Evaluation of stress distribution in an endodontically treated tooth restored with four different post systems and two different crowns- A finite element analysis

Effect of two esthetic digitally produced materials used in fabrication of extracoronal attachments on the stresses Induced in removable partial dentures

BACKGROUND

Preservation of the remaining structures while maintaining an esthetic appearance is a major objective in removable partial prosthodontics. So, the aim of the current study was to compare the stresses induced on the supporting structures by two digitally produced esthetic core materials; Zirconia and Polyetheretherketone when used as an extracoronal attachment in distal extension removable partial dentures using strain gauge analysis.

METHODS

A mandibular Kennedy class II stone cast with the necessary abutments' preparations was scanned. The mandibular left canine and first premolar teeth were virtually removed. An acrylic mandibular left canine and first premolar teeth were prepared with heavy chamfer finish line and scanned. Virtual superimposition of the acrylic teeth in their corresponding positions was done. Two strain gauge slots were designed: distal to the terminal abutment and in the residual ridge. Two models and two sets of scanned teeth were digitally printed. The printed teeth were then placed in their corresponding sockets in each model and scanned. The attachment design was selected from the software library and milled out of Zirconia in the model ZR and Polyetheretherketone in the model PE. Five removable partial dentures were constructed for each model. The strain gauges were installed in their grooves. A Universal testing machine was used for unilateral load application of 100 N (N). For each removable partial denture, five measurements were made. The data followed normal distribution and were statistically analyzed by using unpaired t test. P value < 0.05 was considered to be statistically significant.

RESULTS

During unilateral loading unpaired t test showed statistically significant difference (p = 0.0001) in the microstrain values recorded distal to the abutment between the models ZR (-1001.6 µε ± 24.56) and PE (-682.6 µε ± 22.18). However, non statistically significant difference (p = 0.3122) was observed in the residual ridge between them; ZR (16.2 µε ± 4.53) and PE (15 µε ± 3.74).

CONCLUSIONS

In removable partial dentures, Polyetheretherketone extracoronal attachment induces less stress on the supporting abutments compared to the zirconia one with no difference in the stresses induced by them on the residual ridge.

Stress distribution in endodontically treated external cervical resorption lesions restored with MTA and biodentine - A finite element analysis

Introduction

Root resorption poses a significant challenge in dental practice, with external cervical resorption (ECR) being a common manifestation. ECR is often asymptomatic until advanced stages, complicating its diagnosis and management. Various factors contribute to its etiology, ranging from trauma to orthodontic treatment. The classification system proposed by Patel et al. (2018) offers a comprehensive framework for characterizing ECR lesions based on location and extent. Treatment strategies for ECR involve a combination of endodontic intervention and restorative techniques, with bioactive materials like mineral trioxide aggregate (MTA) and Biodentine emerging as promising options. However, the biomechanical behavior of teeth restored with these materials in the context of ECR remains underexplored.

Materials and methods

This study utilized finite element analysis (FEA) to assess stress distribution in teeth with simulated ECR lesions of varying sizes and locations, restored with MTA or Biodentine. Three-dimensional models of maxillary central incisors were generated based on CBCT scans, incorporating periodontal ligament and surrounding bone structures. Eight experimental models representing different ECR configurations were created and subjected to FEA using Optistruct software based on dimensional classification given by Patel et al., in 2018, A70 M & A70B: 1Ap, A130 M & A130B: 1Bp, B70 M & B70B: 2Ap, B130 M & B130B: 2Bp. All the models were tested for stress distribution by restoring the lesions with either M: MTA or B: Biodentine. Oblique load of 100 N was applied at 45°angle to the long axis 2 mm lingual to incisal edge. vonMises Stress distribution in enamel, dentine, restoration and at all the interfaces were observed.

Results

The analysis revealed that both MTA and Biodentine restorations exhibited uniform stress distribution around ECR lesions, with no significant differences based on lesion location or size. Maximum stress concentrations were observed around the restorations, particularly in subcrestal lesions. However, overall stress levels were comparable between MTA and Biodentine restorations, indicating similar biomechanical performance.

