Polyetheretherketone Framework Research Articles

Mechanical Response of PEKK and PEEK As Frameworks for Implant-Supported Full-Arch Fixed Dental Prosthesis: 3D Finite Element Analysis.

Objective Polymeric framework represent an innovative approach for implant-supported dental prostheses. However, the mechanical response of ultra-high performance polymers as frameworks for full-arch prostheses under the “all-on-four concept” remains unclear. The present study applied finite element analysis to examine the behavior of polyetherketoneketone (PEKK) and polyetheretherketone (PEEK) prosthetic frameworks. Materials and Methods A three-dimensional maxillary model received four axially positioned morse-taper implants, over which a polymeric bar was simulated. The full-arch prosthesis was created from a previously reported database model, and the imported geometries were divided into a mesh composed of nodes and tetrahedral elements in the analysis software. The materials were assumed as isotropic, elastic, and homogeneous, and all contacts were considered bonded. A normal load (500 N magnitude) was applied at the occlusal surface of the first left molar after the model was fixed at the base of the cortical bone. The microstrain and von-Mises stress were selected as criteria for analysis. Results Similarities in the mechanical response were observed in both framework for the peri-implant tissue, as well as for stress generated in the implants (263–264 MPa) and abutments (274–273 MPa). The prosthetic screw and prosthetic base concentrated more stress with PEEK (211 and 58 MPa, respectively) than with PEKK (192 and 49 MPa), while the prosthetic framework showed the opposite behavior (59 MPa for PEEK and 67 MPa for PEKK). Conclusion The main differences related to the mechanical behavior of PEKK and PEEK frameworks for full-arch prostheses under the “all-on-four concept” were reflected in the prosthetic screw and the acrylic base. The superior shock absorbance of PEKK resulted in a lower stress concentration on the prosthetic screw and prosthetic base. This would clinically represent a lower fracture risk on the acrylic base and screw loosening. Conversely, lower stress concentration was observed on PEEK frameworks.

Comparison of two adhesive systems of various polyetheretherketone (PEEK) composites on the shear bond strength

Aim: In this in vitro study, the effect of two adhesive systems applied to surfaces of different polyether-ether-ketone (PEEK) composites on the shear bond strength (SBS) of a composite resin was compared.
 Methodology: Eighty PEEK specimens were divided into four groups (n=20): Unfilled PEEK (UF), carbon-fiber-reinforced PEEK (CFR), glass-fiber-reinforced PEEK (GFR), and ceramic-reinforced PEEK (CR). Each group was further divided into two subgroups (n=10): Visio.link (VL) and Single Bond Universal (SB). The specimens with 8-mm diameter and 5-mm thickness were prepared. SBS was examined using a universal testing machine. Results were statistically analyzed by multivariate analysis of variance and Tukey’s post-hoc test. Failure modes were analyzed using a stereomicroscope at 20× magnification. Surface properties were examined by scanning electron microscopy. The surface properties of the specimens were examined by scanning electron microscopy (SEM). 
 Results: Effect of different PEEK and adhesive systems on SBS was found to be statistically significant (p<0.05). SBS values for CFR-VL and UF-VL groups were statistically more significant than those for CFR-SB and UF-SB groups (p=0.001). SBS values for the GFR-VL group were statistically more significant than that for the UF-VL group (p=0.001). SBS values for the CF-SB group were statistically more significant than those for CFR-SB and CFR-SB groups (p=0.001). Failure modes were examined using a stereomicroscope at 20× magnification, and adhesive and mixed failure modes were observed.
 Conclusion: PEEK composites with different contents and properties can be used in fixed prosthetic restorations. However, additional experimental and clinical studies are required to investigate different PEEK frameworks and composite veneers.
 
