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.

Description of Poly(aryl-ether-ketone) Materials (PAEKs), Polyetheretherketone (PEEK) and Polyetherketoneketone (PEKK) for Application as a Dental Material: A Materials Science Review.

Poly(aryl-ether-ketone) materials (PAEKs), a class of high-performance polymers comprised of polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), have attracted interest in standard dental procedures due to their inherent characteristics in terms of mechanical and biological properties. Polyetheretherketone (PEEK) is a restorative dental material widely used for prosthetic frameworks due to its superior physical, mechanical, aesthetic, and handling features. Meanwhile, polyetherketoneketone (PEKK) is a semi-crystalline thermoplastic embraced in the additive manufacturing market. In the present review study, a new way to fabricate high-performance polymers, particularly PEEK and PEKK, is demonstrated using additive manufacturing digital dental technology, or 3-dimensional (3D) printing. The focus in this literature review will encompass an investigation of the chemical, mechanical, and biological properties of HPPs, particularly PEEK and PEKK, along with their application particularly in dentistry. High-performance polymers have gained popularity in denture prosthesis in advance dentistry due to their flexibility in terms of manufacturing and the growing interest in utilizing additive manufacturing in denture fabrication. Further, this review also explores the literature regarding the properties of high-performance polymers (HPP) compared to previous reported polymers in terms of the dental material along with the current advancement of the digital designing and manufacturing.

Metallic Artifact Reduction in Midfacial CT Scans Using Patient-Specific Polymer Implants Enhances Image Quality.

Midfacial reconstruction after tumor resection surgery is commonly conducted by using autologous bone grafts or alloplastic implants. Titanium is the most frequently used osteosynthesis material in these cases but causes disturbing metallic artifacts in CT imaging. The purpose of this experimental study was to evaluate whether the use of midfacial polymer implants reduces metallic artifacts in CT imaging to improve image quality. Zygomatic titanium (n = 1) and polymer (n = 12) implants were successively implanted in a human skull specimen. Implants were analyzed for their effect on Hounsfield Unit values (streak artifacts) and virtual growth in CT images (blooming artifacts) as well as image quality. Multi-factorial ANOVA and Bonferroni's post hoc test were used. Titanium (173.7 HU; SD ± 5.1) and hydroxyapatite containing polymers (155.3 HU; SD ± 5.9) were associated with significantly more streak artifacts compared to all other polymer materials. There was no significant difference in blooming artifacts between materials. The metallic artifact reduction algorithm showed no significant difference. Image quality was slightly better for polymer implants compared to titanium. Personalized polymer implants for midfacial reconstruction significantly reduce metallic artifacts in CT imaging which improves image quality. Hence, postoperative radiation therapy planning and radiological tumor aftercare around the implants are facilitated.

Effect of Surface Treatments of Polyetherketoneketone as a Post Material on Shear Bond Strength to Root Dentin using Two Types of Resin Cement.

PURPOSE: This study investigated the effects of mechanical and chemical pretreatment of polyetherketoneketone (PEKK) on shear bond strength (SBS) to root dentin using two types of resin cement. MATERIALS AND METHODS: A total of 100 PEKK specimens were prepared and polished. Sixty specimens were mechanically treated by sandblasting (50-µm Al2O3 for 10 s at 0.2-0.25 MPa), and the remaining 40 were untreated. Self-adhesive resin cement and conventional resin cement were used. PEKK specimens bonded to root dentin using self-adhesive resin cement were classified into three groups by pretreatment method: (1) untreated PEKK, (2) mechanical pretreatment (sandblasted PEKK), and (3) both mechanical and chemical pretreatment (PEKK sandblasting as well as application of Scotchbond Universal; 3M Oral Care). Conventional resin cement was pretreated following the same steps (1-3) as those followed for self-adhesive specimens. Each group included 10 specimens. PEKK specimens after surface treatments were examined using SEM. SBS tests were performed using a universal testing machine, and data were statistically analyzed using one-way ANOVA and Tukey's multiple comparison test (p < 0.05). RESULTS: No significant difference was observed between cements with and without sandblasting. However, self-adhesive specimens with both mechanical and chemical pretreatments demonstrated higher SBS than other cements with or without pretreatment. CONCLUSION: Mechanical pretreatment by sandblasting did not improve the PEKK-root dentin SBS. However, combined mechanical (sandblasting) and chemical pretreatment (ScotchBond Universal) significantly improved the SBS between the PEKK and root dentin.

