![]() Multiple studies have investigated the effect of such different combinations between PEEK and veneering materials on the mechanical performance of those bi-layered restorations, yet data is still limited. Consequently, BioHPP, with its high strength, and modulus of elasticity comparable to that of bone and dentin, yet less than satisfactory optical properties, has the potential to be used as a core material for esthetic restorations while being veneered by a variety of materials and techniques. While veneering materials aim to rebuild the outer layer of the restoration, a core material is required to strengthen the integrity and stability of the restoration. In literature, core veneered restorations have been deemed as the cornerstone for prosthetic dentistry where the combination of a strong core together with an esthetic veneer has proven successful for many decades. Consequently and for the time being, its use with additional veneering is crucial. Regardless of its good mechanical properties, the use of BioHPP as a monolithic restoration is limited owing to its high opacity, greyish to white color, and low translucency compared to dental ceramics. It contains ceramic micro-particles such as aluminum oxide and zirconium oxide for optimization of the mechanical properties, better degree of polishability, reduction of plaque retention, and higher color stability over time. ![]() It has been especially optimized for dental use. BioHPP is a PEEK variant exhibiting excellent chemical, mechanical, and thermal properties. Ī modified PEEK material containing 20% ceramic filler has been introduced to the dental market as BioHPP. A 3D-finite element analysis of monolithic full contour posterior crowns revealed that materials with higher elastic modulus present higher tensile stress concentration on the crown intaglio surface and higher shear stress on the cement layer that could facilitate crown debonding in oral conditions. On the other hand, zirconia displays modulus of elasticity of 220 GPa, while that of lithium disilicate is 95 GPa. Through the addition of reinforcing agents such as carbon fibers, such elastic modulus can be improved to 18 GPa which is considered close to that of cortical bone and dentin. One of the most significant properties of PEEK is its low elastic modulus of 3.6 GPa. Additionally, PEEK is light in weight, has high resistance to chemical wear, and is a biologically inert material that is highly compatible with the surrounding tissue. ![]() Fracture resistance of PEEK three-unit fixed dental prosthesis is reported to be 1200–1383 N which is higher than that of zirconia and lithium disilicate glass-ceramic with that of the former is 981–1331 N and that of the later is 950 N. PEEK has superior mechanical properties to zirconia and lithium disilicate. It is a polycyclic, aromatic, thermoplastic polymer that is semi-crystalline and has a linear structure. Polyetheretherketone (PEEK) is a member of the polyaryletherketone polymer family. Clinical significanceĪccording to the results of that study, PEEK cores are best veneered with conventionally layered composite with core to veneering thickness ratio being 1:0.5. Thermocycling negatively impacts the flexural strength of PEEK bi-layered restorations. Veneering material for PEEK together with the thickness ratio between the core and veneering material greatly affect the flexural strength of bi-layered restorations. All groups showed significant decrease in biaxial flexural strength after aging. T C:T V=0.5:1 showed the lowest biaxial flexural strength. ![]() (LC) group had the highest biaxial flexural strength. Material, thickness ratio, and aging all had a significant effect on biaxial flexural strength. The significance level was set at P ≤ 0.05. Three-way ANOVA followed by Bonferroni’s post hoc test were used for data analysis. Half of the specimens of each subgroup were subjected to thermocycling, and the bi-axial flexural strength of all specimens was tested before and after aging. Each group was subdivided into 3 subgroups ( n=10) according to the different thickness ratios between the core and the veneering material (T C:T V). Group (CAD LD): BioHPP discs veneered with CAD milled lithium disilicate ( n=30), group (CAD C): BioHPP discs veneered with CAD milled composite ( n=30), and group (LC): BioHPP discs veneered with conventionally layered composite ( n=30). Ninety specimens of thickness 1.5 mm were divided into three groups according to their veneering material. The purpose of this study was evaluating the biaxial strength of bi-layered PEEK restorations before and after aging using different veneering materials in different thickness ratios. ![]()
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