Volume 52, Issue 3

Abstract: 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

Abstract: 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

Abstract: 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

Abstract: 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

Abstract: 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

Abstract: 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

Abstract: 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

Abstract: Tests on wearing clothes are complex methods of analysis that mainly consist of recording the physiological reactions in the body. An early supervision of these physiological reactions, at a physical charge and under certain climatic conditions, ergometrically shaped, provides precious information on the human body and its status, as well as on the worn clothes. Physical parameters of the environment and biometric parameters were measured during the wearing tests. There were tested 5 subjects, students, for wearing 5 textile garments. In the performed tests there were determined the following parameters: cardiac frequency, respiratory frequency and energetic consumption. Keywords: clothing, wear tests, warm environment, dynamic conditions, comfort, evaluation, biometric parameters

Abstract: Domestic pigs were frequently used in training centers for residents and students in medicine for the stenting procedures at the level of renal arteries. On 12 domestic pigs (all male) with an average weight of 34 kg (30.0-39.9 kg), were analysed the morphological parameters of femoro-iliaco-aorto-renal arterial system. An analysis of the pelvic segment length (I-II-III) and abdominal (IV), shows almost perfect equality of the lengths of the two segments on the right (76.26 ± 5.30 mm / 76.21 ± 4.51 mm) and a mean difference of 1.25 mm in favour of segment IV (abdominal) (75.53 ± 5.10 mm / 76.78 ± 4.44 mm), a difference that correlate with left renal artery cranial origin. Pelvic diameter portions of femoro-iliac arterial axis increase linear in average by 10% per segment (from 3.99 ± 0.40 mm ± 4.89 in segment I at 4.89±0.33 mm in segment III). Increasing the diameter from the segment III to segment IV is approximately of 30%. The diameter of the proximal part of renal artery (3.46 ± 0.36 mm) on the studied material is smaller than the diameter of the proximal part of the external femoral artery (segment I) (3.99 ± 0.40 mm), making it easy retrograde catheterisation of femoro-iliac-aorto-renal arterial axis. Knowledge of the morphological parameters of femoro-iliaco-aortic arterial axis and their evolution in correlation with the weight of laboratory animals -domestic pigs- favours the achievement in good conditions to arterial catheterization for proximal renal artery stenting. Keywords: corrosion casts, domestic pigs; femoro-iliaco-aorto-renal axis; morphological parameters; stenting training

Abstract: The purpose of this work was the detailed study of morphological biodegradation and the citotoxicity effect of some experimental biomaterials. The study has four experimental biomaterials based on polylactic acid, polyethylene glycol, tricalcium phosphate, chitosan and hydroxyapatite in different percent cured in air followed by heat treatment at 1200C. The experimental biomaterials were characterized by AFM (Multimode V-SPM, Veeco) and SEM (Q130 -FEI Company) microscopy. For the citotoxicity were used cell cultures of normal human fibroblasts and the viability testing was made with trypan blue. According to the experimental results, the biomaterial with highest percent in polylactic acid presents a high degradation, compared with the rest of the biomaterials which have HA in composition, who decrease this process. Fibroblasts cell culture showed good adhesion to the surface of the biomaterials. The viability of the biomaterials increases at 48h compared with 24h, which suggest the absence of the materials cytotoxicity. Our results sustain idea that biomaterials based on chitosan with additions can be successfully used for further studies in reparative medicine. Keywords: chitosan, biodegradable polymers, hydroxyapatite, SEM, AFM, citotoxicity

Abstract: The paper aims at evaluating the impact of technological parameters of a drilling process on the parameter of surface roughness Rz (maximum height of roughness profile) of wood-based material (WPC – Wood Plastic Composite). During drilling with tools 3.0, 5.0 and 7.0 mm in diameter, the spindle speed nc and feed rate f were changed. The evaluation of statistical significance was performed using the ANOVA mathematical tool (two-way with repetition). Using a simple conversion, it is possible to assess which of the set parameters affects the final surface quality, which serves as supporting information for the work of an engineer. Keywords: statistical evaluation, composite, surface texture