A preliminary study on surface bioactivation of polyaryletherketone by UV-grafting with PolyNaSS: influence on osteogenic and antibacterial activities.

Polyaryletherketone (PAEK) has good biocompatibility and mechanical properties and thus may have great potential in the fields of reparative medicine and bone intervention. In this study, the key representative PAEKs, polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), were modified by UV grafting with sodium polystyrene sulfonate (polyNaSS) to improve their biocompatibility. Toluidine blue staining and Fourier transform infrared spectroscopic analyses showed that sulfonic acid groups were successfully introduced into PAEK, and the hydrophilicity and protein adsorption capacity of the materials were enhanced in a concentration-dependent manner. The effects of the grafted polyNaSS on osteoinduction and antibacterial properties of PAEK were analyzed in detail. We found that polyNaSS enhanced the viability, alkaline phosphatase activity, calcium mineral deposition, and levels of expression of osteoblast-related genes and proteins of adherent human umbilical cord Wharton's jelly-derived mesenchymal stem cells. In addition, when Escherichia coli, Staphylococcus aureus and Porphyromonas gingivalis were incubated with the materials, bacterial colony counting revealed that grafting of polyNaSS onto PAEK led to more potent inhibition of bacterial adhesion, and polyNaSS-grafted PEKK had stronger antibacterial performance than did polyNaSS-grafted PEEK fabricated under the same grafting conditions. These data show that polyNaSS-grafted PAEK, and particularly polyNaSS-grafted PEKK, may be useful as orthopedic and dental implant materials.

Evaluation of static fracture resistances and patterns of pulpless tooth restored with poly-ether-ketone-ketone (PEKK) post / 대한치과보철학회지

PURPOSE: The purpose of present study was to investigate fracture strength and mode of failure of endodontically treated teeth restored with metal cast post-core system, prefabricated fiber post system, and newly introduced polyetherketoneketone (PEKK) post-core system. MATERIALS AND METHODS: A total of 21 mandibular premolar were randomly grouped into 3 groups of 7 each according to the post material. Group A was for metal cast post core; Group B for prefabricated glass fiber post and resin core; and Group C for milled PEKK post cores. All specimens were restored with metal crown. The fracture strength of each specimen was measured by applying a static load of 135-degree to the tooth at 2 mm/min crosshead speed using a universal testing machine. After the fracture strength measurement, the mode of failure was observed. The results were analyzed using Kruscal-Wallis test and post hoc Mann-Whitney U test at confidence interval α = .05. RESULTS: Fracture resistance of PEKK post core was lower than those of cast metal post and fiber reinforced post with composite resin core. In the aspect of fracture mode most of the root fracture occurred in the metal post core, whereas the post detachment occurred mainly in the fiber reinforced post. In the case of PEKK post core, teeth and post were fractured together. CONCLUSION: It is necessary to select appropriate materials of post for extensively damaged teeth restoration and clinical application of the PEKK post seems to require more research on improvement of strength.

Effect of non-thermal plasma on the shear bond strength of resin cements to Polyetherketoneketone (PEKK).

