Titanium Frameworks Research Articles

Pre-oxidation of selective-laser-melted titanium dental alloy: effects on surface characteristics and porcelain bonding

The heat treatment of dental alloys prior to porcelain application/veneering has been proposed as a way to ensure sufficient oxide scale and to promote the porcelain’s adherence in porcelain-fused-to-metal (PFM) fixed dental prostheses. The present study investigates the relationship between the bond strength of the dental porcelain to selective-laser-melted (SLM) titanium and the temperature of the titanium’s pre-oxidation. The SLM Ti-6Al-4V substrates were airborne-particle abraded and either left to passivate in air at room temperature (control) or pre-oxidized in a furnace under vacuum conditions (10 kPa) at temperatures of 300, 600, 750, or 800 °C. The surface characteristics were determined using contact profilometry to measure the profile roughness (Ra ), atomic force microscopy for the surface roughness (S a ) and Auger electron spectroscopy for the thickness of the oxide scale. Dental porcelain was applied to the metal substrates and the titanium-ceramic bond was assessed according to the ISO standard 9693-1:2012. The metal-ceramic interfaces were analyzed with scanning electron microscopy and energy-dispersive spectroscopy. The R a and S a values showed a strong positive correlation with the pre-oxidation temperature. The oxide scales covering the titanium surfaces thickened markedly at temperatures of 750 °C and above. However, the bond strength was negatively correlated with the pre-oxidation temperature. Room-temperature passivation in air following the airborne-particle abrasion of the SLM titanium resulted in a titanium-ceramic bond that is well above the ISO 9693-1:2012 recommended minimum value for metal-ceramic systems. Thus, no pre-oxidation of SLM titanium frameworks is necessary prior to the application/firing of porcelain.

Effect of modulator connectivity on promoting defectivity in titanium-organic frameworks.

The recognition of defect chemistry as a true synthetic tool for targeted creation of defects and controllable performance remains limited by the pool of frameworks explored. The value of defect engineering in controlling the properties of defective frameworks has been beautifully exemplified and largely demonstrated with UiO-type materials based on Zr(iv) nodes. However, titanium–organic frameworks remain largely unexplored in this context arguably due to the complex chemistry in solution of Ti(iv) and the difficulties in growing crystalline solids. We report a systematic study on the ability of mono- and dicarboxylic modulators (benzoic and isophthalic acid) to promote defect creation in the heterometallic Ti-MOF of the MUV-10 family. Our results indicate that both acids behave as capping modulators at high concentrations, but isophthalic acid is a more efficient defect promoter, yielding defective phases with nearly 40% of missing linkers. Our computational results suggest that this difference cannot be solely ascribed to relative changes in acidity but to the ability of this bidentate linker in compensating the structural distortion and energy penalty imposed by breaking the connectivity of the underlying framework.

A Pilot Study to Evaluate the Influence of Implant Supported Prosthesis Framework Material on the Stress Distribution in Peri-Implant Bone in Anterior Mandible: A Three-Dimensional Finite Element Analysis

Context: Original research. Aims: The aim of the present study to evaluate the effects of prosthetic material on the stress distribution of implant-supported prosthesis in the bone around implants using finite element analysis and to draw a comparison so as to which material causes the least amount of stress on the bone. Settings and Design: In vitro finite element analysis - Comparative study. Methods and Materials: Models of the implants and the mandible were constructed using SOLID WORKS software and then they were transferred to another software ANSYS Work bench for FEA. A four-unit prosthesis was designed in the region of anterior mandible with implants being placed in 32 and 42 regions. The prosthesis was made of different materials in different models, M1 was of made of cobalt chromium framework, M2 was made of Titanium framework, M3 was made of zirconia framework each with layered ceramic. M4 was a monolithic zirconia prosthesis. The values of the Von Mises stresses generated in the implant, superstructure and alveolar bone around were calculated. The total deformation and stress generated in different models were calculated and compared. Statistical analysis used: Von mises Stress Analysis, Unpaired t test. Results: Zirconia and Monolithic zirconia showed comparatively less total deformation and stress levels in peri-implant bone. Titanium prosthesis caused less total deformation and stress distribution as compared to cobalt chromium. Conclusions: The distribution of stress in peri implant bone is evidently dependent on the prosthesis material and different materials cause different amount of deformations as they differ in their clinical properties.

