Effects of different sulfuric acid etching concentrations on PEEK surface bonding to resin composite

Evaluation of stress distribution of different marginal designs on PEEK and PEKK substructure materials, cortical and cancellous Bone:A finite element analysis

BACKGROUND

High-performance polymers are used in different fixed prosthesis treatments due to their many advantages such as biocompatibility, shock absorption ability, high fracture resistance. The effects of marginal design on the forces on high-performance polymers are unknown. This study aimed was to investigate the stress distribution of different marginal designs on Polyetheretherketone (PEEK) and Polyetherketoneketone (PEKK) substructure materials, cortical bone and cancellous bone by finite element analysis.

METHODS

A first maxillary molar tooth was modeled in 3D using the "3D Complex Render" method. Considering the ideal preparation conditions (Taper angle was 6°, step depth was 1 mm, occlusal reduction was 2 mm), four different configurations were modeled by changing the marginal design (chamfer, deep chamfer, shoulder 90°, shoulder 135°). PEEK, PEKK substructure, and composite superstructure were designed on created models. A total of 150 N oblique force from two points and a total of 300 N vertical force from three points were applied from occlusall. and the maximum principal stress, minimum principal stress, von Mises stress findings in the cortical bone, spongiose bone, and substructure were examined. The study was carried out by static linear analysis with a three-dimensional finite element stress analysis method.

RESULTS

The highest maximum principal stress value in the cortical bone was observed when the PEEK + Shoulder 135° step at vertical force. The highest minimum principal stress value in the cortical bone was observed when the PEEK + Shoulder 90° step, and PEEK + deep chamfer step at oblique force. The highest maximum principal stress value in spongiose bone was observed when the PEEK + Shoulder 90° step. The highest minimum principal stress value in spongiose bone was observed when the PEEK + deep chamfer step at vertical force. The highest von Mises stress value in the substructure was observed when the PEKK + Deep chamfer step at oblique force. The lowest maximum principal stress value in the cortical bone was observed when the PEKK + Shoulder 135° step at oblique force. The lowest minimum principal stress value in the cortical bone was observed when the PEEK + Shoulder 135° step, and PEKK + shoulder 135° step at vertical force. The lowest maximum principal stress value in spongiose bone was observed when the PEEK + Shoulder 90° step. The lowest minimum principal stress value in spongiose bone was observed when the PEEK + Shoulder 135° step and PEKK + Shoulder 135° step at vertical force. The lowest von Mises stress value in the substructure was observed when the PEEK + Deep chamfer step at vertical force.

CONCLUSION

When cortical and spongiose bone stress were evaluated, no destructive stress was observed. Considering the stresses occurring in the substructure the highest stress was observed in the chamfer step.

Effect of surface treatment and resin cement type on the bond strength of polyetheretherketone to lithium disilicate ceramic

BACKGROUND

This study aims to evaluate the effect of surface treatment and resin cement on the shear bond strength (SBS) and mode of failure of polyetheretherketone (PEEK) to lithium disilicate ceramic (LDC). This is suggested to study alternative veneering of PEEK frameworks with a ceramic material.

METHODS

eighty discs were prepared from PEEK blank and from lithium disilicate ceramic. Samples were divided into four groups according to surface treatment: Group (A) air abraded with 110 μm Al2O3, Group (AP) air abrasion and primer application, Group (S) 98% sulfuric acid etching for 60 s, Group (SP) Sulfuric acid and primer. Each group was subdivided into two subgroups based on resin cement type used for bonding LDC:1) subgroup (L) self- adhesive resin cement and 2) subgroup (B) conventional resin cement (n = 10). Thermocycling was done for all samples. The bond strength was assessed using the shear bond strength test (SBS). Failure mode analysis was done at 50X magnification with a stereomicroscope. Samples were chosen from each group for scanning electron microscope (SEM). The three-way nested ANOVA followed by Tukey's post hoc test were used for statistical analysis of results. Comparisons of effects were done utilizing one way ANOVA and (p < 0.05).

RESULTS

The highest mean of shear bond strength values was demonstrated in Group of air abrasion with primer application using conventional resin cement (APB) (12.21 ± 2.14 MPa). Sulfuric acid groups showed lower shear bond strength values and the majority failed in thermocycling especially when no primer was applied. The failure mode analysis showed that the predominant failure type was adhesive failure between cement and PEEK, while the remaining was mixed failure between cement and PEEK.

CONCLUSION

The air abrasion followed by primer application and conventional resin cement used for bonding Lithium Disilicate to PEEK achieved the best bond strength. Primer application did not have an effect when self-adhesive resin cement was used in air-abraded groups. Priming step is mandatory whenever sulfuric acid etching surface treatment is utilized for PEEK.

Effects of combined modification of sulfonation, oxygen plasma and silane on the bond strength of PEEK to resin

OBJECTIVE

This study aimed to evaluate the combined effects of sulfonation, non-thermal oxygen plasma and silane on the shear bond strength (SBS) of PEEK to resin materials.

MATERIALS AND METHODS

Two hundred and eighty specimens were randomly divided into four groups: (A) untreated; (B) sulfonation for 60 s; (C) oxygen plasma for 20 min; (D) sulfonation for 60 s and oxygen plasma for 20 min. According to the instructions, 120 samples (N = 30) were coated with silane, adhesive, and resin composites. Each group of bonding specimens was divided into two subgroups (n = 15) to measure immediate and post-aging SBS. The surface morphology and the interface between the samples and adhesive were analyzed through SEM. Physicochemical characteristics of the surface and mechanical properties were determined through XPS, FTIR, light interferometry, contact angle measurement, and three-point bending tests.

RESULTS

Sulfonation produced a porous layer of approximately 20 µm thickness on the surface, and the oxygen plasma increased the O/C ratio and oxygen-containing groups of the sample surface. After coating with silane, the SBS values of sulfonated PEEK and plasma-treated PEEK increased (9.96 and 10.72 MPa, respectively), and dual-modified PEEK exhibited the highest SBS value (20.99 MPa), which was significantly higher than that of blank group (p > 0.01). After 10,000 thermal cycles, the dual-modified PEEK still displayed a favorable SBS (18.68 MPa).

SIGNIFICANCE

Sulfonation strengthened the mechanical interlocking between PEEK and the resin while oxygen plasma established a chemical bonding between silane and PEEK. This dual modification of the surface microstructure and chemical state synergistically improved the bond strength of PEEK to resin and resulted in considerable long-term effects.

Studying and Characterization of Coating of Zein-CaSiO3 Composite on Polyetheretherketone Implant Material

Material-coated implants are placed in the bone and play an essential role in bone regeneration and rapid healing around implants. Polymeric matrix reinforced with ceramic materials is a promising composite material for coating implants. This study aims to determine the effect of mixing various concentrations of zein with CaSiO3 on polyetheretherketone (PEEK) as implant material. The coating was performed using the electrospray method. PEEK disks were used as a control group. The coated disks with different concentrations of zein-CaSiO3 (Group 1: 10% wt, 90% wt), (Group 2: 20% wt, 80% wt), and (Group 3%: 30% wt, 70% wt) were the experimental group. Each group was characterized by atomic force microscopy, field emission scanning electron microscope, Fourier-transform infrared spectroscopy, water contact angle, and adhesion strength. The lowest water contact angle was obtained for Group 1: 10% wt and 90% wt were (26.64° and 27.13°, respectively), and increasing amounts of zein in comparison to quantities of CaSiO3 resulted in increased adhesion strength of the composite material to the substrate. The current study suggested that the higher amount of zein compared to the amount of CaSiO3 mixture coating is achieved by electrospraying, a favorable candidate for coating implants compared to uncoated and coated disks with low concentrations of zein compared to concentrations of CaSiO3.

