:Resin Cements; C009753:fiberglass