Fatigue performance of prosthetic screws used in dental implant restorations: Rolled versus cut threads.

Statement Of Problem: Cold rolling is widely used for screw thread manufacturing in industry but is less common in implant dentistry, where cutting is the preferred manufacturing method.

Purpose: The purpose of this in vitro study was to compare the surface finish and mechanical performance of a specific model of prosthetic screw used for direct restorations manufactured by thread rolling and cutting.

Material And Methods: The thread profiles were measured in an optical measuring machine, the residual stresses in an X-ray diffractometer, the surface finish in a scanning electron microscope, and then fatigue and static load tests were carried out in a direct stress test bench according to the International Organization for Standardization (ISO) 14801.

Influence of vertical misfit in screw fatigue behavior in dental implants: A three-dimensional finite element approach.

Misfit is unavoidable in dental implant-supported prostheses due to machining process or inappropriate assembling, and the definition of an admissible misfit is still a controversial issue. This work aims to understand the behavior of the screws in dental implant-supported prostheses to estimate an admissible vertical misfit value in terms of screw fatigue failure. For that purpose, a finite element model of a dental implant-supported prosthesis was created and analyzed.

Influence of design and clinical factors on the removal force ratio in tapered implant-abutment interfaces.

Statement Of Problem: A previous study investigated the effects of the preload and taper-angle mismatch in tapered implant systems on the removal force characteristics of the self-locking mechanism. The present study builds upon the previous one and introduces the effects of the time elapsed between insertion and removal and the presence of saliva in the implant-abutment interface as 2 new additional parameters.

Purpose: The purpose of this in vitro study was to elucidate the influences of design and clinical parameters on the removal force for implant systems that use tapered interference fit (TIF) type connections by measuring the force needed to remove an abutment from an implant.

Experimental study of the removal force in tapered implant-abutment interfaces: a pilot study.

Statement Of Problem: Conically tapered interface fits (TIF) provide a reliable and strong self-locking mechanism between a dental implant and its matching abutment. On occasion, it may be necessary to remove the abutment for maintenance purposes. The removal of an indexed implant with a TIF-type connection requires the application of a (removal) force to overcome the friction force due to preload.

Dental implants with conical implant-abutment interface: influence of the conical angle difference on the mechanical behavior of the implant.

Purpose: Misfit in the conical implant-abutment interface plays an important role on the mechanical behavior of the implant when masticatory forces are applied. The origin of the misfit adopted in this work is a conical angle difference between implant and abutment, which can be due to a combination of design decisions and manufacturing tolerances. The goal of this work was to investigate the effects of the implant-abutment conical angle difference in the following mechanical features: interfacial microgap, preload loss on the bolt, stress level in the bone, and abutment removal force and/or torque.