Er:YAG laser settings for debonding zirconia restorations: An in vitro study

This in vitro study aimed to determine the optimal frequency and energy settings for debonding zirconia restorations using an erbium-doped yttrium aluminum garnet (Er:YAG) laser. A total of 200 zirconia specimens (5 mm × 5 mm × 1.5 mm) were fabricated from two types of materials: (1) 3 mol% yttria oxide stabilized tetragonal zirconia polycrystalline (3Y-TZP) and (2) 5 mol% yttria oxide stabilized tetragonal zirconia polycrystalline (5Y-TZP). The zirconia specimens were bonded to dentin using resin cement (RelyX Ultimate, 3 M) and divided into 20 groups based on their laser treatments (n = 5). Er:YAG laser treatment was applied at various frequencies (10 Hz and 20 Hz) and energies (80 mJ, 100 mJ, 120 mJ, 140 mJ, 160 mJ, 180 mJ, 200 mJ, 220 mJ, 240 mJ, and 260 mJ). The time required to debond the specimens and the temperature changes that dentin underwent during the laser treatment were recorded. The surface morphologies of the debonded dentin and zirconia specimens were observed using scanning electron microscopy (SEM). Additional zirconia specimens were fabricated for 4-point flexural strength testing and surface roughness measurements. Statistical analyses were conducted using three-way analysis of variance (ANOVA) and Student-Newman-Keuls (SNK)-q tests (α = 0.05). The debonding time of each specimen varied between 4.8 and 160.4 s, with an average value of 59.2 s. The dentin temperature change for each specimen ranged from 2.3 to 3.6 °C, with an average value of 2.7 °C. The debonding time was significantly influenced by the zirconia material type and laser energy, but it was not affected by the laser frequency. Among the specimens, those made of 3Y-TZP needed significantly more time for debonding than 5Y-TZP. The optimal energies were 220 mJ for 3Y-TZP and 200 mJ for 5Y-TZP. The laser frequency, laser energy, and type of zirconia material had no effect on the dentin temperature change. Additionally, no surface alternations were observed on the dentin or zirconia materials after laser treatment. The surface roughness and flexural strength of the zirconia materials remained unchanged after laser treatment. In summary, Er:YAG laser treatment effectively and safely removes zirconia restorations without impacting their mechanical properties, with a safe temperature change of less than 5.6 °C. The optimum frequency and energy settings for debonding 3Y-TZP and 5Y-TZP restorations were found to be 10/20 Hz and 220 mJ and 10/20 Hz and 200 mJ, respectively.

Effect of laser engraving on shear bond strength of polyetheretherketone to indirect composite and denture-base resins

Background/purpose

Polyetheretherketone (PEEK) is a highly sought-after thermoplastic due to its exceptional mechanical properties and biocompatibility. However, bonding PEEK to indirect composite resin (ICR) or denture-based resin (DBR) can be challenging. Laser engraving technology has shown potential to improve bonding for other materials; thus, this study aims to evaluate its effectiveness for PEEK.

Materials and methods

The experiment involved preparing ingot-shaped PEEK samples, which were then categorized into four groups based on the treatment method employed: without treatment, air abrasion, sulfuric acid etching, and laser engraving (LS). Subsequently, the samples were bonded to ICR or DBR, and their shear bond strength (SBS) was tested with or without thermocycling using a universal testing machine. Furthermore, the failure mode was observed, with statistical analyses conducted to compare the results.

Results

The grid-like microslit structure of LS group displayed the highest SBS for bonding PEEK to ICR or DBR (P < 0.05). During the bonding of PEEK to ICR, resin residue and penetration into the microslits were frequently observed in the LS group, indicating cohesive failure. However, when PEEK was bonded to DBR, mixture failure was frequently observed without thermocycling. After thermocycling, only the LS group showed cohesive failure, while the majority of specimens exhibited mixture failure.

Conclusion

Laser engraving significantly improves the SBS between PEEK and both ICR and DBR. Furthermore, it was observed that resin had penetrated the microslits, indicating that laser engraving has great potential as a surface treatment method.

PEEK surface treatment on surface roughness and bond integrity to composite resin utilizing Er: YAG, Rosebengal activated by PDT, and aluminum trioxide particles

AIMS

To evaluate the impact of conditioning protocols, aluminum trioxide (Al2O3), Er:YAG laser (EYL), and Rosebengal (RB), on the surface roughness (Ra) and shear bond strength (SBS) of polyetheretherketone (PEEK) attached to composite restorations.

METHOD

Eighty PEEK discs in total were produced and then divided into four groups (n = 20). Group1:Sulfuric acid (SA), Group 2: PDT (RB), Group 3: Al2O3, Group 4 EYL, respectively. The Ra of PEEK discs was evaluated using the surface profilometer. After being luted, the discs were attached to composite resin discs. After that, samples were put to SBS testing on a Universal testing apparatus. A stereo microscope was also used to evaluate the type of breakdown. The data were analyzed using Tukey's test and one-way analysis of variance.

RESULTS

The SA treated group exhibited the highest Ra. Nevertheless, the RB specimens activated by PDT treatment had the lowest mean Ra score. The group that received the treatment of SA exhibited the highest average score of SBS. In contrast, specimens treated with PDT and activated by RB exhibited the lowest levels of bond fidelity. Cohesive failure emerges as the prevailing kind of fracture within the various groups subjected to testing.

CONCLUSION

The utilization of Al2O3, RB activated by PDT, and EYL shows promise as a viable substitute for Sulfuric acid in enhancing the bond integrity of composite cement and surface roughness in PEEK materials.

Novel Carboxylation Method for Polyetheretherketone (PEEK) Surface Modification Using Friedel-Crafts Acylation

Recently, polyetheretherketone (PEEK) has shown promising dental applications. Surface treatment is essential for dental applications owing to its poor surface energy and wettability; however, no consensus on an effective treatment method has been achieved. In this study, we attempted to carboxylate PEEK sample surfaces via Friedel-Crafts acylation using succinic anhydride and AlBr3. The possibility of further chemical modifications using carboxyl groups was examined. The samples were subjected to dehydration-condensation reactions with 1H,1H-pentadecafluorooctylamine and N,N'-dicyclohexylcarbodiimide. Furthermore, the sample's surface properties at each reaction stage were evaluated. An absorption band in the 3300-3500 cm-1 wavenumber region was observed. Additionally, peak suggestive of COOH was observed in the sample spectra. Secondary modification diminished the absorption band in 3300-3500 cm-1 and a clear F1s signal was observed. Thus, Friedel-Crafts acylation with succinic anhydride produced carboxyl groups on the PEEK sample surfaces. Further chemical modification of the carboxyl groups by dehydration-condensation reactions is also possible. Thus, a series of reactions can be employed to impart desired chemical structures to PEEK surfaces.

