Degree of conversion and surface hardness of two nanocomposites compared to three other tooth-colored restorative materials

The aim of the laboratory study was to evaluate the degree of conversion [DC] and surface hardness of two nanofilled resin composite restorative materials compared to three other tooth-colored restorative materials. A light-emitting diode curing unit was used to photo-activate a hybrid composite [Filtek[TM] Z250], two nanofilled composites [Tetric[restricted] EvoCeram, Filtek[TM] Supreme XT], a nano-ionomer [Ketac[TM] N100] and a compomer [Dyract[restrected] eXtra]. After 24 hours dry storage in the dark at 37°C, the DC was determined using Fourier transformation infrared spectroscopy [FTIR]. A microhardness tester was used to measure the Vickers Hardness Number [VHN]. Data for DC and VHN were analyzed using one-way analysis of variance with Tukey's multiple comparison test, and by using Pearson's correlation test [P=0.05 for statistical significance]. The highest mean value for DC was obtained with Tetric EvoCeram [79.4 +/- 6.7%]. Filtek Z250 showed a significantly lower mean DC [58.3 +/- 1.8%] than any of the other tested materials [P<0.001]. Filtek Supreme XT, Ketac N100, Dyract eXtra and Tetric EvoCeram showed no significant DC differences among them [P>0.05]. Filtek Z250 had the highest VHN [97.6 +/- 2.8 MPa], while the lowest value was recorded with Tetric EvoCeram [55.3 +/- 2.9 MPa]. The VHN was significantly different among all tested materials [P<0.001]. A significant and highly negative correlation existed between the DC and surface hardness [r=0.736, P<0.01]. The study concluded that Nanofilled composites may have a higher DC and a reduced VHN compared to hybrid composites, with clinical implications. Correlation between these two properties for various nanofilled materials requires further investigation

Effect of whitening dentifrices on the surface hardness of tooth coloured restorative material

The present study aims to measure the surface hardness of Z-250 composite resin material and Fuji 11 LC RMGIC after brushing for 15 days and 30 days using 3 different brands of toothpaste each having two forms, regular and whitening. The study was conducted using six different groups for each material. Each group has five disc specimens obtained from [3mm x 8mm diameter] mold. Universal testing machine [Micromet 2100 series microhardness tester] was used for testing Vicker's surface hardness. All groups were stored in distilled water at room temperature. The VHN of the control groups were measured after 24 hours, 15 days and 30 days. All data were statistically analyzed with ANOVA and Tukey's Post Hoc analysis [P=0.05]. Water storage [24 hours, 15 days and 30 days] had no significant difference of surface hardness on Z-250, with Fuji II LC there was an increase in VHN between 24 hours, 15 days and 30 days groups. Signal 2 regular toothpaste showed significant increase in VHN for both Z-250 and Fuji II LC over the control group after 15 days. Although after thirty days, the toothpastes regardless whitening or regular had no effect on surface hardness of Fuji II LC, while, they all increased the surface hardness of Z-250. There was no difference in surface hardness of 250 composite resin and Fuji 11 LC RMGIC due to whitening and regular toothpastes