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Background and Aims: The bond strength of direct composite restoration to the caries affected dentin is a challenging issue. Preparation of dentin with an antibacterial agent is a method for creating durable bonded restorations. The aim of this study was to investigate the effect of curcumin photosensitizer on the bond strength of a universal adhesive to the caries-affected dentin (CAD). Materials and Methods: In this experimental in vitro study, forty-four decayed human molar teeth were selected. After removing the surface enamel and dentin by a water-cooled saw, the decayed mid-coronal dentin was stained with a caries detection solution. The green and soft infected dentin was removed and CAD and hard and healthy surrounding dentin were left. Then, the remaining dentin surfaces were treated by 600 grit silicon carbide papers and polished. The specimens were divided into two groups (n=22): dentin pretreatment group by curcumin and control with no dentin pretreatment group by curcumin. Each group was divided into two subgroups based on the method of application of All-Bond Universal adhesive (Bisco, USA) (etch and rinseand self-etching methods). After placing the Aelite All Purpose Body (Bisco, USA) composite, all specimens were placed in a universal testing machine for microshear bond strength (µSBS) test. The failure mode of the isolated surfaces was evaluated under a stereomicroscope. Two-way ANOVA analysis was used for statistical analysis. Results: Based on the obtained results, intervention with the adhesive application method and surface pretreatment with curcumin had no significant effect on the bond strength. Also, there was no significant difference in the bond strength of the curcumin group in both etch and rinse and self-etching methods (SE=56.3±27.11 MPa; ER=52.4±84.11 MPa) (P=0.847). In the curcumin-free group, there was no significant difference between the two different adhesive application methods (P=0.187). Conclusion: The results obtained in the present study showed that the pretreatment of dentin affected by caries with light-sensitive curcumin and also use of a universal adhesive by either self-etching or self-etchinf methods had no influence on the microshear bond strength of the composite restoration. [ABSTRACT FROM AUTHOR]

In recent years, the most important challenge for wood-based panel's producers has been an increasing demand for wood raw materials, raw material prices, and rising transportation costs. On the other hand, the application of lightweight elements in the manufacture of decorative furniture has received more attention. The present study aimed at evaluating the effect of different levels of size and the amount of expanded polyurethane particles in the production of lightweight particle boards. The size of polyurethane particles at three levels (10, 5, and 15 mm) and the amount at four levels (10, 5, 0, and 15%) were selected as variable factors, and the amount of adhesive consumption, press pressure, board thickness, and final density were considered as fixed factors. The results showed that flexural strength, the flexural modulus of elasticity, internal bonding, and thickness swelling increased significantly with increasing the size of polyurethane particles in the middle layer of the board, but the effect of size was not significant on the water absorption of the samples. Also, increasing the percentage of polyurethane in the middle layer increased the mechanical properties and improved the physical properties compared to the control sample, and it had the largest effect on the internal bonding of the samples. [ABSTRACT FROM AUTHOR]

Poly vinyl acetate (PVAC) adhesive is one of the most important adhesives in wood and furniture manufacturing industry, which has many advantages such as low cost, environment friendliness and non-toxicity. However, it has some disadvantages such as low water resistance and poor boning strength. In this study, the effect of nano silica (NS) on the properties of poly vinyl acetate adhesive was investigated. The adhesive formulation with different NS contents (2, 3 and 4%) was mixed with PVAC. The structure of the prepared adhesive samples was studied by FT-IR and XRD. In order to make joints, maple wood (Acer cappadocicum) was used. Two standards of D882 and ASTM D905 were used for tensile and shear measurements, respectively. Results showed that adding NS to PVAC improved the tensile strength of films. For example, the tensile strength of prepared films was increased by 30% after adding 4% of NS. Moreover, shear strength test showed that NS up to 3% can improve PVAC bond strength. Viscosity measrements showed that increasing the weight of NS up to 3% to PVAC glue initially decreased in the viscosity and then increased. [ABSTRACT FROM AUTHOR]

