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1

FEM simulation of a novel medical device for TMJ therapy

Kwieciński K., Żmudzki Jarosław, Chladek G., Popielski P., Kowalczyk M., Duraj E., Sołtysiak-Niedziela M.

Archives of Materials Science and Engineering

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2023

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Vol. 122, nr 1

34--41

EN

Purpose: Temporomandibular disorders (TMD) are one of the leading health problems in dentistry. The work aimed to evaluate, using FEM, the influence of the material elastic properties of the flexible obstacle of the tongue trainer on the range of deflection and strength. Design/methodology/approach: In prototyping the trainer tongue, the starting point was real models with different extents of the tongue obstacle. moulded from dental wax on a dental stone model. Then versions were tested intraorally for the perception of the space occupied by the tongue. The models were scanned on a 3D scanner, and then a parametric CAD model (NX Siemens) was made on their basis. Finally, in order to take into account, the anatomical aspects, the two extreme ranges of the tongue obstacle, named "Long " and " Short ", were developed. Simulation deflection and material strength tests were made using FEM in the linear range (NX Siemens). Calculations were made for materials with Young's modulus equal to 8 MPa, 80 MPa and 800 MPa. The interaction of the tongue with the force of 5N was assumed. The support was provided by the retention surface on the teeth, with the support of the posterior edge of the obstacle on the palate (palatal variant) or lack of support, i.e., the obstacle freely bending in this area (free variant), was additionally tested. In order to assess the drop or retention of the trainer on the teeth, the second type of simulation was performed with the assumption of horizontal (anteriorly directed) tongue pressure with the force of 10N for the condition of rigid support in the area of the teeth and the periodontal zone from the lingual side. In this variant, a simulation was adopted for a material with a modulus of elasticity E=80 MPa. Findings: The stress values of the flexible obstacle of the trainer were obtained, allowing for the selection of potentially valuable materials for the trainer's construction. The results obtained in the simulations indicate the possibility of using ethylene vinyl acetate (EVA) and its blends. The accumulation of saliva inside the sealed obstacle was found, which indicated the need to look for an area to perforate without losing the load capacity of the obstacle. The structural feasibility of solving the problem of saliva accumulation without a significant change in the load capacity and stiffness of the obstacle was confirmed by simulation. Research limitations/implications: Simplifying the model to a linear range does not allow buckling analysis. In addition, the assumption of a linear material further limits the possibility of analysing materials with softening and plateau characteristics, where the compliance of the structure leads to elastic buckling. Practical implications: The range of deflections and stresses for different stiffness of the elastic element of the trainer was determined in order to select the appropriate material for the medical device (MD). Polyurethanes or silicones provide the range of deflection and strength, but in the case of manufacturing prefabricated trainers thermoformed in the patient's mouth (maximum temperature 75°C), the material that can be used is ethylene vinyl acetate (EVA). Originality/value: Simulation tests made it possible to determine the range of deflections and stress for different stiffness of the flexible obstacle of the trainer in order to select the appropriate material for the medical device.

2

FEM numerical simulation of contact stresses between driving shaft and hub impeller of fuel pump

Wiater M., Chladek G., Żmudzki J.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 113, nr 1

13--21

EN

Purpose: The aim of the work was to test the contact stresses in the model system of the turbine hub cooperating with the fuel pump drive shaft. The hypothesis of the work was that, by means of FEA, it is possible to assess the contact stresses in the materials of the turbine hub and the fuel pump shaft during torque transmission. Design/methodology/approach: A turbine with fibre-reinforced polyphenylene sulphide (PPS) composite cooperating with a stainless steel shaft (X46Cr13/1.4034) in a commonly used D-flat shape joint was selected for the experimental research. To assess contact stresses, the CAD model (NX, Siemens) of the entire turbine was limited to the hub area. The drive shaft is supported in accordance with the bearing in the fuel pump, and the possibility of rotation about the axis along the length of the torque-producing magnet is taken away. The system was loaded with a torque of 200 Nmm on the turbine. The turbine hub and shaft were calculated, taking into account the phenomenon of contact detachment or slip at the value of the friction coefficient of 0.1. Findings: The pressure transmission area was found in the area at the edge of the flat surface D-flat and on the opposite side of the D-convexity. The contact stresses on the D-flat side reached values close to the composite strength. Research limitations/implications: The studies did not take into account the technological inaccuracies, thermal deformation, local material properties, and wear. The value of the friction coefficient was not measured in realistic conditions with fuel lubrication. Practical implications: FEA has been achieved, which allows to reduce the cost of experimental research. Originality/value: The proposed model allows for further studies of the influence of elasticity of various materials and structures on contact stresses in order to assess wear resistance.

