Influence of silanization and filler fraction on aged dental composites

Abstract

The effect of silanization and filler fraction on the mechanical properties of aged dental composites was investigated. Experimental composites (75/25 Bis-GMA/TEGDMA resin reinforced with 0, 12.6, 30.0, and 56.5 vol% 8 microm silanized/unsilanized BaSiO6) were fabricated into 4.7 mm diameter x 2.2 mm thick discs and 3.5 mm diameter x 7.3 mm thick discs for diametral tensile and compressive tests, respectively. The effect of immersion in 75% ethanol at 37 degrees C for 0-30 days on the diametral tensile strength (DTS) and compressive strength (CS) of the samples was evaluated and analysed by ANOVA and Tukey LSD test. The fracture interface between filler and resin matrix was then examined by scanning electron microscope. Results and subsequent statistical evidence from DTS (18.6+/-7.6 MPa, silanized versus 11.7+/-2.6 MPa, unsilanized) and CS (85.1+/-29.7 MPa, silanized versus 56.0+/-11.3 MPa, unsilanized) strongly implies that silanization may greatly enhance the mechanical properties of the resin composites. Furthermore, it also shows that both DTS and CS increased proportionally as the filler fraction of the composites increased. However, in the unsilanized groups, DTS decreased (up to 40%) as the filler fraction increased, and CS showed no relevance to the filler fraction at all. As for the influence of aging, it was found that both DTS and CS showed a significant decrease after immersion in 75% ethanol, and silanization heavily correlated with the filler fraction of aged-resin composites. Microscopic examination of the fractured samples showed that failure primarily occurred within the resin matrix per se for silanized composites and adjacent to the filler particles for unsilanized composites. All the evidence points to the conclusion that mechanical properties of aged-resin composites can be greatly influenced by silanization and the filler fraction.

Investigation of the correlation between the different mechanical properties of resin composites

“…Also, same results could be observed in the posterior composites 57) . In a similar way, the mean CS value correlated with the V f value in the experimental composites 11,47) . However, either of the group comprising for a wide range of early and contemporary resin composites did not show any significant correlation between the filler fraction and the mean CS value 16,24,38,58) .…”

“…For correlation between Vf and DTS, high correlation coefficients (r=0.83-0.89) were observed in the model composite with V f ranging from 0% to 57% 47) . However, in highly filled hybrid composites over 60% in Vf, little variations were observed in the DTS values according to the filler content in previous studies 45,48,49) .…”

Hydrolytic degradation of a resin composite as a function of the curing tip distance and aging

“…It also agreed with previous findings, indicating that significant reductions in the mechanical properties of composites occur only after 7 days of solvent immersion 44 . While the ideal curing tip position appears to be as close to the material as possible 45 this position is not possible in all situations.…”

Effects of filler addition to bonding agents on shear bond strength

“…The study of Lin CT et al 22) support this premise. In their study of investigating the effect of silanization and filler fraction on the mechanical properties of aged dental composites, the result showed that diametral tensile strengths increased proportionally as the filler fraction of the composites increased in silanized groups.…”