Methods: Silica/Barium glass GM27884 (SCHOTT AG, Landshut, Germany), 0.4µm particle size with silane contents of 7 and 13%, densities of 2.5706 and 2.4422 g/cm3 respectively, were compounded with a photoactivated BisGMA/TEGDMA (70/30wt%) and N’Durance resin (Bis-EMA/DDCDMA/UDMA) to yield a series of pastes all with the same volume fraction of filler (45vol%). The composite pastes were prepared using a high speed mixing machine (Flacktek). Refractive index of the fillers was measured using an Abbe refractometer at 20°C. Degree of conversion and translucency parameters were tested for the materials. The data was statistically analyzed (ANOVA, Tukey’s, p<0.05).
Results: Data are summarized in the table below. Pastes compounded with fillers containing variable percentages of silane showed decreasing conversion and translucency parameter with increasing silane content independent of the resin system. Decreases in conversion and translucency could be attributed to changes in the refractive index of the filler which translates to refractive index mismatch between the filler and the resin at higher concentration of silane.
Exp. |
Resin Composition |
% Silane in Filler |
Filler Refractive Index |
Conversion (%) |
TP |
01 |
BisGMA/TEGDMA |
7 |
1.6488 |
60.0±0.2a |
18.3±0.5a |
02 |
BisGMA/TEGDMA |
13 |
1.5936 |
56.3±0.5b |
10.6±0.6b |
03 |
BisEMA/DDCDMA/UDMA |
7 |
1.6488 |
68.1±0.3a |
23.1±1.8a |
04 |
BisEMA/DDCDMA/UDMA |
13 |
1.5936 |
66.4±0.7b |
16.9±0.7b |
Conclusion: Based on the results of the present study, variations in the silane content in the filler have a significant effect on properties of composite paste. Silane content is an important parameter to be considered during the manufacturing of resin based materials to achieve optimal properties.
Acknowledgements: The authors would like to thank Schott AG for their generous donation of fillers.