3

Influence of silver-containing filler on antibacterial properties of experimental resin composites against Enterococcus faecalis

Adeeb S., Adeeb S., Chladek G., Pakieła W., Mertas A.

Journal of Achievements in Materials and Manufacturing Engineering

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2021

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Vol. 109, nr 2

59--67

EN

Purpose: The aim of the presented work was to investigate the impact of the S-P introduction into resin-based composites on their effectiveness against Enterococcus faecalis (E. faecalis). Design/methodology/approach: Seven experimental composites based on typical matrix were developed. Six of them contained a filler with antimicrobial properties (silver sodium hydrogen zirconium phosphate, S-P), while the control material contained only common reinforcement fillers. The materials were characterized in terms of the dispersion of the extender in the matrix and then subjected to microbiological tests. The efficiency in the reduction of E. faecalis in the microenvironment was tested. Findings: The composites show a satisfactory distribution of fillers and a high initial reduction of bacteria colonies for the tested strain of E. faecalis. The reduction in bacteria colonies achieved for S-P concentrations from 7% to 13% was similar (median value from 99.8 to 99.9%, when for control material and compound with 1% S-P the number of colonies increased compared to positive control. Research limitations/implications: Laboratory test results may differ from in vivo test performance. In addition, there are many models for conducting laboratory antimicrobial efficacy studies, the results of which are also varied. The cytotoxic tests, long-term investigations and in vivo experiments need to be performed in future experiments. Practical implications: E. faecalis is a Gram-positive bacterium that is commonly detected in persistent endodontic infections and may enter the root canal through the coronal part. Development of composites with antimicrobial properties against this bacterium is as important as obtaining efficacy against cariogenic bacteria. Originality/value: The antimicrobial effectiveness against E. faecalis of experimental composites with submicrometer-sized particles of S-P was not investigated until now.

4

The Influence of the Process Parameters on the Microstructure and Properties SLM Processed 316L Stainless Steel

Woźniak A., Adamiak M., Chladek G., Kasperski J.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

73--80

EN

Selective Laser Melting (SLM) is a modern manufacturing method with many applications in medicine, aerospace and auto-motive industries. SLM processed materials are characterized by good dimensional accuracy and properties comparable or superior to materials obtained by traditional processing methods. In this paper an SLM process was used to obtain 316L stainless steel parts. This paper presents the microstructure, chemical and phase composition, physicochemical and electrochemical properties of 12 groups of tested samples, differentiated by the SLM processing parameters. Based on the investigation, it can be inferred that the selection of the appropriate SLM parameters is very important to determined final material properties. The samples producedwith the energy density E = 600 J/mm3 were observed to possess optimum properties - a homogeneous structure, density closest to the desired one, good wettability and pitting corrosion resistance.

5

Finite Element Analysis Of Adolescent Mandible Fracture Occurring During Accidents

Żmudzki J., Chladek G., Panek K., Lipiński P.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

65--72

EN

The paper aims was assessing risks of mandible fractures consequent to impacts or sport accidents. The role of the structural stiffness of mandible, related to disocclusion state, was evaluated using the finite element method. It has been assumed, that the quasi-static stress field, due to distributed forces developed during accidents, could explain the common types of mandibular fractures. Mandibular condyles were supposed jammed in the maxillary fossae. The force of 700 N, simulating an impact on mandible, has been sequentially applied in three distinct areas: centrally, at canine zone and at the mandibular angle. Clinically most frequent fractures of mandible were recognized through the analysis of maximal principal stress/strain fields. It has been shown that mandibular fracture during accidents can be analyzed at satisfactory level using linear quasi-static models for designing protections.