Background and Objective: Nowadays, in metropolitan areas, principled and hygienic waste management is very important. Recycling is one of the most appropriate options in waste management. Hereof, the present study was aimed to investigate the possibility of using textile waste fibers in the manufacture of Medium Density Fiberboard (MDF). Materials and Methods: This experimental study was performed on lab-scale. Fabric waste was prepared by separation method at source from a clothing manufacturer in Tehran and converted into fibers. Test boards were made with weight percentage of mixing textile waste fibers to industrial fibers at three levels of 0:100, 10:90 and 15:85, respectively, 10% urea-formaldehyde adhesive, with 16 mm thickness and 0.7 g/cm³ density by hot press. Then, properties of the boards were measured including bending strength, modulus of elasticity, internal bond, hardness, water absorption and thickness swelling. The results were analyzed with ANOVA test. Results: The results of ANOVA showed that the effect of textile waste fibers on the bending strength, modulus of elasticity and swelling thickness of 2 and 24 hours of boards made at 5% probability level was significant. Additionally, the highest values of physical and mechanical properties are related to made boards with 10% of textile waste fibers. Conclusion: The results showed that it is possible to make MDF with textile waste fibers. The use of wastes such as fabrics in the production of new functional products can be considered as one of the strategies to reduce waste and thus to maintain human health and the environment. [ABSTRACT FROM AUTHOR]

Introduction: The clinical success of indirect restorations is influenced by several factors, including selection of a suitable cement. The introduction of adhesive resin systems has led to increased use of bonded all-ceramic restorations. The aim of this study was to review adhesives, particularly adhesive resins and their clinical characteristics, considerations and requirements in an attempt to assist dentists in selecting appropriate adhesive cements in special clinical situations.Materials and Methods: This review paper used a scientific search for library resources, books and websites of Pubmed and ISI Web of Science in connection with articles published up to 2012 on classification and types of dental cements, their clinical applications, the mechanism of curing resin cements, bonding mechanisms and biocompatibility, adhesion principles, current issues in the field of fiber posts in root canal cementation and surface preparation of dental ceramics. In addition, a variety of surface preparation methods available for fiber posts and different dental ceramics were discussed.Conclusion: New materials are constantly marketed by manufacturers, making it difficult to select appropriate cements and to teach cement application. Selection of an appropriate cement is very important because the dentist will be able to apply a suitable surface treatment on the cemented surface. When optimal compressive strength, minimal film thickness and low solubility in water are desirable, conventional cement materials are desirable; however, these cements require ideal tooth surface preparation. Conventional cements are used for porcelains that are not etchable. On the other hand, due to the superior physical properties of resin cements and higher aesthetics compared to conventional cements, they are good choices for cementation of metal-free restorations. Key words: Adhesives, Ceramics, Resin cements

Background and Aims: Re-application of microbrush may affect the micro tensile bond strength of adhesives to dentin. The aim of this study was to evaluate the effect of re-application of microbrushes on the micro tensile bond strength of an adhesive to dentin. Materials and Methods: Thirty freshly extracted molars teeth were collected and enamel of occlusal surface were removed to expose superficial dentin. Then superficial dentin was etched, washed and partially air dried. According to the times of application of microbrush, teeth were divided into two test groups. In group 1, new microbrushs were used, but in group 2, the ones that were already used for twice were included. Ambar dentin bonding agent (FGM/Brazil) was applied to the etched dentin with microbrushes according to the manufacturer's instructions. Then the crown of teeth was built up with LLiss (FGM/Brazil) composite resin. The teeth were sectioned in buccolingual direction to obtain 1mm slabs. Then 50 hourglass- shape samples were made from 30 teeth (25 Specimens per group). The microtensile bond strength of the specimens was tested using MTD500 (SD Mechatronik, Germany). The data were statistically analyzed by T-test. Results: The mean values for the microtensile bond strength were 30.49±7.18 and 23.61±9.06 MPa±SD for the first and second groups, respectively. There was significant difference between the groups (P=0.005). Conclusion: Microbrushes should not be used for more than one cavity preparation. [ABSTRACT FROM AUTHOR]

Presently, because of the human health issues related to the formaldehyde gas emission initiated from traditional wood adhesives like urea formaldehyde, the bio-sbased adhesives has shown a good solution for preventing health hazards for human and the environment. To achieve an acceptable approach in wood based composites production, these adhesive need to qualify different standard limitations. This research was conducted to improve the bio-based soy-tannin adhesive for producing plywood with acceptable properties. For this goal, different adhesive formulations were prepared in the laboratory and they were treated at different temperature (40, 60, 80 ºC). Poplar wood plies with 2 mm nominal thickness were used to produce plywood specimens. The results showed the effectiveness of adhesives with heat pre-treatments at different temperature on shear strength (dry and wet) of plywood specimens. The highest shear strength of plywood specimens was achieved for 40 ºC treated adhesive in both dry and wet condition. Based on the results of shear strength test, all manufactured plywood specimens successfully met EN314-2 standards requirement. Also, the results of delamination test revealed that plywood specimens which prepared by 40 ºC treated adhesive can successfully use for indoor condition, based on ANSI-HPV-1 requirements. [ABSTRACT FROM AUTHOR]