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1

Fatigue life of polymer dental crown

Michalski J., Stręk T.

Vibrations in Physical Systems

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2018

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Vol. 29

art. no. 2018010

EN

In this article fatigue life of polymer dental crown will be analyzed. Chewing forces occurring in repetitive cycles can lead to fatigue destruction of material. To predict a number of cycles to failure finite element method can be applied and results may be used to improve the design of acrylic dental crowns. Also, the modal analysis will be performed in order to find natural frequencies of the system and prevent destruction from vibrations.

2

Assessment of the compressive strength of the metal-ceramic connections in fixed dental restorations

Malara P., Paluch K., Sobolewska K., Pasieka A.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 79, nr 2

66--73

EN

Purpose: The purpose of the work was to evaluate the compressive strength of metalceramic connections in the fixed dental restorations. Design/methodology/approach: Restorations were made on a model of the natural patient's dentition which was developed specifically for this study. The study included 10 metal - porcelain crowns, for each group of teeth. Their production used Remanium 2000+ alloy and porcelain Vita VMK Master. A static compression test was carried out on the final crowns and Vicker's hardness test was performed. Visual observations were carried out on a scanning electron microscope. Findings: On the basis of the research and the discussion it was possible to conclude that metal-porcelain crowns have a greater compressive strength than natural human teeth. Thus, they are more resistant to occlusal forces and the crowns for the first molars are the strongest restorations. Practical implications: The metal-porcelain crowns are a very good option for teeth restoration and they can be used even in the areas of the mouth where the occlusal forces reach the maximum values. Originality/value: The article focuses on testing of compressive strength of metal-ceramic crowns. The comparison with natural human occlusal forces shows the sufficient mechanical properties of metal-ceramic crowns for application in humans. The artificial tooth geometry allows applying prosthetic crowns in the patient's mouth without the risk of ceramic break down.

3

The study of the connection between the zirconia substructure and veneering porcelain in dental crowns subjected to occlusal forces

Malara P., Paluch K., Sobolewska K., Pasieka A.

Archives of Materials Science and Engineering

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2016

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Vol. 81, nr 1

5--13

EN

Purpose: The aim of the study was to examine the connection between the zirconia substructure and the porcelain in the dental crowns subjected to simulated occlusal forces. Design/methodology/approach: All-ceramic dental crowns were subjected to Vickers hardness examination, testing of compressive strength and observations of breakthroughs on the SEM. Findings: Based on the research, it was found that the compressive force at which ceramic crowns brake down, are in the range of maximum occlusal loads exerted by man. There is a mechanical connection between zirconia and porcelain. All-ceramic crowns of premolars showed the highest resistance to compressive force, while the crowns of canines are characterized by the lowest resistance to the loading force. In addition, through the research we found that ceramic crowns under static compressive loads brake down and the fracture line runs through the entire thickness of the wall, because zirconium oxide has more than twice the hardness of the porcelain. There is a difference of stresses between the materials, causing fracture of the restoration. Practical implications: The research work shows that the porcelain crowns on the substructure of zirconia (all-ceramic restoration) are a very good option of the restorative treatment in dentistry, rebuilding missing teeth. Originality/value: The article presents a study on the compressive strength of manufactured crowns, followed by a comparison to the natural forces of occlussion in human. The exact mapped tooth geometry and the appropriate veneering porcelain foundation of zirconium allows the use of prosthetic crowns in the patient's mouth without fear that porcelain will be broken.

4

Ocena szczelności koron protetycznych w zależności od technologii ich wykonania

Ryniewicz W., Ryniewicz A. M., Bojko Ł.

Przegląd Elektrotechniczny

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2015

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R. 91, nr 5

45-48

PL

Celem opracowania była ocena in vitro szczelności koron ze stopu Co-Cr-Mo na zęby przedtrzonowe i trzonowe wykonanych w trzech technologiach: odlewania, frezowania i stapiania laserowego. Dla porównania dopasowania koron do filarów protetycznych stanowiących modele referencyjne wykorzystano skanowanie światłem strukturalnym i modelowanie w programie Geomagic Qualify 12. Badania pozwoliły stwierdzić, że szczelność koron protetycznych wykonanych w badanych technologiach jest porównywalna i spełnia wymogi kliniczne.

EN

The aim of the study was to assess the in vitro tightness crown alloy Co-Cr-Mo on the premolars and molars made in three technologies: casting, milling and laser melting. For comparison fitting crowns to the pillars of prosthetic on which the reference models used structured light scanning and modeling in the Geomagic Qualify 12. The study revealed that the tightness of the prosthetic crowns made in the tested technologies is comparable and meets the requirements of the clinical.

