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The purpose of this study was to determine the three-dimensional coating thickness of two scan sprays used in labside digitalization. An assembly consisting of a CoCr tooth with a standard full ceramic crown preparation and a three-dimensionally printed PLA base was duplicated twenty times out of type IV plaster. The plaster models were digitized using a three-dimensional scanner and reference virtual models were acquired (REF). A homogenous coat of spray A was applied on all models and the models were rescanned. After digitalization, the models were steam cleaned and the same technique was used for spray B. The reference scans were compared separately with the scans of group A and B. The resulting data was analyzed with the Student unpaired t-test (a = .05). While there were significant intergroup differences in the three-dimensional comparison of the root mean square of deviations, both scan sprays showed acceptable coating thicknesses for clinical use.

This investigation concerns the preparation of binary PPR/SEBS and PPR/SBS blends by melt mixing procedure with the goal of studying the effect of thermoplastic elastomers on performance of polypropylene random copolymer (PPR) in the extrusion and injection molding processes. Effect of poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS) and poly(styrene-b-butadiene-b-styrene) (SBS) respectively on the mechanical and thermal properties of PPR have been investigated. The melt processability, melt flow index (MFI), tensile properties, VICAT softening temperature (VST), heat deflection temperature (HDT), Shore hardness and IZOD measurements highlighted that SEBS is more efficient than SBS.

The paper concerns current engineering in plastics processing, the present day studies focusing on the rational solving of problems and on logical reasoning, on the usage of modern mathematical methods in leading and taking decisions, on the usage of instruments which have significantly changed and the development of business: computers, the internet, artificial intelligence. The practice uses engineering techniques by creating mathematical models. Appealing to scenarios ensures the improvement of decisions, involving answers on the improvement of quality and the rational usage of available human and financial resources. The research results are materialized through the development and effective use of a mathematical model in which the incoming data packets are obtained at a quantifiable levels of risk.

The obturators are prostheses used to close palatal defects after maxillectomy, to restore masticatory function and to improve speech, deglutition and esthetics. The most commonly used materials in manufacturing maxillary obturator prosthesis are the acrylic resins. The aim of the paper is to present experimental compression and traction tests in order to determine the material properties of Meliodent® Heat Cure produced by Heraeus Kulzer GmbH Germany. This is a two component heat curing polymer used for manufacturing fixed and removable prosthetic devices. Test results show that the average compressive strength of the samples is 94 MPa, while the average compression modulus for all resin samples tested was calculated at 716 MPa. The average ultimate tensile strength of the samples is 58.72 MPa and the average modulus of elasticity for all resin samples tested was determined to be 4213 MPa.

The loss or absence of an eye creates not only a functional disability, but also an important psychological impact on an individual’s social and professional life. Ocular prostheses are maxillofacial prosthetic devices which are generally custom made to replace a lost eye. Polymethyl methacrylate (PMMA) is the most common material used for manufacturing ocular prostheses. The main component of the ocular prostheses is the artificial iris that needs to be identical to the healthy one. For this reason manufacturing the iris is a challenging task for the maxillofacial anaplastologist. The main procedure used in manufacturing the iris is the manual painting technique which can be time consuming and susceptible to error, mainly regarding the color matching. The subject of this article describes an alternative technique of manufacturing the iris. This technique involves using a digital photographing image of the healthy eye which is edited and printed on photographic paper and it seems to offer good esthetic results being less complicated compared to the conventional manual painting technique. The main deficiency of the method is the color distortion which appears after the iris is embedded in the ocular prosthesis. This is caused by an alteration of the photographic paper during the final polymerization stage of the ocular prosthesis which takes place at high temperature.

Tracheal stenosis is a condition where the trachea narrows or becomes constricted as a result of a laryngotracheal trauma, prolonged tracheal intubation, high tracheostomy or systemic diseases.A possible treatment for tracheal stenosis is tracheal reconstruction with costal cartilage grafts that are implanted into the anterior tracheal wall. In order to secure the graft cartilage to the tracheal sidewalls we can use differnt synthetic resorbable materials, such as polylactic acid and polyglycolic acid, that allow anchoring of the costal cartilage to the tracheal wall. The aim of this paper is to present a fixation device for fixing the cartilage graft on the tracheal side walls. This device is designed using a synthetic resorbable material and allows anchoring of the costal cartilage to the tracheal wall using microscrews made of resorbable material.

