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Bone fracture fixation uses both consecrated materials, such as metals/metal alloys, as well as synthetic materials. Synthetic materials are extremely versatile in terms of simulating biological structures, biocompatibility and, in some cases, avoid the subsequent interventions for removing the prosthetic material. Fixing an osteoporotic fracture presents major risks of failure due mainly to the bone fragility. To reduce the risk of failure, prosthetic materials have been improved with various cements. The purpose of the current study was to assess the mechanical properties of different orthopedic screws covered with a new polyurethane acrylate polymer (PUA) in order to improve the stability of the screw for the subsequent fixation of the fragility fracture. To test the efficiency of the new polymer, the breaking/fracture strength of the orthopedic screws coated with PUA was evaluated, in comparison with the screws without coating material. Our data shows that tested PUA improves the bond between the screw and bone. We estimate that the effect obtained is caused by the partial damping of the loading force due to the elastic component of the polymer.

Disadvantages of diacrilic composite resins and glass ionomers cements have stimulated research to develop hybrid materials to eliminate the downsides and take advantage of their benefits. The purpose of this study was three-dimensional analysis of a flux material with a resin-modified glass ionomer (RMGI) cement in preventive sealing by two techniques of enamel substrate approach, respectively, with acidic conditioning with 37% orthophosphoric acid and free. The best results were observed in the RMGI when no substrate conditioning was performed.

The composition of electrical wires and cables is of critical importance in controlling fire risks. In this respect, polyvinylchloride (PVC) composites are extensively used. Yet, PVC composites are multiple systems in which the final properties depend on the nature and size of the reinforcement or flame-retardant agent and the type of lubricant used for their preparation. Thereby, in this study two series of PVC composites, with stearic acid and calcium stearate as lubricants were prepared in parallel, and additivated with various commercial minerals as reinforcement/flame retardant agents, such as calcium carbonate, alumina trihydrate (ATH) and HMH (a mineral of hydromagnesite and huntite). Following the structure (by FT-infrared), thermal behavior (thermal analyses and differential scanning calorimetry) and mechanical properties (dynamic mechanical analyses, tensile strength and elongation at break) of PVC composites, the flame-retardant effect of the selected minerals was investigated by measuring the limiting oxygen index (LOI). Only ATH and HMH-based composites presented higher flame-resistance, relative to the control samples, making them suitable for the proposed application. The contact angle was evaluated for determining the hydrophobicity of composites when using ATH or HMH, to get an opinion about the stability of the materials in moist environments. Finally, SEM was used to determine the homogeneity of PVC samples.

Biodentine is a tricalcium silicate cement used as a dentin replacement in restorative dentistry. The aim of this study was to assess the influence of cavity moisture on the immediate sealing and morphology of the interface between Biodentine and the dental tissues. 20 class II cavities were prepared in extracted teeth. 10 cavities were dried using the air spray before restoring with Biodentine and 10 cavities were preserved moist for the restorative procedure. The teeth were subjected to a microleakage test and then the axial sections were observed under optical microscope and scanning electron microscope. In most situations Biodentine provided an immediate good marginal sealing and a tide contact with adjacent tissues in both occlusal and cervical margins which did not seem to be influenced by the moisture of the dental supporting tissues.

Changes in the surface roughness of dental restorative materials after tooth brushing are inevitable. The abrasion is known to increase the possibility of dental plaque accumulation which is responsible for several pathologies of the oral cavity. The aim of this in vitro study was to evaluate the changes of surface roughness of microhybrid composite materials produced by different toothbrushes with and without toothpaste. Forty-eight specimens of two composite materials (Charisma and Super-Cor) were prepared using a silicone template according to the manufacturer’s instructions. Each sample was brushed for eight hours. Each group of specimens was divided in two subgroups: half of the samples were brushed using only distilled water and the other half with a mixture of distilled water and toothpaste (Colgate Total; ratio 1:1). The average roughness value (Ra) of surfaces were measured with profilometer three times: the initial measurement was performed before starting the toothbrush simulation, the second was after 4 hours and the third was after 8 hours of brushing. Three different bristle stiffness toothbrush heads were used (medium sensitive, medium and soft). After collecting all numerical data one-way ANOVA and Friedman tests were performed for statistical analysis. All examined microhybrid composites exhibited changes in surface roughness after the toothbrush simulation. The simulation of toothbrushing without toothpaste, only with water as cleaning substrate, showed at every measurement the lowest values of roughness in all three toothbrush heads. Significantly increase of mean Ra values were observed in both tested composite samples when medium and soft toothbrushes with toothpaste were used. The surface roughness changes of tested microhybrid composites depend on the brushing procedure. The toothpaste has a much greater effect on the abrasion than the type of toothbrush.

