جستجوی مقالات مرتبط با کلیدواژه « polyetheretherketone » در نشریات گروه « پزشکی »

Bio-medical implants and prostheses are made of metals and their alloys and are prone to corrosion and wear. Therefore, it seems necessary to develop lightweight reinforced polymer composites with enhanced properties.

Polyetheretherketone (PEEK) has favorable properties that make it able to be used as a denture base material, but it is also susceptible to the adhesion of microorganisms. In this study, we applied Octafluoropentyl (meth) acrylate (OFPA) coating on the PEEK polymer surface by using plasma spray and investigated the functional groups present on the surface, changes in the surface energy and Candida albicans adhesion.

In this experimental study, the samples were placed in a control group without surface preparation and three experimental groups that were subjected to plasma spray for 10, 30, and 60 s and then impregnated with degassed Octa fluoropentyl (meth) acrylate (Sigma‑Aldrich, USA) monomer. Fourier transform infrared spectroscopy (FTIR) was used to identify the functional groups and new chemical bonds between PEEK and OFPA, and Sessile Drop Method was used to evaluate the surface’s wettability. The surface morphology was checked using a LEXT OLS4000 (Olympus®‑Japan) microscope, and the inhibition of C. albicans adhesion was also checked by counting the colonies in terms of colony forming unit/mL (CFU/mL). Kurskal–Wallis analysis was conducted to assess Candida adhesion, while wettability was evaluated using analysis of variance and post hoc analyses. The level of statistical significance was set at P < 0.05.

FTIR analysis confirmed that a chemical between OFPA and PEEK was established. The samples showed a significant increase in the contact angle after 30 s of plasma application (CA = 88.2 ± 7.3). The contact angle decreased again by increasing the surface modification to 60 s (CA = 64.33 ± 5.5). Examining the surface morphology of the samples shows an increase in surface roughness with increasing plasma time up to 60 s. The number of adherent colonies was the lowest in 30 s group, but it was not statistically significant (P = 0.658).

No statistically significant difference in C. albicans CFU/mL count was found between groups. The contact angle of the 30 s group was significantly higher than the control group.

Restoring severely damaged teeth has always been challenging when the remaining crown structure is limited, and retention might be necessary from the root canal using intracanal posts. However, the real challenge is when the root canal walls are also weak, and there is a high risk of vertical root fracture due to the wedging forces of a rigid post. This case report presents a tooth with flared root canal walls successfully restored with a newly introduced polymer made of polyether ether ketone (PEEK) (BioHPPfor2press,Bredent,UK) with one-year follow-up. Regarding its close elastic modulus to dentin, the ability to bond to tooth structure, shock-absorbing ability, and therefore favorable stress distribution, using this material for an intracanal post may minimize the risk of fractures commonly observed with cast metal posts. It combines good fitness of cast posts with low modulus of elasticity and optical properties of prefabricated fiber posts.

Occlusal loading of osseointegrated implants is believed to be an essential determining factor in the long‑term success of an implant treatment. Numerous studies have been conducted on the evaluation of stress distribution by definitive restoration materials for Implant‑supported fixed prosthesis, but very few have evaluated provisional restoration materials for the same. This study aims to evaluate the influence of provisional restoration material – Milled Polymethylmethacrylate (PMMA) and Milled Polyetheretherketone (PEEK), over stress distribution on the peri‑implant bone around an implant‑supported three‑unit, fixed dental prosthesis using finite element analysis method.

Three‑dimensional models of a pair of bone‑level implant system and titanium base abutments were created using the standard tessellation language data of original implant components. A bone block representing the mandibular posterior area was created, and the implants were placed in the bone block with 100% osseointegration in the 2nd premolar to 2nd molar region. A superstructure of an implant‑supported 3‑unit bridge was modeled on top of the abutments, each crown to be 8 mm in height and with an outer diameter of 6 mm in 2nd premolar region and 10 mm in 1st molar and 2nd molar region. Two different models were created according to combinations of provisional restoration materials, namely, Milled PMMA and Milled PEEK based on. In each model, the implants were loaded vertically (300 N) and obliquely (150 N at 30°). The stress distribution in the cortical bone, cancellous bone, and implant was evaluated through the von Mises stress analysis.

The results showed no difference in stress distribution due to the different provisional restorations – Milled PMMA and Milled PEEK. In addition, the vertical load resulted in higher stress values in the implant components, cortical bone, and cancellous bone in both PEEK and PMMA models as compared to oblique loading.

