Load-bearing capacity under fatigue and FEA analysis of simplified ceramic restorations supported by Peek or zirconia polycrystals as foundation substrate for implant purposes

Static and dynamic stress analysis of different crown materials on a titanium base abutment in an implant-supported single crown: a 3D finite element analysis

BACKGROUND

This Finite Element Analysis was conducted to analyze the biomechanical behaviors of titanium base abutments and several crown materials with respect to fatigue lifetime and stress distribution in implants and prosthetic components.

METHODS

Five distinct designs of implant-supported single crowns were modeled, including a polyetheretherketone (PEEK), polymer-infiltrated ceramic network, monolithic lithium disilicate, and precrystallized and crystallized zirconia-reinforced lithium silicates supported by a titanium base abutment. For the static load, a 100 N oblique load was applied to the buccal incline of the palatal cusp of the maxillary right first premolar. The dynamic load was applied in the same way as in static loading with a frequency of 1 Hz. The principal stresses in the peripheral bone as well as the von Mises stresses and fatigue strength of the implants, abutments, prosthetic screws, and crowns were assessed.

RESULTS

All of the models had comparable von Mises stress values from the implants and abutments, as well as comparable maximum and minimum principal stress values from the cortical and trabecular bones. The PEEK crown showed the lowest stress (46.89 MPa) in the cervical region. The prosthetic screws and implants exhibited the highest von Mises stress among the models. The lithium disilicate crown model had approximately 9.5 times more cycles to fatique values for implants and 1.7 times more cycles to fatique values for abutments than for the lowest ones.

CONCLUSIONS

With the promise of at least ten years of clinical success and favorable stress distributions in implants and prosthetic components, clinicians can suggest using an implant-supported lithium disilicate crown with a titanium base abutment.

Biomechanical behavior of implant retained prostheses in the posterior maxilla using different materials: a finite element study

BACKGROUND

The aim of this study is to evaluate the biomechanical behavior of the mesial and distal off-axial extensions of implant-retained prostheses in the posterior maxilla with different prosthetic materials using finite element analysis (FEA).

METHODS

Three dimensional (3D) finite element models with three implant configurations and prosthetic designs (fixed-fixed, mesial cantilever, and distal cantilever) were designed and modelled depending upon cone beam computed tomography (CBCT) images of an intact maxilla of an anonymous patient. Implant prostheses with two materials; Monolithic zirconia (Zr) and polyetherketoneketone (PEKK) were also modeled .The 3D modeling software Mimics Innovation Suite (Mimics 14.0 / 3-matic 7.01; Materialise, Leuven, Belgium) was used. All the models were imported into the FE package Marc/Mentat (ver. 2015; MSC Software, Los Angeles, Calif). Then, individual models were subjected to separate axial loads of 300 N. Von mises stress values were computed for the prostheses, implants, and bone under axial loading.

RESULTS

The highest von Mises stresses in implant (111.6 MPa) and bone (100.0 MPa) were recorded in distal cantilever model with PEKK material, while the lowest values in implant (48.9 MPa) and bone (19.6 MPa) were displayed in fixed fixed model with zirconia material. The distal cantilever model with zirconia material yielded the most elevated levels of von Mises stresses within the prosthesis (105 MPa), while the least stresses in prosthesis (35.4 MPa) were recorded in fixed fixed models with PEKK material.

CONCLUSIONS

In the light of this study, the combination of fixed fixed implant prosthesis without cantilever using a rigid zirconia material exhibits better biomechanical behavior and stress distribution around bone and implants. As a prosthetic material, low elastic modulus PEKK transmitted more stress to implants and surrounding bone especially with distal cantilever.

Conventional-, bulk-fill- or flowable-resin composites as prosthetic core build-up: Influence on the load-bearing capacity under fatigue of bonded leucite-reinforced glass-ceramic

