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Dental composites, some of the most used materials in the last decade, have been and still are the focus of the researches in the last period of time. The present study aims to evaluate three of the most used composites given their different behaviour in practice. There were performed: the flexural strength test, the compression strength and resistance test at diametral compression according to ADA Sp.27/1993 specification. The results were surprising given the differences between the values obtained for the samples of each material. The study concludes that the variable properties of the composites in the same conditions originate from their inconstant microscopic structure. Keywords:dental composites, flexural strength test, compression strength, esistance test

Membrane processes are a way to remove unwanted elements from wastewater stream. The permeability is an important parameter to filter wastewater and membrane fouling is of great interest in membrane filtration because reduce wastewater flow through the membrane. In order to improve the filtration process, many studies have investigated the use of nanoparticles added in the polymeric membranes and how much influence the permeation properties of membranes. A variety of nanoparticles have been used to modify polymer membranes, such as Al2O3, SiO2, TiO2, ZrO2, Fe3O4, Ag. Nanoparticles are used to improve the properties of membranes like hydrophilicity, permeability and fouling resistance. This paper shows the influence of the TiO2 nanoparticles with a concentration of 0.125 wt.%, on the permeation properties and dyes rejection of the PES and PSf membranes and makes a comparison with the results obtained by other authors. Keywords: TiO2 nanoparticles, PES, PSf, membranes

Respiratory movements monitoring is critical in ensuring optimal patient supervision, especially in critical cases and also in diagnosing sleep apnea syndrome.The aim of our paper is to assess the possible role of magnetic impedance (MI) effect in respiratory movements recording.The study was carried out on 6 volunteers using a special mat equipped with quasi-non-contact MI sensors. Evaluation consisted in monitoring and recording the amplitude and frequency of the respiratory movements during normal breathing and while performing Valsalva maneuver.The constancy of pattern and amplitude of waves recorded suggests that this kind of respiratory movement monitoring may have considerable clinical application in monitoring critical patients and also sleep disorders, especially for children suspected of sleep apnea. Keywords: Amorphous Ferromagnetic Materials, Magneto impedance, Sensor, Breathing, Apnea

The aim of this study was to point out the effect of porous clay heterostructure (PCH) and polymer concentration on thermal and dynamic mechanical properties of Sodium Alginate (SA) based hybrid films. New hybrid films based on SA and PCH were prepared by solvent casting method using different polymer concentrations and clay loadings. The interactions between nanofiller (PCH) and polymer matrix (SA), thermal stability and dynamic mechanical properties of neat SA and hybrid films were evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The obtained results showed the influence of PCH within SA on the storage modulus and a moderate change of thermal stability, the glass transition temperature being also recorded. The concentration of SA solution and PCH are significant factors which affect the thermal and mechanical properties of hybrid films. Keywords: sodium alginate, porous clay heterostructures, hybrid films, thermal stability, dynamic mechanical analysis

This study aims to reintroduce the economic circuit of recovered uncontaminated with organic impurities polypropylene sorts, the melt alloying of polyolefin with styrene-isoprene block copolymers. Keywords: styrene-isoprene block-copolymers, recycling waste polypropylene, melt alloying

Protonation, quaternization and addition reactions of poly(N-vinylimidazole) to the imidazole nitrogen atom in the position 3 to obtain the corresponding ionic derivatives were studied by NMR spectroscopy. Information and data on the reaction type and product microstructure are presented. The chain tacticity is a special structure aspect which was in detail studied by means of proton and carbon NMR spectra confirming that the chain configuration is not modified by any of the three polymer-analogous reactions. Keywords: poly(N-vinylimidazole); polyelectrolytes; benzyl chloride; trifluoroacetic acid; acrylic acid; chain tacticity; polymer microstructure

