Influence of preheating and post-curing on a novel fiber-reinforced composite post material

Braz Oral Res. 2018 Oct 29:32:e97. doi: 10.1590/1807-3107bor-2018.vol32.0097.

Abstract

The aim of this study was to investigate the influence of preheating and post-curing methods on diametral tensile strength (DTS), flexural strength (FS), knoop microhardness (KHN), and degree of conversion (DC) of an experimental fiber-reinforced composite (FRC). Specimens (30 wt% of 3-mm-short E-glass fiber, 22.5 wt% of methacrylated-based resin and 47.5 wt% of filler particles) were subjected to: P - photocuring at 1500 mW/cm2 for 40 s (control); P/M - photocuring and microwave post-curing (540W/5 minutes); P/A - photocuring and autoclave post-curing (120°C/15 minutes); PH-P - preheating (60°C) and photocuring; PH-P/M - preheating, photocuring and microwave post-curing; and PH-P/A - preheating, photocuring and autoclave post-curing. Specimens for DTS (Ø 3 x 6 mm) and FS (25 x 2 x 2 mm) were tested at Instron 5965. KHN employed a 50g load for 30s. DC was measured using FTIR spectroscopy. Statistical analysis employed: factorial analysis, normality test, one-way ANOVA and Tukey's HSD test, independent T-test and the Dunnett test. Interaction between factors was not significant (P>0.05). Preheating promoted significantly higher values of FS and KHN (p = 0.0001). Post-curing promoted significantly higher values for KHN (p = 0.0001). For DTS (p = 0.066) and DC (p= 0.724) no statistical difference was found between groups. SEM images showed that preheating promoted better interaction between glass fibers and resin matrix. Preheating increased FS, KHN and DTS, and post-curing increased KHN. DC was not affected by both methods. Preheating and post-curing methods can be used to improve some mechanical properties of FRCs' but degree of conversion remains unaffected.

Publication types

  • Evaluation Study

MeSH terms

  • Analysis of Variance
  • Composite Resins / chemistry*
  • Glass / chemistry*
  • Hardness Tests
  • Hot Temperature*
  • Light-Curing of Dental Adhesives / methods*
  • Materials Testing
  • Methacrylates / chemistry
  • Microscopy, Electron, Scanning
  • Microwaves
  • Polymerization / radiation effects
  • Reference Values
  • Statistics, Nonparametric
  • Surface Properties
  • Tensile Strength
  • Time Factors

Substances

  • Composite Resins
  • Methacrylates
  • fiberglass