The role of cortical zone level and prosthetic platform angle in dental implant mechanical response: A 3D finite element analysis

Mechanical and modal analysis of different implant strategies for loss of three teeth with bone atrophy in the maxillary posterior region

PURPOSE

This study aimed to evaluate the stress distribution and secondary stability involved in five implant strategies, including implant-supported prostheses (ISP) and tooth-implant-supported prostheses (TISP), used for bone atrophy in the maxillary posterior region with teeth loss using finite element analysis, and to explore the more desirable implant methods.

METHODS

Five implant strategies were made to analyze and compare: M1, implant-supported prosthesis consisting of a short implant with a regular implant; M2, implant-supported prosthesis consisting of a tilted implant with a regular implant; M3, cantilever structure; M4, tooth-implant-supported prosthesis consisting of a short implant with a regular implant; M5, tooth-implant-supported prosthesis consisting of a regular implant, and M6, with only the natural teeth as a control group. Dynamic loading of the above models was performed in finite element analysis software to assess the stress distribution of the bone tissue and implants using the von Mise criterion. Finally, the secondary stability of different models was evaluated by modal analysis.

RESULTS

The maximum stress distribution in the cortical bone in M1(60 MPa) was smaller than that in M2(97 MPa) and M3(101 MPa), The first principal strain minimum was obtained in M2 (2271μ ε ). M4 (33 MPa, 10085 Hz) with the best mechanical properties and highest resonance frequency. But increased the loading on the natural teeth.

CONCLUSIONS

Short implants and tilted implants are both preferred implant strategies, if cantilever construction is necessary, a tooth-implant-supported prosthesis consisting of a short implant and a regular implant is recommended.

Finite element analysis of the effect of framework material and thickness on the biomechanical performance of 'All‑on‑Four' full-arch prosthesis

The aim of this research was to evaluate the stress distribution in the 'All-on-Four' prosthesis and the surrounding bone, with different framework materials and thicknesses. Five frameworks (alumina, zirconia, titanium, fiberglass reinforced resin (FRR), and polyether ether ketone (PEEK)) with two thicknesses (3.5 &5.5 mm) were stimulated in this research. A vertical force of 200 N was applied on a 1 mm circular area, at the cantilever, and at the region of the incisors, simulating different mastication mechanisms. The results illustrated that the 5.5 mm framework reduced the stresses on most parts, mucosa, and bone tissues, compared to 3.5 mm.

Specifics of Porous Polymer and Xenogeneic Matrices and of Bone Tissue Regeneration Related to Their Implantation into an Experimental Rabbit Defect

This paper provides a study of two bone substitutes: a hybrid porous polymer and an osteoplastic matrix based on a bovine-derived xenograft. Both materials are porous, but their pore characteristics are different. The osteoplastic matrix has pores of 300-600 µm and the hybrid polymer has smaller pores, generally of 6-20 µm, but with some pores up to 100 µm across. SEM data confirmed the porometry results and demonstrated the different structures of the materials. Therefore, both materials were characterized by an interconnected porous structure and provided conditions for the adhesion and vital activity of human ASCs in vitro. In an experimental model of rabbit shin bone defect, it was shown that, during the 6-month observation period, neither of the materials caused negative reactions in the experimental animals. By the end of the observation period, restoration of the defects in animals in both groups was completed, and elements of both materials were preserved in the defect areas. Data from morphological examinations and CT data demonstrated that the rate of rabbit bone tissue regeneration with the hybrid polymer was comparable to that with the osteoplastic matrix. Therefore, the hybrid polymer has good potential for use in further research and improvement in biomedical applications.

A 3D-FEA study on the impact of different preparation forms and materials on posterior occlusal veneers

OBJECTIVES

To study the stress distribution and bonding performance in posterior occlusal veneers and tooth bodies under different preparation forms and materials.

