Degree of conversion and mechanical properties of a BisGMA: TEGDMA composite as a function of the applied radiant exposure

Fernanda C. Calheiros, Márcia Daronch, Frederick Rueggeberg, Roberto R. Braga

Research output: Contribution to journalArticle

52 Scopus citations

Abstract

Objective: Verify the influence of radiant exposure (H) on composite degree of conversion (DC) and mechanical properties. Methods: Composite was photoactivated with 3, 6, 12, 24, or 48 J/cm2. Properties were measured after 48-h dry storage at room temperature. DC was determined on the flat surfaces of 6 mm x 2 mm disk-shaped specimens using FTIR. Flexural strength (FS) and modulus (FM) were accessed by three-point bending. Knoop microhardness number (KHN) was measured on fragments of FS specimens. Data were analyzed by one-way ANOVA/Tukey test, Student's t-test, and regression analysis. Results: DC/top between 6 and 12 J/cm2 and between 24 and 48 J/cm2 were not statistically different. No differences between DC/top and bottom were detected. DC/bottom, FM, and KHN/top showed significant differences among all H levels. FS did not vary between 12 and 24 J/cm2 and between 24 and 48 J/cm2. KHN/bottom at 3 and 6 J/cm2 was similar. KHN between top and bottom was different up to 12 J/cm2. Regression analyses having H as independent variable showed a plateau region above 24 J/cm2. KHN increased exponentially (top) or linearly (bottom) with DC. FS and FM increased almost linearly with DC/bottom up to 55% conversion. Conclusions: DC and mechanical properties increased with radiant exposure. Variables leveled off at high H levels.

Original languageEnglish (US)
Pages (from-to)503-509
Number of pages7
JournalJournal of Biomedical Materials Research - Part B Applied Biomaterials
Volume84
Issue number2
DOIs
StatePublished - Feb 1 2008

Keywords

  • Composite
  • Degree of conversion
  • Mechanical properties
  • Radiant exposure

ASJC Scopus subject areas

  • Biomedical Engineering
  • Biomaterials

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