In this study, the alkali treatment of sawdust (SD) using different concentration (1%, 3%, 5%, and 7%) of sodium hydroxide (NaOH) was performed. The phases change due to alkali treatment on sawdust particles was examined using Fourier Transform Infrared (FTIR) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM). Result shows that the treatment with 5% NaOH on sawdust particles improved the surface roughness of the filler with 21.1 % diameter reduction. Both treated and untreated sawdust particles were reinforced in HDPE matrix using an extrusion method. For comparison purpose, both treated and untreated high density polyethylene/sawdust composites were tested under static and dynamic loading up to 1100 s-1 using the universal testing machine and the split Hopkinson pressure bar apparatus, respectively. Results indicate that the treated high density polyethylene/sawdust composites with better filler/matrix interlocking characteristic shows better mechanical performances as compared to untreated high density polyethylene/sawdust composites under a wide range of strain rate investigated. Apart from that, the mechanical properties of both treated and untreated polyethylene/sawdust composites also show great dependency on the strain rate applied where yield stress, compression modulus and ultimate compressive strength were steadily increased with increasing strain rate. Unfortunately, the yield strain shows the contrary trend. While for the fractographic analysis under dynamic loading, the untreated composite specimens had undergone a severe catastrophic deformation and damages than that of treated composite specimens.

The oral cavity can be considered a complex biomechanical system. Most researches about oral environment’s biomechanics, related to restorative dentistry, endodontics, orthodontics, prosthodontics and implantology are conducted in vitro. Applying the principles of engineering in dentistry contribute significantly to understand aspects of oral biomechanics. We conducted comparative research by finite element method on mixed prosthetic restorations with metal frame of CoCr and NiCr, subjected to the same experimental occlusal loading to determine what type of metal substrate has a better biomechanical behavior.When applying forces in the frontal region, the area of weakness is, according to carried out analyzes, disto-incisal angle of the lateral incisor and at the application of forces in the lateral region, the most vulnerable is disto-palatal cusp of the second molar. Overall, for the particular case analyzed, it is recommended to make metal-ceramic prosthetic restoration with metal support of CoCr, which is less distorted and strained at the experimental application of masticatory forces, compared with metal-ceramic restoration made of NiCr.

The literature highlights the use of nanoparticles for the treatment of wastewaters containing organic compounds such as hydrocarbons, phenols, etc. The oxidation process of pollutants in wastewater from catalytic cracking was performed on nanostructured catalysts based on Fe, Mn and Fe-Mn mixed. The catalysts were prepared by precipitation-coprecipitation in the presence of anti-caking. Measurements for the determination of particle size distribution were carried out using the method of dynamic light scattering. The oxidation process was conducted in a batch reactor equipped with air bubbling system, in suspension of catalysts at a concentration of 1%, a temperature of 85-90o C, pH 9.2, for a period of 2h, 4h and 6h respectively. The best results were obtained in the presence of Fe - Mn catalyst at 6 hours reaction time. Degree of contaminant removal for this catalyst had maximum values of 72.80% for COD, 77.97% for extractible, 74.4% for phenol, 67.53% for ammonium and 67.57 % for sulfides,. Better behavior of Fe - Mn catalyst in the oxidation reaction was due both to the nature of the catalyst, as to well as the smaller size of this catalyst particles.

The purpose of the study is to assess and compare the effects of different antiseptic mouthrinse solutions on traditional glass-ionomer cements. Thirty samples of three traditional glass-ionomer cements used for base: Ketac Molar Easymix (3M ESPE), for restoration: Fuji IX (GC Corporation) and for sealing: Fuji Triage (GC Corporation) were included into three groups. In group 1, the samples were immersed for 14 days, twice a day one minute each, in Listerine Cool Mint, in group 2 the samples were immersed for 14 days, twice a day one minute each, in Parodontax Extra in group 3, the samples were immersed for 14 days, twice a day one minute each, in Sensodine Cool Mint. In control group the samples were immersed in artificial saliva. Within each group, sub-groups were established according the time of cement ageing (one day,seven days and fourteen days). The samples were analyzed for surface topography using a scanning electron microscope and for chemical composition using EDX detector. The antibacterial mouthrinse solutions Listerine, Parodontax, and Sensodine have an erosive effect on traditional Fuji IX, Ketac Molar and Fuji Triage glass-ionomer cements. The most affected cement by erosive action was Ketac Molar, followed by Fuji IX and Fuji Triage. All three glass-ionomer cements tested in this study proved to be more resistant to erosive action after their ageing.