METHODS

An isolated lower right first molar was prepared with non-retention type (type A), cavity-retained type (type B), and encircling-retention type (type C) forms. MicroCT images of the tooth were obtained and digitally converted into three-dimensional solid models. Three-dimensional models of veneers for the three abutment teeth were designed, fabricated, and divided into nine models (AEM, ALU, AVE, BEM, BLU, BVE, CEM, CLU, and CVE) according to the material used (E.max CAD [EM], Lava Ultimate [LU] and Vita Enamic [VE]). Three-dimensional finite element stress analysis was performed by applying vertical and oblique forces (200 N) to simulate chewing loads using ABAQUS. Finally, an adhesive stiffness degradation diagram was obtained using the rotatory dislocation simulation method.

RESULTS

The BEM model had the largest equivalent stress extreme value (160.50 MP A) when a vertical load was applied to the veneers, while there was no significant difference when it was applied to dental tissues. The equivalent stress extreme values of each part under an oblique load were significantly greater than those under a vertical load. The AEM model had the largest values when the loads were applied to the veneers (350.60 MP A) and the dental tissues (40.13 MP A). The equivalent stress extreme values of the veneers were ranked as LU < VE < EM for different materials, and LU > VE > EM for dental tissues. Bonding performance results were C > B ≈ A and LU > VE > EM.

CONCLUSIONS

The cavity-retained type better protected the veneers and dental tissues than the non-retention and encircling-retention types under lateral forces. E.max CAD material, with a high elastic modulus, reduced the stress transmitted to the remaining dental tissues. Lava Ultimate exhibited the best bonding performance.

A comprehensive biomechanical evaluation of length and diameter of dental implants using finite element analyses: A systematic review

Background

With a wide range of dental implants currently used in clinical scenarios, evidence is limited on selecting the type of dental implant best suited to endure the biting force of missing teeth. Finite Element Analysis (FEA) is a reliable technology which has been applied in dental implantology to study the distribution of biomechanical stress within the bone and dental implants.

Purpose

This study aimed to perform a systematic review to evaluate the biomechanical properties of dental implants regarding their length and diameter using FEA.

Material and methods

A comprehensive search was performed in PubMed/MEDLINE, Scopus, Embase, and Web of Science for peer-reviewed studies published in English from October 2003 to October 2023. Data were organized based on the following topics: area, bone layers, type of bone, design of implant, implant material, diameter of implant, length of implant, stress units, type of loading, experimental validation, convergence analysis, boundary conditions, parts of Finite Element Model, stability factor, study variables, and main findings. The present study is registered in PROSPERO under number CRD42022382211.

Results

The query yielded 852 results, of which 40 studies met the inclusion criteria and were selected in this study. The diameter and length of the dental implants were found to significantly influence the stress distribution in cortical and cancellous bone, respectively. Implant diameter was identified as a key factor in minimizing peri-implant stress concentrations and avoiding crestal overloading. In terms of stress reduction, implant length becomes increasingly important as bone density decreases.

Conclusions

The diameter of dental implants is more important than implant length in reducing bone stress distribution and improving implant stability under both static and immediate loading conditions. Short implants with a larger diameter were found to generate lower stresses than longer implants with a smaller diameter. Other potential influential design factors including implant system, cantilever length, thread features, and abutment collar height should also be considered in future implant design as they may also have an impact on implant performance.

Biomechanical analysis of alveolar bones with compromised quality supporting a 4-unit implant bridge; a possible association with implant-related sequestration (IRS)

OBJECTIVES

This study aimed to investigate the strain in the bone surrounding dental implants supporting a 4-unit bridge and assess the role of excessive strain as a possible risk factor for implant related sequestration (IRS) or peri-implant medication-related osteonecrosis of the jaw (PI-MRONJ).

MATERIALS AND METHODS

A 3D-mandibular model was constructed using computed tomography and segmented it into cortical and cancellous bones. The 4-unit implant-supported bridges replacing the mandibular posteriors were constructed, and each featuring two, three, and four implants, respectively. The Young's modulus was assigned based on the quality of the bone. A maximum occlusal force of 200 N was applied to each implant in the axial and in a 30-degree oblique direction.

