Investigation on fatigue life of HAp and rGO hybrid coating on the PEEK artificial screws for dental implant

Abstract

The mechanical behaviour of dental implants is crucial to their long-term endurance. Despite the demonstrated efficacy of dental implants, mechanical and biological concerns revealed in long-term follow-up studies continue to be a cause for concern. Screw loosening, which is usually caused by masticatory pressures when chewing, and peri-implantitis owing to microleakage are two of them, and if left untreated, they can lead to gradual loss of the supporting crestal bone. This study investigated the influence of hydroxyapatite (HAp) and reduced graphene oxide (rGO) hybrid coatings on the threads of a dental implant retention screw made of polyetheretherketone (PEEK). HAp with different concentrations of rGO (0.25, 0.5, 0.75, and 1%) coatings were investigated. The clamping force (CF) and coefficient of friction (COF) of the screw thread pair, as well as the single load fracture and dynamic fatigue life tests, were assessed to determine the integrity of the implant thread connection. The screw fracture mechanism and screw thread surface erosion morphology were also studied. The results revealed that C4 (HAp/rGO) coating might minimize COF, improve CF, and reduce fracture load. Furthermore, it demonstrated better anti-loosening properties under dynamic load. Most screw fractures happen on the screw's initial thread. The fracture end of a C3 combination coated screw was easily removed, but not that of a C4 combination coated screw.