Conclusion

Finite element analysis provides valuable insights into the biomechanical behavior of teeth with ECR lesions restored with MTA and Biodentine. Both materials exhibit similar stress distribution patterns and offer adequate reinforcement against mechanical forces. Clinicians can confidently utilize MTA or Biodentine in the management of ECR, considering their favorable biomechanical properties and clinical outcomes. Further research is necessary to validate these findings and optimize treatment protocols for ECR.

Fracture resistance and failure mode of three esthetic CAD-CAM post and core restorations

BACKGROUND

The rising demand for improved aesthetics has driven the utilization of recently introduced aesthetic materials for creating custom post and core restorations. However, information regarding the fracture resistance of these materials remains unclear, which limits their practical use as custom post and core restorations in clinical applications. AIM OF THE STUDY: This study aimed to evaluate the fracture resistance of three non-metallic esthetic post and core restorations and their modes of failure.

MATERIALS AND METHODS

Thirty-nine single-rooted human maxillary central incisors were endodontically treated. A standardized post space preparation of 9mm length was performed to all teeth to receive custom-made post and core restorations. The prepared teeth were randomly allocated to receive a post and core restoration made of one of the following materials (n=13): glass fiber-reinforced composite (FRC), polyetheretherketone (PEEK) and polymer-infiltrated ceramic-network (PICN). An intraoral scanner was used to scan all teeth including the post spaces. Computer-aided design and computer-aided manufacturing (CAD-CAM) was used to fabricate post and core restorations. Post and core restorations were cemented using self-adhesive resin cement. All specimens were subjected to fracture resistance testing using a universal testing machine. Failure mode analysis was assessed using a stereomicroscope and SEM. The data was statistically analyzed using One-Way ANOVA test followed by multiple pairwise comparisons using Bonferroni adjusted significance level.

RESULTS

Custom PEEK post and core restorations displayed the least fracture load values at 286.16 ± 67.09 N. In contrast, FRC exhibited the highest average fracture load at 452.60 ± 105.90 N, closely followed by PICN at 426.76 ± 77.99 N. In terms of failure modes, 46.2% of specimens with PICN were deemed non-restorable, while for PEEK and FRC, these percentages were 58.8% and 61.5%, respectively.

CONCLUSIONS

Within the limitation of this study, both FRC and PICN demonstrated good performance regarding fracture resistance, surpassing that of PEEK.

Influence of restorative materials on the mechanical properties of maxillary first molars with different degrees of cryptic fractures and defects: A finite element analysis

This study aimed to apply finite element analysis to evaluate the effects of pile materials with different elastic moduli and cement materials on the stress distribution between the remaining tooth tissue and cryptic fracture defects. A three-dimensional finite element model was established for 20 maxillary first molars with hidden fissures and mesial tongue-tip defects. Two levels of hidden cracks and three types of pile and adhesive materials were used in the design. The stress distribution and maximum stress peak in the remaining tooth tissue and crack defects were determined by simulating the normal bite, maximum bite, and lateral movement forces. When titanium posts, zinc phosphate binders, and porcelain crowns were used to repair the two types of deep cracked teeth, the maximum principal stress at the crack and dentin was the smallest. As the crack depth increased, the maximum principal stress of the residual dentin and crack defects increased.

Comparative analysis of the biomechanical behavior of the maxillary central incisors restored with glass fiber post and cast metal post and core submitted to orthodontic forces: A study with finite elements

INTRODUCTION

Different types of intraradicular restorations and their insertion have an impact on teeth biomechanics. This study aimed to analyze the biomechanical behavior of maxillary central incisors restored with glass fiber post (GFP) and cast metal post and core (CMP) subjected to buccolingual and mesiodistal orthodontic forces using the finite element method.