RESULTS

The maximum principal strain of the fatigue failure range (> 3000 µε) in the bone was analyzed. The volume fraction of fatigue failure was higher in poor-quality bone compared to normal bone and oblique load than in axial load. An increasing number of implants may dissipate excessive strain in poor-quality bones.

CONCLUSIONS

Occlusal force applied to poor-quality bone can result in microdamage. Given that unrepaired microdamage may initiate medication-related osteonecrosis of the jaw, long-term occlusal force on fragile bones might be a risk factor.

CLINICAL RELEVANCE

When planning implant treatment for patients with compromised bone status, clinical modifications such as strategic placement of implants and optimization of restoration morphology should be considered to reduce excessive strain which might be associated with IRS or PI-MRONJ.

Comparative Evaluation of the Effect of Implant Crown Materials on Implant Components and Bone Stress Distribution: A 3D Finite Element Analysis

Background

Choosing implant crown materials for restoration remains challenging in clinical practice. This study assesses the impact of all-ceramic restoration instead of porcelain-fused-to-metal (PFM) restoration on the stress distribution within implant components and the surrounding bone.

Methods

Four 3D models of a mandibular second premolar were meticulously prepared. The study groups comprised zirconia, lithium disilicate, and zirconia lithium silicate monolithic ceramic crowns cemented onto a zirconia hybrid abutment. A PFM crown cemented onto a cementable abutment was chosen as the control group. A total vertical load of 583 N was applied to the occlusal contact areas. Stress distribution within the crown and implant components was analyzed using von Mises stress analysis. Principal stress analyses were employed to assess stress distribution in the peripheral bone.

Results

The PFM model exhibited the highest von Mises stress values for both the implant (428.7 MPa) and crown (79.7 MPa) compared to the other models. The all-ceramic models displayed the highest maximum von Mises stress within the abutment, approximately 335 MPa, compared to the PFM model. von Mises stresses of the abutment and implant in the all-ceramic models were 69% higher and 20% lower, respectively, than those in the PFM model. Screw stresses were relatively consistent across all groups. Principal stresses in spongy bone and minimum principal stress in cortical bone were consistent across all models.

Conclusions

All-ceramic restoration with a hybrid abutment, as opposed to traditional PFM restoration with a cementable abutment, does not adversely affect the implant and abutment screw and reduces crown stresses. Stresses within hybrid abutments were notably higher than those within cementable abutments. Spongy bone stresses remained unaffected by the type of crown or abutment.

Improving dental implant stability by optimizing thread design: Simultaneous application of finite element method and data mining approach

STATEMENT OF PROBLEM

Lack of knowledge regarding the optimal design of thread configuration in dental implants, which can offer a satisfactory level of stability in the implant-bone construct, is a significant challenge in the field of dental biomechanics.

PURPOSE

The purpose of this finite element analysis study was to identify the optimal thread design by investigating the effects of thread parameters such as thread depth (TD), thread width (TW), and thread pitch (TP), as well as upper (α) and lower (β) thread angles, on the maximum principal stress in cancellous and cortical bone, maximum von Mises stress in the dental implant, and maximum shear stress at the implant-bone interface.

MATERIAL AND METHODS

A finite element model of an alveolar bone segment with a dental implant was developed. The Latin hypercube sampling method was used to generate a dataset of virtual experiments, which were analyzed by using the decision tree method to identify suitable thread designs that minimize mechanical stimuli. Additionally, the effectiveness of thread parameters on stress levels in the bone, implant, and their interface were assessed.

RESULTS

The results of this study, verified by comparison with previous literature, indicated that TD, TW, and upper thread angle were the most effective parameters in promoting implant stability.