 How to cite this article: Demirci F, Tekin S. Comparison of two adhesive systems of various polyetheretherketone (PEEK) composites on the shear bond strength. Int Dent Res 2021;11(2):54-61. https://doi.org/10.5577/intdentres.2021.vol11.no2.1
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Trueness and marginal fit of implant-supported complete-arch fixed prosthesis frameworks made of high-performance polymers and titanium: An explorative in-vitro study

PurposeTo investigate the trueness and marginal fit of computer-aided design–computer-aided manufactured (CAD-CAM) complete-arch implant-supported screw-retained fixed prosthesis (CAISFP) made of polyetheretherketone (PEEK), polyetherketoneketone (PEKK) and titanium (Ti) Material and methodsA typodont model with four implants, their multiunit abutments (MUAs), and MUA scanbodies were digitized by using a laboratory scanner. The generated CAD was used to mill CAISFP frameworks in Ti, PEEK, or PEKK (each n = 10). The frameworks were digitized with an industrial light scanner to superimpose resulting standard tessellation language (STL) file with the CAD file. Deviations at five points at the abutment-framework interface of each of the four abutment sites (1:left first molar, 2:left canine, 3:right canine, 4:right first molar sites) were calculated (trueness). Marginal gaps were measured using the triple scan technique. A nonparametric repeated measures ANOVA by Brunner and Puri with factors being abutment location and material was performed to assess the mean deviations for trueness and mean marginal gaps, followed by Mann-Whitney or exact Wilcoxon Signed-Rank tests (alpha=.05). ResultsMaterial type significantly affected the trueness (p<0.0001). PEEK had the lowest deviations (0.039 +/-0.01mm) followed by PEKK (0,049 +/-0.009mm), and Ti (0.074 +/-0.011mm). For marginal gaps, only abutment location's effect was significant (p = 0.003). Within PEKK, gaps at abutment 4 were significantly larger, compared with abutments 2 (p = 0.04) and 3 (p = 0.02). ConclusionsThe trueness of PEEK, PEKK, and Ti frameworks was different after milled. PEEK had the highest trueness. However, the marginal fit of the frameworks was similar and smaller than 90 µm in average. Clinical RelevancePEEK, PEKK, and Ti complete-arch frameworks had clinically acceptable gaps and may therefore be recommended when their fit is considered. Higher trueness after milling did not result in better marginal fit.

Removable Partial Dentures with Polyetheretherketone Framework: The Influence on Residual Ridge Stability.

To provide, in a clinicalcase-control study, 1-year data on edentulous residual ridge dimensional changes for patients wearing removable partial dentures (RPD)with Polyetheretherketone (PEEK) framework, fabricated with a digital workflow, and a control group of untreated patients. Tenpatients were treated withPEEK RPD, and six controls were studied.Intraoral scans at baseline (T0) and after a median period of 1 year (T1) weresuperimposed, trimmed, and reoriented (T0r and T1r),moved to a metrology software, and realigned. A curve (C0) was then traced on T0r, along the residual ridge crest; its projection (C1) on T1r was obtained. The mean distance C0-C1was the dependent variable of interest and represented the 1-year changes in the height of the edentulous ridge. In addition, mean 3D distance between T0 and T1 at each edentulous area was measured. Differences in these outcomes measured between RPD treated and control groups were statistically assessed. Twenty-six and 14 edentulous areas were investigated in the RPD treated and control groups, respectively. No significant differences were observed forpotentially confounding variables, such as median follow-up time (12.5 vs. 13 months, respectively), thealignment accuracy between T0r and T1r (0.01 mm vs. 0 mm, respectively), the median number of remaining teeth (6 vs. 8.5, respectively), and the median length of edentulous areas (25.5 mm vs. 22.8 mm, respectively). For the outcomes of interest, no statistically significant difference was seen in the mean distance between C0 and C1 (i.e., changes in residual ridge height: -0.39 ± 0.52 mm vs. -0.52 ± 0.54 mm, respectively) or in the mean 3D distance at corresponding points of the denture bearing areas (-0.3 ± 0.46 mm vs. -0.4 ± 0.35, respectively). Although 1 year is a relatively short observation period, this clinical study shows that there are no short-term differences in edentulous residual ridge height and overall dimensions between patients wearing PEEK RPD, fabricated with a digital workflow, and controls without an RPD.

