Correlation between degree of conversion, filler concentration and mechanical properties of posterior composite resins

Abstract

The degree of conversion, filler concentration and mechanical properties of seven proprietary light-cured posterior composite resins were investigated. The degree of conversion of composites ranged from 43.5-73.8%. The weight fraction of filler that was obtained was in the range 66.4-85.2%. The volume fraction varied from 58.2-74.2%. The mean values of the observed compressive and diametral tensile strengths ranged from 242.3-324.7 MPa and from 39.8-62.6 MPa, respectively. The Knoop hardness numbers ranged from 41.8-81.9. Significant correlations were observed between the volume fraction of filler and the diametral tensile strength (r = 0.89), and between the volume fraction of filler and the Knoop hardness number (r = 0.89). No correlation was found between the degree of conversion and any of the mechanical properties of the composite resins tested. Because of the positive correlations between the volume fraction of filler and the diametral tensile strength, and between the volume fraction of filler and the Knoop hardness numbers, it is concluded that the filler concentration plays a prominent role in determining the properties of contemporary posterior composite resins.

Surface and bulk properties of dental resin- composites after solvent storage

“…This is in agreement with several studies that relate the filler loading to the surface hardness of the resin-based materials [51][52][53][54][55]. V-BF and SDR Bulk fill materials showed the lowest VHN and this could be explained by their low filler loading [56].…”

“…That was in accordance with other studies, as they found very low correlation between the filler loading and mechanical properties of dental resin-composites [25,67]. On the other hand, Chung et al found a clear correlation between the filler loading and the surface hardness and DTS of group of resincomposites [54,68].…”

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

“…As expected, the CS value did not correlate with all the mechanical properties that were investigated in the present study (Table 4). The finding of lack of correlation between the CS value and the other mechanical parameters was consistent with that in prior reports 16,24) . On the other hand, in this study, the DTS value showed a significant correlation with the FM value (r=0.64) and the V f (r=0.71).…”

“…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) .…”

“…It thus seems plausible that some trends can exist in the relationship between the mechanical properties of resin composites 13) . There is a large amount of data in the literature on the mechanical properties of resin Investigation of the correlation between the different mechanical properties of resin composites 13,24) , HV and FM 25) , FT and BH 22) , HK and FT 26,27) , CS and DTS 28) , FS and DTS 29) , and FS and FM/CS/DTS 16) . Recently, Takahashi et al 30) conducted correlation analysis for the more integrated mechanical parameters including tensile properties, but this analysis was performed in six nano-hybrid and two other composites.…”