Evaluating The Fracture Toughness and Flexural Strength of Pressable Dental Ceramics: An In Vitro Study

Abstract

The study was undertaken to evaluate the biaxial flexural strength, biaxial flexural strength after etching with 9 % HF acid and fracture toughness of three commonly used pressable all ceramic core materials. Ninety glass ceramic specimens were fabricated from three commercially available leucite based core ceramic material (1) Esthetic Empress, (2) Cergo, and (3) Performance Plus. Thirty discs of each material were divided into three groups of 10 discs each. Biaxial flexural strength (30 discs,) Biaxial flexural strength for samples treated with 9 % HF acid (30 discs) and fracture toughness (30 discs) were evaluated. Core material Performance Plus had the lowest biaxial strength of 124.89 MPa, Cergo had strength of 152.22 MPa and the highest value of 163.95 was reported for Esthetic Empress. For samples treated 9 % HF, Performance Plus had the lowest biaxial strength of 98.37 MPa, Cergo had strength of 117.42 MPa and the highest value of 143.74 was reported for Esthetic Empress. Core material Performance Plus had the lowest fracture toughness of 1.063 MPa, Cergo had strength of 1.112 MPa and the highest value of 1.225 was reported for Esthetic Empress. The results shows that Esthetic Empress had better mechanical properties compared to Cergo had Performance Plus in relation to the parameters tested.

Retrospective evaluation of extended heat‐pressed ceramic veneers after a mean observational period of 7 years

“…2,3,5 Therefore, the use of glass-ceramic material with improved flexural strength (>120 MPa) is recommend for the fabrication of ceramic veneers for these high-risk indications (remaining enamel: 50% or less). [18][19][20][21][22] Nevertheless, studies focusing on extended ceramic veneers with larger areas of exposed dentin that enable a risk analysis are still sparse. 18,19 Given that these data were generated in a university setting in a prospective clinical trial under standardized conditions, it is unclear how successful this treatment concept will be in the typical private practice environment.…”

“…It has been suggested that more extensive veneer restorations would benefit from the higher mechanical strength of glass–ceramics, as higher tensile and shear stresses occur when there are large areas of unsupported porcelain or when bonding to more flexible substrates such as dentin . Therefore, the use of glass–ceramic material with improved flexural strength (>120 MPa) is recommend for the fabrication of ceramic veneers for these high‐risk indications (remaining enamel: 50% or less) . Nevertheless, studies focusing on extended ceramic veneers with larger areas of exposed dentin that enable a risk analysis are still sparse …”

Fluorescence and physical properties of thulium and erbium co-doped dental zirconia

“…The fracture toughness values of the specimens co-doped with Tm 2O3 and Er2O3 were 4.27 to 4.64, respectively, which is approximately 4% to 12% lower than the toughness value of 4.83 found in the control samples. However, these values were approximately 3.5 to 3.8 times as high as the fracture toughness of conventional glass ceramics (1.22) 26) . Therefore, the high fracture toughness that characterizes zirconia was maintained.…”

Evaluation of flexural strength of Zirconia using three different connector designs: An in vitro study

“…An important aspect to be taken into consideration when comparing all these results is the fact that most of the available scientific literature[ 9 10 11 12 13 14 15 16 17 18 19 20 ] on zirconia strength uses geometric plane samples that do not reflect the actual configuration of a fixed prosthesis, which has curved lines or uneven material thickness, thus leading to an approach different from the ones applicable in clinical situations.…”