Abstract: In accordance with Terminologia Anatomica, the renal artery gives rise of two branches: anterior branch and posterior branch. Anterior branch gives rise to four segmental arteries: superior, anterior-superior, anterior-inferior and inferior; posterior branch continues with posterior segmental artery. On a total of 150 renal corrosion casts was examined the artery of inferior segment. Three morphological types have been highlighted: Type I, in which the inferior segmental artery originating directly in the trunk of the renal artery (8.0% of cases); Type II, in which the inferior segmental artery arises from the anterior branch of the renal artery (87.33% of cases); Type III, in which the inferior segmental artery arises from the posterior branch of the renal artery (4.67% of cases). In 33.33% of cases the inferior segmental artery arises independently from the trunk or renal artery branches (anterior or posterior). In 66.67% of cases, the inferior segmental artery realizes a common trunk with one or two other segmental arteries (in type II). Knowledge of these aspects is important both to investigate morphological imaging and preforming partial resection of the renal parenchyma. Keywords: kidney; corrosion casts; inferior segmental artery; variations

Abstract: The aim of this study was to evaluate the role of local administration of vitamin D in influencing the rate of orthodontic tooth movement. Six dental arches were included in this study. Every arch was divided intro two hemiarches: experimental hemiarch and control hemiarch. The canines were included in this study. Control canines received orthodontic therapy compared with experimental canines which received orthodontic therapy associated with local administration of calcitriol (1,25 dihydroxycholecalciferol). The rate of tooth movement was measured in both hemiarches. We noticed a difference between the rates of orthodontic treatment in experimental and control hemiarches respectively. This might be attributed to local administration of calcitriol (1,25 dihydroxycholecalciferol). Keywords: bone remodeling, orthodontic tooth movement, vitamin D, bone desorption, bone apposition

Abstract: Partial devulcanization of rubber crumb spent was performed in the presence of oxide nanoparticles. Nanoparticles on the basis of CaO and ZnO were prepared by dry grinding in a laboratory planetary mill and nanoparticles on the basis of Fe3O4 were obtained by precipitation. The distribution of particle sizes based calcium, zinc and iron were measured by dynamic light scattering. Devulcanization of the rubber crumb was carried out in a batch system at a temperature of 200°C and the sulfur content of rubber decreased more than 15 times after devulcanization. Homogeneity of bitumen, determined by fluorescence microscopy, was superior in case of modification with devulcanized rubber compared to the case of modification of bitumen with vulcanized rubber. Adhesiveness of bitumen road increases significantly after modification with desulfurized rubber compared to the case of bitumen modified with vulcanized rubber. Keywoords: waste, desulfurized rubber, bitumen modification, nanoparticles

Abstract: The prevalence of soft tissue graft in anterior cruciate ligament (ACL) reconstruction, as well as the preference for bioabsorbable fixation continues to grow in clinical practice. This paper presents one complication related to biocomposite screw fixation used in ACL reconstruction found in clinical practice associated with a retrieval analysis of a broken biocomposite interference screw made by PLLA-HA (75% PLLA, 25% HA), arthroscopically removed from the tibial site at 8 months after ACL reconstruction with soft tissue autograft in a young patient. The fragment of broken screw was analysed in terms of surface and structural analysis following an established implant retrieval protocol. The retrieved implant surface shows cracks and breakdown signs characteristic to the final phase of resorption but incomplete probably due to biomechanical stress. The present study is important since it is one of the few cases recorded for both a composite implant as well as for an early complication, supporting the idea that the breakage of biocomposite screws should be considered during ACL reconstruction. Keywords: biocomposite screw, biodegradable polymer, ACL reconstruction, retrieval analysis, SEM

Abstract: The paper presents the results obtained by the authors for the mathematical modeling of the mechanical behaviour variation of the composite material with polymeric or elastomeric matrix and reinforced with protein fibers (CFP), depending on the concentration of the reinforced material. The mathematical model of the main mechanical properties of a composite material allows optimal approximation variants of material that is as close to that required in a particular field. The method proposed in this article is generally applied to the composite materials and is valid not only for the case of mechanical properties dependence of a single parameter (the concentration of a constituent) but in the case of dependence on several parameters, case in which the possibilities of achieving a favourable variant are much larger and more accurate. In the category of free parameters of the mathematical model can enter all the constituents’ concentrations, but, in addition, also important are the technological parameters: temperature in the manufacturing process, the reinforced material granulation, the degree of stirring, pressure, etc. Keywords: CFP, mathematical model, variation, mechanical properties, optimal variants

