The effect of silver nanoparticles on composite shear bond strength to dentin with different adhesion protocols

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

Shear Bond Strength of Self-Adhering Flowable Composite and Resin-modified Glass Ionomer to Two Pulp Capping Materials

Introduction: The aim of this study was to compare the shear bond strength of a self-adhering flowable composite (SAFC) and resin-modified glass ionomer (RMGI) to mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement. Methods and Materials: A total of 72 acrylic blocks with a central hole (4 mm in diameter and 2 mm in depth) were prepared. The holes were filled with MTA (sub group A) and CEM cement. The specimens of both restorative materials were divided into 6 groups; overall there were 12 groups. In groups 1 and 4, SAFC was used without bonding while in groups 2 and 5 SAFC was used with bonding agent. In all these groups the material was placed into the plastic mold and light cured. In groups 3 and 6, after surface conditioning with poly acrylic acid and rinsing, RMGI was placed into the mold and photo polymerized. After 24 h, the shear bond strength values were measured and fracture patterns were examined by a stereomicroscope. Data were analyzed using the two-way ANOVA and student’s t-test. Results: The use of bonding agent significantly increased the shear bond strength of FC to MTA and CEM cement (P=0.008 and 0.00, respectively). In both materials, RMGI had the lowest shear bond strength values (2.25 Mpa in MTA and 1.32 Mpa in CEM). The mean shear bond strength were significantly higher in MTA specimen than CEM cement (P=0.003). There was a significant differences between fracture patterns among groups (P=0.001). Most failures were adhesive/mix in MTA specimen but in CEM cement groups the cohesive failures were observed in most of the samples. Conclusion: The bond strength of self-adhering flowable composite resin to MTA and CEM cement was higher than RMGI which was improved after the additional application of adhesive

Evaluation of Histological Impacts of Three Types of Orthodontic Fixed Retainers on Periodontium of Rabbits

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

Cell Adhesion Molecules and Cancer

Theodor Boveri in 1914 recognized the significance of changes in the adhesion of tumor cells to the development of cancer. Cell adhesion is essential in all aspects of in verte-brate cells such as cell growth, cell migration and cell differentiation. The majority of adhesion molecules fall into one of four families: cadherins, integrins, immunoglobulin superfamily (IgSF) and selectins. The cadherins are a family of homophilic CAMs (cell adhesion moleculs), Ca2+ dependent. The most important members of cadherins are E-cadherins (epithelial), P-cadherins (placental) and N-cadherins (neural). Immunoglobu-lin superfamily CAMs (IgSF CAMs) are either homophilic or heterophilic and bind in-tegrins, growth factor receptors cadherins or different IgSF CAMs. The integrins are a family of heterophilic CAMs that bind IgSF CAMs or the extracellular matrix. The se-lectins are a family of heterophilic CAMs that bind fucosylated carbohydrates, e.g. mu-cins. They are calcium-dependent. The three family members are E-selectin (endothelial (, L-selectin (leukocyte) and P-selectin (platelet). Recent experimental results indicate that, as well as mediating intercellular and cell–matrix interactions, cell-adhesion mole-cules also directly modulate signal transduction. Changes in the expression or function of cell-adhesion molecules can therefore contribute to tumor progression via altering the adhesion status of the cell or affecting cell signaling. The ability to colonize a specific organ has been correlated with the preferential adhesion of the cancer cells to endotheli-al cells derived from the target organ. This review summarizes recent findings about role of adhesion molecules in the tumor progression

Evaluation of Histological Impacts of Three Types of Orthodontic Fixed Retainers on Periodontium of Rabbits

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

The Effect of Incorporation of 0.5 %wt. Silica Nanoparticles on the Micro Shear Bond Strength of a Resin Modified Glass Ionomer Cement

Statement of the Problem: The clinical success of glass ionomer restorations depends on the strength of resin-modified glass ionomer (RMGI) cement bonding to dentin and there is limited information available regarding the bond strength of resin modified glass ionomers containing silica nanoparticles to dental structures. Purpose: The aim of this study was to compare the microshear bond strength (µSBS) of RMGI with and without silica (SiO2) nanoparticles to dentin of permanent teeth. Materials and Method: in this experimental study, the occlusal surfaces of 30 freshly extracted intact third molars were ground to expose the flat dentin and after conditioning with 20% poly acrylic acid, were randomly assigned to two main groups (n=15). The first group was filled with RMGI (Fuji II LC, GC) and the second group was filled with RMGI plus 0.5%wt. silica nanoparticles. Then, each main group was divided into three subgroups, and then stored in an incubator at 37 oC with 100% humidity for 1, 7, and 30 days. The µSBS test was performed using a universal testing machine (1 mm/min). The data were analyzed by t-test, repeated measures ANOVA and Tukey test (p< 0.05). Results: There were no statistically significant differences between the mean µSBS of the groups with and without nanoparticles along the different storage periods (p> 0.05). There was significant difference in µSBS values among the three different storage periods in all the tested materials (p< 0.05). Conclusion: Incorporation of 0.5 %wt. silica nanoparticles did not compromise the µSBS of Fuji II LC RMGI to dentin