6

The influence of storage conditions on the physicochemical properties and dimensional accuracy of the alginate impressions

Żelezińska K., Nowak M., Żmudzki J., Krawczyk C., Chladek G.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 87, nr 2

68--76

EN

Purpose: Alginate impression materials are the most commonly used masses for taking impressions. They are characterized by good relation of properties to the price. However, the main problem associated with use of the impression masses is dimensions stability. Manufacturers of alginate masses recommend storage impression without any source of moisture, but dentists frequently store impressions wrapped in a wet materials. This may be the a reason of changes in dimensions and other properties. Moreover, it is recognized, that casting the model in the soon after making impression guarantee better dimensional accuracy. However, models are made usually after 24h. For some masses producers claim unequivocally, that the impressions can be stored for up to 168 h without changing the dimensions. So in this study was investigates how storage conditions affect chosen properties of alginate mass, including the accuracy of the models. Design/methodology/approach: Samples were prepared according to the manufacturer instruction and divided into 5 groups. Measurements were made 20 min after taking the impression and after 24h/168h of storage with/ without the resource of moisture. The measurements of Shore A hardness, tensile strength, mass changes and dimensional changes were made. Accuracies of the dental stone models were investigated with models manufactured after 20 min and 168 h after impressions, in comparison to the master model. Findings: The study showed that the storage conditions and time of storage had influence on properties of alginate impression mass. The resource of moisture has got an influence on dimensions and mass changes, tensile strength, elongation and shore A hardness. The results show that the use of the resource of moisture may be a cause of unfavourable changes in the gypsum model dimensions. Research limitations/implications: The storing of the alginate impressions with the resource of moisture is commonly practiced by the doctors, but it inconsistent with the manufacturer's recommendation. Practical implications: The method storing of the alginate impressions determined not only the materials properties, but also the clinical properties of final products like dentures. Originality/value: The significant of the method of the storing of alginate impression materials on the chosen properties of the materials and the accuracy of the dental stone models were shown.

7

Mechanical properties of Easy Fill composites after storage in mouthwashes

Nowak M., Kalamarz I., Chladek G.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 88, nr 1

25--34

EN

Purpose: The aim of the presented work was to investigate the influence of different mouthwashes on the chosen mechanical properties of different dental restorative composites. The null hypothesis was that the mouthwashes have influence on these properties. Design/methodology/approach: Four different restorative composites were used (Easy Fill Nano, Easy Fill Micro Hybrid, Easy Fill Flowable, Easy Fill Bulk). Samples were conditioned in different media: mouthwashes (Listerine Total Care with ethanol, Listerine Total Care Sensitive – alcohol-free) and distilled water. The samples were polymerized in Teflon moulds. The compressive strength, diametral tensile strength (DTS) and Vickers microhardness were examined. Findings: The research showed that the surface of composite materials was particularly sensitive to the action of mouthwashes. Both types of solutions, containing ethanol and without it lowered the microhardness values. The mouthwashes may also decrease other mechanical properties, like compressive strength of diametrical tensile strength. The results of the carried out investigations showed good mechanical properties of the tested materials, analogous to other materials of this type. Research limitations/implications: Other important properties of dental filling storied in mouthwashes should be analysed in future, including microgap between tooth and filling. Practical implications: The result contradicts the popular view that mouthwashes that do not contain ethanol are in general safer for composites in the context of reduction of mechanical properties. Both types of mouthwashes may reduce mechanical properties. Originality/value: The results of mechanical properties investigations of Easy Fill composites were presented and compared to other commercial materials. The changes of mechanical properties were also analysed after storing in different types of mouthwashes. So far, there has been no such research for these materials.