Comparison of peri-implant submucosal microbiota in arches with zirconia or titanium implant-supported fixed complete dental prostheses: a study protocol for a randomized controlled trial

BackgroundThe success rate of implant-supported prostheses for edentulous patients is relatively high. However, the incidence of biological complications, especially peri-implant mucositis and peri-implantitis, increases yearly after the placement of prostheses. The accumulation of pathogenic bacteria adjacent to a prosthesis is the main cause of biological complications. Titanium, one of the classical materials for implant-supported prostheses, performs well in terms of biocompatibility and ease of maintenance, but is still susceptible to biofilm formation. Zirconia, which has emerged as an appealing substitute, not only has comparable properties, but presents different surface properties that influence the adherence of oral bacteria. However, evidence of a direct effect on oral flora is limited. Therefore, the aim of the present study was to assess the effects of material properties on biofilm formation and composition.MethodsThe proposed study is designed as a 5-year randomized controlled trial. We plan to enroll 44 edentulous (mandible) patients seeking full-arch, fixed, implant-supported prostheses. The participants will be randomly allocated to one of two groups: group 1, in which the participants will receive zirconia frameworks with ceramic veneering, or group 2, in which the participants will receive titanium frameworks with acrylic resin veneering. Ten follow-up examinations will be completed by the end of this 5-year trial. Mucosal conditions around the implants will be recorded every 6 months after restoration. Peri-implant submucosal plaque will be collected at each reexamination, and bacteria flora analysis will be performed with 16S rRNA gene sequencing technology in order to compare differences in microbial diversity between groups. One week before each visit, periodontal maintenance will be arranged. Each participant will receive an X-ray examination every 12 months as a key index to evaluate the marginal bone level around the implants.DiscussionThe current study aims to explore the oral microbiology of patients following dental restoration with zirconia ceramic frameworks or titanium frameworks. The features of the microbiota and the mucosal condition around the two different materials will be evaluated and compared to determine whether zirconia is an appropriate material for fixed implant-supported prostheses for edentulous patients.Trial registrationInternational Clinical Trials Registry Platform (ICTRP) ChiCTR2000029470. Registered on 2 February 2020. http://www.chictr.org.cn/searchproj.aspx?

Can ceramic veneer spark erosion and mechanical cycling affect the accuracy of milled complete-arch frameworks supported by 6 implants?

Statement of problemMilling is a well-established method for manufacturing prosthetic frameworks. However, information about the influence of ceramic veneer and spark erosion on the accuracy of the all-on-six complete-arch fixed frameworks manufactured from different materials is lacking. PurposeThe purpose of this in vitro study was to compare the accuracy of milled complete-arch fixed frameworks with zirconia, cobalt-chromium, and titanium at different steps of their manufacturing process and the influence of mechanical cycling. Material and methodsFifteen milled complete-arch fixed frameworks, supported by 6 implants, were made in zirconia, cobalt-chromium, and titanium (n=5). The fit was measured by the single-screw test protocol. Stress was measured by photoelastic analysis. The loosening torque was evaluated by tightening the screws, retightening them after 10 minutes, and then evaluating the loosening torque 24 hours later. Thereafter, all frameworks received ceramic veneer, and the previous tests were repeated. Cobalt-chromium and titanium frameworks received spark erosion after ceramic veneer, and all analyses were repeated. Before and after mechanical cycling, loosening torque was evaluated. The results were subjected to 2-way repeated-measures ANOVA and the Bonferroni test (α=.05). ResultsTitanium presented higher fit values than zirconia (P=.037) and similar to cobalt-chromium frameworks (P>.05) at baseline. After ceramic veneer, higher fit levels were observed for zirconia (P=.001) and cobalt-chromium (P=.008). Titanium showed higher stress values (P<.05) regardless of time. Baseline for all materials presented lower stress values (P<.05). Higher loosening torque values were found for the titanium group at baseline (P<.001) and after ceramic veneer (P<.001). Spark erosion improved fit and loosening torque values only for cobalt-chromium (P<.05). Mechanical cycling did not influence the loosening torque (P>.05). ConclusionsTitanium milled complete-arch fixed frameworks presented poorer fit values than zirconia, although the loosening torque at baseline was higher. Ceramic veneer increased the fit levels for zirconia and cobalt-chromium, decreased the loosening torque values for cobalt-chromium, and enhanced stress levels. Spark erosion can be a reliable technique to improve fit and loosening torque for cobalt-chromium frameworks. Mechanical cycling did not decrease loosening torque.