The brake pads are one of the basic components for the development an ecological transport. The main objective of the paper is to produce green brake pads used shells as filler material capable to reducing the emission of fine and ultrafine particles resulting from vehicle braking systems. The stages in the development of this goal were: establishing the chemical composition of shells, formulating the recipes of composite materials, selecting parameters of technology, obtaining in laboratory and characterization of new materials in terms of physico-mechanical and tribological characteristics, evaluating their performance compared to similar materials presented in the scientific literature.

The purpose of the present study was to evaluate the mechanical parameters at compression tests for two different restorative composite resins. The materials here under study were: Gradia Direct (GC Corporation, Tokyo, Japan) and Filtek Ultimate Universal Restorative, (3M ESPE, St. Paul, MN, USA). 30 cylindrical samples, 15 for each material, with a thickness of 6 mm and a diameter of 5 mm, were made. The compression behavior at mechanical tests for each sample was analyzed. One-Sample Kolmogorov-Smirnov Test followed by Paired Samples t-Test was used for statistical analysis and determining the level of significance. Gradia Direct had a lower value of Young’s modulus than Filtek Ultimate Universal Restorative, the results being statistically significant (p = 0.001 [ 0.05). The comparative evaluation of the compressive strength did not reveal statistically significant results between the two materials (p = 0.098 ] 0,05). Regarding the compressive strain the values were significantly lower for Filtek Ultimate Universal Restorative (p=0.000 [ 0.05). The microhybrid composite evaluated in the present study proved to have better mechanical properties than the nanofilled composite.

Elastomeric chains, as means of force delivery, are one of the most studied elements of the orthodontic field. Effects on tooth movement are closely related to force degradation degrees of these polymers. Unfortunately, due to varied manufacturing techniques and materials, different brands of elastomeric chains offer different initial force values and different force decay, with direct impact on tooth movement duration and effectiveness and quality of orthodontic treatments.

The aim of this work was the development of a series of glass fiber reinforced composites (FRCs) for CAD/CAM applications in dentistry and the characterization of their structure by SEM, Raman and FTIR spectroscopy. A selection of 2 different types of resins (R1 composed from 25%Bis-GMA, 40%UEDMA, 35% DMTEG and R2 composed from 65%Bis-GMA, 35% DMTEG) with 2 different types of hybrid filler (F1 with 42% quartz, 42% radiopaque glass and 16 % hydroxyapatite and F2 with 90% quartz and 10% colloidal silica) and 3 different types of E type fiber glass geometries (veil 30g/m2, twill 163g/m2 and textile 300g/m2) in 4, 6, 8 and 10 layers were used in this in vitro study. Raman analysis, showed a powerful interaction between the polymer and the fiber glass. FTIR and SEM data revealed that the different fiber glass geometries were well incorporated inside the resin, resulting an acceptable homogeneity. Within the limitation of this study, it is possible to achieve a fiber glass reinforced composite for the use of CAD/CAM technology. Further investigation must be done in order to test all the properties of the new material.

Materials used in additive techniques are initially in a plastic state to be inserted into different cavities or easily molded (a blunt, for example), after which they pass into a rigid phase. This process is carried out by various methods depending on the material nature. The process can be purely physical (solidifying the alloy melt, the termoplasticized macromolecular compounds), modification and rearrangement of the internal structure (sintering of ceramic masses, crystallization of glasses, amalgam intake), a process of evaporation of some components (lacquers, plasticizing polymers) or a chemical process. This latter process can be an acid-base reaction between two inorganic substances (PCZ, CIS cements), a chelating reaction (ZOE cements) between a phenolic range (organic compound, usually eugenol or orthoethoxybenzoic acid) and an inorganic powder (ZnO) or a reaction in which a macromolecular compound is formed. After the type of the reaction, the macromolecules are classified into polymers (the formation reaction is called polymerization, the compounds of which are obtained by monomers, the main chain is formed by the carbon atom only), polycondensates (the formation reaction is called polycondensation, the chain also formed from heteroatom-ON, depending on the type of material) or substances that are obtained by polyaddition ( a repeated addition, the mechanism being different from the polymerization. Our study was conducted in the Dental Clinic and comprises a total of 17 patients. The group was represented by patients aged 50-85 years. Clinical observations have been made on cases of fracture of acrylic bases, with the analysis and assessment of some clinical aspects with increased risk of fracture (jaw / mandible, median / paramedian fracture line, etc.), which increase the risk to and fracture when associated. Clinical observations have shown the presence of the risk of fracture in acrylic prostheses, with the need first of all for the proper design and realization of mobile prostheses, but also for the use of inserts.