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Assesment of the binding strength of selected bonding systems used for cementation of implantoprosthetic suprastructures

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

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 80, nr 1

18--24

EN

Purpose: of this paper is the assessment of the strength of binding of selected bonding systems used for fixing prosthetic works. The characteristics of cement materials used for settling the crowns on the implant abutments were also included. The study has presented the evaluation of the binding strength of selected bonding systems used for fixed prosthetic works. Design/methodology/approach: Metal substructures of single-unit cement-retained crown were designed and manufactured using CAD/CAM technology. Created wax models were changed to metal substructures and settled on the abutments attached to implant replicas with a group of commonly used dental cements. The binding strength was tested on Zwick Z 100 static tensile testing machine. Findings: It was found that MaxCem is the strongest material among the tested cements which can withstand the force of 175 N. Double cured cements containing the resins may withstand very high tensile strengths which can be a problem when the crown needs to be taken off. The bonding strength of the dental cements can be influenced by the width of the film, its thickness, even distribution of the cement between the crown and the abutment and the setting time. The higher the viscosity of the cement, the lower the retention of the crown on the implant abutment. Research limitations/implications: In order to limit the designing and manufacturing errors the whole technological process should be carried out with CAD/CAM technology. The cement should be evenly distributed inside the metal cup to prevent from creation of empty spaces between the crown and the abutment. It may be necessary to design and manufacture special holders to maintain the samples in the testing machine to minimalize the risk of creation initial tensile forces. Practical implications: The research gives an insight into the possibilities of choosing the cement for bonding the crown onto the implant abutment preserving the connection between the bone and the implant in case of necessity of the removal of the crown. Originality/value: The research is focused on the binding strength of the cements most commonly used for settling the crowns on the implant abutments. It helps with clinical decision making when choosing the proper cement for these purposes.

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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.

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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.