A Finite element analysis of stress distribution in all on four system using different framework materials in the mandible

Statement of the problem: All on four immediate function approach rehabilitating mandibular arch is a successful rout of treatment for resorbed ridges, however its outcome depends on amount of stresses transferred to the surrounding structures. To improve mechanical properties of dental structures, stress analyses under various loading circumstances has become an integral part of researches. This study aimed to assess the effect of three different framework materials on stress distribution over implants and bone simulating materials using finite element analyses. Materials and methods: Three-dimensional finite element model was created. Bone and mucosa were modeled with simplification. The modeled parts were transferred to ANSYS for assembly, meshing, and analysis. The framework materials were (Cr Co, Titanium, and PEEK) to be studied under vertical and lateral loads. Results: Bone sensitivity to framework material was demonstrated as, increasing material elasticity reduces bone stresses. While total bone deformation of Cr Co and Titanium frameworks were equivalent, PEEK material showed the highest deformation. All implant complex components showed increasing stresses and deformation with reducing material elasticity. Under the proposed loads, no failure occurred in any model component. Conclusion: Within this study limitations, all materials tested were found to be suitable for usage as all on four system framework. Cr Co material showed the best performance, while Titanium was found nearly equivalent to it, and PEEK caused the highest stresses and deformations on bone and implant complex.

Heterometallic Titanium-Organic Frameworks as Dual-Metal Catalysts for Synergistic Non-buffered Hydrolysis of Nerve Agent Simulants

Summary Mixed-metal or heterometallic metal-organic frameworks (MOFs) are gaining importance as a route to produce materials with increasing chemical and functional complexities. We report a family of heterometallic titanium frameworks, MUV-101(M), and use them to exemplify the advantages of controlling metal distribution across the framework in heterogeneous catalysis by exploring their activity toward the degradation of a nerve agent simulant of Sarin gas. MUV-101(Fe) is the only pristine MOF capable of catalytic degradation of diisopropyl-fluorophosphate (DIFP) in non-buffered aqueous media. This activity cannot be explained only by the association of two metals, but to their synergistic cooperation, to create a whole that is more efficient than the simple sum of its parts. Our simulations suggest a dual-metal mechanism reminiscent of bimetallic enzymes, where the combination of Ti(IV) Lewis acid and Fe(III)–OH Bronsted base sites leads to a lower energy barrier for more efficient degradation of DIFP in absence of a base.

Accuracy of different impression techniques for multiunit implant restoration: A qualitative in vitro study

Statement of problemDisplacement of impression copings and/or implant replicas during impression making and dimensional changes that occur during clinical and laboratory phases of making multiunit implant prostheses may affect the accuracy and fit of the prostheses. PurposeThe purpose of this qualitative study was to investigate and compare 3 different impression techniques for osseointegrated dental implant transfer procedures. Material and methodsThree impression transfer approaches were evaluated and compared: closed-tray impression technique (CTT), impression with plastic snap-fit impression copings; open-tray impression technique (OTT), impression with independent square copings; and OTT joining the impression copings with a photo-polymerized resin (PPT). A reference acrylic resin model with 4 implants was fabricated. Polyvinyl siloxane with a stock tray was used to make 45 impressions (n=15 for each impression technique), and 45 die definitive stone casts. A computer-aided design and computer-aided manufacturing (CAD-CAM) titanium framework was fabricated on the reference model. Three blinded operators evaluated the fit of the CAD-CAM titanium framework on each model to find clinically acceptable fit. The Kappa test was used for the agreement between the examiners (α=.05). ResultsAgreement was found among the 3 examiners on 44 of 45 specimens (Kappa value= 0.939; P<.001). In the CTT group, 14 casts were found to be acceptable. In the OTT group, nearly half of the specimens produced unacceptable fitting casts, whereas in the PPT group, 13 casts were found acceptable. ConclusionsCTT and PPT produced more accurate casts than the OTT technique, which yielded inferior results.

Atomically Precise Titanium–Oxo Nanotube with Selective Water Adsorption and Semiconductive Behaviors

We report the first example of carbon nanotube (CNT)-like assembly of the titanium (Ti) framework, Ti oxo inorganic cluster (Ti6O6) hexagonal rings into a titanium oxide (Ti–O) nanotube, prepared b...