This study aimed to evaluate the fatigue performance of simplified ceramic restorations (leucite-reinforced glass ceramic) adhesively cemented onto substrates of different resin composites. Three options from the same commercial line were selected (Tetric N-Line, Ivoclar), classified as Conventional (CRC), Bulk-fill (BRC) and Flowable (FRC), which were used to make discs using a cylindrical metallic device (n = 19; Ø = 10 mm, thickness = 2.0 mm). A total of 57 discs (Ø = 10 mm, thickness = 1.0 mm) were made from CAD/CAM prefabricated blocks of a leucite reinforced glass-ceramic (Empress CAD, Ivoclar) to simulate a monolithic restoration, then were randomly distributed to be bonded on 19 discs of each three different resin composite substrates (CRC; BRC; or FRC) with a dual resin cement (Multilink N; Ivoclar). The samples were subjected to a compression test with a hemispherical stainless-steel piston (Ø = 40 mm) at a monotonic regimen (n = 4; 1 mm/min loading rate and 500 kgf loading cell until fracture). The cyclic fatigue test was performed underwater at a frequency of 20 Hz (n = 15). The first step was applied using 200N for 5000 cycles, followed by increments of 50N at each step of 10,000 until failure. The outcome considered for both tests was the occurrence of radial crack. Specific statistical tests (α = 0.05) were performed for monotonic (One-way ANOVA; Tukey's test) and fatigue data (Kaplan-Meier test; Log-rank test). Fractography of fractured samples were also performed. The FRC group had the lowest failure load in both test regimes (p < 0.05; monotonic: 726.64N; fatigue: 716.67N). There were no differences between the CRC and BRC groups (p > 0.05; monotonic: 989.30 and 990.11N; fatigue: 810.00 and 833.33N, respectively). The same result was obtained considering cycles for fatigue failure (FRC < CRC=BRC). Leucite glass-ceramic bonded to substrates made of flowable resin composite behaves worse mechanically than bonding to conventional or bulk-fill resin composite substrates.

Repair protocols for indirect monolithic restorations: a literature review

Despite the advancements in indirect monolithic restorations, technical complications may occur during function. To overcome this issues, intraoral repair using resin composite is a practical and low-cost procedure, being able to increase the restoration's longevity. This review aimed to evaluate the need for repair and suggest a standardized repair protocol to the main indirect restorative materials. For this, studies were surveyed from PubMed with no language or date restriction, to investigate the scientific evidence of indirect monolithic restoration repair with direct resin composite. A classification to guide clinical decisions was made based on the FDI World Dental Federation criteria about defective indirect restorations considering esthetic and functional standards, along with the patient's view, to decide when polishing, repairing or replacing a defective restoration. Based on 38 surveyed studies, different resin composite intraoral repair protocols, that included mechanical and chemical aspects, were defined depending on the substrate considering resin-based, glass-ceramic or zirconia restorations. The presented criteria and protocols were developed to guide the clinician's decision-making process regarding defective indirect monolithic restorations, prolonging longevity and increasing clinical success.

Repair of monolithic zirconia restorations with different direct resin composites: effect on the fatigue bonding and mechanical performance

OBJECTIVE

The study aims to evaluate the shear bond and flexural strength fatigue behavior of yttrium-stabilized zirconia (4YSZ) repaired using different resin composites.

MATERIALS AND METHODS

Cylindric specimens of 4YSZ were obtained for the bond strength (Ø = 6 mm, 1.5 mm of thickness) and biaxial flexural strength (Ø = 15 mm, 1 mm of thickness) fatigue tests and divided into 3 groups according to the repair resin composite: EVO (nanohybrid), BULK (bulk-fill), and FLOW (flowable). The zirconia surface was air-abraded with alumina particles, a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primer was applied, and the resin composite was build-up over the zirconia. Fatigue shear bond strength and flexural fatigue strength tests were performed (n = 15). One-way ANOVA and Tukey post hoc tests were carried out for both outcomes, besides scanning electron microscopy and finite element analysis.

RESULTS

The repair material affected the fatigue shear bond strength of zirconia ceramic. The BULK group (18.9 MPa) depicted higher bond strength values than FLOW (14.8 MPa) (p = 0.04), while EVO (18.0 MPa) showed similar results to both groups. No effect was observed for the mechanical behavior (p = 0.53). The stress distribution was similar for all groups.

CONCLUSION

The repair of yttrium-stabilized zirconia (4YSZ) ceramics with bulk-fill resin composites was the best option for high fatigue bond strength. However, the fatigue mechanical performance was similar regardless of the applied repair material.

CLINICAL RELEVANCE

The repair of yttrium-stabilized zirconia (4YSZ) monolithic restorations may be performed with nanohybrid and bulk-fill resin composites in order to promote longevity in the treatment.