Polyurethanes (PU) are synthetic materials with large structural possibilities and mechanical adaptability that have promising perspectives in medical applications. This paper is focused on the hydrolytic stability and biocompatibility of poly(ester-urethane) and poly(ether-urethane) membranes blended with hydroxypropylcellulose (HPC). FTIR analysis and extended biocompatibility tests were performed. Based on our in vitro results this PU sample is expected to promote a better biological tolerance and lower pro-inflammatory reaction in vivo. Keywords: HPC-modified polyurethanes, hydrolytic stability, cytotoxicity, pro-inflammatory potential

The present work reports on the biocompatibility of poly (3-hydroxybutyrate) and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) loaded with bacterial cellulose and microcrystalline cellulose via melt processing. Biocompatibility was tested by physico-chemical and in vitro methods. Physico-chemical tests of biocomposites, such as reducing substances, acidity, alkalinity, absorbance by UV/VIS, residue on evaporation were performed on aqueous extract. The cell viability was evaluated by MTT assay. Cell morphology evaluation of cell culture treated with composites was visualized by light microscopy. Also, thermal properties of biocomposites were investigated by DSC analysis. The obtained results have shown good biocompatibility of all biocomposites. Keywords: biocompatibility, physico-chemical tests, cytotoxicity, melt processing

In this study were evaluated the chemical changes in enamel adjacent to four different composite resin restorations after their contact with hydrochloric acid. Twenty healthy molars were chosen for this study and class I cavities were prepared on occlusal surfaces. Four commercial composite resins were used for filling: Filtek Z250 (3M ESPE, USA), Filtek Ultimate (3M ESPE, USA), Herculite (SDS KERR, USA) and Point 4 (SDS KERR, USA). The samples were obtained by cutting the teeth in two halves. Some of the samples were maintained in distilled water as control group and the others were mentained for 30 min in 0,06 mol/L hydrochloric acid (pH = 1,2). The morphological aspect of the interface between enamel and composite resin was evaluated using scanning electron microscopy (SEM) and the mineral content (calcium, phosphorus, oxygen ions concentration) was assessed using EDX method. Chemical analysis showed significant changes of ions concentration both in enamel and in composite restorations. The enamel adjacent to Filtek Ultimate was less affected by the contact with hydrochloric acid when comparing to other composite resins. Keywords: gastroesophageal reflux disease (GERD), SEM microscopy, EDX method mineral content to enamel adjacent resin composite

Since most areas of dentistry deal increasingly with aesthetics, we conducted this study to evaluate the influence of perioral wrinkles on patients’ subjective assessment for their “beautiful smile” appearance before and after laser resurfacing. Thirty patients were included in the study. All selected patients had previously done reconstructive dental therapy. Prior to wrinkles resurfacing the following aesthetic analyses were performed:dentofacial aesthetic analysis beautiful smile and facial analysis for skin resurfacing using Fitzpatrick alternative classification system for degree of perioral wrinkles.The resurfacing was performed using Life Touch Er:Yag pulsed laser with Life Touch Aesthetic Peri-Oral Handpiece. The energy utilized in all patients ranged from 50 mJ at 10 pulses/sec. The analysis of patients’ degree of perioral wrinkles was performed as objective parameters which will influence the resurfacing outcome. The survey addressed patients’ satisfaction with regard to existing patient’s smile-“beautiful smile” in correlation with the presence of perioral wrinkles. The obtained data showed significant differences in individual assessment likeability versus that of the physician/examiner for appearance of the upper lip, incisal edge to lower lip and midline-relationship of central incisors to philtrum (p < 0.05). Individual likeability of upper lip appearance after resurfacing in correlation with the degree of perioral vary significantly depending on the degree of perioral wrinkles (Kruskal-Wallis H = 15.36, p = 0.005). Assessment concerning the personal likeability of the smile before and after treatment was tested with Wilcoxon Matched pairs test. The obtained results were statistically significant (p < 0.001). Keywords: beautiful smile, dental aesthetic, Er:YAG resurfacing, full mouth reconstruction