Dimensional Changes in Co-Cr Alloys and Titanium Framework of Removable Partial Dentures Evaluation of the dimensions of the dental clasps

Removable partial denture are prosthetic solutions that replace missing teeth of partially edentulous patients, ensuring stomatognathic system functionality with affordable costs.The purpose of this study is to analyze the dimensional variations caused by the execution errors, which can lead to premature deterioration of the removable partial dentures and to conclude what sizes are deficient and can lead to the deterioration of the prosthetic part. The material involved in the present study was represented by the metal framework of 181 removable partial dentures. Of the total of 181 removable prosthetic parts, 88 were maxillary prostheses and 93 were mandibular prostheses. Measurements were made at the retentive arms, opposing arms, minor connectors, rests and junction areas between the body of the clasps and the active arms and studied compared to the edentulous classes. The results are focused on dimensional changes of both the retentive arms and the opposing arms of the clasps, which are roughly modeled in the first 3 edentulous classes, with a significant difference from those achieved in Kennedy`s 4th class edentulous, where these segments of the clasps are much shorter. Regarding the size of the rests, although their thickness approximates the values indicated in the literature, they do not fit into the occlusal relief of the tooth. The length of the retentive arms varies according to the classes of edentulous, the clinical situation, but also the size and type of the tooth (premolars, molars) on which the clasp is applied. Regarding the opposing arm, the observed differences cannot be correlated with the objective criteria of their achievement because the attention is directed towards the realization of the retentive arm.

Corrosion Behavior of Titanium Frameworks under Laser and Tungsten Inert Gas Weldings: Applications in Dentistry

The purpose of this study was to investigate the role of different welding techniques: laser and tungsten inert gas (TIG) on the corrosion behavior of commercially pure titanium (cp-Ti) frameworks in dentistry. Electrochemical tests were conducted in artificial saliva at pH 7.2, 37°C. The surfaces were examined using scanning electron microscopy. The received data were analyzed by one-way ANOVA followed by Tukey’s test for multiple comparisons (α = 0.05). Cp-Ti frameworks welded by TIG were found to be more susceptible to corrosion, where defects in the weld region appeared to be the most important factor for the corrosion behavior. These findings suggested a better corrosion behavior for the laser welding procedure.

Heterometallic Titanium–Organic Frameworks by Metal-Induced Dynamic Topological Transformations

Reticular chemistry has boosted the design of thousands of metal and covalent organic frameworks for unlimited chemical compositions, structures, and sizable porosities. The ability to generate porous materials at will on the basis of geometrical design concepts is responsible for the rapid growth of the field and the increasing number of applications derived. Despite their promising features, the synthesis of targeted homo- and heterometallic titanium-organic frameworks amenable to these principles is relentlessly limited by the high reactivity of this metal in solution that impedes the controlled assembly of titanium molecular clusters. We describe an unprecedented methodology for the synthesis of heterometallic titanium frameworks by metal-exchange reactions of MOF crystals at temperatures below those conventionally used in solvothermal synthesis. The combination of hard (titanium) and soft (calcium) metals in the heterometallic nodes of MUV-10(Ca) enables controlled metal exchange in soft positions for the generation of heterometallic secondary building units (SBUs) with variable nuclearity, controlled by the metal incorporated. The structural information encoded in the newly formed SBUs drives an MOF-to-MOF conversion into bipartite nets compatible with the connectivity of the organic linker originally present in the crystal. Our simulations show that this transformation has a thermodynamic origin and is controlled by the terminations of the (111) surfaces of the crystal. The reaction of MUV-10(Ca) with first-row transition metals permits the production of crystals of MUV-101(Fe,Co,Ni,Zn) and MUV-102(Cu), heterometallic titanium MOFs isostructural with archetypical solids such as MIL-100 and HKUST. In comparison to de novo synthesis, this metal-induced topological transformation provides control over the formation of hierarchical micro-/mesopore structures at different reaction times and enables the formation of heterometallic titanium MOFs not accessible under solvothermal conditions at high temperature, thus opening the door for the isolation of additional titanium heterometallic phases not linked exclusively to trimesate linkers.

