ABSTRACT
OBJECTIVES: This study evaluated the effect of dentin pretreatment with silver nanoparticles (SNPs) and chlorhexidine (CHX) on the microshear bond strength (µSBS) durability of different adhesives to dentin. MATERIALS AND METHODS: Occlusal surfaces of 120 human molars were ground to expose flat dentin surfaces. The specimens were randomly assigned to six groups (n = 20). Three groups (A, B, and C) were bonded with Adper Single Bond 2 (SB) and the other groups (D, E, and F) were bonded with Clearfil SE Bond (SEB). Dentin was pretreated with CHX in groups B and E, and with SNPs in groups C and F. The specimens were restored with Z250 composite. Half of the bonded surfaces in each group underwent µSBS testing after 24 hours and the other half was tested after 6 months of water storage. RESULTS: SNP application was associated with a higher µSBS than was observed in the CHX and control groups for SEB after 24 hours (p < 0.05). A significantly lower µSBS was observed when no dentin pretreatment was applied compared to dentin pretreatment with CHX and SNPs for SB after 24 hours (p < 0.05). The µSBS values of the 6-month specimens were significantly lower than those obtained from the 24-hour specimens for all groups (p < 0.05). This decrease was much more pronounced when both adhesives were used without any dentin pretreatment (p < 0.05). CONCLUSIONS: SNPs and CHX reduced the degradation of resin-dentin bonds over a 6-month period for both adhesive systems.
Subject(s)
Humans , Adhesives , Chlorhexidine , Dentin , Molar , Nanoparticles , Polymorphism, Single Nucleotide , Silver , WaterABSTRACT
Abstract In Dentistry, restorative materials and oral bacteria are believed to be responsible for restoration failure. To make long-lasting restorations, antibacterial agents should be made. Inorganic nanoparticles and their nano composites are applied as good antibacterial agents. Objective The purpose of this study was to investigate the effect of silver nanoparticles on composite shear bond strength using one etch and rinse and one self-etch adhesive systems. Material and Methods Silver nanoparticles were prepared. Transmission electron microscope and X-ray diffraction were used to characterize the structure of the particles. Nanoparticles were applied on exposed dentin and then different adhesives and composites were applied. All samples were tested by universal testing machine and shear bond strength was assesed. Results Particles with average diameter of about 20 nm and spherical shape were found. Moreover, it was shown that pretreatment by silver nanoparticles enhanced shear bond strength in both etch and rinse, and in self-etch adhesive systems (p≤0.05). Conclusions Considering the positive antibacterial effects of silver nanoparticles, using them is recommended in restorative dentistry. It seems that silver nanoparticles could have positive effects on bond strength of both etch-and-rinse and self-etch adhesive systems. The best results of silver nanoparticles have been achieved with Adper Single Bond and before acid etching.
Subject(s)
Humans , Silver/chemistry , Dental Bonding/methods , Resin Cements/chemistry , Dental Cements/chemistry , Dentin/drug effects , Metal Nanoparticles/chemistry , Reference Values , Silver/pharmacology , Surface Properties/drug effects , Acid Etching, Dental/methods , X-Ray Diffraction/methods , Materials Testing , Reproducibility of Results , Analysis of Variance , Shear Strength/drug effects , Dentin/chemistry , Microscopy, Electron, Transmission/methods , Anti-Bacterial Agents/chemistryABSTRACT
Objectives: treatment of chipped or fractured porcelain with composite resin is considered as an economic treatment for minor fractures in ceramics. The aim of this study was to evaluate the effect of different ceramic surface treatments on bond strength of methacrylate-based and silorane-based composite resin to IPS Empress 2
Methods: sixty IPS Empress 2 ceramic discs were fabricated and after etching with 9.6% hydrofluoric acid, they were divided into six groups: [1] P90 primer and bonding agent + Filtek P90 composite resin; [2] Single Bond+ Filtek Z250 composite resin; [3] similar to the first group+ silane pretreatment; [4] similar to the second group+ silane pretreatment; [5] silane pretreatment+ Filtek P90 composite resin; [6] silane pretreatment+ Filtek Z250 composite resin. Each specimen was subjected to shear load until fracture occurred. Statistical analysis was performed using one-way ANOVA, Tukey's test and t-test
Results: regardless of the type of surface treatment, Z250 composite demonstrated significantly higher shear bond strength than P90 composite [P<0.05]. Group 4 showed the highest shear bond strength values with statistically significant difference with other groups while the fifth group showed the least values [P<0.05]
Conclusion: silane coating along with the application of adhesive system and etching in methacrylate-based composite was the most efficient surface treatment in terms of bond strength
ABSTRACT
Statement of the Problem: The bond strength of composites with different adhesive systems with dentin is an important factor in long term durability of composite restorations. The effect of titanium tetrafluoride [TiF4] as anti caries agent and sodium hypo-chlorite [NaOCl] as disinfectant on the shear bond of nanofilled and silorane based composite resins have not been investigated in previous studies
Purpose: This study was conducted to determine bond strength between dentin and two composite systems, by means of shear bond test using TiF4 and NaOCl
Materials and Method: Middle dentin of 60 intact extracted maxillary premolar teeth were exposed by sectioning the crowns at a depth of 2mm from central groove and parallel to the occlusal surface. Standardized smear layer was created using a 600-grit silicon carbide paper and then samples were embedded in acrylic resin blocks. Then the samples were randomly divided into 6 groups summarized as Group I: Z350, Group II: Z350+ NaOCl, Group III: Z350+ TiF4, Group IV: P90, Group V: P90+ NaOCl, Group VI: P90+ TiF4 according to manufacturer's instruction. Then samples were subjected to shear bond strength [SBS] test using universal testing machine and data were analyzed using ANOVA and Tukey tests [p< 0.05]
