Abstract
Advances in all-ceramic systems have established predictable means of providing metal-free aesthetic and biocompatible materials. These materials must have sufficient strength to be a practical treatment alternative for the fabrication of crowns and fixed partial dentures.ObjectivesThe aim of this study was to compare the biaxial flexural strength of three core ceramic materials. Material and methodsThree groups of 10 disc-shaped specimens (16 mm diameter x 1.2 mm thickness - in accordance with ISO-6872, 1995) were made from the following ceramic materials: Turkom-Cera Fused Alumina [(Turkom-Ceramic (M) Sdn Bhd, Puchong, Selangor, Malaysia)], In-Ceram (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany) and Vitadur-N (Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), which were sintered according to the manufacturer's recommendations. The specimens were subjected to biaxial flexural strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The definitive fracture load was recorded for each specimen and the biaxial flexural strength was calculated from an equation in accordance with ISO-6872. ResultsThe mean biaxial flexural strength values were: Turkom-Cera: 506.8±87.01 MPa, In-Ceram: 347.4±28.83 MPa and Vitadur-N: 128.7±12.72 MPa. The results were analyzed by the Levene's test and Dunnett's T3 post-hoc test (SPSS software V11.5.0 for Windows, SPSS, Chicago, IL, USA ) at a preset significance level of 5% because of unequal group variances (P<0.001). There was statistically significant difference between the three core ceramics (P<0.05). Turkom-Cera showed the highest biaxial flexural strength, followed by In-Ceram and Vitadur-N. ConclusionsTurkom-Cera core had significantly higher flexural strength than In-Ceram and Vitadur-N ceramic core materials.
Highlights
In the last few years, numerous new dental restorative materials have been introduced in response to an increasing demand for esthetic and biocompatible materials1.The high-strength all-ceramic materials that are currently used in dentistry consist of alumina, zirconia, pressed, castable or machinable glass ceramics
Strength is an important mechanical property that can assist in predicting the performance of brittle materials33 7KH XQLD[LDO ÀH[XUDO VWUHQJWK tests, including three-point, and four-point bending tests, and biaxial bending tests are the most commonly applied methods for evaluating the strength of dental restorations27,32,33,34
For uniaxial ÀH[XUDO VWUHQJWK WHVWV WKH SULQFLSDO VWUHVV RQ WKH lower surfaces of the specimens is tensile, and it is usually responsible for crack initiation in brittle materials
Summary
In the last few years, numerous new dental restorative materials have been introduced in response to an increasing demand for esthetic and biocompatible materials1.The high-strength all-ceramic materials that are currently used in dentistry consist of alumina, zirconia, pressed, castable or machinable glass ceramics. Several developments have taken place in these areas resulting in the production of ceramic materials for clinical use. These include the aluminous porcelain crown (Vitadur, Vita Zahnfabrik, Bad Säckingen, Baden-Württemberg, Germany), the non shrink ceramic crown (Cerestore, Johnson and Johnson, East Windsor, NJ, USA), the castable mica glass-ceramic crown (Dicor, Caulk/Dentsply, Milford, DE, USA) and the leucite-reinforced glass ceramics (IPS Empress, Ivoclar Vivadent, Schaan, Liechtenstein)8,20,22 . Due to the relatively low strength of the early types of ceramics employed in the conventional porcelain jacket crowns, an alumina-reinforced porcelain core material was developed by McLean. A veneer porcelain placed on a core containing approximately 50% fused alumina crystals, compared to the conventional feldspathic porcelain level of about UHVXOWHG LQ D GHQWDO FHUDPLF ZLWK ÀH[XUDO strength from 100 to 130 MPa14
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