Improving Surface Properties of PEEK for Dental Applications by Using Piranha Solution

Background

"Polyetheretherketone (PEEK)" is a biocompatible, high-strength polymer that is well-suited for use in dental applications due to its unique properties. However, achieving good adhesion between PEEK and hydrophilic materials such as dental adhesives or cement can be challenging. Also, this hydrophobicity may affect the use of PEEK as an implant material. Surface treatment or conditioning is often necessary to improve surface properties. The piranha solution is the treatment of choice to be explored for this purpose.

Methods

PEEK disks of 10 mm diameter and 2 mm thickness were used in this study. Those samples were divided into five groups (each group has five samples). The first is the control group, in which no acid treatment was used; the second group undergoes sulfuric acid treatment. The remaining three groups were treated with Piranha solution; each group used a different concentration (1 : 3, 1 : 5, and 1 : 7 hydrogen peroxide to sulfuric acid, respectively). The period of treatment was 60 s for all groups. Wettability and surface roughness tests were done for the five groups. In statistical analysis, Shapiro-Wilk test was used to check the assumption of normality and to determine the statistical significance among groups; a one-way analysis of variance was employed. Subsequently, for multiple comparisons, Tukey's honestly significant difference post hoc test was performed.

Results

The Piranha solution treatment groups showed a higher wettability compared to the control group and the group treated with sulfuric acid. Additionally, the Piranha solution treatment with a higher concentration of hydrogen peroxide (1 : 3) resulted in greater improvement in surface roughness compared to the control group and the lower concentration groups (1 : 5 and 1 : 7), while the sulfuric acid treated group showed the highest surface roughness.

Conclusion

The results of this study suggest that the piranha solution can be an effective method for improving the surface characteristics of PEEK to be used in different dental applications, especially as a dental implant material, due to the increase in wettability and surface roughness.

Enhancing Dental Cement Bond Strength with Autofocus-Laser-Cutter-Generated Grooves on Polyetheretherketone Surfaces

Polyetheretherketone (PEEK) is widely used in dentistry owing to its exceptional properties, including its natural appearance; however, existing surface treatment methods for bonding PEEK have limitations. Autofocus laser cutters, known for their precise engraving and cutting capabilities, offer potential for surface treatment of PEEK; thus, the objective of this study was to investigate the creation of laser groove structures on PEEK to enhance its bonding capability with dental resin cement. A dental computer-aided design and manufacturing system was used to fabricate PEEK samples, and three groove patterns (circle, line, and grid) were generated on PEEK surfaces, with air-abrasion used as the control group. The surface characteristics, cell viability, and bond strength were evaluated, and the data were statistically analyzed using one-way analysis of variance and post hoc Tukey's tests (α = 0.05). Laser-treated PEEK exhibited a uniform texture with a groove depth of approximately 39.4 µm, hydrophobic properties with a contact angle exceeding 90°, a surface roughness of 7.3-12.4 µm, consistent topography, and comparable cell viability compared with untreated PEEK. Despite a decrease in bond strength after thermal cycling, no significant intergroup differences were observed, except for the line-shaped laser pattern. These findings indicate that the autofocus laser cutter effectively enhances the surface characteristics of PEEK by creating a uniform texture and grooves, showing promise in improving bonding properties, even considering the impact of thermal cycling effects.

Modulation of implants PEEK to composite resin shear bond strength and surface roughness on pre-treatment with contemporary air abrasion techniques vs photodynamic therapy vs conventional diamond grit bur

AIM

The chief aim of the study was to determine/equate the surface roughness (SRa) and shear bond strength (BS) of pretreated PEEK discs with contemporary air abrasion techniques, photodynamic (PD) therapy by curcumin photosensitizer (PS) and conventional diamond grit straight fissure bur adhered to the composite resin discs.

MATERIAL AND METHOD

Two hundred discs of PEEK were prepared of 6 mm × 2 mm × 10 mm dimension. The discs were randomly divided into five groups (n = 40) for treatment, Group I: treatment with deionized distilled water (control group); Group II: PD therapy using curcumin PS; Group III: discs treated and abraded with air-borne particles (ABP) silica (30 μm particle size) modified alumina (Al); Group IV: ABP of alumina (110 μm particle size); and Group V: The PEEK were finished with 600-μm grit size straight diamond cutting bur installed in high speed hand-piece. The surface profilometer was used to evaluate the values of surface roughness (SRa) of pretreated PEEK discs. The discs were luted and bonded to discs of composite resin. The bonded PEEK samples were placed in Universal testing machine to evaluate shear BS. The type of BS failure for PEEK discs pre-treated with five regimes respectively was evaluated under stereo-microscope. The data was statistically analyzed using one-way ANOVA and the comparisons between mean values of shear BS were evaluated by Tukey's test (ρ≤0.05).

RESULTS

The PEEK samples pre-treated with diamond cutting straight fissure burs displayed statistically significant highest value of SRa values (3.258± 0.785 µm). Similarly, the shear BS was observed to be higher for the PEEK discs pre-treated with straight fissure bur (22.37±0.78 MPa). A comparable difference but not statistically significant difference was observed between PEEK discs pre-treated by curcumin PS and ABP-silica modified alumina (ρ ≥ 0.05).

CONCLUSION

PEEK discs pre-treated with diamond grit straight fissure bur displayed highest values of SRa and shear BS. It was trailed by ABP-Al pre-treated discs; whereas the SRa and shear BS values for the discs pre-treated with ABP-silica modified Al and curcumin PS did not show competitive difference.

Research progress of 3D printed poly (ether ether ketone) in the reconstruction of craniomaxillofacial bone defects

The clinical challenge of bone defects in the craniomaxillofacial region, which can lead to significant physiological dysfunction and psychological distress, persists due to the complex and unique anatomy of craniomaxillofacial bones. These critical-sized defects require the use of bone grafts or substitutes for effective reconstruction. However, current biomaterials and methods have specific limitations in meeting the clinical demands for structural reinforcement, mechanical support, exceptional biological performance, and aesthetically pleasing reconstruction of the facial structure. These drawbacks have led to a growing need for novel materials and technologies. The growing development of 3D printing can offer significant advantages to address these issues, as demonstrated by the fabrication of patient-specific bioactive constructs with controlled structural design for complex bone defects in medical applications using this technology. Poly (ether ether ketone) (PEEK), among a number of materials used, is gaining recognition as a feasible substitute for a customized structure that closely resembles natural bone. It has proven to be an excellent, conformable, and 3D-printable material with the potential to replace traditional autografts and titanium implants. However, its biological inertness poses certain limitations. Therefore, this review summarizes the distinctive features of craniomaxillofacial bones and current methods for bone reconstruction, and then focuses on the increasingly applied 3D printed PEEK constructs in this field and an update on the advanced modifications for improved mechanical properties, biological performance, and antibacterial capacity. Exploring the potential of 3D printed PEEK is expected to lead to more cost-effective, biocompatible, and personalized treatment of craniomaxillofacial bone defects in clinical applications.