Cast-free fabrication of a digital removable partial denture with a polyetheretherketone framework

Digital workflows for removable partial dentures have enabled new machinable framework materials, including polyetheretherketone (PEEK). In addition, all denture components can be designed and manufactured digitally. Nonetheless, physical casts are still required for assembly of the components. The adoption of a cast-free fabrication procedure may enhance benefits, including a reduced number of procedures, faster processing, and reduced material waste. The purpose of this technical report was to demonstrate a workflow for the fabrication of a removable partial denture with a PEEK framework, milled teeth, and milled flanges, which uses intraoral scanning and no physical casts.

Digital fabrication of a maxillary obturator prosthesis by using a 3-dimensionally–printed polyetheretherketone framework

The digital fabrication of a maxillary obturator with a 3D-printed polyetheretherketone (PEEK) framework is described. Digital oral data were scanned for the computer-aided design (CAD) of the framework and the 3D printing of a preliminary resin cast. The framework was accurately printed from a PEEK filament material. A secondary impression was made to fabricate the definitive cast. The PEEK framework exhibited precise fit, excellent retention, and reduced weight compared with a typical metal framework.

Clinical Application of PEEK as a Provisional Fixed Dental Prosthesis Retained by Reciprocated Guide Surfaces of Healing Abutments During Dental Implant Treatment.

The aim of this study was to evaluate the clinical use of a high-performance polymer, polyether ether ketone (PEEK), as a material for use in provisional fixed dental prostheses (FDPs) that can be retained by reciprocated guide surfaces of hexagonal-shaped healing abutments during dental implant treatment. Patients requiring teeth replacement with dental implants for partially and fully edentulous cases in the maxilla and mandible were included. The provisional FDP was fabricated with hex castable copings and PEEK granules using the lost wax technique. The common path of insertion was established by reducing the coping that is in obstruction to the healing abutment. Retention was provided by the reciprocated guide surfaces of multiple hexagonal-shaped healing abutments. Twenty-three custom provisional PEEK FDPs supported by 166 implants in 20 partially and fully edentulous patients were provided during the treatment period. The mean functional periods of the provisional PEEK FDPs for maxillary and mandibular cases were 6.95 ± 0.84 months and 1.90 ± 0.62 months, respectively. All provisional PEEK FDPs functioned as intended for the entire treatment period. There were a total of 10 complications: 4 cases had resin and denture veneers debond from the PEEK framework; 3 partially edentulous cases required supplementary screw retention; and 3 implants in separate cases did not osseointegrate, requiring extended use of the provisional prosthesis. Two provisional mandibular PEEK FDPs with prolonged usage (over 2 years) were excluded from calculations. No fracture of the PEEK framework was observed. The results from this study suggest that PEEK can be a suitable material for use in provisional FDPs during dental implant treatment. Prosthetic complications were frequent but were resolved intraorally. The reciprocated guide surfaces of multiple hexagonal-shaped healing abutments can provide adequate retention and resistance for edentulous cases during the implant treatment period. However, in partially edentulous cases, a prosthesis without cross-arch stabilization supplementary screw retention was required.

Three-dimensional finite element analysis of different framework materials in implant-supported fixed mandibular prosthesis

Objective: To evaluate the biomechanical behaviors of different framework materials in implant-supported fixed mandibular prosthesis using three-dimensional finite element analysis. Methods: A model of implant-supported fixed mandibular prosthesis was established. The simulations were divided into six groups according to the framework materials: pure titanium, cobalt-chromium alloy, gold alloy, zirconia, polyether ether ketone (PEEK) and carbon fiber-reinforced PEEK. An oblique load of 300 N with a 75° angle to the occlusal plane was applied from the lingual side on the buccal cusps of the two premolars and the first molar teeth. The stresses on implants, surrounding bones and frameworks were analyzed and compared among the framework materials both quantitatively and qualitatively. Results: In implant-supported fixed mandibular prosthesis model, the highest stresses were located around the neck of the implants and cortical bone during oblique loading among six designs. In addition, the stresses were concentrated on the buccal and distal cortical bone around the implants of the posterior region. Stress values of implants and cortical bones from low to high were as follows: zirconia, cobalt-chromium alloy, pure titanium, gold alloy, carbon fiber-reinforced PEEK, PEEK. The von Mises stress values of implant and cortical bone in the first molar site of PEEK framework material were 44.96 and 29.13 MPa, while the von Mises stress values of implant and cortical bone in the first molar site of zirconia framework material were 21.29 and 17.79 MPa. The zirconia and medal framework materials were more advantageous in stress distribution around implants than PEEK framework material. Conclusions: In implant-supported fixed mandibular prostheses, biomechanical analysis showed that the zirconia and medal framework materials were more advantageous in stress distribution around implants than PEEK framework materials.