METHODS

Two models of the maxillary central incisor with periodontal ligament, cortical bone, and trabecular bone were made. One of the models included intraradicular restoration with GFP, whereas, in the other, the incisor was restored with CMP. After creating the tridimensional mesh of finite elements, applying 2 orthodontic forces were simulated: 65 g of buccolingual force and 70 g of mesiodistal force. The forces were applied parallel to the palatal plane in the region of the bracket slot, located 4 mm to the incisal edge.

RESULTS

The maximum stresses generated in the GFP-restored root were 3.642 × 10-1 MPa and 4.755 × 10-1 MPa from the buccolingual and mesiodistal forces, respectively. Likewise, the stresses in the CMP restored root were 2.777 × 10-1MPa and 3.826 × 10-1MPa. The radicular area with higher stress on both models was located in the cervical third: on the buccal surface when the buccolingual force was applied and on the mesial surface when the mesiodistal force was applied. The highest stress levels were found on the CMP structure.

CONCLUSIONS

The incisor restored with cast metal post revealed lower stress values transferred to the root than the one restored with GFP. The stresses on the structure of the GFP were lower and more homogeneous than the ones found on the cast metal post. The difference among the stress values in the materials is within a safe margin for using both materials in relation to orthodontic forces.

Influence of the Fiber Post Length on the Fracture Strength of Endodontically Treated Teeth

Background and Objectives: Although fiber posts are widely used in the restoration of endodontically treated teeth (ETT), their ideal cementation depth into the root canal is still debated in literature. The aim of the present study was to evaluate whether the different intra-radicular insertion lengths of the fiber posts influence the fracture strength of ETT. Materials and Methods: A total of 10 permanent human lower incisors with straight roots of similar length and volume extracted for periodontal reason were sectioned 2 mm above the cement-enamel junction (CEJ) to a total length of 18 mm and endodontically treated in the same manner, then randomly divided into two groups of five each (Groups 1 and 2, n = 5). Two sound incisors, with no endodontic treatment, were used as the control group (Group 3, n = 2). After one week of storage in a humid environment, spaces for fiber post no. 1 (Reforpost, Angelus, Londrina, PR, Brazil) were prepared in the first two groups at a depth of 5 mm (Group 1) and 7 mm (Group 2), and the fiber posts were adhesively cemented using self-adhesive resin cement (Maxcem Elite, Kerr GmbH, Herzogenrath, Germany). After 7 days, the samples were vertically positioned and fixed in a self-curing transparent acrylic resin, up to 2 mm below the CEJ level, and mechanically tested in compression after another week of storage using a displacement-controlled testing machine up to each sample's fracture. The force-displacement curves were recorded for each sample, the means were calculated for each group and a statistical comparative analysis between groups was conducted. Results: Although no statistically significant differences between groups were observed, the highest mean fracture force (N) was recorded in Group 2 (1099.41 ± 481.89) in comparison to Group 1 (985.09 ± 330.28), even when compared to the sound, non-treated teeth (1045.69 ± 146.19). Conclusions: Within the limitations of this in vitro study, teeth where fiber posts were placed deeper into the root canal (7 mm) recorded slightly higher fracture forces in comparison with shorter lengths (5 mm). However, similar biomechanical performances obtained in the mechanical tests showed no statistical differences between the 7 mm and the 5 mm inserted posts.

Mechanical properties, biosafety, and shearing bonding strength of glass fiber-reinforced PEEK composites used as post-core materials

OBJECTIVE

To investigate the mechanical properties, biosafety, and shearing bonding strength of glass fibers-reinforced polyether-ether-ketone (PEEK-GF) for post-core materials.

METHODS

PEEK-GF composites with different glass fiber contents were prepared by extrusion injection and named PEEK-GF30, PEEK-GF40, and PEEK-GF50. Mechanical properties including flexural modulus, flexural strength, Vickers hardness, and compression strength were tested. The cross-sectional morphology was examined using scanning electron microscopy (SEM). Cytotoxicity was studied in vitro with Cell-counting kit-8 (CCK-8). Cell morphology was observed under a microscope. Cell growth on the composites' surfaces was analyzed with DAPI staining. The shearing bonding strength (SBS) of PEEK-GF50 was assessed after applying different pretreatments. Failure modes were evaluated by microscopy. SEM and contact-angle measurements were performed on the surfaces. Statistical analysis was conducted using one-way ANOVA (P < 0.05).