Effect of abutment screw-access hole on the fatigue performance of implant-supported lithium-disilicate luted simplified restorations

The present study aimed to evaluate the impact of the existence of an abutment screw-access hole and the filling effects on the fatigue mechanical behavior of a luted lithium-disilicate glass-ceramic. Seventy-two discs (Ø = 10 mm, 1.0 mm in thickness) of lithium disilicate (IPS e.max CAD, Ivoclar AG) were obtained from prefabricated blocks. Thirty-six abutment specimens of an opaque zirconia (Yz - IPS e.max ZirCAD, Ivoclar AG) and titanium (Ti - Luminesse Ti-Cam discs, Talladium Inc.) were confectioned, and allocated according to 6 groups: Yz and Ti rigid (without screw access hole); Yz unfilled, Yz filled, Ti unfilled and Ti filled (with the screw access (Ø = 2.5 mm) in the center). For the unfilled groups, only a polytetrafluoroethylene tape was used. Resin composite (Tetric N-Ceram, Ivoclar AG) was applied to the screw access hole for the filled groups (Yz and Ti). A cyclic fatigue test was carried out (load of 200 N, 10,000 cycles each; 20 Hz of frequency, step size of 100 N until failure detection (radial/cone crack). The fatigue failure load (FFL) and number of cycles until failure (CFF) were recorded for statistical purposes. The stress distribution (MPa) was evaluated by finite element analysis. A statistically positive effect of the abutment material and the presence of the screw access hole was observed (p ≤ 0.05). The rigid groups (without screw access holes) depicted almost 100% of survival after the fatigue tests. Among the other groups, the Yz-filled group showed the best performance (p ≤ 0.05), followed by the Yz unfilled group. The Ti groups depicted lower values of FFL and CFF, with the Ti unfilled group showing the most unfavorable fatigue behavior (p ≤ 0.05). The lowest tensile stress concentration in the restorative material was observed with the use of rigid abutments, the filled groups depicted intermediate values, while unfilled groups showed the highest stress concentration (Yz rigid = 306.3 MPa; Ti rigid = 310.4 MPa < Yz filled = 490.7 MPa; Ti filled = 498.9 MPa < Yz unfilled = 707.6 MPa; Ti unfilled = 719.7 MPa). Therefore, the presence of a screw-access hole decreases the mechanical performance of a lithium disilicate ceramic regardless of the abutment material. In the presence of a screw-access hole, zirconia abutments depicted a higher fatigue failure load when compared with titanium. The filling of the abutment screw-access hole with resin composite increased the mechanical performance of the simulated restoration.

Cyclic fatigue of a repaired 4 YSZ ceramic: Effect of the repair protocol on the adhesive and mechanical behavior

Objective

To evaluate the effect of different surface treatments on the morphology, shear bond, and flexural fatigue strength of a repaired translucent zirconia.

Methods

Monolithic disc-shaped specimens of translucent zirconia were prepared and ground to simulate repair areas. Four groups underwent different treatments: Air-MDP (air-abrasion with alumina particles and 10-MDP primer), Si-Sil (silica-coated alumina particles with MDP-containing silane), Si-MDP (silica coating with 10-MDP primer), and Uni adhe (universal adhesive). After roughness measurements and treatments, repairs were done using resin composite. Shear bond and flexural (n = 15) fatigue tests were performed. Surface topography, interfacial analysis, fractographic, and finite element analysis were conducted.

Results

The zirconia roughness was similar between the groups, however, the surface topography was modified according to the surface treatments. Si-Sil generated higher and more stable bond strength values (20.69 MPa) between translucent zirconia and resin composite when compared to Uni adhe (15.75 MPa) considering the fatigue bond strength scenario, while it was similar to Si-MDP (17.70 MPa) and Air-MDP (18.97 MPa). Regarding the mechanical behavior, Si-Sil (680.83 MPa) also showed higher and significantly different fatigue strength when compared to Uni adhe (584.55 MPa), while both were similar to Si-MDP (634.22 MPa) and Air-MDP (641.86 MPa).

Conclusion

The association of mechanical and chemical approaches is essential for long-term bond strength and optimized mechanical behavior, being air-abrasion protocols and the use of silane and/or MDP-based primers suitable for zirconia repair protocols. It was found that relying solely on a universal adhesive was not as effective as other options available.

Clinical significance

The surface treatment of repair protocols affects translucent zirconia's morphology. To enhance fatigue behavior in repaired monolithic zirconia, air abrasion is crucial. Exclusive use of a universal adhesive is less effective than other choices. A primer containing silane/MDP holds the potential for stable bond strength and optimized mechanical performance.

