Ceramic Core Materials Research Articles

Shear bond strength of different types of luting cements to an aluminum oxide-reinforced glass ceramic core material

Objective. The aim of this study was to find the optimal choice of luting cement to Synthoceram, an aluminum oxide-reinforced glass ceramic material. The bond strength of five different commercial luting cements to the ceramic material was evaluated. The effect of surface treatments, etching, sandblasting, silanizing, and combinations of these treatments was also investigated. Methods. Shear bond strength tests were performed using the ceramic material as substrate with each of the luting cements. Cements rods were prepared on pre-treated ceramic surfaces. The shear bond strength was determined 24 h after cementation. The effect of surface treatments: etching, sandblasting, and sandblasting followed by etching, respectively, on the morphology of the material, was investigated with SEM. Results. The shear bond strength increases significantly from Ketac Cem, Rely X Luting, Fuji Plus, Panavia F to Xeno Cem. The surface treatments etching and/or sandblasting followed by silanization generally provide the highest bond strength values. Significance. Based on the results of this study, the use of resin composite based cements is preferred for cementation of an all-ceramic restoration with an aluminum oxide-reinforced glass ceramic base. Surface treatment of etching and/or sandblasting followed by silanization is recommended.

The influence of the veneering porcelain and different surface treatments on the biaxial flexural strength of a heat-pressed ceramic

Statement of problem The strength of all-ceramic restorations can be adversely affected by surface defects, leading to restoration failures. Additionally, when a 2-layer all-ceramic restoration is required for esthetic purposes, part of the stronger ceramic core material is replaced by veneering porcelain. Purpose This study evaluated the effect of different surface treatments on the strength of a ceramic core material and veneering porcelain, as well as the influence of veneering porcelain on the strength of a 2-layer ceramic structure. Material and methods Fifty heat-pressed ceramic cores and 30 veneering porcelain discs (17 mm diameter × 2 mm) were made. From the ceramic core group, 20 discs were selected and reduced to a thickness of 1 mm and veneered with 1 mm of porcelain. These specimens were divided into 2 groups of 10 each. The remaining 30 ceramic core and the 30 veneering porcelain discs were divided into 2 sets of 3 equal sized groups (n=10). Ceramic core groups were prepared for testing having the following surfaces: airborne-particle abrasion, ground, and overglazed. Veneering porcelain groups were tested: as fired (no additional treatment), ground, and overglazed. Biaxial flexural strength was measured using the ball-on-ring test method. All specimens were loaded to fracture. One and 2-way analysis of variance were used to analyze the data (α=.05). Results The ceramic core discs were significantly ( P=.001) stronger than the veneering porcelain discs for the airborne-particle abrasion, as-fired, and ground surface treatments (82 ± 11 MPa vs 51 ± 8 MPa and 93 ± 14 MPa vs 60 ± 6 MPa, respectively). For the overglazed treatment, there was not a significant difference between the core (115 ± 1 4 MPa) and the veneer materials (107 ± 14 MPa). The ground 1-layer core was significantly ( P=.015) stronger (93 ± 14 MPa) than the 2-layer with the core tested in tension (72 ± 19 MPa). There was no significant difference between 1-layer veneer overglazed (107 ± 14 MPa) and 2-layer discs when tested with the veneer in tension (105 ± 16 MPa). Conclusion The overglazed surface treatment significantly improved the strength of the materials tested, as well as the strength of 2-layer discs with the veneer in tension. The veneering porcelain influenced the strength of 2-layer specimens only when tested with the ground ceramic core surface in tension.

Mechanical properties of commercial high strength ceramic core materials

Objective. The objective of the present study is to evaluate and compare the flexural strength, dynamic elastic moduli and true hardness ( H o) values of commercial Vita In-Ceram ® alumina core and Vita In-Ceram ® matrix glass with the standard aluminous porcelain (Hi-Ceram ® and Vitadur ®), Vitadur N ® and Dicor ® glass and glass-ceramic. Methods. The flexural strength was evaluated ( n=5) using 3-point loading and a servo hydraulic Instron testing machine at a cross head speed of 0.5 mm/min. The density of the specimens ( n=3) was measured by means of the water displacement technique. Dynamic Young's shear and bulk moduli and Poisson's ratio ( n=3) were measured using a non-destructive ultrasonic technique using 10 MHz lithium niobate crystals. The true hardness ( n=3) was measured using a Knoop indenter and the fracture toughness ( n=3) was determined using a Vickers indenter and a Tukon hardness tester. Statistical analysis of the data was conducted using ANOVA and a Student–Newman–Keuls (SNK) rank order multiple comparative test. Results. The SNK rank order test analysis of the mean flexural strength was able to separate five commercial core materials into three significant groups at p=0.05. Vita In-Ceram ® alumina and IPS Empress ® 2 exhibited significantly higher flexural strength than aluminous porcelains and IPS Empress ® at p=0.05. The dynamic elastic moduli and true hardness of Vita In-Ceram ® alumina core were significantly higher than the rest of the commercial ceramic core materials at p=0.05. Significance. The ultrasonic test method is a valuable mechanical characterization tool and was able to statistically discriminate between the chemical and structural differences within dental ceramic materials. Significant correlation was obtained between the dynamic Young's modulus and true hardness, p=0.05.