RESULTS

The mechanical properties of PEEK-GF composites improved with increased GF content. The PEEK-GF50 group exhibited flexural modulus (17.4 ± 0.5 GPa) close to that of dentin (18.6 GPa) and showed the highest flexural strength (350.0 ± 2.9 MPa), Vickers hardness (47.6 ± 4.5 HV), and compressive strength (264.0 ± 18.0 MPa). The SEM analysis demonstrated that the PEEK matrix combined well with glass fibers. The CCK-8 results confirmed the biosafety of all groups. DAPI staining indicated that cells were growing well on the composites' surface. The sample that was pretreated with sandblasting and plasma showed the highest SBS (16.0 ± 1.7 MPa).

SIGNIFICANCE

The PEEK-GF composites demonstrated excellent mechanical properties, biosafety, and SBS, and have great potential to serve as post-core materials.

Measurement of the Dentin Wall Thickness of the Maxillary Central Incisor in Relation to the Stage of Root Development: A Pilot Study

Objective

The aim of this study was to determine the average dentin wall thickness (DWT) of the maxillary central incisor (MCI) required for performing finite element analysis (FEA) models of root development.

Material and methods

A total of 137 intraoral periapical radiographs of MCI in children aged 7 to 11 years were examined and then classified into 5 groups according to root development stages, which included 1/2 of root development (S1), 3/4 of root development (S2), more than 3/4 of root development (S3), complete development with wide-open apex (S4) and complete development with closed apex (S5). DWT was measured at three reference (horizontal) lines: at a distance of 1 mm from the apex (M), 4 mm from the apex (L) and at the cervical line (K). The distal dentin wall thickness (M1, L1, and K1), the pulp thickness (M2, L2, and K2), the mesial dentin wall thickness (M3, L3, and K3), and the apex thickness (N) were measured using the diagnostic software Soredex Scanora 5.1.2.4. Statistical analysis compared the values of the parameters K, L, and M between developmental stages (multivariate ANOVA) and the linear correlations between the parameters (Pearson's correlation analysis). All analyses were performed at significance level α = 0.05.

Results

There were statistically significant differences between the developmental stages for parameters L and M, while no significant differences were found for parameter K. Most of the correlations between the parameters were statistically significant, with the values of the Pearson correlation coefficient R > 0.6 considered practically significant. All parameters on the same reference line for distal and mesial dentin wall thickness and for pulp thickness correlated well with each other (R = 0.46 - 0.68), but there was no statistically significant correlation with total root thickness on the same reference line (parameters K, L, or M), except for parameter K3 (R = 0.42).

Conclusion

Despite the limitations of this study, the mean values of the selected parameters for the 5 groups of developmental stages of the maxillary central incisor could be used to model dentin wall thickness using finite element analysis.

Evaluation of Poly(etheretherketone) Post's Mechanical Strength in Comparison with Three Metal-Free Biomaterials: An In Vitro Study

The thinking about metallic replacement has begun in a global context of reducing metallic alloys' use in odontology. Among the materials proposed for their replacement, poly(etheretherketone) may present interesting properties, especially in removable dentures' frames. The purpose of this study is to evaluate fracture resistance of PEEK posts-and-cores compared to non-metallic CAD/CAM materials and fiber glass posts. Forty extracted maxillary central incisors were prepared to receive posts. Samples were divided into four groups depending on whether they had been reconstructed with LuxaCam® PEEK, Enamic®, Numerys GF® or LuxaPost®. Samples were submitted to an oblique compressive test and results were statistically analyzed with ANOVA and Student's tests (or non-parametric tests depending on the conditions). Glass fiber posts and Numerys GF® reveal a significantly higher fracture resistance than LuxaCam® PEEK and Enamic®. No exclusively dental fracture has been noted for the Enamic group, which significantly distinguishes these samples from the three other groups. In our study, it appears that the conception of posts and cores with hybrid ceramic never conducts to a unique tooth fracture. By weighting the results according to the materials used, our data, obtained for the first time on this type of PEEK block, cannot confirm the possibility of using PEEK for inlay-core conception, excepted for specific cases when the material is considered in a patient presenting allergies or systemic disease contraindicating resin or metal.

