Effect of different light sources on degree of conversion, hardness and plasticization of a composite

Authors

  • Bruno de Castro Ferreira Barreto Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
  • Anderson Catelan Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil
  • Ricardo Coelho Okida Department of Restorative Dentistry, Araçatuba School of Dentistry, State University of São Paulo, Araçatuba, SP, Brazil
  • Gisele Fernanda Gonçalves Department of Restorative Dentistry, Araçatuba School of Dentistry, State University of São Paulo, Araçatuba, SP, Brazil
  • Gisele Rodrigues da Silva Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
  • Paulo Henrique dos Santos DDS, MS, PhD, Associate Professor
  • Tathy Aparecida Xavier Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
  • Flávio Henrique Baggio Aguiar Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil
  • Carlos José Soares Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil

DOI:

https://doi.org/10.19177/jrd.v1e22013134-139

Keywords:

Composite resins, Polymers, Hardness, Dental materials

Abstract

Clinical performance of composite resins depends largely on their mechanical properties, and those are influenced by several factors, such as the light-curing mode. The purpose of this study was to evaluate the influence of different light sources on degree of conversion (DC), Knoop hardness (KHN) and plasticization (P) of a composite resin. Disc-shaped specimens (5 x 2 mm) of Esthet-X (Dentsply) methacrylate-based microhybrid composite were light-cured using quartz-tungsten-halogen (QTH) Optilight Plus (Gnatus) or light-emitting diode (LED) Ultraled (Dabi Atlante) curing units at 400 and 340 mW/cm2 of irradiance, respectively. After 24 h, absorption spectra of composite were obtained using Nexus 670 (Nicolet) FT-IR spectrometer in order to calculate the DC. The KHN was measured in the HMV-2000 (Shimadzu) microhardness tester under 50 g loads for 15 s, and P was evaluated by percentage reduction of hardness after 24 h of alcohol storage. Data were subjected to t-Student test (alpha = 0.05). QTH device showed lower P and higher KHN than LED (p < 0.05), and no difference between the light-curing units was found for DC (p > 0.05). The halogen-curing unit with higher irradiance promoted higher KHN and lower softening in alcohol than LED.

Author Biographies

  • Bruno de Castro Ferreira Barreto, Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
    DDS, Ms, PHD, Pos-doc
  • Anderson Catelan, Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil
    DDS, Ms, PHD student
  • Ricardo Coelho Okida, Department of Restorative Dentistry, Araçatuba School of Dentistry, State University of São Paulo, Araçatuba, SP, Brazil
    DDS, MS, PhD, Assistant Professor
  • Gisele Fernanda Gonçalves, Department of Restorative Dentistry, Araçatuba School of Dentistry, State University of São Paulo, Araçatuba, SP, Brazil
    Undergraduate
  • Gisele Rodrigues da Silva, Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
    DDS, Ms, PHD student, Assistant Professor
  • Paulo Henrique dos Santos, DDS, MS, PhD, Associate Professor
    Department of Dental Materials and Prosthodontics, Araçatuba School of Dentistry, State University of São Paulo, Araçatuba, SP, Brazil
  • Tathy Aparecida Xavier, Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
    DDS, Ms, PHD, Pos-doc
  • Flávio Henrique Baggio Aguiar, Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil
    DDS, Ms, PHD, Professor
  • Carlos José Soares, Department of Operative Dentistry and Dental Materials, Dental School, Federal University of Uberlandia, Uberlandia, MG, Brazil
    DDS, Ms, PHD, Professor and Chairman

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Published

2013-08-08

Issue

Vol. 1 No. 2 (2013)

Section

Articles

License

CC Attribution-NonCommercial-NoDerivatives 4.0