The new polymer, PEEK was seen to provide comparable stress generation in the current study without exceeding the physiological limits of peri‑implant bone. Thus, it can be considered as a good alternative to PMMA resin as a provisional crown material since it provides certain additional benefits.

It is unclear which the material is a better choice for post and core rehabilitation systems in endodontically treated teeth. This study aimed to compare the fracture resistance of three different postcore systems.

In this in vitro study, 33 extracted premolars were treated endodontically and divided into three groups, namely (A) the prefabricated fiberglass postcomposite core, (B) the Ni‑Cr cast postcore, and (C) the polyetheretherketone (PEEK) postcore groups. After postcementation, the core was restored with Ni‑Cr crown. By a universal testing machine, the fracture resistance of the posts was assessed. Furthermore, types of fractures were determined with radiography and confirmed objectively by cutting the acryl resin boxes. The data of the fracture resistance were analyzed using the one‑way ANOVA and Tukey test, and the data of the fracture pattern were analyzed using Fisher’s exact test (P < 0.05).

The fracture resistance was significantly higher in Group B (Ni‑Cr) than in Group C (PEEK) (P = 0.001) and Group A (fiberglass) (P < 0.001). Moreover, the fracture resistance was higher in Group C (PEEK) than in Group A (fiberglass) but was not statistically significant (P = 0.405). The fracture pattern was different in all the groups based on the types of fracture (P = 0.009) and the repairability of fracture (P = 0.036).

The present study showed that the fracture resistance was significantly higher in the Ni‑Cr post than in the fiberglass and PEEK posts. Further, the fracture mode was more repairable in teeth restored with the PEEK post, as compared to the other posts.

Poly-etheretherketone is a novel material used in the construction of the removable partial dentures frameworks instead of the metal frameworks. This material can be fabricated by various techniques. Most common methods are the injection molding or Computer Aided Design/Computer Aiding Manufacturing (CAD/CAM) milling techniques. The fabrication technique may affect the adaptation of the frameworks by influencing the retention.

To assess the effect of the processing techniques of high performance Poly-etheretherketone either by injection molding (pressing) or  CAD/CAM  milling techniques on removable partial denture frameworks retention for rehabilitation of upper class I Kennedy classification.

This in vitro studywas performed on one epoxy resin model representing the partially edentulous maxillary arch with natural teeth extending from first premolar to first premolar. First premolars and canines were reduced to receive porcelain fused to metal crowns with 0.50mm mesio-buccal retentive undercuts, distal guiding planes and mesial occlusal rest seat on first premolars and cingulum rest seat on canines. Considering the construction technique of frameworks, twenty samples were divided into two groups. In the group I, ten frameworks were fabricated by injection molding, and in the group II, ten frameworks were fabricated by CAD/CAM. The removal and insertion was carried out at 120, 720 and 1440 cycles for both groups, respectively. The retention values were measured by using Universal Testing Machine before cycling and after each interval.

Independent t-test showed significant difference on retention at different simulation cycles between groups. Group II exhibited significantly less retention than group I (p< 0.001), while comparing the retention at different cycles within each group by paired sample t-test exhibited significant decrease of retention till the end of the cycling (p< 0.001).

From the retention point of view, high performance poly-etheretherketone frameworks fabricated by injection molding technique provided a promising method over CAD/CAM technique milling method.

This study aimed to investigate the marginal adaptation of implant-supported three-unit fixed restorations fabricated in excessive crown height by various frameworks namely zirconia, nickel-chromium (Ni-Cr) alloy, and Polyetheretherketone (PEEK) before and after veneering.

A basic model with two implant fixtures was made to receive posterior three-unit fixed partial dentures (second premolar to second molar) in 15 mm crown height. A total of 30 frameworks were fabricated using Ni-Cr, zirconia, and PEEK (n=10). All specimens were veneered and vertical marginal discrepancy was evaluated before and after veneering using a stereomicroscope (×75). The effect of framework material and veneering on marginal discrepancy was evaluated by repeated-measures and one-way ANOVA, and paired t test (α=0.05).

There was a significant difference between the groups (P<0.001) before and after veneering. The vertical marginal discrepancy of zirconia frameworks was significantly lower than that of other groups both before and after veneering (P<0.001). Statistical analysis revealed that the veneering process had a significant effect on marginal adaptation (P<0.001).