Results: Application of 5% NaOCl caused a significant decrease in SBS of nanofilled composite resin [p= 0.004], and also silorane based composite resin [p= 0.006]. Appli-cation of 4% TiF4 caused a significant increase in SBS of silorane based composite resin [p= 0.001]. The effect of TiF4 on nanofilled composite was not statistically significant
Conclusion: Using TiF4 has a positive effect on increasing the shear bond while NaOCl has negative effect on bond strength
ABSTRACT
Statement of the Problem: Monomer viscosity and solvent evaporation can be affected by the adhesive system temperature. Higher temperature can elevate the vapor pressure in solution and penetration of adhesive in smear layer. Bonding mechanism may be influenced by the adhesive temperature
Purpose: This study aimed to evaluate the effect of pre-heating on shear bond strength of etch-and-rinse and self-etching adhesives to ground bovine dentin surfaces, at temperatures of 4[degree sign], 25[degree sign] and 40[degree sign]
Materials and Method: In this experimental study, 60 maxillary bovine incisors were randomly divided into 6 groups [n=10]. The central part of labial dentin surfaces was exposed with a diamond bur and standardized smear layer was created by using silicon carbide paper [600 grit] under water-coolant while the specimens were mounted in acrylic resin. Two adhesive systems, an etch-and-rinse [Adper single bond] and a self-etch [Clearfil SE Bond] were stored at temperatures of 4[degree sign], 25[degree sign] and 40[degree sign] for 30 minutes and were then applied on the prepared labial surface according to the manufacturer's instructions. The composite resin [Z350] was packed in Teflon mold [5 mm in diameter] on this surface and was cured. The shear bond strength [MPa] was evaluated by universal testing machine [Zwick/Roell Z020, Germany] at cross head speed of 1mm/min. The results were statistically analyzed by using ANOVA and Tukey tests [p< 0.05]
Results: No significant difference was found between the shear bond strength of Clearfil SE Bond adhesive in different temperature and single Bond adhesive system at 25[degree sign] and 40[degree sign]. However, there were significant differences between 4[degree sign] of Adper single bond in comparison with 25[degree sign] and 40[degree sign] [p= 0.0001]
Conclusion: Pre-heating did not affect the shear bond strength of SE Bond, but could promote the shear bond strength of Adper Single Bond
ABSTRACT
Statement of the Problem: Fixed retainers were developed to maintain incisor alignments after orthodontic treatments. Although the effects of fixed retainers on periodontal health are clinically studied, no studies have still evaluated the histological changes in the periodontium after the placement of thefixed retainers
Purpose: The aim of this study was to evaluate the effects of customised retainers on periodontium histologically
Materials and Method: Forty pairs of maxillary and mandibular central incisors of twenty rabbits were randomly divided into four equal groups: The first group was considered as the control and in the second group, Fiber Reinforced Composite [FRC], in the third group, 0.014 inch stainless steel [SS] wire and in the fourth group, 0.175 inch multistrand stainless steel [MSS] wire were bonded on the labial surfaces of the incisors. After sixty days; animals' periodontium were evaluated histologically
Results: The number of bone resorption lacuna in the control group was significantly less than FRC and 0.014 SS groups. The periodontal vessel count and their diameter in the control group was significantly lower than the other groups. The pulp vessel count and their diameter in controls were significantly more than the 0.014 SS and the 0.175 MSS groups
Conclusion: Findings of this study suggest that FRC fixed retainer might cause detrimental effects on the periodontal ligaments and supporting bone and the 0.014- inch and 0.175- inch fixed retainers can cause hyalinization and possibly the necrosis of the pulp
ABSTRACT
Breast cancer is the second leading cause of cancer death in women. Cisplatin is a traditional cancer drug commonly used in chemotherapy for killing cancer cells. Modulation at the mRNA levels of apoptotic related genes often correlate with the sensitivity of various types of cancer cells to chemotherapeutic agents. Nanoparticulate drug delivery systems are being developed to effectively deliver smaller doses of chemotherapeutic agents and control drug distribution in the body. In this study, we evaluate the expressions of BCL2 and BAX genes in T47D treated with cisplatin and cisplatin nanoparticles, which can result in a new approach to breast cancer therapy. In this study, we treated T47D cells with different concentrations of cisplatin and cisplatin nanoparticles at 48 h. The IC50 was determined. We extracted RNA by using RNX solution, after which cDNA was synthesized. The precise primers for the BCL2, BAX and TBP genes were designed by specific software. The quantity of BCL2 and BAX gene expression compared to TBP gene [reference gene] was analyzed using real-time PCR. BCL2 and BAX gene expression levels in T47D cells treated by cisplatin were 0.7 [BCL2] and 1.48 [BAX], in T47D cells treated with cisplatin-loaded nanoparticles, the gene expressions were 0.03 [BCL2] and 2.41 [BAX]. In this study, the results have shown that cisplatin-loaded nanoparticles are effective anticancer agents. Cisplatin nanoparticles induce apoptosis in human breast cancer cell lines. We have shown that cisplatin nanoparticles strongly increased cytotoxicity in comparison to the free drug in the T47D cell line