Finite element analysis of the effect of framework materials at the bone–implant interface in the all-on-four implant system

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.

Digital fabrication of an adult speech aid prosthesis by using a 3-dimensionally printed polyetheretherketone framework

This article presents a digital fabrication method for a speech aid prosthesis by using a 3D-printed polyetheretherketone (PEEK) framework. The computer-aided design (CAD) of the speech aid prosthesis framework was based on oral scan data. The framework was printed with PEEK filament material supplemented with nanoTiO2 powder by fused deposition modeling (FDM). A resin preliminary cast was 3D printed, and an altered cast technique was adopted to fabricate the definitive cast. The PEEK framework exhibited precise fit, toothlike color, excellent mechanical properties, and reduced weight as compared with a typical metal framework. This technique describes the successful clinical application of 3D-printed PEEK material for the fabrication of an adult speech aid prosthesis.

Hybrid Polyetheretherketone (PEEK)-Acrylic Resin Prostheses and the All-on-4 Concept: A Full-Arch Implant-Supported Fixed Solution with 3 Years of Follow-Up.

Background: The aim of this three-year prospective study was to examine the outcome of a solution for full-arch rehabilitation through a fixed implant-supported hybrid prosthesis (polyetheretherketone (PEEK)-acrylic resin) used in conjunction with the All-on-4 concept. Methods: Thirty-seven patients (29 females, 8 males), with an age range of 38 to 78 years (average: 59.8 years) were rehabilitated with 49 full-arch implant-supported prostheses (12 maxillary rehabilitations, 13 mandibular rehabilitations and 12 bimaxillary rehabilitations). The primary outcome measure was prosthetic survival. Secondary outcome measures were marginal bone loss, plaque and bleeding scores, veneer adhesion issues, biological complications, mechanical complications, and the patients’ subjective evaluation. Results: There were two patients (maxillary rehabilitations) lost to follow-up, while one patient withdrew (maxillary rehabilitation). One patient with bimaxillary rehabilitation fractured the mandibular PEEK framework, rendering a 98% prosthetic survival rate. Implant survival was 100%. Average (standard deviation) marginal bone loss at 3-years was 0.40 mm (0.73 mm). Veneer adhesion was the only technical complication (n = 8 patients), resolved for all patients. Nine patients (n = 11 prostheses) experienced mechanical complications (all resolved): fracture of acrylic resin crowns (n = 3 patients), prosthetic and abutment screw loosening (n = 4 patients and 3 patients, respectively), abutment wearing (n = 1 patient). One patient experienced a biological complication (peri-implant pathology), resolved through non-surgical therapy. A 90% satisfaction rate was registered for the patients’ subjective evaluation. Conclusions: Based on the results, the three-year outcome suggests the proposed rehabilitation solution as a legitimate treatment option, providing a potential shock-absorbing alternative that could benefit the implant biological outcome.

A Pilot Randomized Controlled Crossover Trial Comparing Early OHRQoL Outcomes of Cobalt-Chromium Versus PEEK Removable Partial Denture Frameworks.