8

The Effect of Atomic Layer Deposition of ZrO2 on the Physicochemical Properties of Cobalt based Alloys Intended for Prosthetic Dentistry

Ziębowicz A., Woźniak A., Ziębowicz B., Kosiel K., Chladek G.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1077--1082

EN

The paper presents the effect of ZrO2 layer deposition by the ALD process on the physicochemical properties of cobalt-based alloys (Realloy C and EOS CoCr SP2) intended for application in prosthetic dentistry. The paper shows the results of the surface roughness measurements made by the AFM method as well as the wettability and free surface energy measurements. Additionally, potentiodynamic tests of pitting corrosion resistance and electrochemical impedance spectroscopy in a solution of artificial saliva were carried out. Tests were carried out on the samples in the initial state and after surface modification with the ZrO2 layer. Based on these results, the usefulness (e.g. enhancement of corrosion resistance and biocompatibility) of the proposed ZrO2 layer on the cobalt alloys was assessed.

9

Influence of Chemical Composition on the Properties of Experimental Silicone-Based Soft Lining Composites

Jabłońska-Stencel E., Pakieła W., Żmudzki J., Kasperski J., Chladek G.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1371--1377

EN

The paper analyses the influence of chemical composition of silicone-based composites on their properties in the aspect of using them as long-term soft denture lining materials. Different concentrations of filler and methylhydrosiloxane-dimethylsiloxane copolymer were used. The filler was introduced into the composite with mechanical mixing combined with ultrasonic homogenization. Scanning electron microscopy was used to investigate the quality of filler dispersion. Shore A hardness, tensile strength, sorption, solubility and tensile bond strength to poly(methyl methacrylate) were measured. Tests show satisfactory results for some experimental composites, which met all the requirements for such materials.

10

Effects of Different Inorganic Fillers on Mechanical Properties and Degree of Conversion of Dental Resin Composites

Stencel R., Pakieła W., Barszczewska-Rybarek I., Żmudzki J., Kasperski J., Chladek G.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1361--1369

EN

The aim of the study was to evaluate the influence of different fillers on the chosen functional properties of experimental composites based on typical polymeric matrix, in order to understand the effect of different fillers on their properties and to develop a simple base composite for further investigations with experimental fillers, e.g. with antimicrobial properties. Previous experiments have been usually based on commercially available composites of unknown composition or compilation of monomers, without reinforcing fillers. Scanning electron microscopy was used to investigate the quality of fillers’ dispersion, which was satisfying. Results showed significant differences between materials’ diametral tensile strength (p = 0.0019), compressive strength (p < 0.0001), Vickers microhardness (p < 0.0001), flexural modules (p = 0.0018), and the degree of conversion (p < 0.0001), but flexural strength was not significantly different (p = 0.0583). Investigations indicated that no filler type had an especially positive impact on the mechanical properties, but reinforcement effect was achieved by proper compilation of silica nanofiller and variable glass fillers. Nanofiller decreased the degree of conversion.

11

Effects of magnetostimulation on muscle activity and pain in edentulous adults with temporomandibular disorders

Rój R., Chladek G., Wyszyńska M., Morawiec T., Kasperski J.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 2

89--99

EN

Introduction: Multifactorial aetiologies of painful temporomandibular disorders (TMD) have an impact on correct diagnosis and consequently prevent proper treatment. Aim of the study: The aim of the study was to evaluate the effect of magnetic stimulation on electromyographic activity in temporal muscles and masseters in patients using occlusal splints. Materials and methods: The examined group consisted of 40 edentulous patients with TMD. The patients were examined based on Helkimo Index. Next, electromyographic activity of the temporal muscle and masseter were investigated using 8-channel surface electromyography. All patients received acrylic occlusal splints for 12 weeks. The group qualified for the study included 20 randomized patients, whose therapy was additionally carried out by extremely low-frequency magnetic fields for a period of 21 days. Following examinations were conducted after 3, 6 and 12 weeks with surface electromyography recording of the examined muscles. Patients received occlusal splint corrections using the T-Scan III system. The clinical evaluation of TMD was analysed using Helkimo index and VAS scale before and after the treatment. All the data were analysed using Statistica 12.5 PL. Results: Patients with combination therapy had lower asymmetry of temporal muscle activity. Conclusions: Combination therapy using magnetic stimulation reduced intensity of pain in patients with TMD and decreased values of the Helkimo indices.