In implant prostheses with excessive crown height, zirconia had the greatest marginal adaptaion significantly, followed by Ni-Cr. Veneering caused a significant increase in marginal discrepancy of all the materials.

The flexural strength (FS) of a denture base material is of great concern, and many approaches have been used to strengthen the denture acrylic resins. The present study aimed to evaluate the effect of high‑performance polymer (BioHPP) and metal mesh reinforcement on the FS of a heat‑cured poly methyl methacrylate (PMMA) acrylic resin.

This experimental study was done on 30 rectangular specimens (64 mm × 13 mm × 3 mm) of a heat‑cured PMMA resin. The specimens were divided into three groups (n = 10) to be reinforced with either metal mesh or BioHPP mesh; one group was left nonreinforced, serving as the control group. The FS of specimens was assessed through a 3‑point bending test by using a universal testing machine at a crosshead speed of 2 mm/min. Kruskal–Wallis H and Dunn’s post hoc tests were used to compare the FS among the groups (alpha = 0.05).

The FS in the metal‑reinforced group was statistically significantly higher than the two other groups (P < 0.001). However, the FS of the BioHPP‑reinforced samples was not statistically significantly higher than the nonreinforced ones (P = 0.614).

Reinforcing the PMMA with metal mesh significantly enhances its FS while BioHPP has no significant effect on the PMMA FS.

The flexural strength (FS) of a denture base material is of great concern, and many approaches have been used to strengthen the denture acrylic resins. The present study aimed to evaluate the effect of high‑performance polymer (BioHPP) and metal mesh reinforcement on the FS of a heat‑cured poly methyl methacrylate (PMMA) acrylic resin.

This experimental study was done on 30 rectangular specimens (64 mm × 13 mm × 3 mm) of a heat‑cured PMMA resin. The specimens were divided into three groups (n = 10) to be reinforced with either metal mesh or BioHPP mesh; one group was left nonreinforced, serving as the control group. The FS of specimens was assessed through a 3‑point bending test by using a universal testing machine at a crosshead speed of 2 mm/min. Kruskal–Wallis H and Dunn’s post hoc tests were used to compare the FS among the groups (alpha = 0.05).

The FS in the metal‑reinforced group was statistically significantly higher than the two other groups (P < 0.001). However, the FS of the BioHPP‑reinforced samples was not statistically significantly higher than the nonreinforced ones (P = 0.614).

Reinforcing the PMMA with metal mesh significantly enhances its FS while BioHPP has no significant effect on the PMMA FS.

Interim restorations play a critical role in success of restorative treatments. However, they need to preserve their integrity in the oral environment. Microhardness is an important factor in preservation of the integrity of restorations. This study aimed to compare the microhardness of three interim restorative materials namely polyether ether ketone (PEEK), an indirect composite, and polymethyl methacrylate (PMMA).

This in vitro, experimental study evaluated 10 disc-shaped specimens, measuring 15 mm in diameter and 1 mm in thickness, fabricated from PEEK, an indirect composite, and PMMA. The microhardness of the specimens was measured at three points of each specimen using the Vickers’ hardness test before and after water storage for 30 days. Data were analyzed using repeated measure ANOVA, one-way ANOVA and Tukey’s test.

Indirect composite showed maximum microhardness, which was significantly higher than that of the other two materials (P=0.001). However, no significant difference was noted in microhardness of PEEK and PMMA (P=0.33). The microhardness of the materials did not significantly change after 30 days of water storage (P=0.06). Conclusion The microhardness of indirect composite was higher than that of PEEK and PMMA. Also, 30 days of water storage had no significant effect on microhardness of the materials.

Objectives

This paper describes the fabrication of a new porous 3D-printed scaffold composed of polycaprolactone (PCL) and polyether-ether ketone (PEEK) micro-particles for bone tissue engineering (BTE) applications.

In order to improve the compatibility of the reinforcing PEEK powder with polycaprolactone, the PEEK powder was surface-modified by an amino-silane coupling agent. After modification, Fourier-transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC) were used to investigate the chemical reaction between PEEK and silane coupling agent. In order to increase the compressive modulus of the 3D printed PCL scaffold, 10% silane-modified PEEK was incorporated into the PCL polymeric matrix. Scanning electron microscopy (SEM) was used for cell morphology and attachment evaluation.

The results indicated that the silane coupling agent was successfully grafted onto the particle surface. The compressive modulus of PCL scaffold increased by incorporating the silane-modified PEEK, despite having higher porosity, compared with the pure PCL scaffolds. Addition of amino-silane had a positive impact on cell response, and that surface modification led to improved particle dispersion.

