Browse Articles

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.

The current trend is the introduction of antimicrobial agents for the purpose of inhibiting or avoiding (adherence) adhesion and (increasing) the multiplication of their microorganisms on the surface of the impression materials. This study aims to determine the properties of antibacterial and antifungal elastic impression materials in full agreement with (bacterial flora) microflora specific for every patient ( with identification of existing species ). In the same time there are considered modern methods of sterilization and insertion of antiseptics, trajectories with profound impact in the field of biocompatibility. The obtained microorganisms were transplanted on differentiated and selective (differentiated) culture medium in order to obtain pure cultures.Each microbial strain obtained was tested to identify several characteristics. The examinations carried out by means of the electron microscopy very accurately detect the microbial load in the structure of the impression materials, sounding an alarm signal on its use in particular clinical situations. Alginates present in their structure polysaccharide structures that represent an excellent substrate of microorganisms.

The developement and regeneration of healthy bone tissue is a complex process that includes the interaction of different cell types and requires a set of coordinated processes. The loss of bone tissue may occur due to various reasons: surgical removal, bone trauma (i.e., fractures) or systemic bone loss (i.e., osteoporosis). When the natural bone tissue is destroyed, the regeneration capacity of the bone is not always satisfactory. The result consists therefore in many functional and structural aberrations. In order to improve and accelerate the healing process, bone substitutes have been developed. Hydroxyapatite has been widely used in bone applications due to its excellent biocompatibility, osteoconductivity and bioactivity [1,2]. The objective of this research is to obtain a new composite biomaterial that can be used as bone substitute. In this study, bovine hydroxyapatite obtained from freshly calcined bovine femur was used. The objective of this research is to obtain a new composite biomaterial that can be used as bone substitute. The experimental composite samples were obtained using bovine hydroxyapatite as matrix and tricalcium phosphate, respectively, magnesium oxide as reinforcement materials. The synthesis process of these new biomaterial composites, the effect of chemical composition, surface structure, chemical and phase composition as well as mechanical features have been investigated.

The current study relates to the immobilization of the nasal region with splints using modern materials such as thermoplastic compounds in patients that have undergone rhinoplasty. The objectives of the research are to highlight the main characteristics of thermoplastic splints and to perform a comparative analysis in relation with traditional splints. The research was conducted on 2 batches, the first batch involving 24 patients that have undergone rhinoplasty, the postoperative immobilization being performed using metallic splints and the second batch involving 29 patients, thermoplastic splints being used for immobilization after the surgery. The results of the study are focused on evaluating both thermoplastic and traditional splints based on several criteria, such as modeling capacity, toxicity, surgical risks and patients’ degree of satisfaction.

Zinc oxide (ZnO) is an inorganic compound used for its antiseptic and skin healing properties. It is an excellent protective filter against UV radiation and it can be used as white pigment in pharmaceutical preparations. In this study, nano-ZnO particles were obtained by ultrasound treatment, and respectively by repeated freezing/heating process. The influence of synthesis method and of ultrasound generator parameters on the particles size and stability was observed. The results reveal that were obtained samples with a very good stability and sizes between 15 and 96 nm. It was found that synthesis based on ultrasound treatment lead to the formation of nanoparticles with lower sizes.