Abstract: This paper presents a method to improve the performance of glass fiber processing by cutting of the fiber reinforced polymeric materials based on the application of ultrasonic vibrations on the cutting tool. General conditions of the process are established and, based on the analysis of the processing mechanism, the authors provided the fundamental condition for the selection of the cutting speed values in the case of ultrasonically assisted cutting of glass fiber reinforced polymeric materials. The paper also presents the theoretical foundations of rising the macrogeometric accuracy of ultrasonically assisted cutting in the case example of the universal grip turning. Keywords: polymeric materials, ultrasonic cutting, glass fiber

Abstract: The elements of afferent pedicle of the liver have a segmental distribution to the liver parenchyma. Divergence part of the hepatic portal vein is the main element of intraparenchymatous spatial distribution vasculo-ductal systems. On 500 divergence (intraparenchimal) portions of of hepatic portal vein (125 pieces of liver corrosion casts, 125 ultrasound images, 125 images of MDCT angiography and 125 images of MR angiography), it was highlighted a number of six morphological types of intraparenchymatous part of hepatic portal vein, which are presented as follows. Symmetric bifurcation (standard portal vein anatomy) (Type I - 76.2%) in which the main portal vein trunk divides into right and left portal branches. Trifurcation, (Type II - 10.4%) in: the left branch, the (right) anterior branch, and the (right) posterior branch. Quadrifurcation, (Type III - 0.2%) in: anterior and posterior branches in the right part, and lateral and medial branches in the left part. Asymmetric bifurcation, (Type IV - 7.4%) in which the (right) posterior branch is the first branch of the main portal vein trunk Asymmetric bifurcation of the right branch, (Type V - 4.4%) in which the branch for segment V or VIII (anterior branch) is the first branch of the right branch. Asymmetric bifurcation of the right branch, (Type VI - 1.4%) in which the branch for segment VI or VII (posterior branch) is the first branch of the right branch. Knowledge of these aspects is important both to investigate morphological imaging, and in performing partial resection and liver transplantation. Keywords: hepatic portal vein branches; morphological types; corrosion casts; ultrasound images; MDCT angiography; MR angiography; clinical and surgical inplications

Abstract: Dislocation of the humeral head is a very common traumatic disorder of the shoulder. Most of the time the dislocation is antero-inferior, which causes a detachment of the antero-inferior capsulolabral complex. This injury predisposes to redislocation, thus requiring surgical fixation, the so called Bankart repair, during which the labrum is reinserted to the glenoid cavity. The aim of our study is to follow the particularities of the outcome after the arthroscopic Bankart repair, accomplished with two different types of suture anchors, bioabsorbable and metallic anchors. Considering the surgical technique there is no difference between the implantation of the two types of suture anchors. There was no significant difference in the rehabilitation outcome between the studied groups. Our results correspond with the findings of other research papers. The arthroscopic management of Bankart lesion is less invasive, which shortens the rehabilitation period. The main disadvantages of metallic suture anchors are the loosening of the anchor and the revision surgery, which also can be complicated. Keywords: Bankart lesion, shoulder arthroscopy, shoulder recovery, suture anchors

Abstract: The orthodontic appliances can be built in a great diversity of resin that could be classified by one of the criteria, in thermoplastic and thermo set. This paper has as purpose to compare three resins used for orthodontic appliances, one thermoplastic and two thermo set –Biocryl C (Scheu Biostar), Orthocryl (Dentaurum), Orthoplast (Vertex Dental) – from the mechanical properties respect such as surface hardness and indentation elastic modulus. We tested six specimens; two from each type of these resins. Each specimen was fixed on a support and they were tested with Nano Indenter G200 from Keysight (Agilent). We obtained as a result that the thermoplastic material has a lower elastic modulus than the other thermo set. Keywords: thermoplastic resin, thermo set resin, elastic modulus, hardness, nanoindentation

Abstract: Among the reinforced composites the ones with fabric reinforcements are studied due to of their excellent properties. This type of materials allows the control of properties due to the placement of fabrics in the reinforcement structure. This study is carried out to identify the effect of reinforcement sheets orientation on the mechanical properties of composites with epoxy matrix and the effect of modified matrix on the same properties. Four types of fabrics had been used as reinforcements for materials each material being reinforced with a single type of fabric excepting the medial sheet which is the same for all the materials. Both three point bending tests and compressive tests were performed perpendicular on the reinforcement plane. Keywords: epoxy resin, modified epoxy, fabrics, bending tests, compressive tests