Load-bearing capacity under fatigue of bonded-yttria tetragonal zirconia polycrystals and -yttria-stabilized zirconia: Effects of the viscosity of a dual-cured resin cement

This study aimed to evaluate the effect of low and high viscosities of dual-cured resin cement on the mechanical fatigue behavior of yttria tetragonal zirconia polycrystals (3Y-TZP) and yttria-stabilized zirconia (4YSZ) adhesively luted to a dentin analogue (glass fiber-reinforced epoxy resin). Ceramic discs were randomly divided into four groups (n = 20) based on the following study factors: dual-cured resin cement viscosities (low and high) and zirconia microstructure (3Y-TZP and 4YSZ). The discs were treated by air abrasion with aluminum oxide particles (50 μm), followed by the application of primer, and then luted with high or low viscosity resin cement to the dentin analogue. Subsequently, the luted sets underwent a step-stress fatigue test, which involved an initial load of 200 N, step increments of 100 N, 10,000 cycles per step, and a frequency of 20 Hz. Data on fatigue failure load (FFL) and the number of cycles for failure (CFF) were collected and analyzed using survival tests, including Kaplan-Meier and Mantel-Cox analyses, as well as Weibull analysis. Additionally, topography analysis, fractographic features, bonding interface analysis, and Raman spectroscopy were performed. The results revealed that 3Y-TZP exhibited superior fatigue behavior compared to 4YSZ, regardless of the viscosity of the resin cement used for luting. Among all groups, 3Y-Low exhibited the best fatigue performance, while 4YSZ luted with low or high viscosity resin cements yielded the lowest fatigue behavior (FFL). There were no significant differences in Weibull modulus among the groups. After air abrasion, both ceramics showed similar topography. Raman analysis indicated that the surface of 3Y-TZP ceramics prior to sintering had a monoclinic phase, which transitioned predominantly to tetragonal phase peaks after sintering. A similar transition was observed in 4YSZ ceramics. In summary, 3Y-TZP exhibited superior mechanical fatigue behavior compared to 4YSZ. The influence of resin cement viscosity on fatigue behavior was more pronounced in 3Y-TZP, with low-viscosity resin cement enhancing its performance. However, the mechanical fatigue behavior of 4YSZ was less affected by the viscosity of the dual-cured resin cement, showing similar results with both low and high viscosities. In conclusion, 3Y-TZP demonstrated superior mechanical fatigue behavior compared to 4YSZ. The impact of resin cement viscosity on fatigue behavior was more pronounced in 3Y-TZP, with low-viscosity resin cement enhancing its performance. Conversely, the mechanical fatigue behavior of 4YSZ was less sensitive to the viscosity of the dual-cured resin cement, resulting in similar outcomes with both low and high viscosities.

Advanced lithium disilicate: A comparative evaluation of translucency and fatigue failure load to other ceramics for monolithic restorations

The aim of this in vitro study was to evaluate the surface roughness, translucency, fatigue failure load (FFL), and number of cycles for fatigue failure (CFF) of a recently released lithia-based material called advanced lithium disilicate and three other ceramics indicated for monolithic restorations. First, ALD (advanced lithium disilicate, CEREC Tessera, Dentsply Sirona), LD (lithium disilicate, IPS e. max CAD, Ivoclar), LS (lithium silicate-disilicate, Suprinity, Vita Zahnfabrik), and 4Y-PSZ (Yttria-stabilized zirconia, IPS e.max ZirCAD MT, Ivoclar) discs (n = 15, Ø = 10 mm and thickness = 1.0 mm) were fabricated from CAD/CAM blocks/discs, A2 shade. The discs were sintered/crystallized and subsequently analyzed by a rugosimeter (Mitutoyo SJ-410) to determine Ra and Rz surface roughness parameters. Next, they were evaluated to determine the translucency parameter (TP) using a bench-top spectrophotometer (SP60, EX-Rite). The discs were subsequently cemented to glass fiber epoxy resin discs, and the specimens were tested under cyclic loading (Step-test), immersed in distilled water at a frequency of 20 Hz, with an initial cyclic load of 200 N for 5,000 cycles and increments of 50 N every 10,000 cycles until failure. Fatigue failure load (FFL) and number of cycles for fatigue failure (CFF) were recorded for subsequent Kaplan Meier analysis, with post-hoc Mantel-Cox and Weibull analysis (α = 0.05). Complementary fractographic, topographic and energy dispersive spectroscopy analyses (EDS) were performed. 4Y-PSZ showed higher survival (p < 0.05), with higher FFL and CFF (1077 N; 180,333 cycles), followed by LD (980 N; 161,000 cycles), LS (937 N; 152,333 cycles) and ALD (910 N; 147,000 cycles). No differences were observed between the tested groups regarding Weibull modulus. ALD presented TP (28.14) equal to DL (28.27) and higher than LS (25.51). All lithia-based materials had higher translucency than 4Y-PSZ (TP = 8.62) (p < 0.05). ALD appears to have a similar elemental composition to LD and LSD for oxygen and silicon. ALD and LSD have a similar zirconium content. Fractures originated on the cemented surface of the ceramic discs. Lithia-based ceramics showed lower surface roughness, with ALD (Ra = 0.04 μm; Rz = 0.66 μm) showing the lowest values (p < 0.05). Despite showing lower FFL when compared to LD and 4Y-PSZ, ALD has compatible translucency and mechanical fatigue performance with its indication for fabricating monolithic, anterior and posterior adhesively cemented single-unit restorations. However, further studies are needed to substantiate its clinical performance.