12

CAD/CAM silicone auricular prosthesis with thermoformed stiffening insert

Żmudzki J., Burzyński M., Chladek G., Krawczyk C.

Archives of Materials Science and Engineering

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2017

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Vol. 83, nr 1

30--35

EN

Purpose: Epitheses (facial prostheses) for large facial tissue defects manufactured from silicones exhibit unsatisfactory rigidity and its stiffening is required, which creates technological problems. Moreover, facial epitheses have to be replaced in a relatively short period of use which creates a significant costs, often impossible to realize. The hypothesis of the study was that with use of additive manufacturing is possible to obtain the reusable form for thermoforming of the stiffening insert of auricular prosthesis and the mould which allows multiple casting of silicone prosthesis with the insert. Design/methodology/approach: Manufacturing of the epithesis consisted of designing and manufacturing. In the first step, the auricular prosthesis and the stiffening insert were designed with use of engineering CAD software. In this first computer step, the split form for vacuum thermoforming of the stiffening insert and the split mould for casting of the silicone ear were designed. In the second step, additive printing was used for manufacturing the split and reusable model for vacuum thermoforming of the stiffening insert and the split form of ear. In the third step, stiffening insert was made of thermoformed polyurethane sheet of 0.1 mm thick (Biolon, Dreve), where dental thermoforming machine (Drufosmart, Dreve) was used. In the fourth step, the stiffening insert was located in the mould and the ear was casting of silicone. Findings: CAD/CAM of epitheses with stiffening insert for large tissues defect/loss was proposed, where in case of re-producing, it required only thermoforming of insert and casting silicone with use of the reusable models. Dental technician, in case of damage or loss of a forms, is not much involved in their creation. Research limitations/implications: Bond strength test between stiffening insert vs. soft silicone and manufacturing tolerance of epitheses have not been investigated. Practical implications: Method of casting in a negative form, despite the more timeconsuming when comparing with epithesis direct-printing, allows introducing a stiffening insert and performing a manual adjustment of margin shape and thickness. Method of negative form allows the use of a commercially available medical silicone without the need for medical tests of a new printed materials.

13

DMA analysis of the structure of crosslinked poly(methyl methacrylate)s

Barszczewska-Rybarek I. M., Korytkowska-Wałach A., Kurcok M., Chladek G., Kasperski J.

Acta of Bioengineering and Biomechanics

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2017

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Vol. 19, no. 1

47--53

EN

Purpose: This paper presents the study aimed at the development of crosslinked poly(methyl methacrylate)s (X-PMMA) of varied crosslink density and the investigation of the relationships between the polymer network structure and dynamic mechanical properties. Methods: A series of model X-PMMA networks were crosslinked by the introduction of: 1, 2, 5, 10 and 20% of triethylene glycol dimethacrylate (TEGDMA). The copolymerizations led to various glass-rubber relaxation properties of the polymer networks, as revealed by dynamic-mechanical analysis (DMA). Glass temperature (Tg) and storage modulus above the Tg ( ) Erubbery  were a sensitive function of network architecture. DMA data were used for calculating the network parameter (Mc), crosslink density (q) and its alternative measure – the degree of crosslinking (DX). Results: The viscoelastic properties as well as structural parameters calculated from those showed correlation with the amount of the crosslinker. The increase in TEGDMA content resulted in the Tg, q and DX increases, whereas Mc decrease. The possible incomplete conversion of double bonds was detected in the DMA analysis, which was confirmed by the degree of conversion (DC), measured by FTIR spectroscopy. Additionally, some amount of sol fraction was found by 1H NMR experiments. Conclusions: The structure-property relationships developed for the system presented in this work could be useful in tissue engineering, where X-PMMA is applied. The direct measure of storage modulus values before and above glass transition may serve as a simple and fast indicator of the X-PMMA crosslink density.

