Fracture resistance and finite element analysis of single-piece PEEK implant restorative system versus titanium single-piece implant restorative system : an in-vitro study /

Abstract

Implant dentistry became a highly predictable option to restore missing dentition in cases of full or partial edentulism. It is a treatment option that is now commonly used in daily practice and offers lots of biological and functional advantages to other fixed and removable prosthetic options. Titanium has been the gold standard material in implant dentistry since introduction in the market, but they have some drawbacks such as hypersensitivity, high difference in modulus of elasticity compared to bone, and esthetic issues. As a result of continuous optimization and enhancement of treatment outcomes and longevity, new materials have emerged as potential alternatives for already existing implant fixture materials. PEEK is a recent dental material with great properties that include resistance to wear, chemical stability, inherently white color, and most importantly, its modulus of elasticity that is close to bone which indicates less stress shielding and a favorable stress distribution. The present study was conducted to compare the fracture resistance and stress distribution between two materials when used as implants: PEEK and titanium. 16 models were fabricated and divided into two groups for fracture resistance comparison: Group (Ti): One-piece titanium implants with PEEK crowns. Group (P): One-piece PEEK implants with PEEK crowns. To ensure standardization, a prefabricated one-piece titanium implant, Dentium SlimLine, was scanned using an extraoral desktop scanner in order to 3D print eight burnout resin models which later were processed into eight Bredent BioHPP PEEK implants using pressing technique. All 16 implants were then embedded into epoxy resin bases to simulate the bone. The implants were fixed into place using a surveyor to ensure standardization, centralization, and parallelism to the long axes of the bases. One crown simulating a lower premolar scenario was designed using a biogeneric copy on the ExoCAD software. Each implant was then scanned individually, and the crown design was adapted to each implant abutment. The 16 crowns milled into CAD Wax using CAD/CAM technology. The CAD wax models were then processed through pressing into PEEK crowns. The intaglios of all crowns and the PEEK implant abutments were surface treated with sandblasting and primed using a special composite primer, Bredent Visio.link, and the titanium abutments were primed using a special metal primer, Bredent MKZ primer. An adhesive resin cement, Bredent DTK Kebler Resin Cement, with auto-mixing tips was used to avoid air bubble entrapment and hand mixing errors and guarantee unified cementation. A cementation device was used to unify the cementation process for all models. Fracture resistance was done using a universal testing machine (UTM) which applied a uniform static vertical load to the central fossa of the fixed restorations until the first drop in resistance occurred. The loads were recorded using a special software in Newton (N) at the exact point of crack or fracture. A microscope was used to photograph all specimens for Failure Mode documentation. 3D Finite Element Analysis (FEA) was employed to analyze the stress distribution of the two restorative models and to study the transfer of load to all the supporting structures.