CONCLUSIONS

By analyzing the decision trees, optimum ranges for all the thread parameters were determined as follows: 0.25 Collapse

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Affiliation(s)

Masoud Arabbeiki Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy
Mohammad Reza Niroomand Department of Mechanical Engineering, Payame Noor University, Tehran, Iran.
Gholamreza Rouhi Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran

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Effect of Antirotational Two-Piece Titanium Base on the Vertical Misfit, Fatigue Behavior, Stress Concentration, and Fracture Load of Implant-Supported Zirconia Crowns

This study investigated the effects of antirotational titanium bases on the mechanical behavior of CAD/CAM titanium bases used for implant-supported prostheses. The aim was to assess the impact on the marginal fit, fatigue behavior, stress concentration, and fracture load of implant-supported CAD/CAM zirconia crowns. Forty titanium implants were divided into two groups: those with antirotational titanium bases (ARs) and those with rotational titanium bases (RTs). Torque loosening and vertical misfit were evaluated before and after cyclic fatigue testing (200 N, 2 Hz, 2 × 10⁶ cycles). Fracture resistance was assessed using a universal testing machine (1 mm/min, 1000 kgf), and failed specimens were examined with microscopy. Three-dimensional models were created, and FEA was used to calculate stress. Statistical analysis was performed on the in vitro test data using two-way analysis of variance and Tukey's test (α = 0.5). Results show that the presence of an antirotational feature between the implant and titanium base reduced preload loss and stress concentration compared to rotational titanium bases. However, there were no differences in vertical misfit and resistance to compressive load.

Hybrid Prosthesis versus Overdenture: Effect of BioHPP Prosthetic Design Rehabilitating Edentulous Mandible

Aim

To compare the BioHPP (biocompatible high-performance polymer) as a substructure for the hybrid prosthesis versus the BioHPP bar supporting and retaining implant overdenture by radiographic evaluation to identify bone height alteration around the implants and to evaluate satisfaction based on visual analoge scale questionnaire.

Materials and Methods

Ill-fitting mandibular dentures were chosen for 14 fully edentulous male patients with adequate dental hygiene, enough interarch space, and free of systemic diseases and parafunctional habits. Patients who received new dentures (CDs) were randomly allocated into each group using computer software, and four interforaminal implants were inserted in parallel using a surgical guide. Three months after osseointegration, the patients received either CAD-CAM BioHPP framework hybrid prosthesis (Group I) or BioHPP bar supported and retained overdenture (Group II). Using digital preapical radiography, the bone loss is evaluated 6, 12, and 18 months after insertion. The subjective patient evaluation was done using a questionnaire based on the VAS includes five points for chewing, comfort, esthetics, speech, oral hygiene, and general satisfaction.

Results

The overall marginal bone loss (MBL) revealed that Group I (hybrid prosthesis) was more than Group II (bar overdenture) at all intervals in the anterior and posterior implants' mesial and distal surfaces. The patient satisfaction survey results showed that, after 18 months, the difference was statistically not significant between them all (P > 0.05) except for the comfort (for the overdenture group, 4.43 ± 0.53 while the fixed hybrid was 5.00 ± 0.00).

Conclusion

BioHPP framework material is an alternative material for implant rehabilitation of edentulous mandible with minimal MBL in BioHPP bar overdenture compared to BioHPP hybrid prosthesis.

Influence of Different Implant Designs on Replacement of Four Teeth of The Posterior Free-end Edentulism: Three-dimensional Finite Element Analysis and Clinic Case Validation

BACKGROUND

With periodontal disease having an increasing incidence, mandibular free-end edentulism caused by periodontitis is clinically more common. Finite element analysis and clinical case reports were used to evaluate the influence of different designs on the load distribution of implant prosthesis in mandibular posterior free-end edentulism.

