J Korean Acad Conserv Dent.  2009 Jul;34(4):364-370. 10.5395/JKACD.2009.34.4.364.

Effect of fiber direction on the polymerization shrinkage of fiber-reinforced composites

• Yom J
• Lee IB

• KMID: 2176170
• DOI: http://doi.org/10.5395/JKACD.2009.34.4.364

Abstract

The aim of this study was to evaluate the effect of fiber direction on the polymerization shrinkage of fiber-reinforced composite. The disc-shaped flowable composite specimens (d = 10 mm, h = 2 mm, Aeliteflo A2, Bisco, Inc., IL, USA) with or without glass fiber bundle (X-80821P Glass Fiber, Bisco, Inc., IL, USA) inside were prepared, and the longitudinal and transversal polymerization shrinkage of the specimens on radial plane were measured with strain gages (Linear S-series 350omega, CAS, Seoul, Korea). In order to measure the free polymerization shrinkage of the flowable composite itself, the disc-shaped specimens (d = 7 mm, h = 1 mm) without fiber were prepared, and the axial shrinkage was measured with an LVDT (linear variable differential transformer) displacement sensor. The cross-section of the polymerized specimens was observed with a scanning electron microscope to examine the arrangement of the fiber bundle in composite. The mean polymerization shrinkage value of each specimen group was analyzed with ANOVA and Scheffe post-hoc test (alpha=0.05). The radial polymerization shrinkage of fiber-reinforced composite was decreased in the longitudinal direction of fiber, but increased in the transversal direction of fiber (p<0.05). We can conclude that the polymerization shrinkage of fiber-reinforced composite splint or restoratives is dependent on the direction of fiber.

Keyword

fiber-reinforced composite; longitudinal direction; transversal direction; polymerization shrinkage; strain gage; linear variable differential transformer

MeSH Terms

Barium Compounds
Bisphenol A-Glycidyl Methacrylate
Composite Resins
Displacement (Psychology)
Electrons
Glass
Polymerization
Polymers
Silicon Dioxide
Splints
Sprains and Strains
Barium Compounds
Bisphenol A-Glycidyl Methacrylate
Composite Resins
Polymers
Silicon Dioxide

Figure

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  Figure 1 a) Experimental setup for the measurement of radial linear shrinkage using a strain gage. b) Definition of directions on a disc shaped specimen in the measurement.

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  Figure 2 Electric circuit design for the strain measurement (Vo: output voltage, Va: voltage between two fixed resistances, Vb: voltage between two strain gages, Vs: input voltage, R: fixed resistance, ΔR: resistance difference, SG: strain gage).

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  Figure 3 Experimental setup for the measurement of axial linear shrinkage using an LVDT probe.

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  Figure 4 a) Representative curves of radial shrinkage strains for composite specimens as a function of time. b) Post-gel shrinkage strains for four groups.

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  Figure 5 SEM photomicrographs showing the cross-section of composite specimens. a) Some voids were observed between fibers. The arrows show fiber bundles (F). b) There was an intimate contact between the strain gage and composite. The arrow shows the strain gage (SG).

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