To investigate differences in the performance of polyether ether ketone (PEEK) frameworks vs traditional metal frameworks for removable partial dentures (RPDs) in terms of OHRQoL, patient preference, periodontal indices, and denture satistfaction. Twenty-six participants were recruited to a randomized controlled crossover trial and were provided with either PEEK or cobalt-chromium (Co-Cr) RPDs. After 4 weeks, the participants were provided with the other RPD. After both 4-week testing periods, the participants chose their preferred RPD and were followed up again at 6 months and 1 year. The primary outcome measure was effect on OHIP-20 score, which was compared among patients using repeated measures ANOVA. Secondary outcomes were participant preference compared using chi-square analysis; Plaque Index and Gingival Bleeding Index (PI and GBI, respectively) compared using repeated measures ANOVA; and McGill Denture Satisfaction Questionnaire (MDSQ) score compared between the two 4-week follow-ups using paired-samples t test. Both Co-Cr and PEEK frameworks resulted in a significant improvement in OHIP-20 score (P < .001), but the material was not a significant factor in changes over 1 year (P = .87). There were no statistically significant differences in participant preference at 1 year (P = .491), nor between RPD materials in their effect on GBI (P = .476), PI (P = .967), or MDSQ (P = .368). Both Co-Cr and PEEK RPDs improved OHRQoL to a degree greater than the minimum clinically important difference at 4 weeks, 6 months, and 1 year compared to baseline. No significant preference or improved denture satisfaction score was seen for either material. PEEK frameworks seem to be associated with similar degrees of periodontal effects as Co-Cr frameworks.

Comparative Evaluation of Stress Distribution of Zirconia, Cobalt Chromium and Polyetheretherketone (PEEK) Framework Material on an Atrophic Maxilla in All-on-6 Implant Treatment Concepts – A 3 Dimensional Finite Element Analysis

Aims: To evaluate the effect of prosthetic framework material on the stress distribution patterns of All-on-Six implant support system under vertical and oblique loading. Methods and Material: The CBCT images of the maxilla were converted to stereo lithography file. HYPERMESH software system was accustomed to convert 3D pictures into numerical models. Geometric model of short implant and zirconia, cobalt chromium and polyetheretherketone (PEEK) framework material were created using SOLID EDGE software and were then be inserted in the bone model. A total of six models were constructed with three different types of framework materials with four implants in the anterior maxilla region and two distal short implants and mini-abutments. The prosthetic frameworks were made with 14 teeth (central incisors to second molar bilaterally). The models were transferred through the solid works simulation program for finite element analysis and stress distribution investigation. An oblique load of 150N with 300 inclination in the linguo-buccal direction and vertical loads parallel to long axis of the tooth with 100 N magnitude were applied unilaterally on the posterior teeth of each framework. Results: Principal and Von misses stress in PEEK framework were least when compared to stresses in zirconia and cobalt chromium framework on vertical loading and oblique loading. Conclusions: PEEK as a framework material had least stress for the All on Six implant treatment concepts on vertical and oblique forces than zirconia and cobalt chromium framework.

A three-dimensional finite element analysis of mechanical function for 4 removable partial denture designs with 3 framework materials: CoCr, Ti-6Al-4V alloy and PEEK

Polyetheretherketone (PEEK) is a new material used for the frameworks of removable partial dentures (RPD). The questions whether the PEEK framework has similar stress distribution on oral tissue and displacement under masticatory forces as titanium alloy (Ti-6Al-4V) or cobalt-chromium alloy (CoCr) remain unclear and worth exploring. A patient’s intraoral data were obtained via CBCT and master model scan. Four RPDs were designed by 3Shape dental system, and the models were processed by three-dimensional finite element analysis. Among three materials tested, PEEK has the lowest maximum von Mises stress (VMS) on periodontal ligament (PDL), the greatest maximum VMS on mucosa, the maximum displacement on free-end of framework, and the lowest maximum VMS on framework. Results suggested that PEEK framework has a good protective effect on PDL, suggesting applications for patients with poor periodontal conditions. However, the maximum displacement of the free-end under masticatory force is not conducive for denture stability, along with large stress on the mucosa indicate that PEEK is unsuitable for patients with more loss of posterior teeth with free-end edentulism.

Comparison of Marginal Adaptation of Different Implant-Supported Metal-Free Frameworks Before and After Cementation.