Mechanical Behavior of Repaired Monolithic Crowns: A 3D Finite Element Analysis

This study evaluated the mechanical behavior and risk of failure of three CAD-CAM crowns repaired with different resin composites through a three-dimensional (3D) finite element analysis. Three-dimensional models of different cusp-repaired (conventional nanohybrid, bulk-fill, and flowable resin composites) crowns made of zirconia, lithium disilicate, and CAD-CAM resin composite were designed, fixed at the cervical level, and loaded in 100 N at the working cusps, including the repaired one. The models were analyzed to determine the Maximum Principal and Maximum Shear stresses (MPa). Complementary, an in vitro shear bond strength test (n = 10) was performed to calculate the risk of failure for each experimental group. The stress distribution among the models was similar when considering the same restorative material. The crown material affected the stress concentration, which was higher for the ceramic models (±9 MPa for shear stress; ±3 MPa for tensile stress) than for the CAD-CAM composite (±7 MPa for shear stress; ±2 MPa for tensile stress). The shear bond strength was higher for the repaired CAD-CAM resin composite (±17 MPa) when compared to the ceramics (below 12 MPa for all groups), while the repair materials showed similar behavior for each substrate. The stress distribution is more homogenous for repaired resin composite crowns, and a flowable direct resin composite seems suitable to repair ceramic crowns with less risk of failure.

Substrate Rigidity Effect on CAD/CAM Restorations at Different Thicknesses

OBJECTIVES

 This article evaluated the effect of substrates rigidities on the post-fatigue fracture resistance of adhesively cemented simplified restorations in lithium disilicate glass ceramic.

METHODS

 Precrystalized computer-aided design/computer-aided manufacturing ceramic blocks were processed into disc-shaped specimens (n = 10, Ø = 10 mm), mimicking a simplified restoration at two thicknesses (0.5 and 1.0 mm). Thereafter, the discs were cemented onto different base substrates (dentin analogue [control], dentin analogue with a central core build-up of resin composite [RC], or glass ionomer cement [GIC]). The specimens were subjected to mechanical cycling in a chewing simulator (100 N, 1 × 106 cycles, 4 Hz) and then subjected to thermocycling aging (10,000 cycles, 5/37/55°C, 30 seconds). After the fatigue protocol, the specimens were loaded until failure (N) in a universal testing machine. Finite element analysis calculated the first principal stress at the center of the adhesive interface.

RESULTS

 The results showed that "restoration thickness," "type of substrate," and their interaction were statistically significant (one-way analysis of variance; p < 0.001). Regardless the restoration thickness a higher fracture load was observed for specimens cemented to dentin analogue. Among the base materials, RC build-up presented the highest fracture load and lower stress magnitude for both restoration thicknesses in comparison with GIC build-up. The 0.5-mm restoration showed higher stress peak and lower fracture load when submitted to the compressive test.

CONCLUSION

 More flexible base material reduces the fracture load and increases the stress magnitude of adhesively cemented lithium disilicate restorations regardless the ceramic thickness. Therefore, more rigid substrates are suggested to be used to prevent restoration mechanical failures.

