ABSTRACT
Metallic nano-particles show exclusive biological, chemical and physical characteristic. The purpose of this research was to evaluate the effect of various amounts of nanosilver incorporation [0 [as control], 20, 40, 80, 120, 200 ppm] on the mechanical Properties [compressive and flexural strength] of resin modified Glass ionomer Cement. Based on ISO 4049 and ISO 9971 for polyalkenoid cements, 90 cases in each group were prepared for the flexural and compressive strength. Specimens in 6 groups with different amounts of nanosilver [20, 40, 80, 120 and 200 ppm] and control [Fuji II LC improved], stored in distilled water at 37[degree sign] C for 1 day and 30 days. Flexural strength, using a three-point bending method, Modulus of elasticity and the compressive strength were measured by universal testing machine [Zwick] with crosshead speed of 0.5 mm/min. Data were analyzed using two-way ANOVA and Tukey post HOC test. The flexural strength and modulus of various amounts of nanosilver incorporation of resin modified glass-ionomer cement were not significantly different [P>0.05]. The compressive strength of incorporating of 20 ppm compared with control [P=0.01], 40 ppm [P=0.02] and 80 ppm compared with control [P<0.001] were increased. The flexural strength and compressive strength of Fuji II LC, containing nanosilver particles were increased after 1 day and 1 month significantly [P<0.001]. Incorporation of 20 to 80 ppm nanosilver into Fuji II LC had increased mechanical properties compared to the original cement
Subject(s)
Silver , Metal Nanoparticles , Compressive StrengthABSTRACT
Tooth-colored non-metal posts are adhered to the canal walls with the use of resin cements and dentin adhesives. Degree of conversion of these cements is especially important to ensure the durability of the restoration. The present study aimed at evaluating the degree of conversion [DC%] of self-cure and dual-cure resin cements at different depths and time points when using a DT. Light Post. In this experimental study, metal molds with 5 and 10 mm heights and internal diameter of 0.8 mm were used. Posts were vertically placed in the center of molds. Spectrum of absorption of the dual cure cement was measured before curing using Fourier transform infrared [FTIR] spectroscopy device. The uncured samples were then removed from the device and placed beneath the molds. After light irradiation, samples were transferred again to the FTIR device and their spectrum of absorption was measured. DC% was calculated using the relevant formula. For self-cure cements, spectrum of absorption was measured at 0, 2, 5, 10 and 15 minutes by the FTIR. Results were statistically analyzed using SPSS software. Self-cure cement had a DC of 5% at 0, 2, 5 and 10 minutes and a DC of 20% at 15 minutes. DC of the dual-cure cement was 44%, 15% and 8% at 0, 5 and 10 mm depths, respectively. Two-way ANOVA and Tukey's Post Hoc test [HSD] revealed that in the dual-cure cement the DC at 5 and 10 mm depths was significantly different [P<0.05]. DC was 20% at 15 minutes which was the highest. DC% of the dual-cure cement was higher than that of the self-cure cement which is attributed to the optimal characteristics of the dual-cure cement and also the ability of fiber post to pass light
ABSTRACT
The main reason for failure in application of fissure sealant is its loss of bond to tooth and development of secondary decays. Nanoparticles of hydroxyapatite have convenient biologic properties and we can try to benefit from these characteristics by adding them to repair materials. The present study was performed with the aim to assess the effect of addition of various amount nanoparticles of hydroxyapatite on mechanical properties such as microshear bond strength and physical properties like curing depth and degree of conversion as well as evaluation of teeth enamel remineralization. In the present laboratory experimental study different weight percentages comprising 0% [control], 1%, 3%, 5%, 10% and 15% of nanoparticles of hydroxyapatite with 50 nm dimensions were separately added to fissure sealant. Then degree of conversion test by Fourier Transform Infrared Spectroscopy [FTIR] and curing depth according to ISO 4049 standard were performed on prepared samples. For the microshearbond strength test 35 premolar teeth without caries were used. The substance properties measurement device [Zwick] was used to do the test. Remineralization of permanent teeth enamel was assessed by Scanning Electron Microscopy [SEM]. Raw data obtained were statistically analyzed by normal distribution test [Kolmogorov-Smirnov], one way ANOVA and Tukey Post Hoc. Results showed that microshear bond strength and degree of conversion had no significant difference in various concentrations of fissure sealant containing hydroxyapatite nanoparticles [P>0/05]. Between microshear bond strength and degree of conversion means of 3M commercial fissure sealant and usual fissure sealant there was no significant difference [P>0/05]. Curing depth in concentrations of 10% [P=0] and 15% [P=0] statistically significantly decreased compared to previous groups [P<0/05]. Curing depth of 3M commercial fissure sealant group was lower compared to conventional fissure sealant group [P=0] and the difference was statistically significant [P<0/05]. A remineralized region on the surface between the fissure sealant and tooth enamel was observed by SEM. This region was more remarkable in higher concentrations. Fissure sealant containing hydroxyapatite nanoparticles with effect on remineralization on the surface of tooth enamel can lead to reduction of micro-leakages and prevention of development of secondary caries while mechanical properties do not decline