To compare marginal adaptation before and after cementation of implant-supported metal-free frameworks fabricated from zirconia, polyetheretherketone (PEEK), or composite. Thirty-six CAD/CAM frameworks were constructed from zirconia, PEEK, or composite (n = 12 per material). Marginal gap was measured using a Video Measuring Machine (VMM) system, and repeated-measures analysis of variance was employed for data analysis (P < .05). Absolute marginal discrepancies of all frameworks decreased significantly after cementation (P < .05). Zirconia and composite frameworks' marginal gap values were clinically acceptable, while PEEK frameworks were judged as being on the borderline of acceptability. Zirconia demonstrated significantly better marginal adaptation than PEEK (P < .05). Zirconia showed the best marginal adaptation of the three tested metal-free frameworks.

Bacterial leakage and bending moments of screw-retained, composite-veneered PEEK implant crowns

Due to its elastic modulus close to bone, the high-performance material PEEK (polyetheretherketone) represents an interesting material for implant-supported dental prostheses. Besides a damping effect of masticatory forces, it might have a sealing effect against bacterial leakage of the implant-abutment interface (IAI). So far, PEEK has only been used for provisional implant crowns. Therefore, the aim of the study was the evaluation of the bacterial tightness of screw-retained PEEK crowns on titanium implants with conical IAI during masticatory simulation and subsequent bending moment testing.Ten screw-retained implant crowns in the shape of an upper central incisor consisting of a PEEK crown framework veneered with composite were connected to NobelActive RP titanium implants (4.3 × 11.5 mm, Nobel Biocare AB, Göteborg, Sweden) with a tightening torque of 15 Ncm.Prior to tightening, the interior of the implant was inoculated with a bacterial suspension of Enterococcus faecium. The specimens were overmolded with indicating agar (Kanamycin-Aesculin-Azid-Agar (KAAA), Oxoid Limited, Basingstoke United Kingdom), that turns black in contact with E. faecium. The specimens were subjected to a cyclic masticatory simulation whereby a force of 50 N cm was applied at an angle of 30° to the implant axis for 1.2 million cycles. Afterwards, the specimens were subjected to a static loading test according to ISO 14801:2007 to determine the bending moment.During masticatory simulation neither a loosening of the implant screws nor any damage to the veneer or the PEEK framework occurred. Furthermore, no bacterial leakage could be observed in any of the specimens. The average maximum bending moment was measured at 352.13 ± 48.96 N cm.Regarding masticatory forces, PEEK implant crowns seem to be applicable as definitive implant-supported restorations. Furthermore, the bacterial tightness of the IAI of screw-retained one-piece PEEK implant crowns is advantageous compared to superstructures of conventional materials. Further studies are necessary to substantiate the clinical significance of these findings.

Short-term report of an ongoing prospective cohort study evaluating the outcome of full-arch implant-supported fixed hybrid polyetheretherketone-acrylic resin prostheses and the All-on-Four concept.

More research is needed on the study of new materials for fixed prosthetic implant-supported rehabilitations. The purpose of this study was to report the short-term outcome of full-arch implant-supported fixed hybrid polyetheretherketone (PEEK)-acrylic resin prostheses and the all-on-four concept. This prospective cohort clinical study included 37 patients (29 women, eight men) with an average age of 60 years (range: 38-78 years) with 49 full-arch hybrid PEEK-acrylic resin prosthesis supported by implants through the all-on-four concept. Primary outcome measures were prosthetic survival. Two patients with two maxillary prostheses were lost to follow-up. One patient with a double full-arch rehabilitation fractured the mandibular PEEK framework, rendering a 98% prosthetic survival rate. No implants were lost. The average (SD) marginal bone remodeling after 1 year of follow-up was 0.37 mm (0.58 mm). Technical complications concerning the veneer adhesion occurred in six patients and were resolved in all patients (with exception of the patient with prosthetic failure) through the creation of mechanical retentions and changing the bonding primer. Mechanical complications occurred in three patients and five prostheses consisting in prosthetic screw loosening (n = 2 patients) and fracture of the acrylic resin teeth (the patient with a prosthetic failure). Within the limitations of this study, the results suggest that hybrid polymer (PEEK)-acrylic resin prostheses supported by implants for full-arch rehabilitation may represent a valid treatment option, still requiring longer-term validation.