High-versus low-viscosity resin cements: Its effect on the load-bearing capacity under fatigue of a translucent zirconia

The purpose of the present study was to characterize the elastic modulus and Poisson's ratio of a resin cement with distinct viscosities, and to evaluate their impact on the static and fatigue strength of a translucent zirconia (4Y-PSZ) after air-abrasion surface treatment. Bar-shaped specimens of two different viscosities of resin cement (high and low) were obtained (25 × 10 × 3 mm). Sonelastic and Maxwell principles tests were performed to determine the elastic modulus and Poisson's ratio of each resin cement. Disc-shaped specimens of 4Y-PSZ were made (Ø = 15 mm, 1.2 mm in thickness) for the mechanical tests and allocated into groups according to two factors: surface treatment (presence or absence of air-abrasion with alumina particles; 45 μm grain-size); cement (absence, low or high viscosity). The static (n = 10) and cyclical (n = 15) biaxial flexural strength tests were performed by piston-on-three-balls geometry. A fatigue strength test was executed (20 Hz, initial stress of 60 MPa [12% of the mean static biaxial flexural strength], followed by increments of 25 MPa [5% of the mean static biaxial flexural strength] at each step of 10,000 cycles until the failure). The obtained data were analyzed by Weibull analysis. Survival rates were tabulated by the Kaplan-Meier test. Complementary analyses of surface roughness, topography, cross-sectional interfacial zone, fractography, and zirconia crystalline content (X-ray diffraction) were also performed. The evaluated resin cements with high and low viscosity presented similar elastic modulus (13.63 GPa; 12.74 GPa) and Poisson's ratio (0.32; 0.30), respectively. The air-abraded groups depicted higher mechanical strength of the zirconia ceramics than non-abraded groups (p˂ 0.05), regardless of the resin cement. 4Y-PSZ adhesively bonded to a high or low viscosity resin cement have statistically similar behavior (p˃ 0.05). The mechanical structural reliability of the 4Y-PSZ was not affected by the factors. Therefore, resin cement with high and low viscosity presented similar properties and potential to fill the zirconia surface, and did not affect the mechanical behavior of 4Y-PSZ. However, the air-abrasion surface treatment increased the static and fatigue flexural strength of the translucent zirconia.

A brief review on fatigue test of ceramic and some related matters in Dentistry

The characteristics of dental ceramics have been extensively studied over the years to provide highly qualified materials for use in prosthetic restorations. The ability to adhere to dental substrates, outstanding aesthetics (translucency, color, and substrate masking ability) and improved mechanical properties provide these materials with optical features and high strength to withstand masticatory stimuli. Different classifications are adopted, and it is generally considered that glass-ceramics have better optical characteristics due to the high glass content, and polycrystalline ceramics have superior strength favored by their densified and organized crystals, hampering crack growth. This knowledge was largely built-up during years of scientific research through different testing methodologies, but mainly employing static loads. It is important to not only take into account the intensity of loads that these materials will be exposed to, but also the effect of the intermittence of cyclic load application leading to mechanical fatigue and the influence of factors related to the crack origin and their propagation under this condition. Furthermore, the bonding surface of ceramic restorations requires surface treatments that improve the bond strength to luting agents; however, these treatments require caution because of their potential to produce defects and affect the structural behavior. Moreover, ceramic restorations often require internal adjustments for proper seating or external adjustments for fitting the occlusal contact with the antagonist. In this sense, finishing/polishing protocols may alter the defect population, as luting agents may also interact by filling in the superficial defects on the restoration intaglio surface. Thus, the balance among all these factors will define the performance of a restorative setup, as well as the posterior exposure to the humid environment and the masticatory stimuli (cyclical loading), which may favor developing slow and subcritical growth of cracks in ceramic materials and the degradation of the bond interface. Therefore, it is essential that the concepts which explain the fatigue mechanism are understood, as well as the crack propagation and failure patterns of restorative ceramic materials.

Tribological and Antibacterial Properties of Polyetheretherketone Composites with Black Phosphorus Nanosheets

Over the past few decades, polyetheretherketone (PEEK) artificial bone joint materials faced problems of poor wear resistance and easy infection, which are not suitable for the growing demand of bone joints. The tribological behavior and wear mechanism of polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) with black phosphorus (BP) nanosheets have been investigated under dry sliding friction. Compared with pure PEEK, the COF of PEEK/10 wt% PTFE/0.5 wt% BP was reduced by about 73% (from 0.369 to 0.097) and the wear rate decreased by approximately 95% (from 1.0 × 10⁻⁴ mm³/(N m) to 5.1 × 10⁻⁶ mm³/(N m)) owing to the lubrication of the BP transfer film. Moreover, BP can endow the PEEK composites with excellent biological wettability and antibacterial properties. The antibacterial rate of PEEK/PTFE/BP was assessed to be over 99.9%, which might help to solve the problem of PEEK implant inflammation. After comprehensive evaluation in this research, 0.5 wt% BP nanosheet-filled PEEK/PTFE material displayed the optimum lubrication and antibacterial properties, and thus could be considered as a potential candidate for its application in biomedical materials.