Investigation of the Role of Dental Ceramic Core Material using Finite Element Analysis

Investigation of the Role of Dental Ceramic Core Material using Finite Element Analysis

In-Ceram Fixed Partial Dentures: Three-Year Clinical Trial Results

In-Ceram is a sintered, high-alumina-content, glass-infiltrated ceramic core material reported to have sufficient strength for all-ceramic fixed partial dentures. While Vita/Vident recommends that In-Ceram should be used only for anterior FPDs, the purpose of this study was to push the sintered alumina material to its limits by testing posterior FPDs with premolar and molar pontics. This prospective clinical trial tested the longevity of 61 three-unit In-Ceram alumina FPDs. The failed specimens were analyzed to determine factors contributing to failure. The abutment teeth were prepared for full crown retainers with shoulder margins and 1.3 mm of axial reduction. All FPDs were cemented with an encapsulated glass ionomer. None of the patients reported postcementation sensitivity. During the three-year period, seven FPDs fractured through the connector area. By location of the pontic, failure rates were 0 percent for anteriors, 11 percent for premolars and 24 percent for molars. Based on the results of this clinical study at the three-year point, In-Ceram alumina can be reliably utilized for anterior FPDs as indicated by a 100 percent success rate. The findings do not support the use of In-Ceram alumina for posterior FPDs as was advised by the porcelain manufacturer. Glass ionomer cement can be predictably used to cement In-Ceram FPDs with few clinical side effects. Because of a technological malfunction, this article could not be presented with the others on ceramic restorations that appeared in the February issue.

Biaxial flexural strength and indentation fracture toughness of three new dental core ceramics

The traditional gold and porcelain fused to metal crowns have been challenged by the esthetic all-ceramic crown materials. Only previous experience with poor mechanical properties, lack of standardized tooth preparation, and processing challenges have prevented universal acceptance of all-ceramic crowns. However, stronger and tougher ceramics and unique processing methods for ceramics have been developed in the past 20 years. In this study, three new ceramic crown core materials were tested to compare their biaxial flexural strength and indentation fracture toughness. Ten specimens of Empress, In-Ceram, and Procera AllCeram ceramics were prepared according to their manufacturers' recommendations. The results revealed significant differences in flexural strength for the three materials ( p ≤ 0.05). The average flexural strengths of AllCeram, In Ceram, and Empress ceramics were 687 MPa, 352 MPa, and 134 MPa respectively. There was no statistically significant difference between the fracture toughness of Procera ( 4.48 MPa · m 1 2 ) and In-Ceram ceramics ( 4.49 MPa · m 1 2 ); however, both ceramics had significantly higher fracture toughness ( p < 0.005) than Empress ceramic ( 1.74 MPa · m 1 2 ).

Technical Examination of the Classical Bronze Horse from the Metropolitan Museum of Art

A thorough technical examination of the Metropolitan Museum of Art Bronze Horse (Ace. No. 23.69) has revealed that the technical evidence used to condemn it does not hold up under critical evaluation. The composition of the metal and core, the nature of the corrosion and its method of manufacture are consistent with the object being of ancient origin. Thermoluminescence experiments performed on the ceramic core material of the horse have proved that the bronze horse was manufactured in antiquity.

Technical Examination of the Classical Bronze Horse from the Metropolitan Museum of Art

A thorough technical examination of the Metropolitan Museum of Art Bronze Horse (Ace. No. 23.69) has revealed that the technical evidence used to condemn it does not hold up under critical evaluation. The composition of the metal and core, the nature of the corrosion and its method of manufacture are consistent with the object being of ancient origin. Thermoluminescence experiments performed on the ceramic core material of the horse have proved that the bronze horse was manufactured in antiquity.