Effect of material on stress transmission to the supporting structures in Kennedy Class I restored by Telescopic-retained Removable Partial Denture. (Strain Gauge Study)

Objectives: The aim of this in-vitro study was to compare the stresses transmitted to the abutments in mandibular Kennedy class I restored with telescopic-retained removable partial denture (RPD) made from two different materials; PolyEther Ether Ketone (PEEK) and Co-Cr alloy. Materials and Methods: One mandibular model representing Kennedy class I, with second premolars as the last standing abutments, was fabricated using epoxy resin. Poly Vinyl Siloxane (PVS) impression material was used to simulate the mucosa and the periodontal ligament. The acrylic first and second premolar teeth bilaterally were prepared to receive primary telescopic copings. The latter and two removable partial denture (RPD) frameworks were fabricated out of PEEK and Co-Cr alloy. The 2 frameworks were then processed into fully finished RPDs using heat cured acrylic resin and acrylic teeth following the conventional techniques. Four strain gauges were installed in the epoxy resin model 1 mm mesial to the socket of the 1st premolar and 1 mm distal to that of the 2nd premolar, on the right and left sides respectively; channel 1, 2, 3 and 4. A load of 100 N was applied to the area of the first molar unilaterally on the right side and then bilaterally. The same procedure was repeated six times. Data on stresses were then collected, tabulated and statistically analyzed using one-way ANOVA and Tukey HSD Test (P≤0.05). Results: In the unilateral loading condition, the highest compressive micro-strains were recorded at channel 3 for the Co-Cr alloy-group (-40±3.16 µm/m). While the least compressive micro-strains were recorded at channel 3 for the PEEK-group (-10±3.16 µm/m). The highest tensile micro-strains were recorded at channel 2 for the PEEK-group (540±10 µm/m). While the least tensile micro-strains were recorded at channel 4 for the PEEK-group (15±4.47 µm/m). In the bilateral loading condition, the highest tensile micro-strains were recorded at channel 2 for the PEEK-group (355±11.83 µm/m). While the least tensile micro-strains were recorded at the same channel for the Co-Cr alloy-group (50±3.16 µm/m). The highest compressive micro-strains were recorded at channel 1 for the PEEK-group (-170±11.4 µm/m). While the least compressive micro-strains were recorded at channel 3 for the Co-Cr alloy-group (-95±8.94 µm/m). Conclusions: The distal abutments always receive the highest stresses, regardless of the loading conditions and the materials from which the prosthesis was fabricated. Telescopic-retained RPD with metallic frameworks generate less strain to the supporting structures in Kennedy Class I compared to those with PEEK frameworks. The bilaterally applied force resulted in more favorable stress distribution pattern when compared to the unilateral one.

The all-on-4 modified polyetheretherketone treatment approach: A clinical report

A modified polyetheretherketone (PEEK) implant framework material in combination with prefabricated high-impact poly(methyl methacrylate) (PMMA) veneers was used as an alternative material for the fabrication of a complete maxillary arch implant-supported fixed restoration. The elastic performance of the PEEK framework (elastic modulus of 4 GPa) combined with PMMA veneers may reduce the occlusal forces, protecting the implant-supported restoration and the opposing dentition, especially in all-on-4 treatments, where lack of proprioception and wide interimplant distance are present. Long-term clinical evidence is required before recommending the application as an alternative restorative material for such a prosthesis.

Interim rehabilitation of occlusal vertical dimension using a double-crown-retained removable dental prosthesis with polyetheretherketone framework

Polyetheretherketone (PEEK) is a polymeric material that has recently been introduced in dentistry and can be used as framework material for fixed and removable dental prostheses. This clinical report describes the fabrication of a double-crown–retained prosthesis with a PEEK framework in a patient with a substantially diminished occlusal vertical dimension. The insertion of the removable dental prosthesis with a PEEK framework resulted in the functional and esthetic rehabilitation of the patient; however, removable dental prostheses fabricated from PEEK should currently be regarded as interim restorations because of the limited available scientific evidence.