A prefabricated modular substructure for a 4-implant-supported fixed complete denture: A dental technique

A substructure is required for an implant-supported fixed complete denture that is sufficiently strong and supportive to function reliably. A novel prefabricated modular system that allows for the analog generation of a passively fitting, supportive, titanium framework for a 4-implant fixed complete denture is described. The process allows the delivery of an immediate, definitive prosthesis on the same or the next day.

Effect of framework type on survival probability of implant-supported temporary crowns: An in vitro study.

BackgroundThis in vitro study evaluated the effect of framework type on the survival probability of temporary implant-supported crowns and on the implant platform structure after dynamic fatigue. Material and MethodsThirty (30) external hexagon implants (3.75 x 10 mm) were embedded in acrylic resin following the ISO-14801. Standardized temporary crowns (n=10, N=30) were manufactured in acrylic resin and divided according to the framework type: Total plastic, Plastic with CoCr base and Titanium. The crowns were installed onto the implants (20N.cm) and fatigued (100N, 2 Hz) to determine the crowns’ survival probability for missions of 300.000 and 600.000 cycles. Fatigue data were submitted to the Kaplan-Meier test followed by Wilcoxon and Log Rank, all with α = 5%. The implant platforms were parametrically inspected based on the scanning before and after the fatigue to evaluate the damage. The strain values were analyzed using One-way ANOVA and Tukey test, all with α = 5%. ResultsANOVA revealed that the Total plastic showed less implant damage (-0.07 ± -0.03 mm) than the Plastic with CoCr base (-0.08 ± -0.04 mm) and the Titanium (-0.10 ± -0.01 mm) frameworks. Therefore, the framework type to manufacture implant-supported temporary crowns influences the fatigue survival of the restoration and the implant platform damage. The Plastic with CoCr base and Titanium frameworks showed superior reliability than the Total plastic framework which could not survive 600,000 cycles. ConclusionsThe Plastic with CoCr base and the Titanium framework are suitable for restorations over 3 months in use, without a difference in the implant platform damage. Key words:Implant dentistry, axial loading, occlusion, methodo­logical study.

Effect of modified tray design on accuracy of different impression techniques for parallel and divergent implants.

This study evaluated the effect of a modified tray design on the accuracy of implant impressions in comparison with the non-splinted and splinted impression techniques. Two titanium frameworks were produced to fit two parallel implants and two divergent implants with a 15o angle. According to the frameworks employed, two acrylic resin master models were fabricated. For each model, 10 impressions were taken with every technique. The maximum framework principal strain was calculated for every generated cast. For the parallel implant model, the strains of the non-splinted (118.4 με), splinted (89.0 με), and modified tray design impression (49.4 με) techniques were statistically similar (P = 0.16). For the divergent implant model, all the impression techniques showed a considerably higher strain than the parallel implant model. The splinted (287.0 με) and the modified (262.9 με) tray design impression techniques showed similar strains for the divergent implant model, which were significantly less than the strains for the non-splinted impression (518.0 με) technique (P < 0.05). Therefore, for two parallel implants, all the impression techniques exhibited similar accuracy. When angulation existed between the implants, the splinted and the modified tray design impression techniques were more accurate than the non-splinted impression technique.

Heterometallic Titanium-Organic Frameworks as Dual Metal Catalysts for Synergistic Non-Buffered Hydrolysis of Nerve Agent Simulants

