Volume 56, Issue 3

Abstract: In order to evaluate the possibility of reuse of some mixed waste from plastic and paper, composite samples of both HDPE and PP basis were made with different filler contents of crushed postage envelope waste. From the morphostructural characterization (SEM images) of the samples obtained it was observed that the HDPE and PP samples had had a homogeneous single-phase structure in contrast to the composite samples with filler from mixed plastic and paper waste. The latter, have a biphasic heterogeneous structure in which the cellulose particles are uniformly distributed. Determinations performed through the dielectric spectroscopy technique indicated that the cellulose content of the composite samples leads to a systematic increase of the dielectric losses (up to about 40% for the HDPE samples, respectively about 30% for the samples with PP), the increases being in direct correlation with the cellulose content of the composite.Mechanical determinations have shown that the average values of tensile strength recorded on the achieved samples, systematically decrease at the increase in the chips content of the samples - decreases up to 10% at an addition up to 15% chips from the waste are explained by the substantially lower mechanical strength of waste paper than that of the HDPE, respective PP.

Abstract: The present paper describe the production and characterization of novel collagen films containing propolis encapsulated in chitosan nanoparticles, for biomedical applications such as cutaneous wound healing. Structural and morphological details were investigated by ATR FTIR spectroscopy, SEM and nanoindentation measurements, revealing the collagen fibers aligned in a quasi-parallel distribution, which might be favorable for biomedical applications. Moreover, the vibrational marker bands of propolis were well preserved in the final polymeric mixture, indicating the stability of bioactive compounds upon the encapsulation procedure. The antibacterial effect depends on the nanoparticles concentration in collagen film, the effect being more evident with respect to E. coli than S. aureus. The antioxidant capacity monitored by CUPRAC assay, indicated a synergic effect of chitosan nanoparticles matrix and propolis extract, incorporated in collagen films.

Abstract: Soil pollution with plastics represents a great threat to plants, animals, but especially to humans, as a very small quantity of the plastic which is discarded daily is recycled or incinerated in waste facilities, much of it reaching landfills where their decomposition lasts up to 1000 years and during this time the toxic substances penetrate the soil and the water. If, initially, the pollution with plastics has been identified and recognized in the aquatic environment, recent studies show that plastics residues exist in huge quantities in the soil. The present study focuses on the analysis of factors that pollute soil, so the various studies that have been carried out claim that soil pollution with plastic is much higher and increases in an aggressive manner, being estimated to be 4 to 23 times higher than water pollution with plastics, and the accumulation of microplastics in the soil has a negative impact on soil biota. Thus, once the plastic material accumulates in the soil, it is assimilated to organic matter and the mineral substitutes of the soil and persists for several hundred years.

Abstract: In the recent years, the electric vehicles have drawn great attention worldwide as a feasible solution for clean transportation. The charging infrastructure for electric vehicles is expanding throughout the world, encouraged by large investments from the automotive industry, to reduce carbon emissions. The purpose of this paper is to design the shell of an electrical vehicle charger by using polymeric composite materials. The manufacturing technology is proposed and the analysis of the product behaviour during the wind action in extreme conditions is presented. The paper includes studies and research regarding the design, the manufacturing and the simulation for the action of wind upon the product’s walls. The simulations are performed for the actual used material (ordinary sheet steel) and for the proposed composite material in order to compare the results. The composite material seems to be an adequate solution for the electric charger shell.

Abstract: The damages and casualties inflicted by mine and IED attacks in security challenging areas generated a strong and quick response from nations all over the world. As a part of this response several national and private research facilities increased their efforts in identifying and implementing new ways or technologies to enable blast wave mitigation. The current paper aim to investigate the opportunity of using polyurea coated steel plates as a possible new blast mitigation approach, as suggested by several investigators. In order to objectively conclude about the ability of polyurea coated plates to sustain locally blast loads several experimental tests were performed according to STANAG 4569 demands for a 1/6 scaled plate structure. In order to numerically validate the experimental results several Autodyn simulations were set-up. The numerical and experimental results exibits a fair correlation, both pointing towards a dismiss of the idea of using polyurea coated steel plates as structural and cost effective blast mitigation approach.

Abstract: Designing a sample to be made by FDM 3D printing is a fundamental problem in further studies related to such printed structures as material properties vary depending on filament orientation and G-code particularities. Samples designed to simulate wall structures inside 3D printed parts have been tested to allow separate evaluation of key components in such parts. Results show a very long plastic region in filaments without imperfections. As filament strands break steps of similar values appear in the reaction force measured by the machine.

