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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.

Successfully used in bone surgery for more than 65 years, self-hardening organic cements (CCOs), in particular acrylic cements, are today, the most advanced complementary biomaterials used in articular endoprosthesis. One of the strategies for obtaining of performing anchorage of artificial implants is to develop new acrylic cements with improved physical, chemical and biomechanical characteristics. The aim of this paper was to identify the compositional and morpho-structural changes of acrylic cements induced by the composition of the liquid phase of the material. Such changes influence the potential to generate the physical bonds responsible for fixation and stabilization of endoprosthesis. The samples studied had different compositions due to the mixture of acrylic monomers, methyl methacrylate (MMA) and butyl acrylate (BuA) in the liquid component of cement. The MMA / BuA ratio varied between 1/0 v / v and 1/4 v / v. Changes in the composition and morphology of cement samples have been highlighted by ESCA (Electron Spectroscopy for Chemical Analysis), EDX (Energy-Dispersive X-ray Spectroscopy), IR spectroscopy and SEM images. The obtained data show that minor changes in cement composition can significantly influence morpho-structural characteristics such as pore size and their distribution in the mass of fixing material.

The thermoplastic materials studied are biphasic. They consist of a polymer mass and a short glass fiber, the percentage being between 10 and 30%. We have shown, both analytically and graphically, the evolution of wear occurring on the steel surface in contact with glass fiber-reinforced polymers. The evolution in time of this process depends on the evolution of the friction coefficient in the process of the dry linear contact between different polymers and different types of steels. We have made a connection between the theoretical case and the experimental results. The experimental method used was the wear imprint method through which the wear depth and wear volume were determined. The wear process is complex and is accompanied by adhesion and corrosion phenomena. Any modification of the input parameters such as speed, temperature, load, quantity of glass fibers in the polymer lead at a certain one evolution of the wear behaviour of the composite material.

This paper presents the results of an investigation into the structure and properties of intraocular lenses (IOL) that are available on the ophthalmological market. The majority of implants of this type are based on acrylics or poly(methyl methacrylate) (PMMA). The acrylic lenses can be curled, which allows the making of just a minor incision during the associated implant surgery. The drawback of PMMA implants is their high rigidity, resulting in the need for a larger incision during the implant surgery. The benefits accrued from wearing such an implant are (1) the correction of focus for clear vision and (2) protection of the retina against UV-A radiation. X-ray diffractometry has confirmed the amorphous structure of all of the lenses investigated in this paper. The absorption and transmittance of the selected implants have been measured; differences found in the directional values of the transmittance and absorbance suggest the presence of differences in the implant coating (such as: different thickness or lack of coating on one side). It has been found that the PMMA-based implants exhibit the better properties with a level of light transmission in the visible spectrum of almost 40% and total protection against UV radiation. The acrylic implants feature lower transmittance in the visible light spectrum, and two of the investigated acrylic lenses failed to provide adequate protection against the UV radiation.

Modern coronary restorative materials have a vulnerable aspect, represented by the excessive wear, which determines the severe limitations of applications in the areas of the occlusal contact. In this study, the experimental researches on the abrasive wear behaviour were performed on five direct restorative dental materials belonging to some different classes from the structural point of view: compomer (Compoglass), ceramic (Empress), silver amalgam (Ventura Plus), poly-glass (Artglass), light-cured lining composite resin (Herculite 1). The analysis of the abrasive wear behaviour of direct restorative dental materials imposed their initial characterization from the microstructural point of view and according to the Vickers hardness. Experimental determinations pointed out absolute and relative mass loss, mass intensity and wear speed. The results of the study are useful in choosing a direct resistant and esthetical restoration material.

The aim of this study was to evaluate the potential of coloring of two commercial beverages: coffee and wine, and cigarette smoke, on three materials (ICON infiltration resin, MI Varnish Recaldent, and a sealant based on composite resin) currently used in incipient caries therapy. The study group included 75 extracted teeth that were divided into 3 groups corresponding to each material used. The groups were divided into 5 subgroups that corresponded to each colorant (A. red wine, B. coffee, C. cigarette smoke, D. association of the three colorants, E. control group). The coloration degree of the samples was measured both after the moment of coloring (M3) and after polishing (M4). The results showed a significant increase of the coloring degree for the samples subjected to the combined action of the three colorants (M3), for all the three materials used (DE1*: Id = 23.56, IId = 25.87, IIId = 19.87), and in terms of the coloring degree after the polishing procedure (M4), a decrease of the values was observed (DE2*: Id = 17.56, IId = 21.67, IIId = 16.78). In conclusion, both exposure to the two beverages used in the study and cigarette smoke (C) leads to the appearance of color changes, but the most significant changes were obtained by combining the three colorants (D). Also, the polishing procedure leaded to an improvement of the color variation for all three materials.

Since the discovery of exceptional properties of graphene, a lot of researchers focused on the discovery of another nobel two-dimensional (2D) materials. Recently, an elegant exfoliation approaches was proposed as a method to synthesis a new family of transitional 2D metal carbide or nitrades of MXene from a layered MAX phase. A layered MAX phase of Ti3AlC2 was synthesized through pressureless sintering (PLS) the initial powder of 3TiH2/1.1Al/2C without preliminary dehydrogenation under argon atmosphere at 1350 oC. An elegant exfoliation approach was used to eliminates Al from its precursor to form a layered-structure of Ti3C2. In this study, thermal conductivity of MAX phase and MXene were studied using absolute axial heat flow method to measure the abilities sample to conduct heat and the data was collected using Picolog 1216 Data Logger. Electrical conductivity of these two materials was also compared by using two-point probe, due to its simplicity. Radiation properties of 2D MXene Ti3C2 was studied by using an established radon monitor, placed in closed, fabricated container. Morphological and structural properties of this 2D material were also studied using an established FESEM and XRD apparatus. SEM images shows two types of morphology which is a layer of Ti3C2 and the agglomerates Al2O3 with graphite. XRD pattern reveals three phases in this material which is a rhombohedral Al2O3, rhombohedral graphite and rhombohedral Ti3C2 phases, respectively. Thermal and electrical conductivity of MXene were proven higher than MAX phase. Radon concentration for this material for five consecutive days explains the radiation level of this material which is under the suggestion value from US Environmental Protection Agency (EPA). From this finding, it is can conveniently say that the MXene material can be promising material for electronic application.