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Effects of core characters and veneering technique on biaxial flexural strength in porcelain fused to metal and porcelain veneered zirconia.

Oh JW, Song KY, Ahn SG, Park JM, Lee MH, Seo JM - J Adv Prosthodont (2015)

Bottom Line: Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness.Thus, there were four groups with 20 cores/group.Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted.

View Article: PubMed Central - PubMed

Affiliation: Department of Prosthodontics, School of Dentistry and Institute of Oral Bio-Science, Chonbuk National University, Jeonju, Republic of Korea.

ABSTRACT

Purpose: The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia.

Materials and methods: Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgroups with two different veneering methods (conventional powder/liquid layering technique and the heat-pressing technique). Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted. Factors influencing fracture strength were analyzed through three-way ANOVA (α≤.05) and the influence of core thickness and veneering method in each core materials was assessed using two-way ANOVA (α≤.05).

Results: The biaxial flexural strength test showed that the fabrication method of veneering porcelain has the largest impact on the fracture strength followed by the core thickness and the core material. In the metal groups, both the core thickness and the fabrication method of the veneering porcelain significantly influenced on the fracture strength, while only the fabrication method affected the fracture strength in the zirconia groups.

Conclusion: The fabrication method is more influential to the strength of a prosthesis compared to the core character determined by material and thickness of the core.

No MeSH data available.


Related in: MedlinePlus

Biaxial flexural strength was measured by theuniversal testing machine.
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Figure 1: Biaxial flexural strength was measured by theuniversal testing machine.

Mentions: The biaxial flexural strength was measured by the piston using the three ball method following ISO standard 6872:2008. The universal testing machine (Instron, Norwood, MA, USA) was used to measure the strength for the fracture with a crosshead speed of 1.0 mm/min (Fig. 1). The veneering porcelain was placed on the tensile surface and the core material was placed on the compressed surface. The thin plastic sheet (0.05 mm thick) was placed between the sample and the piston. The load for the fracture of the sample was recorded. The biaxial flexural strength was calculated using the equation below. The samples used in the study did have a heterogeneous structure where two different materials were physically attached to each other, while keeping their own physical characteristics. Since the bilayer structure has a relatively weak interface and is more vulnerable compared to the monolithic structure, it was not proper to apply the conventional equation to calculate the biaxial flexure strength. Therefore, we made use of Roark's formulae based on the bending theory, which reflects the characteristics of each material and analyzes the stress on the tensile surface and the stress on the compressed surface separately. The formulae are :


Effects of core characters and veneering technique on biaxial flexural strength in porcelain fused to metal and porcelain veneered zirconia.

Oh JW, Song KY, Ahn SG, Park JM, Lee MH, Seo JM - J Adv Prosthodont (2015)

Biaxial flexural strength was measured by theuniversal testing machine.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644775&req=5

Figure 1: Biaxial flexural strength was measured by theuniversal testing machine.
Mentions: The biaxial flexural strength was measured by the piston using the three ball method following ISO standard 6872:2008. The universal testing machine (Instron, Norwood, MA, USA) was used to measure the strength for the fracture with a crosshead speed of 1.0 mm/min (Fig. 1). The veneering porcelain was placed on the tensile surface and the core material was placed on the compressed surface. The thin plastic sheet (0.05 mm thick) was placed between the sample and the piston. The load for the fracture of the sample was recorded. The biaxial flexural strength was calculated using the equation below. The samples used in the study did have a heterogeneous structure where two different materials were physically attached to each other, while keeping their own physical characteristics. Since the bilayer structure has a relatively weak interface and is more vulnerable compared to the monolithic structure, it was not proper to apply the conventional equation to calculate the biaxial flexure strength. Therefore, we made use of Roark's formulae based on the bending theory, which reflects the characteristics of each material and analyzes the stress on the tensile surface and the stress on the compressed surface separately. The formulae are :

Bottom Line: Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness.Thus, there were four groups with 20 cores/group.Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted.

View Article: PubMed Central - PubMed

Affiliation: Department of Prosthodontics, School of Dentistry and Institute of Oral Bio-Science, Chonbuk National University, Jeonju, Republic of Korea.

ABSTRACT

Purpose: The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia.

Materials and methods: Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgroups with two different veneering methods (conventional powder/liquid layering technique and the heat-pressing technique). Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted. Factors influencing fracture strength were analyzed through three-way ANOVA (α≤.05) and the influence of core thickness and veneering method in each core materials was assessed using two-way ANOVA (α≤.05).

Results: The biaxial flexural strength test showed that the fabrication method of veneering porcelain has the largest impact on the fracture strength followed by the core thickness and the core material. In the metal groups, both the core thickness and the fabrication method of the veneering porcelain significantly influenced on the fracture strength, while only the fabrication method affected the fracture strength in the zirconia groups.

Conclusion: The fabrication method is more influential to the strength of a prosthesis compared to the core character determined by material and thickness of the core.

No MeSH data available.


Related in: MedlinePlus