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In this paper, we have studied the vibrations damping capacity for some composite materials that have as matrix a combination of Dammar and epoxy resin. We have used flax, cotton and silk fabrics as reinforcement materials. For comparison, half of the studied materials were made with Sandarac core. We have suggested a mathematical model for studying the vibrations of composite bars with three layers and rectangular section, based on a bar section non-linear strain. Singularizing the obtained model, there are achieved the Timoshenko equations for bars with rectangular section. For the considered bars, we have experimentally determined the damping and loss factors.

The purpose of this paper is to study the performance of composite and structures materials (laminates composites reinforced with carbon fiber and sandwich materials with laminated composite faces and foam core) by theoretical and experimental analysis on damping capacity vibration. Experiments were carried to determine the elastic and damping characteristics of composite materials on a small-scale configuration of a machine tool structure having the purpose of knowing the damping vibration ability of a column position on a Polypad structure.

Two types of sutures made by two different biopolymers were tested in terms of hydrolytic biodegradation in phosphate buffered saline solution, which simulates the physiological conditions, varying the pH of the medium and the immersion time. The determination of the degradation rate was conducted by measuring the weight loss of the sutures. The study revealed that both investigated surgical suture exhibit quite different hydrolytic degradation at various immersion times and pH level, a more intense degradation being recorded in the alkaline environment.

The dimensional stability and structural integrity of composite luting cement are key factors of clinical performance and intraoral durability. The solubility both in water and saliva of a composite luting cement is influenced by the absorption of liquid by that cement. The aim of this study is to evaluate the solubility and water sorption of three different adhesive cements (Variolink, Nexus, Dualcim) in two different environments: artificial saliva (Artisial/Biocodex, France) and distilled water at different timed intervals. Water sorption is dependent on the chemical composition of the material, the time and the immersion medium.Water sorption was different for the three cements tested, at all three time periods, both in distilled water and in artificial saliva. ANOVA test results show that for all three materials used there are statistically significant differences (p < 0.002) between the mean values for the three tested periods, both in terms of solubility and absorption. Between 7 and 14 days the water sorption continued to increase significantly for all materials tested, showing a stabilizing trend in most cases only between 14 to 21 days.

The purpose of this in vitro study was to evaluate and compare the degree of microleakage of the enamel-sealants interface when used four different materials. Analysis of the penetration of sealing materials shows that they adhere different to the enamel and the characteristics of resin composite materials used in clinical practice as sealants, influencing dental material penetration to the surface once the viscosity of the inorganic filler.

Skeleton prosthesis is defined as a complex partial movable restoration, which involves a fixed component (dental bridge cemented on the remaining prepared teeth), and movable component part. Recently, a new high performance polymer, BioHPP, based on polyether-ether-ketone (PEEK) polymer was introduced as dental material for manufacturing the framework of these types of partial dentures.The purpose of this article is to present the results of the clinical trials referring to the benefits of skeleton prostheses wearers’ patients with BioHPP framework. The research has been carried out on 48 patients. The recording of the benefits in the using this polymer for partial dentures, in accordance with seven evaluation criteria, was performed in three dental schools from Romania, during three years, at every three months.The results of survey demonstrate that BioHPP polymer frameworks for skeleton movable restorations present many benefits and advantages, therefore this PEEK type of dental material represent a beneficial new acquisition for the partial edentulous patients.

The aim of this clinical study was to investigate the comparative effectiveness of two dental desensitisers based on 2-hydroxyethyl methacrylate (Gluma desensitizer and Shield activ desensitizer), in decreasing the dentinal painful sensitivity caused by cervical erosions.The clinical trial consisted of 63 patients (323 teeth), with minimum three teeth which presented cervical erosion with dentinal hypersensitivity. The sensitive teeth were treated with Gluma Desensitizer-Heraeus Kulzer (first batch of teeth), Shield activ desensitiser (second batch) and distilled water (third batch of teeth=control group). We effectuated in total three desensitisation sessions, at 5 days difference. The level of cervical dentinal hypersensitivity (CDH) was determined in six sessions, after the patient’s response to air-blast stimuli. We used the Visual Analog Scale (VAS) to assess the CDH. The results proved the effectiveness of used desensitizing agents in treating CDH in the first and the second batch of teeth, in comparison with the control group teeth. We noticed that after the second application of Gluma and Shield products significant differences, in comparison with the baseline, appeared. After 3 month follow-up, we ascertained that both products induced the decreasing of CDH. No significant differences were recorded between the two products. A placebo effect in reduction of CDH was observed in the group of teeth treated with distilled water. Both dentin desensitizing agents have proven effective in reducing CDH.

We report the case of a patient with simultaneously two intrauterine devices with different mechanism of action. By cumulating the effects and adverse reactions of the two intrauterine devices, the patient had severe dysfunctional bleeding and pelvic-abdominal pain. Using scanning electron microscope, we analyzed the surfaces of the two retrieved intrauterine devices in order to establish the physio-pathological mechanisms that occurred and lead to a local but also a hormonal disorder in the reported patient. We would also like to draw the alarm that a complete evaluation (clinical and imagistic) are mandatory prior to the insertion of an intrauterine device.

The paper presents an experimental study on the influence of the polyurea layer on the behaviour of metal plates loaded through air blast while the polyurea coat is placed on the loading face of the plate. To assess the influence of polyurea layer, the permanent maximal deflections of tested plates were used. A strong dependence between the effect of polyurea coating on the permanent deflection and stand-off was found. The analysis based on comparison between theoretical predictive functions and test result have shown that in almost all tested scenarios the bilayered plates results are less promising than the predicted results of monolithic steel plates of equal areal density.

The etiology of the TMJ disorders is a very controversial topic in the orthodontic literature. The symptoms include pain, muscle spasms, clicking and limitations of the mandibular movements. This pathology is also known as myofacial pain dysfunction and it appears to be more common in young female patients. Muscle hyperactivity, occlusal trauma and parafunctional oral habits are often associated with this syndrome. There are several noninvasive ways to treat this type of pathology (medication, removable appliances, TENS therapy) but the most common refers to acrylic splints. Nonpermissive or repositioning acrylic splints, that often include an acrylic bite plane, representthe most popular treatment alternative nowadays. These appliances can set the condyle in a centric relation in order to reduce muscle spasm, pain and the levels of cellular hypoxia.