Evaluation of Microleakage and Biocompatibility of Universal Adhesive Containing Titanium Dioxide Nanoparticles: A Comparative In Vitro Study

Background & Objective: Although dental composites have undergone a high level of development in recent years, there are still difficulties including microleakage. The incorporation of nanoparticles (NPs) in dental materials can produce antibacterial effects, but the effect of TiO2 NPs on microleakage has not yet been investigated. The present study aimed to determine the effect of TiO2 NPs incorporation in the universal single bond and pretreatment with them on microleakage of clV cavities using both total-etch and self-etch approaches. Materials & Methods: Standard clV cavities were prepared on the buccal surfaces of the sixty non-carious human molar teeth. The restoration of samples was carried out with 6 different methods and randomly divided into six groups of ten subjects. Microleakage in both gingival and occlusal margins was determined after placement in 2% basic fuschin solution for 24h. Biocompatibility of a universal single bond was evaluated by MTT assay. Results: In both occlusal and gingival margins in all groups, the application of TiO2 NPs was better than no application. We observed the relatively low cytotoxic effect of TiO2 NPs incorporated in the universal adhesive on NIH-3T3 cell viability. Conclusion: Regarding the limitations of the present investigation, using TiO2 NPs with both total-etch and self-etch approaches to universal single bond may lead to a decrease in the microleakage of resin composite restorations

The effect of silver nanoparticles on composite shear bond strength to dentin with different adhesion protocols

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

The Effect of Different Light Curing Units and Composite Thicknesses on the Shear Bond Strengthof Composite to Dentin

Background and Aim : Development of new composite resins is one of the most important technological advances in the field of cosmetic dentistry. The aim of this study was to investigate the effectiveness of different light curing units and composite thicknesses on the shear bond strength composite to dentin .   Materials and Methods : In this experimental in-vitro study, the test groups were composed of 80 dentinal samples, prepared on occlusal surfaces of 80 maxillary premolar teeth and routinely divided into 8 groups of 10. Two cylindrical molds (2×2 and 2×5 mm) were filled in bulk using P60 and Ceram X composites and light cured with LED and QTH light curing units .After curing and 3 months aging in 370c water, shear bond strength of all samples were obtained using a universal testing machine with 1mm/min crosshead speed. One- and three-way ANOVA were used for statistical analysis using SPSS software .   Results : The highest mean of shear bond strength (31.75 MPa) was in group (P60, QTH, 2) and the lowest (15.34 MPa) was recorded in (Ceram X, LED, 5). Type and thickness of composites had significant effects on the value of shear bond strength and no significant differences were obtained between two light curing units .   Conclusion : The shear bond strengths of P60 and CeramX composites tested were much lower when cured in a 5-mm than in a 2-mm increment. The two types of light curing units tested did not show any significant differences in the amount of shear bond strengths

The LncRNA H19 rs217727 Polymorphism Is Associated with Oral Squamous Cell Carcinoma Susceptibility in Iranian Population

Lack of protein-coding capacity is a main characteristic of long noncoding RNAs (lncRNAs) which, as molecular biomarkers, have found a novel pharmacological application in cancer and are reported to be important regulators of gene expression. H19 is reportedly involved in cancer progression and tumorigenesis. One of the most common types of head and neck cancers is oral squamous cell carcinoma (OSCC). The main objective of the present study was to evaluate the correlation of OSCC susceptibility with H19 gene in an Iranian population. This research was performed on 400 subjects of both sexes referred to the Namazi Hospital affiliated with the Shiraz University of Medical Sciences (SUMS). Individuals aged 15-88 years were divided into two groups: pathologically diagnosed patients with new-onset OSCC and healthy controls. After written and informed consent was obtained from the individuals, genomic DNA was extracted. The tetra-primer ARMS-PCR technique was performed for DNA genotyping by the use of specific primer pairs. The susceptibility of OSCC and H19 gene polymorphism sites was further analyzed (rs217727 and rs2107425). The allele and genotype frequencies of H19 rs2107425 polymorphism were similar between OSCC cases and controls. The H19 rs217727T allele frequency was significantly higher in OSCC cases (P=0.002), and the polymorphism of H19 rs217727 was associated with OSCC susceptibility in the codominant (OR=6.04, 95%CI=1.70−21.42, P=0.001 for TT genotype), dominant (OR=1.62, 95%CI=1.08−2.43, P=0.01), and recessive (OR=5.32, 95%CI=1.51−18.69, P=0.003) models. This study showed that rs217727 and OSCC susceptibility were statistically correlated in the Iranian population