Abstract: The aim of our study was to determine the wear resistance of vacuum-formed retainers (VFRs) made out of polyethylene terephthalate glycol (PETG), from four different manufacturers (Essix, Leone, Erkodent, Bio-Art), under high load forces (600 N), for 10000 cycles. Forty thermoplastic sheets were divided in four groups, each group consisting of a set of ten sheets from each manufacturer, thermoformed on two matching study models with an ideal occlusion. The Instron 8874 equipment was used to simulate the accelerated wear of VFR surfaces. The surfaces of the VFRs were visually inspected using a KEYENCE VHX-600 digital microscope, but this proved difficult because of the surface shine. 3D models were generated using a GOM industrial laser surface scanner. Several wear areas were identified, having various degrees of roughness, with no evident tear points or perforations. One-way ANOVA analysis showed no statistically significant differences in net mass loss between the four groups.

Abstract: The high global production of electric and electronic equipment increases in the same manner the amount of the waste that needs to be recycled. Special attention is given to the plastics recycling from the waste in addition to the metals recovery that brings economic advantages. Considering that the plastic amount contains about 80% polystyrene polymers, the paper presents a recycling study of this fraction as reinforcing agent for a styrene-butadiene block copolymer. In order to reduce the melt viscosity, some of the composites were extended with paraffin-naphthenic “heavy white oil”. The blends were characterized by mechanical testing, thermal and dynamo-mechanical analysis. Based on the resulted properties, it can be concluded that the extended and reinforced composites can be used as material for shoe soles.

Abstract: New nanogels (NGs) with tailored properties were obtained using a mini-emulsion technique, from poly(ethylene glycol) diacrylate (PEGDA) self-crosslinking macromers of various molecular weight. By modifying synthesis parameters (hydrophilic-lipophilic balance, emulsifier and the ratio of organic-aqueous medium), optimum recipes of NGs were selected. Therefore, the molecular weight distribution and the functionalization degree of the PEGDA2000 macromer were assessed by Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (NMR), respectively. Furthermore, the PEGDA-NGs were investigated by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) for size distributions and morphology. DLS and TEM results confirm that these new PEGDA-NGs hold potential for biomedical applications.

Abstract: The hypercaloric diet leads to obesity which is a risk factor for developing many systemic diseases such as diabetes, cardiovascular diseases and cancer. The purpose of our study was to observe the antioxidants effects of entrapped alfa-tocopherol (vitamin E) and lutein in Poly Lactic-CO-Glycolic acid (PLGA) in Wistar rats that received 3 weeks hypercaloric diet. Hepatic and splenic lysates have been used to detect changes in total antioxidant capacity (TAC) and advanced oxidative protein products (AOPP). The AOPP liver levels were statistically decreased in the case of rats groups that received a daily dose of PLGA-lutein or PLGA-vitamin E versus the control group. The AOPP level was decreased but statistically insignificant in Wistar rats spleen who received a daily dose of PLGA-lutein. At hepatic level, TAC was statistically increased in rats groups that received a daily dose of vitamin E or lutein. An increased statistical level of TAC was observed in the spleen cell lysing in Wistar rats who received the daily dose of PLGA-vitamin E. Entrapment of vitamin E and lutein in PLGA structure has diminished the effects of hypercaloric diet and can be considered a attractive and promising approach to enhance the bioavailability and activity of poorly water soluble compounds.

Abstract: The purpose of this experimental study is to present the design and biomechanical characteristics of mobile bearing postero-stabilised total knee prosthesis type MC2®- C2F® and to evaluate their use in severe primary knee osteoarthritis. The experimental part was carried out on 20 patients who benefited from mobile bearing postero-stabilised total knee prosthesis type MC2® in University Hospital Sf Spiridon Iasi, Romania. From the radiological point of view there were no mechanical complications in a 3 year follow-up. The functional recovery had a good outcome and patients currently have an active flexion between 70° and 110°, with extension between 0° and -15°. No pain was registered in full weight bearing and in active joint movement.The clinical and radiological outcome at 3 year follow-up is satisfactory and the results convinced the authors that this type of prosthesis is a good option in any primary knee osteoarthritis with no significant bone loss.

Abstract: This in vitro study analyses the biochemical interaction between saliva and three types of dental composite resins (a direct resin, an indirect resin and a dual-cure resin used for cementation of indirect dental restorations). The resin samples were obtained following a specific protocol and in line with the producers’ recommendations; the resin samples were incubated with saliva samples collected from 19 healthy volunteers. The obtained results showed that the tested composite resins did not produce significant changes in oxidative stress parameters that were analysed (albumin, uric acid, GGT / gamma glutamyl transferase, OXSR-1 / oxidative stress responsive kinase 1) and do not influence the inflammatory salivary status reflected by the levels of IL-6 - an inflammatory marker.