Abstract: The lower jaw is frequently exposed to fracture, by accidents, violence, accidental falls, sports injuries, pathological fracture, etc. We have investigated the behaviour of mandibular bone in a particular clinical case of fracture, in which we experimentally applied two osteosynthesis plates and analyzed the effects of occlusal loading on the fracture line by finite element method. We observed that in this case, maximum deformations occur in the mandibular condyles and the maximum and minimum normal stresses occur in the osteosynthesis plates. Even if bite and mastication determine important efforts on osteosynthesis plates, titanium alloy supports well these loads, and, as an important aspect, the bone parts during healing are not the object of excessive mechanical loads. Keywords: FEA, mastication, osteosynthesis, fracture, mandible

Abstract: In this paper is presented an experimental, theoretical and numerical study about the use of a biodegradable composite material in the manufacturing process of the suspension elements for plane sieves used in mills from bakery industry. The material was obtained by reinforcing an unsaturated polyester resin with cotton fabric. Tensile tests were performed for materials having one, three, five and seven layers of cotton fabric and the optimum solution was chosen. The material properties, obtained from the experimental tests, were used in a finite element model realized for the strength calculus of the suspension element. The numerical results were validated analytically. The study confirms that the biodegradable materials can be used for manufacturing of the suspension elements of a plansifter and can be adapted for other parts or industrial structures. Keywords: sifting, biodegradable material, polyester resin, finite element, cotton

Abstract: Computerized reconstruction of anatomical structures is becoming very useful for developing anatomical teaching modules and animations. The first computer-aided 3D reconstruction was achieved in 1965 by Glaser and Van der Loos. With the improvements in computer hardware and software tools, computerized modeling of anatomical structures has become very useful for visualizing complex 3D forms. Three-dimensional visualization of various microanatomic structures using special preparation and staining methods is important. Although databases exist consisting of serial sections derived from frozen cadaver material, plastination represents an alternate method for developing anatomical data useful for computerized reconstruction. Plastination is used as an excellent tool for studying different anatomical and clinical questions. The sheet plastination technique is unique because it offers the possibility to produce transparent slices series, which can easily be processed morphometrically. A female pelvis was obtained, plastinated, sectioned and subject to 3D computerized reconstruction using WinSURF modeling system (SURFdriver Software). Qualitative observations revealed that the morphological features of the model were consistent with those displayed by typical cadaveric specimens. Morphometric analysis indicated that the model did not significantly differ from a sample of cadaveric specimens. This data supports the use of plastinates for generating tissues sections useful for 3D computerized modeling. Keywords: plastination, 3D reconstruction, anatomy, female pelvis, urinary bladder, uterus

Abstract: The use of thermoplastic aligners has a vast history in the orthodontic field. These appliances have several indications regarding mild malocclusions, tooth replacement, retainers after active treatment, etc. The manufacturing protocol is simple and easy to apply. Several tooth movements are harder to obtain ( torque, intrusion, correction of rotations). The aligners must be well fitted and provide enough stiffness in order to maintain the desired orthodontic effect and minimize the unwanted dental movements or anchorage loss. We evaluated a manufacturing protocol for such appliances and analyzed how thermoplastic thickness material, due to the manufacturing process , can influence orthodontic treatment. Several foils were sectioned and measured before and after the manufacturing protocol(0.5mm;0.8mm;1 mm). Although some differences were observed due to foil types and thickness, the appliances are rigid and capable of assuring orthodontic success. Keywords: orthodontic aligners, thermoplastic materials, foil thickness reduction

Abstract: The aim of this paper is based on neural network model for tribological analyses of an Epoxy composite system. The created epoxy based composites with aramidic powders, were tribologically tested with diverse parameters in order to obtain the following properties: wear rate and friction coefficient. With all the studied tribological properties was created a Neural Network (NN) model. The created NN model can perform optimisations for concentration of aramidic powder in final used composites for different domains of applications. Keywords: epoxy composites, bloc on ring, friction coefficient, neural network analysis, optimisations