Using Peek as a Framework Material for Maxillofacial Silicone Prosthesis: An In Vitro Study

There are often bonding problems between acrylic resins and silicone. PEEK (polyetheretherketone), which is a high-performance polymer, has great potential for the implant, and fixed or removable prosthodontics. The aim of this study was to evaluate the effect of different surface treatments on PEEK to be bonded to maxillofacial silicone elastomers. A total of 48 specimens were fabricated from either PEEK or PMMA (Polymethylmethacrylate) (n = 8). PMMA specimens acted as a positive control group. PEEK specimens were divided into five study groups as surface treatments as control PEEK, silica-coating, plasma etching, grinding, or nano-second fiber laser. Surface topographies were evaluated by scanning electron microscopy (SEM). A platinum-primer was used on top of all specimens including control groups prior to silicone polymerization. The peel bond strength of the specimens to a platinum-type silicone elastomer was tested at a cross-head speed of 5 mm/min. The data were statistically analyzed (α = 0.05). The control PEEK group showed the highest bond strength (p < 0.05) among the groups. No statistical difference was found between control PEEK, grinding, or plasma etching groups (p > 0.05). The lowest bond strength was seen in the laser group, which was not statistically different from silica-coating (p > 0.05), and statistically different from control PEEK, grinding, or plasma groups (p < 0.05). Positive control PMMA specimens had statistically lower bond strength than either control PEEK or plasma etching groups (p < 0.05). All specimens exhibited adhesive failure after a peel test. The study results indicate that PEEK could serve as a potential alternative substructure for implant-retained silicone prostheses.

Surface conditioning of PEEK post using Nd: YVO4 laser, Photodynamic therapy, and sulfuric acid on the pushout bond strength to canal dentin

AIM

To assess the push-out bond strength (PBS) of polyetheretherketone (PEEK) post-to-root dentin using post-surface conditioners i.e., Neodymium-doped yttrium orthovanadate (Nd: YVO4) and Riboflavin (RF) and Rose Bengal (RB) mediated photodynamic therapy (PDT) compared to sulfuric acid (SA).

MATERIALS AND METHODS

Decoronation of forty human single-rooted premolar teeth was performed. Followed by chamber opening, working length (WL) was established at 15 mm. Root canal preparation was completed using ProTaper Ni-Ti rotary system till F3 finishing file along with root canal disinfection. The canals were dried with paper cones followed by obturation using gutta-percha (GP) and AH sealer. Post space was prepared by drilling out 11 mm of GP using a Gates Glidden drill #3. PEEK posts were fabricated using the CAD-CAM system and then randomly allocated into 4 groups based on the post-surface conditioning (n=10). Group 1: SA, group 2: PDT RF, group 3: PDT RB, and group 4: Nd: YVO4 laser. The PEEK post was then cemented in their respective canal. PBS and failure mode assessment were performed using a universal testing machine and stereomicroscope at 40x magnification. The SBS data set was subjected to a one-way analysis of variance (ANOVA) and Tukey's Post Hoc test at a significance level of 0.05.

RESULTS

The samples in group 4 (Nd: YVO4 laser) coronal third (7.99±0.24 MPa) demonstrated the highest PBS. The apical third of samples in group 1 PEEK post surface conditioned with SA (5.15± 0.52 MPa) exhibited the minimum values of PBS. Intergroup comparison analysis showed that samples in group 1 (SA), group 2 (RF activated by PDT), group 3 (RB activated by PDT), and group 4 (Nd: YVO4 laser) demonstrated comparable outcomes of bond scores (p>0.05) CONCLUSION: Neodymium-doped yttrium orthovanadate (Nd: YVO4) and riboflavin and Rose bengal activated by photodynamic therapy (PDT) have been investigated as potential alternatives for the surface conditioning of PEEK (polyetheretherketone) posts.

Bond Strength of Sandblasted PEEK with Dental Methyl Methacrylate-Based Cement or Composite-Based Resin Cement

Poly-ether-ether-ketone (PEEK) is commonly employed in dental prostheses owing to its excellent mechanical properties; however, it is limited by its low bond strength with dental resin cement. This study aimed to clarify the type of resin cement most suitable for bonding to PEEK: methyl methacrylate (MMA)-based resin cement or composite-based resin cement. For this purpose, two MMA-based resin cements (Super-Bond EX and MULTIBOND II) and five composite-based resin cements (Block HC Cem, RelyX Universal Resin Cement, G-CEM LinkForce, Panavia V5, and Multilink Automix) were used in combination with appropriate adhesive primers. A PEEK block (SHOFU PEEK) was initially cut, polished, and sandblasted with alumina. The sandblasted PEEK was then bonded to resin cement with adhesive primer according to the manufacturer's instructions. The resulting specimens were immersed in water at 37 °C for 24 h, followed by thermocycling. Subsequently, the tensile bond strengths (TBSs) of the specimens were measured; the TBSs of the composite-based resin cements after thermocycling were found to be zero (G-CEM LinkForce, Panavia V5, and Multilink Automix), 0.03 ± 0.04 (RelyX Universal Resin Cement), or 1.6 ± 2.7 (Block HC Cem), whereas those of Super-Bond and MULTIBOND were 11.9 ± 2.6 and 4.8 ± 2.3 MPa, respectively. The results demonstrated that MMA-based resin cements exhibited stronger bonding to PEEK than composite-based resin cements.

Characteristics of Hybrid Bioglass-Chitosan Coatings on the Plasma Activated PEEK Polymer

Polyetheretherketone (PEEK) is a biocompatible, chemically and physically stable radiolucent polymer that exhibits a similar elastic modulus to the normal human bone, making it an attractive orthopedic implant material. However, PEEK is biologically inert, preventing strong enough bonding with the surrounding bone tissue when implanted in vivo. Surface modification and composite preparation are the two main strategies for the improvement of the bioactivity of PEEK. In this study, the plasma activated PEEK surfaces with the embedded bioglass, chitosan, and bioglass-chitosan mixed layers applying from the solution dip-coating technique were investigated. The most prominent factors affecting the coating biocompatibility are strictly connected with the composition of its outer surface (its charge and functional groups), hydrophilic-hydrophobic character, wettability and surface free energy, and topography (size of pores/substructures, roughness, stiffness), as well as the personal characteristics of the patient. The obtained surfaces were examined in terms of wettability and surface-free energy changes. Additionally, FTIR (Fourier Transformation Infrared Spectrometry) and SIMS (Secondary Ion Mass Spectrometry) were applied to establish and control the coating composition. Simultaneously the structure of coatings was visualized with the aid of SEM (Scanning Electron Microscopy). Finally, the obtained systems were incubated in SBF (Simulated Body Fluid) to verify the modifications' influence on the bioactivity/biocompatibility of the PEEK surface. Different structures with variable compositions, as well as changes of the wettability, were observed depending on the applied modification. In addition, the incubation in SBF suggested that the bioglass-chitosan ratio influenced the formation of apatite-like structures on the modified PEEK surfaces.