Abstract: The purpose of this study was the synthesis of two types of biodegradable materials with synthetic polymers (PLGA) or natural polymers (collagen) and hydroxyapatite, followed by determination of the encapsulation percentage of the drug in the polymer. Regardless of the chosen method, the percentage of the encapsulated drug was found to be quite high: 15.92% in the Coll-HA-Genta material and 19.59% respectively in the PLGA-Genta biocomposite. The therapeutic value of gentamicin was improved by encapsulating it in delivery systems, contributing to sustained release for a long time (about 30 days).

Abstract: This paper presents an experimental study to determine the behaviour of composite panels, made of polyurea sprayed on Kevlar or Dyneema support layers, under blast and fragments produced by an improvised explosive device (IED). The fragments used for tests were steel bearing balls of 8 and 10 mm propelled by a plastic explosive charge and bullets cal. 7.62 mm, type Full Metal Jacketed Armor Piercing (FMJ AP) and Hollow Point Boat Tail (HPBT), with impact velocity greater than 500 m/s. To determine the fragments attenuation, their velocities before and after the impact with the composite panel were measured and compared. In order to assess the blast attenuation, the reflected pressures measured by two face-on sensors, one of which was covered by the composite panel, were compared. Also, to explain the behaviour of composite panels under blast, the shock polars of materials in the panel‘s composition were plotted. The results have shown that the composite panels have a low rate of attenuation of fragment velocities but a very good ability to attenuate the pressure and impulse associated with the shock wave.

Abstract: Hormonal Intrauterine Devices (IUD) were developed based on copper IUD with the role to release a daily amount of hormones. From a structural point of view Levonorgestrel-IUD (L-IUD) is a small T-shaped piece of plastic, which contains levonorgestrel. When compared with the oral route of L-IUD administration, it provides some advantages because it releases levonorgestrel directly into the uterus. Our aims were: (1) to compare the thickness of uterine jonctional zone (UJZ) in two groups of patients with and without inserted L-IUD, (2) to evaluate the changes in thickness of UJZ after the insertion of L-IUD in two patients with adenomyosis, and (3) to obtain and to characterize a similar T-shaped polyurethane (PU) foam used as a levonorgestrel delivery system. On the one hand, the results confirm that L-IUD is effective in thinning the UJZ and in the treatment of adenomyosis, while on the other hand, the characterization of the PU materials (Zetasizer measurements, their thermal degradation, UV-Vis spectra and skin irritation tests) revealed that this polymer can be used as a safety and prolonged levonorgestrel carrier.

Abstract: Dental caries and secondary caries are the most common problems in dentistry. Many studies provided evidence for the anticariogenic effect of fluorides. The incidence of secondary caries is decreased in teeth restored with fluoride releasing materials. The purpose of the present in vitro study is to evaluate the fluoride release and uptake capability of two glass-ionomer cements and two compomers. A total number of 60 specimens were prepared according to the manufacturer’s instructions using silicone molds. The specimens were transferred in plastic containers containing artificial saliva (pH=7), incubated at 37°C for 24 h and divided in three subgroups: control group, varnish treated group and dentifrice treated group. The fluoride ion content was measured on five times during a period of 30 days using an Orion 720A fluoride meter with 9609 BN fluoride ion electrode. The self-curing glass-ionomer cement released the highest amounts of fluoride ions at the beginning and after the one month study period. The samples of the four materials tested in the varnish treated groups showed significant differences compared to their control groups on the second day. Dentifrice treated groups did not show significant differences compared to their control groups, except values measured after 30 days. Application of fluoride varnish produced an increase of fluoride release for the first 24 h in case of all materials. However, results suggest that the use of fluoridated dentifrice would be more effective in caries prevention due to their fluoride uptake capability.

Abstract: \Six new products were obtained by deposition of para-tert-butylcalix[4]arene (t-Bu-C4OH), calix[4]arene (C4OH) and tetra-methoxy-calix[4]arene (C4OMe) on two types of SBA-15 mesoporous silica. All the products were characterized through thermogravimetric methods and SEM microscopy. The obtained results confirm the functionalization of the silica materials with the calixarene macrocycles. Considering all the obtained products, the thermal analysis suggests the strongest connectivity to form between the C4OMe systems and mesoporous silica substrate.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: With technology becoming more and more advanced, the medical system is being consistently improved. From intraoral scanners that started to replace conventionally impressions technique to printed surgical guides that directs the drilling systems of implants, dentistry is one of the beneficiars of new and advanced treatments that are ergonomic, safe and put both the medical team and the patient in a more pleasant experience. The purpose of our article is to summarize the application of acrylic and metacrylic resin in 3D printing of surgical guides used in orthodontics.