ABSTRACT
OBJECTIVES: This study aimed to assess the effect of surface treatment by bur and laser and application of universal adhesive on repair bond strength of composite resin. MATERIALS AND METHODS: A total of 120 composite blocks measuring 6×4×4 mm were fabricated of Filtek Z250 composite. All samples were subjected to 5,000 thermal cycles and divided into two groups for surface preparation by bur and by Er,Cr:YSGG laser (n = 60). The surfaces were then etched with orthophosphoric acid, rinsed with water and divided into three groups (silane, silane plus Single Bond and silane plus Single Bond Universal). Repair composite was then bonded to aged composite. Half of the samples in each group were stored in distilled water at 37°C for 24 hours and the other half underwent 5000 thermal cycles. All samples were then subjected to shear bond strength testing using a universal testing machine at a crosshead speed of 1 mm/minute. The data were analyzed using one-way ANOVA and Tukey's HSD test. Mode of failure was determined using a stereomicroscope. RESULTS: Bur preparation plus universal adhesive yielded the highest bond strength (30.16 µ 2.26 MPa). Laser plus silane yielded the lowest bond strength (5.63 µ 2.43 MPa). Bur preparation yielded significantly higher bond strength than laser (P < 0.001). Also, application of universal adhesive significantly improved bond strength compared to conventional adhesive and silane (P < 0.001). Bond strength after aging (5000 thermal cycles) had no significant difference with primary bond strength at 24 hours within each group (P = 0.182). CONCLUSION: Surface preparation of aged composite by bur and application of universal adhesive can improve the repair bond strength of composite. Application of silane (without adhesive) in the process of repair cannot provide adequately high repair bond strength.
ABSTRACT
BACKGROUND AND AIMS: Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. MATERIALS AND METHODS: 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. RESULTS: The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P < 0.05). For UDMA the interaction was significant only after 1 week. In microhybrid composites, the CO subgroup showed more monomer release than LBH and LBO. In nanohybrid composites, LBH showed more monomer release than CIB and CO subgroups. For BIS-GMA monomers the interaction was significant at all time periods and the LBH subgroup of nanohybrid composite had significantly more BIS_GMA release in comparison to other subgroups. CONCLUSION: Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.
ABSTRACT
AIM: To compare the antibacterial effect of hydro alcoholic extract of Salvia officinalis, Pimpinella anisum, Satureja hortensis, Rhus coriaria, Carum copticum, Mentha longifolia, Achillea millefolium against Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces viscosus through two in vitro methods. METHODS: In this experimental study, hydro-alcoholic extracts have been prepared from the shoot of Salvia officinalis, Satureja hortensis, Mentha longifolia and Achillea millefolium, the seed of Pimpinella anisum and Carum copticum and the fruit of Rhus coriaria with maceration method. Their antibacterial activity against Streptococcus mutans, Lactobacillus rhamnosus and Actinomyces viscosus have been evaluated with broth macrodilution and agar diffusion methods. RESULTS: In Broth macrodilution method MIC (Minimum Inhibitory Concentration) of Pimpinella anisum, Salvia officinalis, Mentha longifolia, Achillea millefolium, Satureja hortensis, Carum copticum and Rhus coriaria for Streptococcus mutans were respectively 12.5, 6.25, 12.5, 50, 50, 12.5 and 50 µg/ml, for Lactobacillus rhamnosus 12.5, 1.56, 3.12, 12.5, 6.25, 6.25 and 6.25 µg/ml and for Actinomyces viscosus 50, 12.5, 100, 50, 100, 25 and 25 µg/ml. In Agar diffusion method Pimpinella anisum, Salvia officinalis and Rhus coriaria against Streptococcus mutans, Pimpinella anisum, Carum copticum and Rhus coriaria against Lactobacillus rhamnosus and Mentha longifolia, Rhus coriaria and Carum copticum against Actinomyces viscosus had antibacterial effects. CONCLUSION: All seven extracts had growth inhibitory effects on all three bacteria. Salvia officinalis had the greatest inhibitory effect on growth of all three bacteria. All of the extracts except Carum copticum had bactericidal effect in the range of concentration. By agar diffusion method Rhus coriaria had antibacterial effect against all three cariogenic bacteria.
ABSTRACT
OBJECTIVE: The aim of this study was to determine the effects of 40% hydrogen peroxide and 15% carbamide peroxide on microhardness and color change of a silorane-based composite resin in comparison with two methacrylate-based composites. MATERIALS AND METHODS: Fifty-four disc-shaped specimens (A3 shade) were fabricated of Filtek P90 (P90), Filtek Z350XT Enamel (Z350) and Filtek Z250 (Z250) (3MESPE) (n=18). The samples of each composite were randomly divided into three subgroups of 6. The control subgroups were immersed in distilled water; the test groups were exposed to Opalescence Boost (OB) once; and Opalescence PF (OP) (Ultradent) for two weeks. Vickers microhardness testing and a spectrophotometric analysis of the color of samples were performed before and after each intervention. RESULTS: The baseline microhardness of P90 was significantly lower than that of the other two composites (P=0.001), but no difference was found between Z250 and Z350 in this respect (P=0.293). Bleaching treatments significantly decreased the microhardness of Z250 and Z350 (P< 0.001), but no change was observed in P90 test and control subgroups (P> 0.05). No significant difference was detected between the two types of bleaching (P>0.05). After bleaching with OB, ΔE value was measured to be 3.12(1.97), 3.31(1.84) and 3.7(2.11) for P90, Z250 and Z350, respectively. These values were 5.98(2.42), 4.66(2.85) and 4.90(2.78) after bleaching with OP with no significant difference. CONCLUSION: Bleaching decreased the microhardness of methacrylate-based but not silorane-based composites. Although no significant differences were found in ΔE of composites, ΔE of all groups did not remain in the clinically acceptable range after bleaching except for P90 after bleaching with 40% H2O2 (ΔE < 3.3).