Abstract: Crown preparation and cementation are two critical parameters for the success of a prosthetic treatment. Marginal fit is important because a large marginal opening allows plaque and oral liquids to penetrate, resulting in micro-leakage, caries and periodontal disease. The purpose of this study is evaluating and comparing the marginal fit of Cr-Ni metallic crowns using three different wax-up techniques made on molars, extracted because of orthodontic reasons. The freshly extracted teeth were kept in artificial saliva to reduce penetration of microorganisms and simulating oral environment. In vitro cementation with Ketac Cem was carried out after disinfection and drying. Samples were maintained for 24 h at 37oC in distilled water and then gold plated. The marginal gap was analyzed using scanning technique with an electronic microscope in several points for every surface of each tooth. Data were statistically analyzed. Measuring the internal fit requires sectioning of specimens and allows obtaining a small number of samples (1-2 per specimen) which means a limited number of measurements per specimen. Another problem consists in the reduced size of the samples after sectioning. The scanning technique enhances measurements of the marginal gap without sectioning and provides an objective evaluation of preparation and cementation techniques. Key words: scanning electron microscopy, marginal gap, crowns

Abstract: Low-volume production components represent a possibility to create prototypes from the same process and materials that someone use for the final product and to bring new products to market instead of waiting for final components to arrive from the machine shop. Additive FDM create geometrical products through the deposition of ABS (Acrylonitrile-Butadiene-Styrene) filaments layer by layer satisfying this necessity. Since the specialized literature offers little information on the properties of such plastic materials, in this paper the authors present some experimental procedures in order to evaluate the elastic and mechanical properties of such a plastic material. The specimens have been printed on a 3D “ULTIMAKER –2” printer. Keywords: Acrylonitrile-Butadiene-Styrene, Fused Deposition Modeling, 3D printing, integrated software home manufaturing

Abstract: The puropose of this paper was the approaching the patology of the oral mucosa in older patients, induced by acrylic resins in removable dentures. Prosthetics resolves many problems in older adults (mastication, aesthetics, phonation, etc.) but the wearing of dentures has consequences on all the living tissues in contact with them. The reactions of buccal mucosa are the result of mechanic irritations, plaque build-up and of toxic and/or allergic action of the denture materials, therefore the field cannot be neglected. An essential aspect of the clinic goal of removable prosthetic restorations is the consistency between the biomaterials used, their biological integration, the approached technological line, and the particularity of the prosthetic field of the older patient. Keywords: oral mucosa, acrylic resins, removable dentures, irritating toxic phenomena, biocompatible

Abstract: The viscous flow over a shrinking permeable sheet with partial slip is investigated. The flow is governed by a third-order nonlinear differential equation and heat transfer by a second-order differential equation. The equations of motion are solved analitically by Optimal Homotopy Perturbation Method (OHPM). This procedure is highly efficient and it controls the convergence of the approximate solutions. A few examples are presented, showing the exceptionally good agreement between the analytical and numerical solutions. OHPM is very efficient in practice, ensuring a very rapid convergence after only one iteration. Keywords: Optimal homotopy perturbation method, viscous flow, partial slip, shrinking sheet,heat transfer

Abstract: Gingival enlargement is also known as gingival hyperplasia or hypertrophy and it is an abnormal overgrowth of gingival tissues. This type of lesions can be produced by a large group of pathologic processes. The most common are the reactive hyperplasia which develops in response to a chronic tissue injury that stimulates an excessive tissue repair response. Often, dental prosthesis have been reported to cause this type of lesions due to a mechanical chronic irritation or by a reaction of the oral tissue to substances released into the oral environment by the materials used in manufacturing this type of prosthesis. One of these substances is the methylmethacrylate (PMMA), a widely used in dentistry. The first step in treatment of these lesions is the removal of the irritative factor which sometimes can lead to healing depending on the type of lesion. The challenge is to differentiate a lesion caused by a mechanical irritation from a lesion in which the cytotoxicity of PMMA may be the cause. Often, surgery is the only treatment option for the first situation. When we have an irritative reaction and a cytotoxicity reaction, we must treat them both. Keywords: methylmethacrylate, acrylic resin, TNF alfa, citotoxicity

Abstract: The medical industry has greatly benefited from the aid of various additive manufacturing (AM) technologies, especially for applications that include the fabrication of bespoke implants and guides, devices and surgical instruments. Manufacturing functional prototypes that can behave as close as possible to the final product is a key factor in developing successful anatomically compliant medical products. The current research is intended to evaluate the optimum AM technology to fabricate medical prototypes with thin wall structures, destined for anatomical functional tests and surgical practitioner feedback. The main criteria of evaluation were: speed of fabrication from *.STL file to final prototype, mechanical characteristics and manufacturing costs. Keywords: bespoke medical prototype, optimum additive technology, functional simulations, anatomical thin structures