PEEK for Oral Applications: Recent Advances in Mechanical and Adhesive Properties

Polyetheretherketone (PEEK) is a thermoplastic material widely used in engineering applications due to its good biomechanical properties and high temperature stability. Compared to traditional metal and ceramic dental materials, PEEK dental implants exhibit less stress shielding, thus better matching the mechanical properties of bone. As a promising medical material, PEEK can be used as implant abutments, removable and fixed prostheses, and maxillofacial prostheses. It can be blended with materials such as fibers and ceramics to improve its mechanical strength for better clinical dental applications. Compared to conventional pressed and CAD/CAM milling fabrication, 3D-printed PEEK exhibits excellent flexural and tensile strength and parameters such as printing temperature and speed can affect its mechanical properties. However, the bioinert nature of PEEK can make adhesive bonding difficult. The bond strength can be improved by roughening or introducing functional groups on the PEEK surface by sandblasting, acid etching, plasma treatment, laser treatment, and adhesive systems. This paper provides a comprehensive overview of the research progress on the mechanical properties of PEEK for dental applications in the context of specific applications, composites, and their preparation processes. In addition, the research on the adhesive properties of PEEK over the past few years is highlighted. Thus, this review aims to build a conceptual and practical toolkit for the study of the mechanical and adhesive properties of PEEK materials. More importantly, it provides a rationale and a general new basis for the application of PEEK in the dental field.

Surface Modifications of High-Performance Polymer Polyetheretherketone (PEEK) to Improve Its Biological Performance in Dentistry

This comprehensive review focuses on polyetheretherketone (PEEK), a synthetic thermoplastic polymer, for applications in dentistry. As a high-performance polymer, PEEK is intrinsically robust yet biocompatible, making it an ideal substitute for titanium-the current gold standard in dentistry. PEEK, however, is also inert due to its low surface energy and brings challenges when employed in dentistry. Inert PEEK often falls short of achieving a few critical requirements of clinical dental materials, such as adhesiveness, osseoconductivity, antibacterial properties, and resistance to tribocorrosion. This study aims to review these properties and explore the various surface modification strategies that enhance the performance of PEEK. Literatures searches were conducted on Google Scholar, Research Gate, and PubMed databases using PEEK, polyetheretherketone, osseointegration of PEEK, PEEK in dentistry, tribology of PEEK, surface modifications, dental applications, bonding strength, surface topography, adhesive in dentistry, and dental implant as keywords. Literature on the topics of surface modification to increase adhesiveness, tribology, and osseointegration of PEEK were included in the review. The unavailability of full texts was considered when excluding literature. Surface modifications via chemical strategies (such as sulfonation, plasma treatment, UV treatment, surface coating, surface polymerization, etc.) and/or physical approaches (such as sandblasting, laser treatment, accelerated neutral atom beam, layer-by-layer assembly, particle leaching, etc.) discussed in the literature are summarized and compared. Further, approaches such as the incorporation of bioactive materials, e.g., osteogenic agents, antibacterial agents, etc., to enhance the abovementioned desired properties are explored. This review presents surface modification as a critical and essential approach to enhance the biological performance of PEEK in dentistry by retaining its mechanical robustness.

Clinical report of six-month follow-up after cementing PEEK crown on molars

We conducted a six-month clinical follow-up on computer-aided design/computer-aided manufacturing-fabricated molar polyetheretherketone PEEK crowns to investigate their therapeutic effect. Only the PEEK crowns were examined as our study focused on short-term clinical evaluation of the new PEEK material. Twenty-three cases of PEEK crowns placed on the molars of 20 subjects (7 males and 13 females, mean age: 60.6 ± 14.2 years) were included in the study. The evaluation items were the condition of the crowns at the time of cementation and after six months, patient satisfaction, masticatory ability, and occlusal force. Mann-Whitney U tests with a significance level of 5% were used to examine the difference in glucose concentration by masticatory ability, occlusal pressure, and occlusal force, with and without PEEK crowns. The occlusion, margin fit, and contact of all 23 cases at the time of cementing were good. Six months after cementation, there was no crown desorption, fracture or crack, and prosthodontics was not needed in the 22 cases (one patient dropped out). No wear of the dental antagonist was observed. Patient satisfaction was generally high. There was no significant difference in masticatory ability between the groups with and without PEEK crowns. The subject's occlusal force was within the normal range. PEEK crowns used on molars can replace metal crowns and hold promise for an appropriate and effective treatment.

Fracture strength, pull-out bond strength, and volume of luting agent of tooth-colored CAD-CAM post-and-cores

STATEMENT OF PROBLEM

Little is known about the fracture strength, retention, and adaptation of post-and-cores fabricated with novel tooth-colored materials by computer-aided design and computer-aided manufacturing (CAD-CAM).

PURPOSE

The purpose of this in vitro study was to investigate the fracture strength, pull-out bond strength (POBS), and volume of luting agent of endodontically treated premolars restored with post-and-cores milled from different CAD-CAM materials.

MATERIAL AND METHODS

Post spaces were prepared in 80 human premolars in which post-and-cores fabricated with polyetheretherketone (PK; Ceramill PEEK), nanohybrid composite resin (BB; Brava Block), polymer-infiltrated ceramic (EN; VITA Enamic), and fiber-reinforced epoxy resin (GF; Fiber Cad Post & Core) CAD-CAM materials were luted (n=20). All specimens were subjected to thermal aging (3000 cycles at 5 °C and 55 °C with a 20-second dwell time). Half of the specimens were subjected to mechanical fatigue (250 000 cycles at 5 Hz) before fracture strength testing, while the other half was submitted to POBS testing and volume of luting agent measurement. Fracture strength data were analyzed by 1-way ANOVA, while POBS and volume of luting agent data were submitted to Kruskal-Wallis followed by the Bonferroni-Dunn multiple comparison tests. The correlation between POBS and the volume of luting agent was determined by the Spearman test (α=.05).

RESULTS

POBS of GF was significantly higher than that for PK (P<.001); however, failure load (P=.160) and volume of luting agent (P=.390) values did not differ. EN showed the highest percentage of catastrophic failures (20%), while PK exhibited only core deformations. POBS and cement film volume were not significantly correlated (P>.05).

CONCLUSIONS

Different CAD-CAM materials did not influence the fracture strength and volume of luting agent of post-and-cores. Post-and-cores made with PEEK blocks showed lower bond strength to intracanal dentin than those made with fiber-reinforced epoxy resin blocks. No significant correlation was found between bond strength and the volume of luting agent.

PEEK in Fixed Dental Prostheses: Application and Adhesion Improvement

Polyetheretherketone (PEEK) has been widely applied in fixed dental prostheses, comprising crowns, fixed partial dentures, and post-and-core. PEEK’s excellent mechanical properties facilitate better stress distribution than conventional materials, protecting the abutment teeth. However, the stiffness of PEEK is not sufficient, which can be improved via fiber reinforcement. PEEK is biocompatible. It is nonmutagenic, noncytotoxic, and nonallergenic. However, the chemical stability of PEEK is a double-edged sword. On the one hand, PEEK is nondegradable and intraoral corrosion is minimized. On the other hand, the inert surface makes adhesive bonding difficult. Numerous strategies for improving the adhesive properties of PEEK have been explored, including acid etching, plasma treatment, airborne particle abrasion, laser treatment, and adhesive systems.

Shear bond characteristics and surface roughness of poly-ether-ether ketone treated with contemporary surface treatment regimes bonded to composite resin

AIM

To evaluate and compare the influence of contemporary surface treatments of air abrasions, sulfuric acid, and Photodynamic therapy (PDT) on the adhesive bonding and surface roughness of Poly-ether-ether-ketone (PEEK) bonded to resin composite.