METHOD

A finite element model of a mandible with posterior free-end edentulism was established. Considering the implant position and selection of single crown repair or splint repair, four designs were conducted including model A: 3435×37(four-unit fixed bridge supported by three implants, implant positions were 34, 35, 37); model B: 34,35×37, (34: a single implant crown) (35×37: three-unit fixed bridge supported by two implants, implant positions were 35, 37); model C: 34×3637(four-unit fixed bridge supported by three implants, implant positions were 34, 36, 37); and model D: 34×36, 37(37: a single implant crown)(34×36: three-unit fixed bridge supported by two implants, implant positions were 34, 36). Stress distribution and the Von Mises stress value of the implants, the crown and the bone around the implants were analyzed at vertical and 45° inclined load.

RESULTS

Stress in the cortical bone was mainly concentrated around the implant neck, and maximum Von Mises stress (MVMS) of the four models was 11.6-16.1MPa at vertical load and 61.74-96.49MPa at 45° inclined load. Stress in the cancellous bone was concentrated around the implant base, and MVMS of four models was 3.075-3.899MPa at vertical load and 5.021-6.165MPa at 45° inclined load. Stress of the restoration crowns was mainly concentrated in the connector of the bridge, and MVMS of four models was 23.38-26.28MPa at vertical load and 53.14-56.35MPa at 45° inclined load. Stress of the implant interface was mainly concentrated on the surface of the smaller implants near the bridge, and MVMS of four models was 21.12-33.25MPa at vertical load and 83.73-138.7MPa at 45° inclined load.

CONCLUSION

There was favorable stress distribution of the four models at vertical load and 45° inclined load. Design of a three-unit fixed bridge combined with a partial crown may be an available option for devising patient treatment plans with mandibular free-end edentulism.

Removal of broken screws on implant abutment by digital guide plate: A case report and literature review

Implant restoration is currently the most mainstream method for repairing missing teeth. With the increasing number of plantings, various planting complications begin to be paid attention to. Among them, there are many reports of disability phenomena such as loose and broken abutment screws and broken top screws, which cause the implant to fail or fail to function. In recent years, with the development of computer-aided software and its application in the field of oral treatment, digital guide plates based on 3D printing of oral CBCT scanning data are widely used in oral implants. Therefore, we explore the application prospect of post-core crown restoration after removing broken screws from the implant abutment with a digital guide plate. We reported a case of upper right first molar implant abutment screws broken, which were removed by a digital guide plate and customized turning bur. The resin-matrix ceramics crown post core was prepared, and then the occlusal force was tested by the T-ScanIII system. It provides a reference for the application of digital guide plates in special cases such as broken screws of implant abutment.

Stress distribution in resin-based CAD-CAM implant-supported crowns

OBJECTIVE

This study aimed to evaluate the influence of new resin-based CAD-CAM implant-supported materials on posterior crown restoration stress and strain concentrations.

METHODS

A previous 3D implant model was edited to receive a cement-retained posterior crown manufactured with different CAD/CAM materials (Estelite P Block, Estelite Block II or Estelite Layered Block). Each solid model was exported to the computer-aided engineering software and submitted to the finite element analysis of stress and strain. Material properties were assigned to each solid with isotropic and homogeneous behavior according to the manufacturer information. A vertical load of 600 N was applied in the occlusal region of the crown, via a simulated food bolus, and stress was calculated in Von Misses (σVM) for the implant, abutment and screw, Maximum (σMAX) Principal Stresses for the crown and microstrain for the bone.

RESULTS

All simulated materials showed acceptable stresses levels with a similar stress pattern among the models. At the crown intaglio region and cement layer, however, differences were observed: Estelite P Block showed a lower tensile and shear stresses magnitude when compared to other resin-based materials with lower elastic modulus.

SIGNIFICANCE

The stress effect of different resin-based CAD-CAM implant-supported crowns is predominant in the crown and cement layer, with Estelite P Block showing 7.4 % versus 9.3 % and 9.2 % for Estelite Block II and Estelite Layered Block of crown failure risk.