In conclusion, it seems that the incorporation of surface-modified PEEK micro-particles into the PCL porous scaffold could enhance its mechanical properties, and may be applicable for the management of large bone defects.Keywords Polyetheretherketone; Polycaprolactone; Amino-propyl-triethoxysilane; Tissue Scaffolds; Printing, Three-Dimensional

The “All‑on‑four” concept for treatment of edentulous arches incorporates four implants that are placed in between mental foramina in the mandible. The prosthetic framework is an important parameter in stress/strain concentration at the implants, prosthesis, and the underlying bone. Materials such as titanium, zirconia, and carbon fibers have been used for fabrication of framework in the past. The aim of this study was to analyze the effect of framework materials in the “All‑on‑four” implant system.

Finite element three‑dimensional (3D) model of edentulous mandible was simulated using a computerized tomographic scan data of an edentulous patient. Threaded implants were replicated along with the abutments using 3D modeling software and the framework was designed and simulated using material properties of titanium, zirconia, and polyetheretherketone (PEEK). Axial and nonaxial load of 200 N was applied at the abutment region of right distal implants. The computer‑generated numerical values were tabulated and analysed by ANSYS software.

Principal strain, von Mises stress and micromotion were assessed in the peri‑implant bone region to evaluate its stress condition. Zirconia framework showed the least stress/strain values at axial and oblique loading. Maximum strain values were seen at the PEEK framework material. Zirconia framework in all models showed the least micromotion/displacement.

The stress distribution pattern at implant–bone interface was influenced by the framework material used. The framework material, loading site, and direction of forces influenced the stresses and displacement at the bone–implant interface.

The aim of this study was to evaluate the micro-shear bond strength of an indirect composite resin to three different types of cores.

In this in-vitro study, 14 blocks (5×5×2 mm) were designed and milled by computer from cobalt-chromium (Co-Cr) alloy, zirconia, and polyether ether ketone (PEEK). Each sample was treated according to the manufacturer’s instructions, and the appropriate primer, and a layer of Crea.lign opaquer were applied on the surface. For micro-shear bond strength test, a plastic tube with an internal diameter of 1 mm and height of 2 mm was placed on each block, and Crea.lign paste was condensed in it. The Crea.lign paste and opaquer were light-cured separately for 180 s, and finally for 360 s. All samples were placed in 37°C distilled water for 24 h and thermocycled for 5000 cycles (5 to 55°C). The microtensile tester machine was used to measure the micro-shear bond strength. The samples were also evaluated for failure modes. Data were analyzed using one-way ANOVA (P<0.05).

According to one-way ANOVA, the mean micro-shear bond strength (MPa) in Co-Cr alloy, zirconia, and PEEK groups was 25.19±5.53, 23.49±5.48, and 20.58±5.68 MPa, respectively. There was no significant difference in micro-shear bond strength of the three groups (P= 0.099). The most frequent mode of failure in all three groups was adhesive, followed by mixed, and cohesive.

Applying the standard procedure, type of core material had no significant effect on the micro-shear bond strength of Crea.lign composite veneer.

Fracture strength is an important factor influencing the clinical long-term success of implant-supported prostheses especially in high stress situations like excessive crown height space (CHS). The purpose of this study was to compare the fracture strength of implant-supported fixed partial dentures (FPDs) with excessive crown height, fabricated from three different materials.
Two implants with corresponding abutments were mounted in a metal model that simulated mandibular second premolar and second molar. Thirty 3-unit frameworks with supportive anatomical design were fabricated using zirconia, nickel-chromium alloy (Ni-Cr), and polyetheretherketone (PEEK) (n=10). After veneering, the CHS was equal to 15mm. Then; samples were axially loaded on the center of pontics until fracture in a universal testing machine at a crosshead speed of 0.5 mm/minute. The failure load data were analyzed by one-way ANOVA and Games-Howell tests at significance level of 0.05.
The mean failure loads for zirconia, Ni-Cr and PEEK restorations were 2086±362N, 5591±1200N and 1430±262N, respectively. There were significant differences in the mean failure loads of the three groups (P According to the findings of this study, all implant supported three-unit FPDs fabricated of zirconia, metal ceramic and PEEK materials are capable to withstand bite force (even para-functions) in the molar region with excessive CHS.