Effect of PEEK and PTFE coatings in fatigue performance of dental implant retaining screw joint: An in vitro study

Coating Materials to Prevent Screw Loosening in Single Dental Implant Crowns: A Systematic Review

Oral rehabilitation with dental implants has resulted in high success rates. However, some complications have been described, such as the loss of the prosthetic screw. Some manufacturers sell screws with different coatings to avoid screw loosening, but even these types of screws can come loose. We aimed to investigate the screw coatings that can be applied during a dental appointment to avoid screw loosening. Following PRISMA Guidelines, we searched PubMed/Medline, Embase and Web of Science for studies published up to January 2024. All studies of single dental implant crowns, in which the prosthetic screw was coated with a lubricant and the preload and/or the removal torque value (RTV) was recorded, were analyzed. We excluded studies applying the finite element method (FEM) as well as studies without a control group. The risk of bias was assessed with a tool developed by our research group. Of the 1959 records identified, 19 were selected. Ten studies were considered to have a low risk of bias, and nine were considered to have a medium risk of bias. The coatings tested were adhesives, saliva, chlorhexidine, Vaseline, silicone gel, Polytetrafluoroethylene (PTFE) tape, blood, fluoride, Listerine® Mouthwash and normal saline. The preload, the RTV with and without cyclic loading and the percentage of RTV loss were recorded. Some coatings show promise, although there is no clear evidence that any option is superior in minimizing screw loosening.

Influence of heating temperature and time on mechanical-degradation, microstructures and corrosion performances of Teflon/granite coated aluminum alloys used for non-stick cookware

This study explores the functional characteristics (erosion, corrosion, mechanical damage, and microstructural features) of non-stick cookware made from aluminum alloys. Typically coated with polytetrafluoroethylene (PTFE-Teflon) or ceramic for non-stick properties, we conducted a systematic investigation using corrosion, abrasion, and mechanical tests on six types of cookware from different manufacturers (Manuf-1-6). The cookware was heated at various temperatures [Room temperature (RT), 100, 175, 250, & 350 °C] and times (45 & 120 min). Tests included Taber wear, Adhesive Pull-off, hot & RT corrosion, and surface roughness measurements. Characterization involved optical microscopy, scanning electron microscope (SEM) with electron backscattered diffraction (EBSD), and x-ray diffraction (XRD). Ceramic-coated cookware from Manuf-4 demonstrated superior mechanical strength, wear, and corrosion resistance due to refined microstructures. Manuf-1's PTFE-coated cookware also performed well. Optimal results were observed when heating below 250 °C for up to 45 min. Prolonged heating and temperatures beyond 250 °C adversely affected internal structures of all cookware. Thus, it is advisable to use Al-based non-stick cookware below 250 °C for a maximum of 45 min.

Biomechanical Fatigue Behavior of a Dental Implant Due to Chewing Forces: A Finite Element Analysis

The use of titanium as a biomaterial for the treatment of dental implants has been successful and has become the most viable and common option. However, in the last three decades, new alternatives have emerged, such as polymers that could replace metallic materials. The aim of this research work is to demonstrate the structural effects caused by the fatigue phenomenon and the comparison with polymeric materials that may be biomechanically viable by reducing the stress shielding effect at the bone-implant interface. A numerical simulation was performed using the finite element method. Variables such as Young's modulus, Poisson's coefficient, density, yield strength, ultimate strength, and the S-N curve were included. Prior to the simulation, a representative digital model of both a dental implant and the bone was developed. A maximum load of 550 N was applied, and the analysis was considered linear, homogeneous, and isotropic. The results obtained allowed us to observe the mechanical behavior of the dental implant by means of displacements and von Mises forces. They also show the critical areas where the implant tends to fail due to fatigue. Finally, this type of non-destructive analysis proves to be versatile, avoids experimentation on people and/or animals, and reduces costs, and the iteration is unlimited in evaluating various structural parameters (geometry, materials, properties, etc.).

Fatigue properties of plasma nitriding for dental implant application

STATEMENT OF PROBLEM

Fatigue failure of implant components is a common clinical problem. Plasma nitriding, an in situ surface-strengthening method, may improve fatigue properties of dental implants.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of plasma nitriding on the fatigue behavior of implant systems.

MATERIAL AND METHODS

The preload and friction coefficient of plasma nitrided abutment screws, as well as settlement of the implant-abutment interface, were measured. Then, the reverse torque values and pullout force were evaluated after cyclic loading. Finally, the fatigue properties of the implant system were investigated with static fracture and dynamic fatigue life tests, and the morphology of the fracture on the surface of the implant system was observed.

RESULTS

The plasma nitriding treatment reduced the friction coefficient; increased the preload, settlement value, reverse torque values, pullout force, and static fracture load; and prolonged fatigue life. Furthermore, abutment screws with plasma nitriding treatment showed a different fatigue fracture mode.

CONCLUSIONS

Plasma nitriding improved mechanical performance and may be a suitable way to optimize the fatigue behavior of dental implants.