Comparative Stress Analysis of Custom-Made PEEK Dental Post-Cores versus Conventional Post-Cores in Incisor Restorations: A Finite Element Study

BACKGROUND We conducted a finite element analysis to evaluate stress levels in incisor teeth restored with custom polyetheretherketone (PEEK) dental post-cores compared to conventional post-cores. MATERIAL AND METHODS Using micro-computed tomography (μCT) imaging data, a 3D model of a maxillary incisor was created. For each material type, 3D mesh models were developed via specialized software. Two post diameters, 2.5 mm and 3.5 mm, were considered. Five different post materials were examined: Unfilled polyetheretherketone (Group UP); Glass fiber-reinforced polyetheretherketone (Group GP); Carbon fiber-reinforced polyetheretherketone (Group CP); Metal (Group M); and Zirconia ceramic (Group Z). Each model underwent finite element analysis, after which the von Mises equivalent stress values were determined. RESULTS For models involving both wide and narrow diameter posts across the crown, crown cement, post cement, and dentin, PEEK posts (Group UP, GP, and CP) exhibited higher von Mises stress values than Groups Z and M. However, the reverse trend was noticed in the post model itself. In the post cement model, stress values appeared similar only for the narrow-diameter post groups. Notably, results for Groups Z and M were largely consistent with each other. CONCLUSIONS PEEK posts, which have a lower modulus of elasticity, demonstrated different stress values when contrasted with zirconia and metal posts. As the post diameter expanded, the residual dentin decreased, influencing the stress values among various materials. Further in vitro and clinical examinations are essential to comprehensively understand PEEK posts.

Effect of Dental Glass Fiber Posts on Root Stresses and Fracture Behavior of Endodontically Treated Maxillary Central Incisors: A Finite Element Analysis Study

OBJECTIVE

 In this work, the influence of glass fiber posts with different designs on the root stress that had endodontic treatment was examined using the finite element method.

METHOD

 Using two distinct materials (metal and glass fiber) and two different prototypes (tapered and parallel-sided), four three-dimensional (3D) finite element models of an upper central incisor were made and studied. Each 3D model received an oblique loading of 100 N. All forces were dispatched as distributed pressure to the aforementioned region. There were no considerations made for potential stresses when performing the endodontic procedure. The endodontic treatment was conducted without taking into account any potential stressors. The root stresses were then recorded.

RESULTS

The largest tensile stress is often focused at the apical third of the post and post/cement contact, as well as at the coronal third of the root on both the labial and palatal sides of the root, independent of the post's design and material. Restoration of endodontically treated maxillary central incisors with glass fiber posts has been shown to have less stress concentration than titanium posts. Regardless of the post materials employed, the tapered post design generated a higher tensile stress distribution than the parallel side design.

CONCLUSIONS

 Prefabricated fiber posts used in model restoration resulted in more evenly distributed stress and less concentrated stress on the root. Reduction in modulus of elasticity of post materials used generally shows less stress concentration.

Three-Dimensional Finite Element Study of Endodontically Treated Maxillary Central Incisors Restored Using Different Post and Crown Materials

BACKGROUND/PURPOSE

Restoring endodontically treated teeth is a common problem in dental practice. Post and core restorations are one of the major options in the rehabilitation of these teeth. However, there is no final decision regarding the best material or technique to be used with these restorations. So, this study aimed to evaluate the effect of different post and crown materials on the biomechanical behavior of restored maxillary central incisor using the finite element method.