MATERIAL AND METHODS

One hundred and fifty PEEK (disc-shaped) specimens of 10 mm diameter and 2mm thickness were prepared. Specimens were subjected to the following surface treatments, Control (no treatment), PDT, air abrasion using Alumina particles (110 μm) (AA-AP), Sulfuric acid (SA), and air abrasion using diamond particles (10-20 μm) AA-DP. Surface roughness (Ra) of treated samples were evaluated using surface profilometer. Universal testing machine was used to evaluate shear bond strength after composite resin build-up. Stereomicroscope was utilized for failure analysis of de-bonded samples of all five groups. Statistical analysis was performed utilizing one-way analysis of variance (ANOVA) to measure means and standard deviations of SBS among studied groups and the means of SBS were paralleled by Tukey multiple comparison tests (p>0.05).

RESULTS

The highest SBS was observed by 98% SA (19.25 ± 0.68 MPa). While specimen treated with PDT (11.69 ± 0.12 MPa) showed the lowest SBS. PEEK surface, treated with PDT and AA-DP demonstrated comparable SBS (p>0.05). PEEK when pretreated with 98% SA (2.658 ± 0.658μm) exhibited a significantly higher Ra value as compared to other surface-treated groups (p< 0.05).

CONCLUSION

PEEK surface treated with SA showed the highest SBS and surface roughness compared to other groups. Surface roughness of PEEK treated with PDT, AA-AP, and AA-DP demonstrated no difference in Ra. PEEK surface treatment technique should be further investigated to develop reliable adhesive resin bonding.

Assessment of different surface treatments and shear bond characteristics of poly-ether-ether-ketone: An in vitro SEM analysis

Aim:

The aim of this study is to assess the surface roughness and shear bond characteristics of pol-ether-ether-ketone after different surface treatments.

Setting and Design:

An in vitro, prospective.

Materials and Methods:

One hundred and twenty disc-shaped samples of 10 mm diameter and 2 mm thickness were milled and subjected to following surface treatments: 110 μm alumina particles, 98% concentrated sulfuric acid, and 10–20 μm synthetic diamond particles. Surface characteristics of treated sample were studied under SEM with ×500 and ×1000 magnification. Shear bond strength (SBS) with composite resin discs embedded in acrylic blocks after luting with self-etch resin cement and resin-modified glass ionomer cement (RMGIC) was evaluated using the universal testing machine (Instron®, Massachusetts U. S. A).

Statistical Analysis Used:

The data collected were evaluated using the Analysis of variance and Tukey's honest significant difference post hoc test.

Results:

Highest SBS and SR were noted with self-etch resin cement in the given order: 98% sulfuric acid (2.106 ± 0.186 μm), followed by alumina particles (1.706 ± 0.160 μm) and synthetic diamond particles (1.101 ± 0.167 μm).

Conclusion:

The SBS of self-etch resin cement was higher compared to RMGIC for all three surface treatments done on test samples. Hundred percent samples treated by all three surface treatment methods showed mixed type of failure.

Comparison of the Mechanical Properties of Temporary Abutments Made of Polyetheretherketone and Photopolymeric Resin

Background:

Provisional abutments are widely used in the rehabilitation of dental implants as it allows the use of a provisional crown in order to restore patient aesthetics while the final restoration is being carried out; most of the temporary abutments available on the market are made of titanium alloygrade V (type Ti-6Al-4Va) and polyetheretherketone (PEEK), a material that exhibits very low adhesion to polymethylmethacrylate (PMMA).

Objective:

This research is aimed to compare the mechanical properties of commercially available PEEK abutments and abutments made using an additive technique with photopolymeric resin.

Methods:

Eighteen commercial temporary abutments manufactured in PEEK and eighteen experimental abutments manufactured by 3D printing using photopolymeric resin were used. The two groups of abutments were subjected to compression, bending and adhesion tests using six abutments of each type by test. Statistical analysis was performed with STATA 14 software. The data were analyzed by means of the Wilcoxon Mann-Whitney test, as these were two independent samples of reduced size. Values ​​lower than (p <0.05) were considered statistically significant in all tests and rejected the null hypothesis of equality between the group medians.

Conclusion:

The results indicate that it is possible to make abutments with good mechanical properties in photopolymeric resin (CLEAR FLGP04) using additive techniques to be used as temporary abutments.

Comparison of the fracture strength of endodontically treated teeth restored with polyether ether ketone, zirconia and glass-fibre post-core systems

PURPOSE

This study aimed to compare the fracture resistance and fracture mode of maxillary central incisors restored with four different sizes and three different post-core systems.

MATERIALS AND METHODS

One hundred and twenty maxillary incisors were endodontically treated and randomly divided into three groups (12 subgroups). Post cavities for the narrow subgroups were prepared with 1.4-mm-diameter drills in lengths of 7.5 mm (SN) and 10 mm (LN). Post cavities for the wide subgroups were prepared with 1.6-mm-diameter drills in lengths of 7.5 mm (SW) and 10 mm (LW) (n = 10). Group F was restored with glass-fibre post and composite resin core, Group P was restored with custom PEEK post-core and Group Z was restored with custom zirconia post-core. All posts were cemented with a dual-cure resin cement. Zirconia copings were cemented. Specimens were loaded on the palatal surface with a universal testing machine, and the fracture strengths of the teeth were statistically analysed using ANOVA and post hoc Tukey tests.

RESULTS

Statistically significant differences existed between the fracture strengths of the post materials. The highest fracture strength was in Group F, and the lowest was in Group P. Evaluation of the fracture strengths of the post lengths and diameters demonstrated that the short-narrow group of Group Z had the lowest fracture strength (P < .05). The long-wide group of Group F showed the highest fracture resistance. In Group P, no statistically significant difference existed between the post-cores of different dimensions (P > .05). Irreparable fractures were observed mostly in Group Z, and decementation was more common in Group P.

CONCLUSIONS

PEEK post-cores showed sufficient fracture strength for the anterior region, similar to the other two post-core materials. PEEK post-cores showed more decementation and repairable fractures at lower forces, while restoration failure was mostly catastrophic for glass-fibre and zirconia posts.

On the synergistic effect of sulfonic functionalization and acidic adhesive conditioning to enhance the adhesion of PEEK to resin-matrix composites

OBJECTIVE

The objective of this study was to evaluate the combined effect of the sulfuric acid etching and an acidic adhesive conditioning on the shear bond strength of PEEK to a resin-matrix composite.

MATERIALS AND METHODS

Forty PEEK specimens were assigned randomly to 4 groups for H₂SO₄ etching followed by universal adhesive (pH at 2.5) conditioning for 0, 1, 3, and 5 min. Thirty PEEK specimens were divided into 3 groups for only acidic adhesive conditioning for 0, 1, 3, and 5 min. After the light-curing of the adhesive, a nanohybrid resin composite was applied onto the surfaces and then light-cured following the manufacturer`s guidelines. All specimens were stored in distilled water at 37 °C for 24 h mechanical testing. Shear bond strength tests were performed using a universal testing machine. Surfaces were analyzed by SEM, light interferometry, FTIR, and liquid contact angle measurement. Statistical analysis was performed by one-way ANOVA and Tukey's post hoc tests (p < 0.05).