State-of-the-art polyetheretherketone three-dimensional printing and multifunctional modification for dental implants

Polyetheretherketone (PEEK) is a high-performance thermoplastic polymer with an elastic modulus close to that of the jawbone. PEEK has the potential to become a new dental implant material for special patients due to its radiolucency, chemical stability, color similarity to teeth, and low allergy rate. However, the aromatic main chain and lack of surface charge and chemical functional groups make PEEK hydrophobic and biologically inert, which hinders subsequent protein adsorption and osteoblast adhesion and differentiation. This will be detrimental to the deposition and mineralization of apatite on the surface of PEEK and limit its clinical application. Researchers have explored different modification methods to effectively improve the biomechanical, antibacterial, immunomodulatory, angiogenic, antioxidative, osteogenic and anti-osteoclastogenic, and soft tissue adhesion properties. This review comprehensively summarizes the latest research progress in material property advantages, three-dimensional printing synthesis, and functional modification of PEEK in the fields of implant dentistry and provides solutions for existing difficulties. We confirm the broad prospects of PEEK as a dental implant material to promote the clinical conversion of PEEK-based dental implants.

To determine the effect of plasma nitriding treatment 56 on screw loosening and surface topography of different 78 implant-abutment screw systems with and without thermocycling: An in vitro study

Aim

The aim of this study was to evaluate and compare the effect of plasma nitride-treated abutment screws of two different implant systems on screw loosening and surface topography with and without thermocycling.

Settings and Design

This was an in-vitro experimental study.

Materials and Methods

Fifty-two abutment screws (Group A: 26 Genesis and Group B: 26 Bredent) underwent plasma nitride treatment and were subdivided into two groups, one without thermocycling and one with thermocycling. Dynamic load was applied and detorque values were evaluated for determining the screw loosening using "independent t-test" with the help of IBM SPSS Statistics 20 and scanning electron microscopy was done to check for surface topography.

Statistical Analysis Used

Inter- and intragroup comparisons were done using independent t-test (SPSS: Statistical Package for the Social Sciences software version 20).

Results

Plasma nitriding treatment genesis implant system abutment screw showed more screw loosening (P < 0.05) and surface roughness as compared to bredent with and without thermocycling.

Conclusion

From the present study, it was shown that plasma nitride-treated abutment screws decreased the occurrence of screw loosening favoring the bredent implant-abutment system more than the genesis implant-abutment system.

Mechanical behavior of 3D-printed PEEK and its application for personalized orbital implants with various infill patterns and densities

This study proposed a 3D-printed PEEK with a specific design to restore the damaged orbit shape. Such printed personalized implants are greatly affected by the process parameters, wherefore the effects of the nozzle temperatures, printing speed and layer thickness on the tensile properties were investigated based on the Taguchi approach. The optimal mechanical properties, i.e., the tensile strength and Young's modulus, were found to be 54.97 MPa and 2.67 GPa, respectively. These properties were obtained by adjusting the nozzle temperature to its high level (450 °C), while the layer thickness (0.1 mm) and printing speed (20 mm/s) were set to their low levels. Secondly, the mechanical behavior of a personalized orbital implant with these optimized properties was evaluated via finite elements analysis with various infill patterns and densities, at three thicknesses: 0.3, 0.5 and 0.7 mm. It was found that all thicknesses were acceptable for the 100% filling. For the honeycomb pattern, the thicknesses 0.5 and 0.7 mm were satisfactory with a fill rate of 70% and 55% whereas only the thickness of 0.7 mm was suitable for the 40% filling. The honeycomb pattern with 40% filling and a maximum stress (7.186 MPa) and strain (0.00627 mm) should be beneficial for light-weight orbital implants.

Recent Advancements in Materials and Coatings for Biomedical Implants

Metallic materials such as stainless steel (SS), titanium (Ti), magnesium (Mg) alloys, and cobalt-chromium (Co-Cr) alloys are widely used as biomaterials for implant applications. Metallic implants sometimes fail in surgeries due to inadequate biocompatibility, faster degradation rate (Mg-based alloys), inflammatory response, infections, inertness (SS, Ti, and Co-Cr alloys), lower corrosion resistance, elastic modulus mismatch, excessive wear, and shielding stress. Therefore, to address this problem, it is necessary to develop a method to improve the biofunctionalization of metallic implant surfaces by changing the materials' surface and morphology without altering the mechanical properties of metallic implants. Among various methods, surface modification on metallic surfaces by applying coatings is an effective way to improve implant material performance. In this review, we discuss the recent developments in ceramics, polymers, and metallic materials used for implant applications. Their biocompatibility is also discussed. The recent trends in coatings for biomedical implants, applications, and their future directions were also discussed in detail.

A review of advances in tribology in 2020–2021

Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.

Preparation and Performance Evaluation of Duotone 3D-Printed Polyetheretherketone as Oral Prosthetic Materials: A Proof-of-Concept Study

Literature has reported the successful use of 3D printed polyetheretherketone (PEEK) to fabricate human body implants and oral prostheses. However, the current 3D printed PEEK (brown color) cannot mimic the vivid color of oral tissues and thus cannot meet the esthetical need for dental application. Therefore, titanium dioxide (TiO₂) and ferric oxide (Fe₂O₃) were incorporated into PEEK to prepare a series of tooth-color and gingival-color PEEK composites in this study. Through color measurements and mechanical tests, the color value and mechanical performance of the 3D printed PEEK composites were evaluated. In addition, duotone PEEK specimens were printed by a double nozzle with an interface between tooth-color and gingival-color parts. The mechanical performance of duotone PEEK with two different interfaces (horizontal and vertical) was investigated. With the addition of TiO₂ and Fe₂O₃, the colors of 3D printed PEEK composites become closer to that of dental shade guides. 3D printed PEEK composites generally demonstrated superior tensile and flexural properties and hence have great potential in the dental application. In addition, duotone 3D printed PEEK with a horizontal interfacial orientation presented better mechanical performance than that with a vertical one.