14

Full Contoured Tooth-Implant Supported 3-Pointic All-Ceramic Denture During Occlusal Load Transfer in Lateral Region

Żmudzki J., Malara P., Chladek G.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

843--846

EN

Implant and a tooth supported dentures are avoided by dentists because of uneven distribution of occlusal loads between a stiffer implant and a more pliable tooth. The hypothesis was that a 3-point all-ceramic bridge supported on a natural second premolar tooth and a two-pieces typical implant bears safely mastication loads. The finite element analysis showed that the implant splinted by all-ceramic zirconium bridge with the second premolar was safe under lateral mastication load, but there was found an overload at wide zone of bone tissue around the implant under the load of 800 N. The patients can safely masticate, but comminution of hard food should be avoided and they should be instructed that after such an indiscretion they need to contact a dental professional, because, in spite of integrity of the prosthesis, the bone tissue around the implant may fail and there is a hazard of intrusion of the tooth.

15

The properties of experimental silicones reinforced with silica fillers for dentistry

Kalamarz I., Chladek G., Pokój M., Łukowiec D., Krawczyk C., Stencel R., Jabłońska-Stencel E.

Archives of Materials Science and Engineering

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2016

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Vol. 81, nr 1

22--29

EN

Purpose: Silicone materials crosslinked during the hydrosilylation reaction are common in dental prosthetics and dentistry. These materials are characterized by a relatively very good properties. However, one of the fundamental problems associated with the use of such polymers is a low resistance to microbial colonization. Numerus fillers with antimicrobial potential have been used experimentally for a decade. Anyway point of concern in this type of work is the use of commercially available materials as the matrix. However, the composition of the matrix for this materials is not clearly known. Therefore, the aim of this study was to obtain a two-component silicone material, crosslinking at room temperature, with properties corresponding to the needs of dental prosthetics, in particular as denture soft linings. Such material would be a starting point to obtain more sophisticated compositions, however, of known composition in full. Design/methodology/approach: As the matrix the mixtures of polymers were prepared. As the “catalyst” component a vinyl polydimethylsiloxane with platinum catalyst in xylene was prepared. As the “base” component a mixture of vinyl polydimethylsiloxane with methylhydrosiloxane - dimethylsiloxane copolymer was made. One of the two fillers differing in the functionalizing was added into prepared substrates (10 or 15% by weight) and ultrasonically homogenized. The Shore A hardness, tensile strength, bond strength to denture base material, water sorption and solubility were investigated. Measurements were made after different aging periods in distilled water at 37±1°C. Findings: The study showed an increase in mechanical properties with increasing concentrations of fillers. The type of filler significantly affects the test results. Increasing the aging time effects on increasing the hardness of materials. Water absorption and solubility were within the desired range. Research limitations/implications: Research limitations/implications The results of the presented research may be generally dependent on technology of fillers introduction into polymers matrix. Practical implications: The results show promising properties of the tested materials. It can be used as starting material for further studies on soft or super soft denture lining and other materials characterized by similar requirements. Originality/value: The method of receiving silicone - based composites with properties required for the selected prosthetic materials, especially denture soft linings was presented. Their properties were similar to commercially available products.

16

The influence of silver nanoparticles introduced into RTV-silicone matrix on the activity against Streptococcus mutans

Chladek G., Mertas A., Krawczyk C., Stencel R., Jabłońska-Stencel E.