MATERIALS AND METHODS

A total of 10 3D models of endodontically treated maxillary central incisors restored with two prefabricated posts and three custom-made posts were modeled and grouped according to post material (gold, nickel-chrome, zirconia, and glass fiber) and crown material (lithium disilicate, and zirconia). Finite element analysis was conducted, and stress distribution was evaluated using von Mises criteria.

RESULTS

Both crown materials showed stress concentration at the force application site mainly on the intaglio palatal surface of the crown. However, more stress values were observed within zirconia crowns. All posts showed stress concentration at their buccal sides. However, more stress values were observed in zirconia and metal cast posts compared to glass fiber posts that transfer more stress to root dentin.

CONCLUSIONS

 Post and crown materials affect the stress distribution in the tooth-restoration complex. Using high elastic modulus posts slightly decreased stress in root dentin despite concentrating more stress within their structure. However, glass fiber posts resulted in more homogenous stress distribution in the tooth-restoration complex. Crown material did not influence the stress distribution in root dentin. Custom-made posts decreased stress within crowns, regardless of the crown material. However, more stress values were observed within zirconia crowns. Custom-made zirconia posts and cores showed a similar stress distribution as non-precious metal cast posts, so they may be used as a suitable option where esthetic is desirable.

High Performance Composites Based on Highly Filled Glass Fiber-Reinforced Polybenzoxazine for Post Application

Glass fiber post based on the new polymeric material, polybenzoxazine, is prepared and the effects of glass fiber contents on mechanical and thermal properties are evaluated. The mechanical response to externally applied loads of tooth restored with glass fiber-reinforced polybenzoxazine composite posts is also simulated by finite element analysis of a tridimensional model and compared with the response to that of a natural tooth. The reinforcing of glass fiber can help improve the mechanical and thermal properties of the polybenzoxazine influenced by the interfacial adhesion between the glass fiber and polybenzoxazine matrix, except for the relatively high mechanical property of the glass fiber. The mechanical data, i.e., elastic modulus under flexure load or flexural modulus by three-point bending test of the glass fiber-reinforced polybenzoxazine composites are agreed with the elastic modulus of dentin and then used in the finite element model. The restoration using the glass fiber-reinforced polybenzoxazine composite post provided the maximum von Mises equivalent stress at the cervical third area of the endodontically treated tooth model as similarly observed in the natural tooth. In addition, the maximum von Mises equivalent stress of the tooth restored with the glass fiber-reinforced polybenzoxazine composite post is also quietly like that of the natural tooth. The finding of this work provided the essential properties of the glass fiber-reinforced polybenzoxazine composite for dental restorations and appliances.

Comparative Evaluation of Different Post Materials on Stress Distribution in Endodontically Treated Teeth Using the Finite Element Analysis Method: A Systematic Review

The aim of this systematic review is to summarize and conclude findings to reveal the stress ranges developed by various post materials by finite element analysis. This, in turn, aids in the selection of better post material clinically. The electronic databases PubMed and Google Scholar were searched in this review by using specific inclusion and exclusion criteria. Among 14586 articles, 22 articles were included in this systematic review, as they satisfied the eligibility criteria. The search covered all articles published from 1997 to December 2021. All records identified were retrieved and imported into the Rayyan bibliographic software, which is a systematic review screening software. Later, data extraction and analysis of 22 articles were done. Twenty-two articles, which were all finite element analysis studies, were included. Among these, 18 studies used maxillary central incisor scanned models, two studies used a maxillary canine model, and the remaining two used the mandibular premolar model for finite element analysis. All these tooth models are restored with post models made of different materials. This systematic review revealed a difference in stress distribution in endodontically treated teeth when using different post materials. Among 22 studies, 15 studies evaluated glass fiber posts and the results showed that they induce less stress on restored endodontically treated teeth when compared to other posts, with maximum stress concentration at the cervical third of the root. Prefabricated posts like stainless steel and Titanium showed more stress on the restored tooth structure with stress concentration at the cervical and apical third of the root. Prefabricated zirconia also showed more stress on the restored tooth with maximum stress concentration at the middle third of the root.