RESULTS

No adhesion was achieved between untreated PEEK a resin-matrix composite, regardless of the adhesive conditioning time points. Shear bond strength of H₂SO₄-etched PEEK to resin-matrix composite increased with time (0 mmin. 4.95 ± 2.86 MPa < 1 min: 9.35 ± 2.26 MPa < 3 min: 17.84 ± 2.82 MPa < 5 min: 21.43 ± 5.00 MPa). SEM images revealed a significant modification of PEEK surface topography after the H₂SO₄ etching.

SIGNIFICANCE

The acidic adhesive was unable to modify the untreated PEEK surface to establish an effective adhesion although a synergistic effect was noticed when the universal (acidic) adhesive was applied over a H₂SO₄-etched PEEK surface, thus improving the PEEK to resin-matrix composite adhesion.

Influence of chairside surface treatments on the shear bond strength of PEKK polymer to veneering resin materials: An in vitro study

STATEMENT OF PROBLEM

High-performance thermoplastics have been adopted as an alternative restorative material to metal or ceramics. However, a straightforward surface modification process to provide a durable bond strength between the polymer and the veneering material is lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the shear bond strength (SBS) of different veneering resin materials to polyetherketoneketone (PEKK) after different surface treatments.

MATERIAL AND METHODS

Rectangular (7×7×2 mm) PEKK specimens (N=120) were randomly allocated to the following 6 groups (n=20): untreated (Cnt); nonthermal plasma (NTP) treated; tribochemical silica airborne-particle abrasion with 30-μm silica-modified Al₂O₃ (Tbc); abraded with a coarse-grit diamond rotary instrument (Ab); tribochemical silica airborne-particle abrasion + plasma treated (Tbc_NTP); abraded + plasma treated (Ab_NTP). After a bonding agent (PEKK Bond) was applied to the specimens, each group was divided into 2 subgroups according to the applied veneering resin materials: polymethylmethacrylate (PMMA) and nanohybrid composite resin (NHC, n=10). The specimens were stored in water for 24 hours at 37 °C and subjected to the SBS test by using a universal testing machine, and failure modes were evaluated using a stereomicroscope. Two-way analysis of variance (ANOVA) was performed followed by the Tukey honestly significant difference (HSD) test to statistically analyze the data (α=.05).

RESULTS

The 2-way ANOVA showed that surface treatment methods, veneering material, and their interactions were significantly different on the SBS values (P<.001). The highest SBS values were determined for the Tbc and Tbc_NTP treatment groups not only for PMMA (10.71 to 11.63 MPa) but also for NHC (19.80 to 20.60 MPa) veneering resin materials (P<.05).

CONCLUSIONS

The bonding capacity of PEKK to the PMMA and NHC veneering resin materials can be significantly improved by using tribochemical silica airborne-particle abrasion alone or with nonthermal plasma surface treatment techniques. Furthermore, using NHC veneering resin material is recommended over PMMA.

Combination of Polydopamine Coating and Plasma Pretreatment to Improve Bond Ability Between PEEK and Primary Teeth

Preformed crowns are preferred to reduce the failure risk of restoration of primary teeth, but some drawback of conventional material is still a main barrier for their clinical use. Polyether etherketone (PEEK), a tooth colored, high-performance thermoplastic polymer, has been recognized as a promising alternative to manufacture the restoration of primary teeth. However, the hydrophobic surface and low surface energy of PEEK make it hard to establish a strong and durable adhesion. In this study, we have evaluated a modification method of polydopamine (PDA) coating with plasma pretreatment for the PEEK films by physical and chemical characterization, bonding properties, and biocompatibility. The surface properties of PEEK were well-characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The adhesive strength of the PEEK films was greatly improved without significant reduction of the proliferation rate of human gingival fibroblast cells in MTT and Live/Dead assays. Therefore, PDA coating with plasma pretreatment may give a new solution for effective clinical application of PEEK in primary performed crowns.

Effect of different surface treatments on the bond strength of milled polyetheretherketone posts

STATEMENT OF PROBLEM

Polyetheretherketone (PEEK) can be used as a framework material for removable and fixed dental prostheses. However, information about the use of PEEK as a post-and-core restoration is scarce.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of different surface treatments on the push-out bond strength of milled polyetheretherketone posts to resin cement.

MATERIAL AND METHODS

Sixty intact human maxillary central incisors were selected and endodontically treated, and standardized post spaces were prepared. Sixty PEEK posts were milled from a prefabricated PEEK blank by using a computer-aided design and computer-aided manufacturing (CAD-CAM) system and divided into 3 groups (n=15) according to the surface treatment: acid etching by using 98% sulfuric acid (AE); airborne-particle abrasion by using 50-μm Al₂O₃ (AA); nonthermal plasma treatment (NTP); in addition, PEEK posts (n=15) received no treatment (NT) and served as a control. All posts were bonded by using a self-adhesive resin cement. Three sections (coronal, middle, and apical) were obtained for each specimen. Push-out bond strength measurements (MPa) for each section were recorded by using a universal testing machine at a crosshead speed of 0.5 mm/min until failure occurred. The post-cement interfaces and failure modes were evaluated by using scanning electron microscopy. The data obtained were statistically analyzed by using 1-way ANOVA and the pair-wise Tukey (HSD) test to study the difference between group mean values (α=.05).

RESULTS

The overall mean ±standard deviation of the push-out bond strength was 11 ±2 MPa for AE group, 6 ±1 MPa for AA group, 5 ±1 MPa for NTP group, and 3 ±1 MPa for NT group. A statistically significant difference was found among all groups subjected to different surface treatments as indicated by the ANOVA test (P<.001). The pair-wise Tukey honestly significant difference (HSD) test showed a significant difference among the AE group and all groups (P<.001); however, no significant difference was observed between the AA and NTP groups (P>.05). Moreover, a significant difference was observed among all root sections (P<.001).

CONCLUSIONS

Surface treatment of PEEK posts with 98% sulfuric acid for 60 seconds showed significantly higher bond strength values than those in other groups. The bond strength of PEEK posts to resin cement was significantly higher in the coronal section than that in other sections.

Suitability of the new Aryl-Ketone-Polymer indicated for removable partial dentures: Analysis of elastic properties and bond strength to denture resin

Elastic properties of Aryl-Ketone-Polymer (UAKP) and tensile bond strength (TBS) to denture resin (PalaXpress) were tested. Indentation modulus (E_IT) and indentation hardness (H_IT) were measured via Martens hardness (n=10 specimens) with 4.2±0.6 kN/mm² and 261±8 N/mm² respectively. TBS was tested in dependence of different adhesives (visio.link (VL), Adhese Universal (AU), All-Bond Universal (ABU), CLEARFIL UNIVERSAL BOND (CUB), G-Premio BOND (GPB), iBOND Universal (IBU), ONE COAT 7 UNIVERSAL (OCU), Scotchbond Universal (SBU) and without adhesive (CG), n=18/group) and the application of opaquer (n=9/group) after thermocycling (5°C/55°C, 10,000×). TBS was affected by the adhesive (η (P²=0.715, p<0.001) followed by the opaquer (η_P²=0.335, p<0.001). VL and CG showed highest TBS followed by AU and ABU. IBU and GPB resulted in lowest TBS. Opaquer increased TBS for all adhesives (p<0.05), except VL and CG (p<0.258). Elastic properties are well-suited for the indication of removable partial dentures. Bonding to denture resin is no limiting factor.