Archives of Materials Science and Engineering

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2016

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Vol. 78, nr 2

59--65

EN

Purpose: The silicone based room temperature vulcanized (RTV) polymers are commonly used materials for medicine, especially for dentures and maxillofacial prostheses. Unfortunately, the colonization of those materials by pathogenic microorganisms is wellknown problem related with their applications. The aim of presented study was to examine antibacterial properties of RTV silicone for dentistry modified with silver nanoparticles. Design/methodology/approach: The silver nanoparticles were introduced into twocomponent system silicone based materials. The presence of silver nanoparticles was investigated with scanning electron microscope (SEM). The antibacterial activity against Streptococcus mutans was determined. The result were statistically analysed with a Statistica 12.5 software and non-parametric Kruskal-Wallis test (α = 0.05). Findings: The silver nanoparticles introduction into RTV - silicone allowed to enhance the antimicrobial resistance against standard strain of Streptococcus mutans. Research limitations/implications: In this research only Streptococcus mutans bacterium strain was used. In future activity of presented materials against other pathogenic bacteria living in oral cavity should be determined. Additionally long term investigation should be prepared. Practical implications: The colonization of dental materials with pathogenic bacteria and fungus is one of the most important and still unresolved problems related to exposition on oral environment. The low microbiological resistance of RTV-silicones and antimicrobial potential of silver were reported in numerous studies. The gram-positive Streptococcus mutans is commonly found in the human oral cavity and it is an important factor to tooth decay. Originality/value: The resistance against Streptococcus mutans of modified material was enhanced. The investigated materials could be a potential factor a potential conducive to reducing the risk of oral cavity infections.

17

Influence of aging solutions on wear resistance and hardness of selected resin-based dental composites

Chladek G., Basa K., Żmudzki J., Malara P., Nowak A. J., Kasperski J.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

43--52

EN

Purpose: The purpose of this study was to investigate the effect of different plasticizing aging solutions on wear resistance and hardness of selected universal resin-based dental composites. Methods: Three light cured (one nanofilled, two microhybride) and one hybride chemical cured composites were aged at 37 °C for 48 h in distillated water, ethyl alcohol solution or Listerine mouthwash. After aging the microhardness tests were carried out and then tribological tests were performed in the presence of aging solution at 37 °C. During wear testing coefficients of friction were determined. The maximal vertical loss in micrometers was determined with profilometer. Results: Aging in all liquids resulted in a significant decrease in hardness of the test materials, with the largest values obtained successively in ethanol solution, mouthwash and water. The effect of the liquid was dependent on the particular material, but not the type of material (interpreted as the size of filler used). Introduction of mouthwash instead of water or ethanol solution resulted in a significant reduction in the coefficient of friction. The lowest wear resistance was registered after aging in ethanol and for the chemical cured hybrid composite, but the vertical loss was strongly material dependent. Conclusions: The effect of different aging solution, including commercial mouthrinse, on hardness and wear was material dependent, and cannot be deduced from their category or filler loading. There is no simple correlation between hardness of resin-based dental composites and their wear resistance, but softening of particular composites materials during aging leads to the reduction of its wear resistance.

18

Chewing efficiency and occlusal forces in PMMA, acetal and polyamide removable partial denture wearers

Macura-Karbownik A., Chladek G., Żmudzki J., Kasperski J.

Acta of Bioengineering and Biomechanics

|

2016

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Vol. 18, no. 1

137--144

EN

Purpose: Thermoplastic materials, such as acetal (AC) and polyamide (PA), constitute an alternative to polymethyl methacrylate (PMMA) based resins as the materials for removable partial dentures. However, none of the previous studies compared chewing efficiency and occlusal forces in the wearers of dentures made of various materials. Therefore, the aim of this study was to determine and compare the chewing efficiency and occlusal forces in PMMA, PA and AC RPDs’ wearers. The hypothesis was that the type of denture base material shows a significant effect on chewing efficiency (expressed as a degree of food fragmentation) and occlusal force. Methods: The experiment included the group of 30 patients using removable partial dentures. The dentures made of PMMA, acetal and polyamide were tested in each patient. Each denture was worn for 90 days, with a random sequence of the denture manufacturing and insertion. After 7, 30 and 90 days of each denture wear, chewing efficiency coefficient was determined with the aid of a sieving method, and occlusal force was measured with a dynamometer. Results: The use of dentures made of PMMA or acetal was reflected by a marked increase in chewing efficiency and occlusal force. None of these parameters changed significantly with the time of denture wear. Moreover, no significant correlation was found between chewing efficiency and occlusal forces. Conclusions: Denture base material exerts significant effects on the degree of food fragmentation and the level of occlusal forces. The use of dentures and clasps made of materials with lower modulus of elasticity is associated with lower chewing efficiency and lower occlusal forces.