PURPOSE: This study aimed to assess the effect of non-thermal plasma on the shear bond strength of resin cements to polyetherketoneketone (PEKK) in comparison to other surface treatment methods. MATERIALS AND METHODS: Eighty PEKK discs were subjected to different surface treatments: (1) Untreated (UT); (2) Non-thermal plasma (NTP); (3) Sandblasting with 50 µm Al2O3 particles (SB); and (4) Sandblasting + Non-thermal plasma (SB+NTP). After each surface treatment, the contact angle was measured. Surface conditioning with Visio.Link was applied in all groups after pre-treatment. RelyX Unicem resin cement was bonded onto the PEKK specimens. After fabrication of the specimens, half of each group (n=10) was initially tested, while the other half was subjected to thermocycling (5℃ to 55℃ at 10,000 cycles). Shear bond strength (SBS) testing was performed using a universal testing machine, and failure modes were assessed using stereomicroscopy. The SBS results were analyzed statistically using one-way ANOVA followed by Tukey's post hoc test. Independent t-test was used to examine the effect of thermocycling (P<.05). RESULTS: The highest SBS values with or without thermocycling were observed with PEKK specimens that were treated with SB+NTP followed by the SB group. The lowest SBS results were observed in the UT groups. CONCLUSION: The shear bond strength between PEKK and resin cements was improved using non-thermal plasma treatment in combination with sandblasting.

Comparison of the Microtensile Bond Strength of a Polyetherketoneketone (PEKK) Tooth Post Cemented with Various Surface Treatments and Various Resin Cements.

The aim of this in-vitro research was to evaluate the microtensile bond strength in the newly introduced PEKK tooth post with various surface treatments and resin cements. A fiberglass tooth post was included in order to compare it with PEKK as a possible post material. The microtensile bond strengths of the fiberglass post (FRC Postec Plus) and the PEKK post (Pekkton®) were tested using three kinds of self-adhesive resin cements (G-CEM LinkAce, Multilink Speed, and RelyX U200) and one self-etching resin cement (PANAVIA F2.0). The surface treatments of the fiberglass posts were processed according to the manufacturer's recommendations (F1, application of 37% phosphoric acid etching gel and silanization). For the PEKK post groups, various surface treatments were performed like no surface treatment (P1), sandblasting (P2), silica-coating and silanization (P3), and sandblasting with a composite primer (P4). In the surface treatment, PEKK posts with silica coating and silane treatment (P3) showed a significantly higher microtensile bond strength (mean MPa: 18.09, p < 0.05). The highest microtensile bond strength was shown when the PEKK posts were treated with a silica coating and silane treatment and cemented with RelyX U200 (mean MPa: 22.22). The PEKK posts with surface treatments of silica-coating and silanization or sandblasting displayed superior microtensile bond strengths (mean MPa: 18.09 and 16.25, respectively) compared to the conventional fiberglass posts (mean MPa: 14.93, p < 0.05).

Effect of non-thermal plasma on the shear bond strength of resin cements to Polyetherketoneketone (PEKK)

PURPOSE: This study aimed to assess the effect of non-thermal plasma on the shear bond strength of resin cements to polyetherketoneketone (PEKK) in comparison to other surface treatment methods. MATERIALS AND METHODS: Eighty PEKK discs were subjected to different surface treatments: (1) Untreated (UT); (2) Non-thermal plasma (NTP); (3) Sandblasting with 50 µm Al2O3 particles (SB); and (4) Sandblasting + Non-thermal plasma (SB+NTP). After each surface treatment, the contact angle was measured. Surface conditioning with Visio.Link was applied in all groups after pre-treatment. RelyX Unicem resin cement was bonded onto the PEKK specimens. After fabrication of the specimens, half of each group (n=10) was initially tested, while the other half was subjected to thermocycling (5℃ to 55℃ at 10,000 cycles). Shear bond strength (SBS) testing was performed using a universal testing machine, and failure modes were assessed using stereomicroscopy. The SBS results were analyzed statistically using one-way ANOVA followed by Tukey's post hoc test. Independent t-test was used to examine the effect of thermocycling (P < .05). RESULTS: The highest SBS values with or without thermocycling were observed with PEKK specimens that were treated with SB+NTP followed by the SB group. The lowest SBS results were observed in the UT groups. CONCLUSION: The shear bond strength between PEKK and resin cements was improved using non-thermal plasma treatment in combination with sandblasting.