Effect of crown stiffness and prosthetic screw absence on the stress distribution in implant-supported restoration: A 3D finite element analysis

This in-silico investigation evaluated the mechanical impact of Morse tape implant-abutment interface and retention system (with and without screw) and restorative materials (composite block and monolithic zirconia) by means of a three-dimensional finite element analysis (3D-FEA). Four 3D models were designed for the lower first molar. A dental implant (4.5 × 10 mm B&B Dental Implant Company) was digitized (micro CT) and exported to computer-aided design (CAD) software. Non-uniform rational B-spline surfaces were reconstructed, generating a 3D volumetric model. Four different models were generated with the same Morse-type connection, but with a different locking system (with and without active screw) and a different crown material made of composite block and zirconia. The D2 bone type, which contains cortical and trabecular tissues, was designed using data from the database. The implants were juxtaposed inside the model after Boolean subtraction. Implant placement depth was simulated for the implant model precisely at crestal bone level. Each acquired model was then imported into the finite element analysis (FEA) software as STEP files. The Von Mises equivalent strains were calculated for the peri-implant bone and the Von Mises stress for the prosthetic structures. The highest strain values in bone tissue occurred in the peri-implant bone interface and were comparable in the four implant models (8.2918e-004-8.6622e-004 mm/mm). The stress peak in the zirconia crown (64.4 MPa) was higher than in the composite crown (52.2 MPa) regardless of the presence of the prosthetic screw. The abutment showed the lowest stress peaks (99.71-92.28 MPa) when the screw was present (126.63-114.25 MPa). Based on this linear analysis, it is suggested that the absence of prosthetic screw increases the stress inside the abutment and implant, without effect on the crown and around the bone tissue. Stiffer crowns concentrate more stress on its structure, reducing the amount of stress on the abutment.

Effect of Sinus Perforation with Flaplessly Placed Mini Dental Implants for Oral Rehabilitation: A 5-Year Clinical and Radiological Follow-Up

Background: Flaplessly placed one-piece mini dental implants (MDI) are an option to support maxillary overdentures. Evenly distribution of the implants over the atrophic alveolar process implies a risk of accidental sinus perforation in the posterior area which could induce sinus-related pathology. Methods: Thirty-one patients received 5–6 maxillary MDIs. Schneiderian membrane swelling was assessed with CBCT at the deepest point of the sinus in the mid-sagittal plane prior to surgery (baseline), after 2 and 5 years. Additionally, subjective patient-reported rhinosinusitis complaints, the effect of smoking, and gender differences were investigated. Results: Mean thickness of the Schneiderian membrane was 2.87 mm at baseline, 3.15 mm at 2 years, and 4.30 mm at 5 years in 27 of 31 initially treated patients. MDI perforation was detected in 21/54 sinuses. At 2 years, perforation length does not affect membrane thickness whereas baseline swelling does. In smokers, each perforated mm induced 0.87 mm additional swelling. After 5 years, the effect of baseline swelling becomes smaller whereas perforation length became statistically significant, with 0.53 mm increase for every perforated mm. The effect of smoking lost its significance. No relations between gender, membrane thickness changes, or subjective clinical sinus complaints and MDI perforation were found. Conclusion: Accidental MDI sinus perforation induces Schneiderian membrane swelling but does not interfere with clinical sinusal outcome after 5 years.

Influence of Bone-Level Dental Implants Placement and of Cortical Thickness on Osseointegration: In Silico and In Vivo Analyses