19

Occlusal load transfer in full-contour ceramic implant fixed denture

Żmudzki J., Chladek G., Krawczyk C.

Archives of Materials Science and Engineering

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2015

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Vol. 72, nr 2

61--68

EN

Purpose: Many clinicians use dentures with metallic core due to fears of insufficient strength of ceramic bridges. The aim of work was finite element strength analysis of fullcontour ceramic implant supported denture in lateral region. Design/methodology/approach: Finite element analysis (Solidworks) of occlusal load transfer in all-ceramic implant supported denture for missing second premolar, first molar and second molar teeth was made. Bridgework from zirconia was supported on two implants 4x12 mm (diameter x length) placed in bone with good quality and quantity. Model was loaded with lateral maximal occlusal force of 800 N. Findings: In the bridgework in the connector with premolar tooth Huber-Mises stress reached 375 MPa. Stress in implants was about 1000 MPa and small plastic deformation zones can occur close to the implant edge under pressure of abutment. Stress in abutment screw reached about 800 MPa in the first thread root and up to 400 MPa in the shank. Stress in bone tissues around implant neck and slightly lower of the beginning of the thread exceeded 140 MPa. Research limitations/implications: Linear isotropic behavior of materials and tied contact between components were assumed in the model. Practical implications: Detrimental effect of maximal occlusal force on the osseointegration between implant and bone showed that patients must be warned against loading of the denture over normal mastication. Stress in the abutment screw reached dangerous value and specific design to prevent fatigue failure is required. Originality/value: An impact of torsion and oblique bending are rarely considered in investigations. This result is relevant for the design of bridgeworks and graded materials for ceramic restoration.

20

Effect of silica filler on properties of PMMA resin

Chladek G., Żmudzki J., Basa K., Pater A., Krawczyk C., Pakieła W.

Archives of Materials Science and Engineering

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2015

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Vol. 71, nr 2

63--72

EN

Purpose: Of this paper was to investigate the effect of silica nanofiller addition to PMMA-based denture material. The null hypothesis was that no difference exists between the mean flexural strength, hardness, sorption among materials without and with different content of silica filler. Design/methodology/approach: The nanosilica was introduced into “powder” component of commercially available PMMA resin for dentistry in concentrations 2, 5 and 10%. The SEM observations were made to confirm dispersion quality. To confirm presence of silica filler the X-ray microanalysis have been made. The influence of nanosilica addition on flexural strength, flexural modulus, hardness and sorption were investigated. Samples were stored at distilled water and ethanol solution. Statistical analysis were prepared with the one-way or the two-way analysis of variance ANOVA ( α =0.05), and Newman-Keuls significant difference post hoc test was used to determine the differences between mean values ( α =0.05). Findings: The result show that all investigated properties were changed after silica filler addition. Initially flexural strength decreased, but after accelerated again in ethanol incised. Flexural modulus and hardness increased. Sorption was decreased in both aging liquids. Research limitations/implications: Limitations resulting from the specificity of the conditions of laboratory tests and aging conditions so it does not allow to fully translate obtained results to expected results of clinical trials. Practical implications: The PMMA drawback is still insufficient mechanical properties, so it can be easily damaged during an accidents or when a patients applies high mastication force to the denture which show areas for further mechanical properties improvement. One of the ways of improving the mechanical properties of PMMA based materials may be nanoparticle addition, including commonly used nanosilica fillers. Originality/value: Influence of destructive plasticizing solutions on chosen properties of materials with different concentrations of silica fillers have been investigated.