Surface characterization and bonding properties of milled polyetheretherketone dental posts

PEEK has been used in many dental applications except intra-radicular post. The aim of this study is to test polyetheretherketone (PEEK) as a dental post material through tensile bond strength (TBS) and surface roughness (SR), and to compare it with glass-fiber and cast-metal posts. Thus, 60 human maxillary central incisors with a single root were endodontically treated and divided into three groups (n = 20) according to the type of post (Group P: PEEK, Group F: Glass-fiber, Group M: Cast-metal). Appropriate surface treatment was employed for each group and SR was determined by a three-dimensional non-contact profilometer before cementation. All posts were luted to the canal dentin using self-etch resin cement (Panavia F2.0). Pull-out test was performed on a universal testing machine at a speed of 0.5 mm/min crosshead speed until failure, and TBS were calculated. One-way ANOVA, Tukey's HSD, and Pearson chi-squared tests were performed for statistical analyses (α = 0.05). According to the results, group F demonstrated the highest SR (2.93 ± 0.18 µm) and lowest TBS values (10.05 ± 0.53 MPa), while group P exhibited lowest SR (1.37 ± 0.11 µm) and highest TBS values (14.33 ± 0.58 MPa) (p < 0.001). No significant differences in failure modes were identified among groups, mostly adhesive (p = 0.243). As conclusion, PEEK may be a reliable and contemporary option for dental post systems when used with appropriate surface treatment and luting agent. This high-performance polymer may be a novel candidate as a contemporary dental post system due to its superior mechanical, chemical, thermal, and esthetical properties with low risk of fracture.

Three-Dimensionally-Printed Polyether-Ether-Ketone Implant with a Cross-Linked Structure and Acid-Etched Microporous Surface Promotes Integration with Soft Tissue

Polyether-ether-ketone (peek) is one of the most common materials used for load-bearing orthopedic devices owing to its radiolucency and favorable mechanical properties. However, current smooth-surfaced peek implants can lead to fibrous capsule formation. To overcome this issue, here, peek specimens with well-defined internal cross-linked structures (macropore diameters of 1.0–2.0 mm) were fabricated using a three-dimensional (3D) printer, and an acid-etched microporous surface was achieved using injection-molding technology. The cell adhesion properties of smooth and microporous peek specimens was compared in vitro through a scanning electron microscope (SEM), and the soft tissue responses to the both microporous and cross-linked structure of different groups were determined in vivo using a New Zealand white rabbit model, and examined through histologic staining and separating test. The results showed that the acid-etched microporous surface promoted human skin fibroblasts (HSF) adherence, while internal cross-linked structure improved the ability of the peek specimen to form a mechanical combination with soft tissue, especially with the 1.5 mm porous specimen. The peek specimens with both the internal cross-linked structure and external acid-etched microporous surface could effectively promote the close integration of soft tissue and prevent formation of fibrous capsules, demonstrating the potential for clinical application in surgical repair.

Effect of Surface Treatments on Shear Bond Strength of Polyetheretherketone to Autopolymerizing Resin

These days, new prosthodontic materials are appearing with the development of digitalization. Among these, the use of polyetheretherketone (PEEK) as the clasp of removable partial dentures has been proposed. The adhesive strength between the PEEK and acrylic resin influences the probability of denture fracture. To investigate the effect of PEEK surface treatments on the shear bond strength to acrylic resin, five surface treatment conditions of PEEK were analyzed: 1. no treatment; 2. ceramic primer application; 3. Al₂O₃ sandblasting; 4. Rocatec; and 5. Rocatec with ceramic primer application, comparing with a metal primer-treated Co-Cr alloy. Two kinds of autopolymerizing resin (Unifast II and Palapress Vario) were used as bonding materials. The specimens were evaluated to determine the bond strength. Rocatec treatment with ceramic primer application yielded the highest bond strengths (12.71 MPa and 15.32 MPa, respectively, for Unifast II and Palapress Vario). When compared to a metal primer-treated Co-Cr alloy, the bond strength of PEEK to Unifast II was similar, whereas it was about 60% of that to Palapress Vario. Rocatec treatment, combined with ceramic primer, showed the highest bond strength of PEEK to acrylic resin. Treatment of PEEK will enable its use as the clasp of removable dentures and the fixation of PEEK prostheses.

Influence of SiO2 content of polyetheretherketone (PEEK) on flexural properties and tensile bond strength to resin cement

In the present study, the influence of the SiO₂ content of polyetheretherketone (PEEK) on the bonding between PEEK and resin cement, and the corresponding mechanical properties, were evaluated. Three experimental PEEK samples with varying amounts of SiO₂, and PEEK containing 20 wt% of TiO₂ (DK), were investigated. The tensile bond strength (TBS) was evaluated before and after 10,000 thermal cycles, upon polishing, sandblasting, and conditioning of the specimens with BONDMER lightless containing a silane coupling agent, and bonded with ESTECEM II. The crystallinity, flexural modulus, and flexural strength were determined after 10,000 thermal cycles. TBS values were analyzed by two-way ANOVA and a t-test with Bonferroni correction (α<0.05), while the crystallinity, flexural modulus, and flexural strength were analyzed with one-way ANOVA followed by a t-test with Bonferroni correction (α<0.05). The TBS improved with increasing SiO₂ content in PEEK; moreover, DK and the sample with 40 wt% SiO₂ exhibited the highest flexural strength.

Effect of laser groove treatment on shear bond strength of resin-based luting agent to polyetheretherketone (PEEK)

PURPOSE

The mechanical properties of polyetheretherketone (PEEK) are ideally suited for fixed dental prostheses. However, PEEK typically has low adhesion strength to resin-based luting agent. This study assessed the shear bond strength between laser groove treated PEEK and resin-based luting agent.

METHODS

A total of 230 specimens were randomly divided into five groups (n=46): no-treatment, air abrasion treatment, 100μm-deep, 150μm-deep, and 200μm-deep laser groove treatments. The surface roughness was measured, scanning electron microscopy was used to observe the specimen surfaces, and X-ray photoelectron spectroscopy (XPS) was used to analyze the surfaces. Each group was divided into four resin-based luting agent subgroups: Panavia V5, RelyX Ultimate Resin Cement, G-CEM Link Force, and Super-Bond C&B. After the resin-based luting agent was bonded to the specimens, the bond strength was measured using shear tests and the failure modes were assessed by stereomicroscopy. The surfaces were also observed by scanning electron microscopy (SEM) after the shear bond strength measurements. The data were statistically analyzed using a two-way analysis of variance and Tukey's honest significant difference test (α=0.05).

RESULTS

The PEEK surface after laser groove treatment groups exhibited the highest mean Ra values. In the XPS analysis, the laser treated PEEK surface exhibited an effective surface composition for bonding with resin-based luting agent. The shear bond strengths for the laser groove treated samples were significantly higher (p<0.05) than those of the no-treatment and air abrasion treatment groups.

CONCLUSIONS

The shear bond strength between PEEK and resin-based luting agent was substantially improved by laser groove treatment.