Young's Modulus and Degree of Conversion of Different Combination of Light-Cure Dental Resins
N Emami1, *, KJ Söderholm2
Identifiers and Pagination:Year: 2009
First Page: 202
Last Page: 207
Publisher ID: TODENTJ-3-202
Article History:Received Date: 01/4/2009
Revision Received Date: 21/5/2009
Acceptance Date: 31/7/2009
Electronic publication date: 1/10/2009
Collection year: 2009
open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.
To evaluate Young's modulus and degree of conversion of several combinations of bisGMA, UEDMA, TEGDMA light-cure dental resin.
Young's modulus and DC% were studied for 21 different resin combinations of bisGMA, TEGDMA and UEDMA. Small universal testing machine and photo-calorimetry were used for the tests. The results were evaluated using ANOVA and Duncan's multiple range tests and regular t-test.
Young's modulus varied between 2.37±0.2 GPa (100% TEGDMA) and 4.15±0.2 GPa (100% bisGMA). By adding TEGDMA to bisGMA or UEDMA, the Young's modulus decreased significantly (p<0.05). Degree of conversion was significantly (p<0.05) higher when the wt% of TEGDMA was high in the mixtures than for highly concentrated bis-GMA (resin mixtures with TEGDMA in comparison to mixture with bisGMA had higher degree of conversion). DC% was significantly higher (p<0.05) for binary mixtures of UEDMA and TEGDMA, and significantly lower for 100 wt% bis-GMA (p<0.05). The DC% values were between 53.1%±0.9% (100% bisGMA) and 85.6%±1% (80% UEDMA-20% TEGDMA). The concentration of bisGMA, in the monomer mixture, affected DC% and Young's modulus oppositely.
The differences in the values for DC% were mostly justified by the differences in the molecular structures of the different monomers. It was also revealed that higher DC% does not always result in a higher Young's modulus, because molecular and network structural parameters play major roles in the final physical properties of the mixtures.