5

Application of finite element method for the analysis of a prefabricated post-and-core – tooth system

Loska S., Paszenda Z., Basiaga M., Kiel-Jamrozik M.

Challenges of Modern Technology

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2015

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Vol. 6, no. 1

11--22

EN

In recent years in the area of prosthetic treatment, great emphasise was put on leaving a residual dentition inside mouth. In a teeth after endodontic treatment or with broken crown a healthy root is a natural implant that can be used for further reconstruction. Use of posts-and-cores is one of possible methods of widely damaged tooth crowns treatment. There is a lot of different types of prefabricated posts-and-cores. Numerical analysis of the prefabricated post-and-core – tooth system was conducted by the authors. The prefabricated Flexi-Flange post-and-core from the Essential Dental System was selected for the analysis. The scope of the analysis has covered calculation of displacements, strains and stresses in each elements of the analysed system – depending on the applied post material and load applied on the prosthetic crown. The analysis reviled that there is a significant influence of the type of the post material and load on results. It was found that the most unfavourable variant of load is the one with force applied on the labial surface at the angle of 45° to the axis of the tooth. The results of the analysed system provided a valuable guidelines for proper design of its form, geometrical properties, selection of the mechanical properties and the optimal strengthening degree of metallic biomaterial.

6

The role of friction in the mechanism of retaining the partial removable dentures with double crown system

Dąbrowa T., Dobrowolska A., Wieleba W.

Acta of Bioengineering and Biomechanics

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2013

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Vol. 15, no. 4

43--48

EN

Cylindrical telescopic crowns belong to bolt dentures, because their adhesion strength is based on the friction force. The magnitude of static and slide friction forces depends on the strain within the contact area and properties of materials employed. Friction force value between telescope elements declines in the first phase of wearing period and, subsequently, maintains particular constant value of 8 to 10 N. In the telescopic technique, homo and heterogenic joints are used. The following prosthodontic materials have been examined: goldbase alloys (Degudent Kiss, Degulor M), cobalt-base alloy (Brealloy 270), ceramics (Zircon Oxide, Zirconia) during tribological investigations on FGP composite resin. The cooperating surfaces were moistened with synthetic saliva. The research confirmed the dependence of the static friction coefficient on the contact pressure for the analyzed pairs of materials used in prosthodontics. The biggest effect of the contact pressure on the coefficient of friction value occurs when the ceramic rubs on FGP composite resin. The most stable friction coefficient in the context of contact pressure changes as well as life has been found in the case of the cobalt alloy Brealloy 270. An interesting material is a gold alloy Degulor M, for which the coefficient of friction varies only slightly with pressure in the range of 0.6 to 0.9 MPa.

7

Materiały ceramiczne dla protetyki stomatologicznej - badanie właściwości fizycznych i mikrostruktury tworzyw cyrkonowych

Jaegermann Z., Michalik R.

Szkło i Ceramika

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2010

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R. 61, nr 6

32-38

PL

W niniejszym artykule opisano wstępne próby otrzymania ceramicznego tworzywa cyrkonowego charakteryzującego się wysoką wytrzymałością mechaniczną na zginanie i wysoką odpornością na kruche pękanie, służącego do wytwarzania ceramicznych koron zębowych metodą CAD/CAM. Aby zrealizować powyższy cel przeprowadzono próby formowania poprzez prasowanie osiowe i izostatyczne granulatu cyrkonowego oraz próby wstępnego wypalania wyprasek. Zbadano właściwości fizyczne wyprasek, wstępnie wypalonych kształtek oraz właściwości wytrzymałościowe i mikrostrukturalne spieków cyrkonowych. Otrzymano ceramiczne tworzywo cyrkonowe, charakteryzujące się wysoką wytrzymałością mechaniczną (na zginanie w granicach 1010-1040 MPa) i wysoką odpornością na kruche pękanie (KIC - 9,1-9,4 MPam ig 1/2), które uzyskało pozytywną ocenę formowania koron ceramicznych metodą skrawania przy użyciu obrabiarki CNC.

EN

The article concerns preliminary attempts of obtaining zirconia ceramic material characterized by high bending strength and high resistance to fracture toughness. Such properties are required for the production of ceramic dental crowns by CAD/CAM technique. In order to achieve this objective, axial and isostatic pressing of zirconia powder followed by pre-sintering of compacted blocks were performed. Physical properties of the compacts and pre-sintered blocks as well as mechanical properties and microstructure of finally sintered zirconia were evaluated. The zirconia material characterized by high mechanical resistance (bending strength - 1010-1040 MPa) and high resistance to fracture toughness (KIC - 9,1-9,4 MPam sup 1/2) was obtained. The pre-sintered blocks were positively evaluated as a material applied in forming ceramic crowns by numerically controlled milling machine.