[Maximum compressive stress analysis in upper central incisors rehabilitated with fiberglass posts and three types of crowns. A study with the finite element method]

Objective

To evaluate the maximum compressive stress in maxillary central incisors restored with fiberglass posts and three types of crowns by the FEM finite element method.

Materials and methods

The study was a virtual, descriptive, and laboratory trial. Three virtual models were made using the SolidWorks 2017 software from upper central incisors rehabilitated with fiberglass posts and a metal-ceramic crown, a monolithic lithium disilicate crown, and a zirconium-ceramic crown. They were then subjected to an oblique occlusal load of 150N with an angulation of 45°, distributed towards the palatal aspect. The stress analysis proceeded by comparing the maximum, minimum, and equivalent von Mises stresses.

Results

The maximum compressive stress was found at the cervical level in the vestibular area of each of the crowns. Zirconium-ceramic crown (Design 3) was the one with the highest compressive stress with 73.89 MPa, followed by Lithium Disilicate crown (Design 2) with 63.42 MPa and the metal-ceramic crown (Design 1) with 48.4 MPa.

Conclusion

The zirconium-ceramic crown better distributes the stress along the tooth since, due to its rigidity, it absorbs the stresses that are concentrated especially in the cervical area, which could indicate that it is the most appropriate option to rehabilitate endodontically treated teeth.

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.

Stress distribution in restorations with glass fiber and polyetheretherketone intraradicular posts: An in silico analysis

This study evaluated stresses generated at maxillary central incisor (21) root restored with lithium disilicate crown (LDC), and glass fiber (GFP) or polyetheretherketone (PEEK) post. 3D models created by computed tomographic image (i-CAT Cone Beam 3D Dental Imaging System) reproduced maxillary central incisor. Each model had prosthetic LDCs (2.0 mm thick) cemented to GFP or PEEK posts with dual resin cement. Different loads were applied to each model (cervical, incisal, axial, middle). At maximum principal stress, PEEK showed higher stress than GFP in all loads, but with qualitative similarity. At minimum principal stress, PEEK and GFP showed qualitative and quantitative similarities, except axial load. Maxillary central incisor restored with GFP or PEEK and LDC presented, in general, similar stress intensity and distribution for main occlusal loads. Only two of sixteen occlusal loads tested (cervical for maximum principal; axial for minimum principal) showed significant quantitative difference.

Stress distribution around different abutments on titanium and CFR-PEEK implant with different prosthetic crowns under parafunctional loading: A 3D FEA study

Aim & objectives

Clinical trials had concluded a significant relationship between implant failure and bruxism. A three-dimensional (3D) finite element analysis (FEA) was done to evaluate the stress distribution in straight and angled abutments around titanium and carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implant with 2 different prosthetic crowns under parafunctional loading.

Materials and method

Twelve 3D models of bone block were created representing the maxillary right premolar area with osseointegrated implants. The models were divided in two group; CFR-PEEK implant (n ​= ​6) and group titanium implant (n ​= ​6).Each group was subdivided based on implants with three different abutments (straight, 15°, 25° angled abutments) and having two different prosthetic crowns: porcelain fused to metal (PFM) and polyetheretherketone (PEEK). A vertical load of 1000 ​N was applied to the central fossa and an oblique load of 500 ​N (30°) was applied to the buccal incline of the palatal cusp. The von Mises stresses and principal stresses were analyzed using ANSYS software.

Results

CFR-PEEK and titanium implants produced similar stress in bone under vertical and oblique loading. Straight abutment showed better results than 15° and 25° angled abutments in all the groups. PEEK crown produced lesser stress than PFM crown under vertical and oblique loading.

Conclusion

The study concluded that straight abutment along with PEEK crown could be given in patients with bruxism to reduce the stress concentration in bone, thus preventing possible implant failure. Titanium and CFR-PEEK implants with straight abutments if given, then it should be provided with an occlusal splint.