The purpose of this research is to study the biomechanical response of dental implants in bone-level type locations, 0.5 mm above and below the bone level. In addition, the influence of the thickness of the cortical bone on osseointegration is determined due to the mechanical loads transfer from the dental implant to the cortical and trabecular bone. The thicknesses studied were 1.5 mm and 2.5 mm. Numerical simulations were performed using a finite element method (FEM)-based model. In order to verify the FEM model, the in silico results were compared with the results obtained from a histological analysis performed in an in vivo study with 30 New Zealand rabbits. FEM was performed using a computerized 3D model of bone-level dental implants inserted in the lower jawbone with an applied axial load of 100 N. The analysis was performed using different distances from the bone level and different thicknesses of cortical bone. The interface area of bone growth was evaluated by analyzing the bone–implant contact (BIC), region of interest (ROI) and total bone area (BAT) parameters obtained through an in vivo histological process and analyzed by scanning electron microscopy (SEM). Bone-level implants were inserted in the rabbit tibiae, with two implants placed per tibia. These parameters were evaluated after three or six weeks of implantation. FEM studies showed that placements 0.5 mm below the bone level presented lower values of stress distribution compared to the other studied placements. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that this position presented the highest BIC value after three or six weeks of implantation. In this placement, vertical bone growth could be observed up the bone level. The smallest thickness of the study showed a better transfer of mechanical loads, which leads to a better osseointegration. In silico and in vivo results both concluded that the implants placed 0.5 mm below the cortical bone and with lower thicknesses presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.

Evaluation of Zirconia and High Performance Polymer Abutment Surface Roughness and Stress Concentration for Implant-Supported Fixed Dental Prostheses

Background: The High Performance Polymer is a based polymer biomaterial that was introduced as dental material to manufacture dentures superstructure and dental implants abutments. However, its surface characteristics and stress state still need to be properly described. The aim of this study was to compare the surface characteristics of a High Performance Polymer (Bio-HPP, Bredent, Senden, Germany) for computer-aided design and computer-aided manufacturing (CAD/CAM) milling and a Zirconia (Zirkonzahn, Steger, Ahrntal, Italy). Methods: The abutments surface roughness (Ra) was evaluated for each abutment material (N = 12) using a confocal laser microscope. Data were evaluated using One-Way ANOVA and Tukey tests (p < 0.05). In addition, a finite element analysis software was used to present stress measurement data as stress maps with 100 N loading. Results were generated according to Von-mises stress criteria and stress peaks were recorded from each structure. Results: Results showed a mean Ra of 0.221 ± 0.09 μm for Bio-HPP and 1.075 ± 0.24 μm for Zirconia. Both surface profiles presented a smooth characteristic regardless the measurement axis. The stress peaks from implant fixture and screw were not affected by the abutment material, however the high performance polymer showed the highest stress magnitude for the abutment region. Conclusions: Comparing the present results with the literature it is suggested that the CAD/CAM High Performance Polymer abutments present an adequate surface roughness with acceptable values of stress.

Influence of Framework Material and Posterior Implant Angulation in Full-Arch All-on-4 Implant-Supported Prosthesis Stress Concentration

This study evaluated the influence of distal implants angulation and framework material in the stress concentration of an All-on-4 full-arch prosthesis. A full-arch implant-supported prosthesis 3D model was created with different distal implant angulations and cantilever arms (30° with 10-mm cantilever; 45° with 10-mm cantilever and 45° with 6-mm cantilever) and framework materials (Cobalt–chrome [CoCr alloy], Yttria-stabilized tetragonal zirconia polycrystal [Y-TZP] and polyetheretherketone [PEEK]). Each solid was imported to computer-aided engineering software, and tetrahedral elements formed the mesh. Material properties were assigned to each solid with isotropic and homogeneous behavior. The contacts were considered bonded. A vertical load of 200 N was applied in the distal region of the cantilever arm, and stress was evaluated in Von Misses (σVM) for prosthesis components and the Maximum (σMAX) and Minimum (σMIN) Principal Stresses for the bone. Distal implants angled in 45° with a 10-mm cantilever arm showed the highest stress concentration for all structures with higher stress magnitudes when the PEEK framework was considered. However, distal implants angled in 45° with a 6-mm cantilever arm showed promising mechanical responses with the lowest stress peaks. For the All-on-4 concept, a 45° distal implants angulation is only beneficial if it is possible to reduce the cantilever’s length; otherwise, the use of 30° should be considered. Comparing with PEEK, the YTZP and CoCr concentrated stress in the framework structure, reducing the stress in the prosthetic screw.