J Korean Acad Conserv Dent.  2004 May;29(3):249-266. 10.5395/JKACD.2004.29.3.249.

Effect of pH and storage time on the elution of residual monomers from polymerized composite resins

• Jeon CM
• Yoo HM
• Kwon HC

• KMID: 1987101
• DOI: http://doi.org/10.5395/JKACD.2004.29.3.249

Abstract

OBJECTIVES
The purpose of this study was to determine whether pH and time has any influence on the degradation behavior of composite restoration by analyzing the leached monomers of dental composites qualitatively and quantitatively after storage in acetate buffer solution as a function of time using high performance liquid chromatography (HPLC) / mass spectrometer.
MATERIALS AND METHODS
Three commercial composite restorative resin materials (Z-250, Heliomolar and Aeliteflo) with different matrix structure and filler composition were studied. Thirty specimens (7mm diameterx2mm thick) of each material were prepared. The cured materials were stored in acetate buffer solution at different pH (4, 7) for 1, 7 and 45days. As a reference, samples of unpolymerized composite materials of each product were treated with methanol (10 mg/ml). Identification of the various compounds was achieved by comparison of their mass spectra with those of reference compound, with literature data, and by their fragmentation patterns. Data were analysed statistically using ANOVA and Duncan's test.
RESULTS
1. Amounts of leached TEGDMA in Aeliteflo were significantly larger than those of UDMA in Z-250 and Heliomolar at experimental conditions of different storage time and pH variation (p < 0.001). 2. As to comparison of the amounts of leached monomers per sorage time, amounts of leached TEGDMA in Aeliteflo and UDMA in Z-250 and Heliomolar were increased in the pH 4 solution more significantly than in the pH 7 solution after 1day, 7days and 45days, respectively (p < 0.001). 3. In total amounts of all the leached monomers with storage times, the overall amounts of pH 4 extracts were larger than those of pH 7 extracts for all resin groups, but there was no significant difference (p > 0.05).

Keyword

Light cured composite resin; Leaching of residual monomers; pH variation; High performance liquid chromatography (HPLC)

MeSH Terms

Chromatography, Liquid
Composite Resins*
Hydrogen-Ion Concentration*
Methanol
Polymers*
Composite Resins
Methanol
Polymers

Figure

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  Figure 1 LC / MS-chromatogram of STD from Aeliteflo (Unpolymerized material)

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  Figure 2 LC / MS-chromatogram of pH 4 extract from Aeliteflo (Polymerized material)

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  Figure 3 LC / MS-chromatogram of pH 7 extract from Aeliteflo (Polymerized material)

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  Figure 4 LC / MS-chromatogram of STD from Z-250 (Unpolymerized material)

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  Figure 5 LC / MS-chromatogram of pH 4 extract from Z-250 (Polymerized material)

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  Figure 6 LC / MS-chromatogram of pH 7 extract from Z-250 (Polymerized material)

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  Figure 7 LC / MS-chromatogram of STD from Heliomolar (Unpolymerized material)

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  Figure 8 LC / MS-chromatogram of pH 4 extract from Heliomolar (Polymerized material)

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  Figure 9 LC / MS - chromatogram of pH 7 extract from Heliomolar (Polymerized material) Peak A ; Internal caffeine standard, fragmented methyl methacrylate, methacrylic acid, etc. Peak B ; TEGDMA (triethyleneglycol dimethacrylate) Peak C ; UDMA (urethane dimethacrylate) Peak D ; Bis-GMA (Bisphenol A diglycidyl ether dimethacrylate) Peak E ; Unidentified, probably related to Bis-EMA (Ethoxylated bisphenol A dimethacrylate) Peak F,G ; A certain dimer or oligomer

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  Figure 10 MS spectra of Caffeine (9min)

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  Figure 11 MS spectra of TEGDMA (14min)

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  Figure 12 MS spectra of UDMA (21min)

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  Figure 13 MS spectra of Bis-GMA (23min)

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  Figure 14 Leached TEGDMA of Aeliteflo

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  Figure 15 Leached UDMA of Z-250

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  Figure 16 Leached UDMA of Heliomolar

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  Figure 17 Total amount of leached monomers according to storage time

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