Heterometallic or mixed-metal Metal-Organic Frameworks (MOFs), incorporating two or more metal ions to the inorganic node of the frameworks, are increasingly gaining importance as a route to produce materials with increasing chemical and functional complexity. Heterometallic MOFs can offer important advantages over their homometallic counterparts to enable targeted modification of the adsorption properties, structural response, electronic structure or chemical reactivity of the framework. This field is still in its infancy likely due to the difficulties of controlling the formation of heterometallic nodes by direct synthesis. This restriction is even more acute in the case of titanium frameworks for which their challenging chemistry renders post-synthetic doping of preformed materials as the only route available. However, this often results in partial or non-homogeneous metal substitution in detriment of the potential benefits of controlling metal distribution at an atomic level toward performance improvement. We report the first family of heterometallic titanium frameworks that can be prepared by direct synthesis from metal precursors and trimesic acid. MUV-101 frameworks [TiM2(µ3-O)(O2CR)6X3] (M = Mg, Fe, Co, Ni; X = H2O, OH-, O2-) combine mesoporosity with good chemical stability. We use these materials to exemplify the advantages of controlling metal distribution across the framework in heterogeneous catalysis by exploring their activity toward the degradation of a nerve agent simulant of Sarin gas. MUV-101(Fe) is the only pristine MOF capable of catalytic degradation of (diisopropyl-fluorophosphate) DIFP in non-buffered aqueous media without the presence of a basic/nucleophilic co-catalyst. Compared to MUV-101(Fe), other titanium heterometallic and homometallic MOFs as MUV-101(Mg, Co and Ni), MUV-10(Mn), MIL-100(Ti and Fe) or UiO-66(Zr), all display a poorer performance or are poisoned by the degradation products. The catalytic activity of MUV-101(Fe) cannot be explained only by the association of Ti(IV) and Fe(III) but to their synergistic cooperation. Our simulations suggest that the combination of Ti(IV) Lewis acid and Fe(III)-OH Bronsted base sites in this dual metal catalyst leads to a much lower energy barrier for more efficient degradation of DIFP in absence of a base. Overall, this mechanism resembles the activity of the metalloenzyme purple acid phosphatase that displays also bimetallic active sites.

Analysis of fit on implants of chrome cobalt versus titanium frameworks made by cad / cam milling.

BackgroundThis study analyzed the degree of passive and vertical fit achieved in frameworks using either cobalt-chromium (Co-Cr) or titanium (Ti) implant-supported fixed partial dentures ( FPDs) fabricated with a CAD/CAM milling technique. Material and Methods33 3-unit FDPs, 17 of Co-Cr metal alloy (test group) and 16 of Ti (control group), were manufactured with two implants by copy milled technology. Optical microscopy was used to measure passive fit (PF) and vertical fit (VF) in all frameworks. The PF was evaluated by using the Single Screw test and the VF with the screws tightened at 20 Ncm. Descriptive and inferential analysis were performed to evaluate statistically significant differences in the tested groups for each fit. Brunner-Langer models were applied to assess potential material and implant area effects on the measurements. An ANOVA test was performed to estimate both main effects and interactions. ResultsThe average PF values in the screwed implant were 4.43 ± 0.52 µm for Ti and 5.50 ± 1.61 µm for Co-Cr and in the non-screwed implant 5.59 ± 1.32 µm in the group Ti and 6.25 ± 1.55 µm the Co-Cr group. In this last implant, it was not observed statistically significant differences between both types of alloy (p = 0.178) nor between zones. Ti control group exhibited a significantly better VF than Co-Cr (p = 0.046) in the screwed implant but there were no differences in the implant not screwed. The VF in the non-screwed implant was better in lingual than in buccal zone. ConclusionsThe PF and VF measurements observed in Co-Cr frameworks are clinically acceptable. 3-unit implant supported FPDs made with Co-Cr alloy using milling technique showed similar dimensional accuracy than those obtained with Ti. Key words:Cobalt- chromium alloy, misfit, passive fit, vertical fit, milling.

Effect of Framework Type on the Biomechanical Behavior of Provisional Crowns: Strain Gauge and Finite Element Analyses.

The aim of this study was to evaluate the effects of different frameworks on the biomechanical behavior of implant-supported provisional single crowns to indicate or not the use of plastic framework as infrastructure. For finite element analysis, a hemi-jaw stone model was scanned and modeled with an external hexagon implant. A framework was screwed onto the implant and a crown was constructed over it. The set was made in triplicate according to framework type: plastic, cobalt-chromium (CoCr), and titanium. Models were exported in volumetric format to analysis software where structures were considered isotropic, linear, elastic, and homogeneous. Axial loads (100, 200, and 300 N) were applied to the fossa bottom, and the system's fixation occurred on the bone base. For strain-gauge analysis, the same hemi-jaw model was built in polyurethane and an implant was placed on it. Three crowns were made, each one with a different framework. Four strain gauges were glued around the implant to obtain microstrain values. The data were analyzed by three-way analysis of variance (ANOVA) and Tukey tests (P < .05). Finite element analysis exhibited microstrain results for bone, von Mises stress values for the implant and screw, and maximum principal stress values for the crown. For computational method, as the applied load increased, so did the stress generated. Titanium frameworks concentrated more stress in the crown and bone, while plastic ones concentrated more in the implant and screw. ANOVA showed that the higher the load value and the framework elastic modulus, the higher the generated microstrain in bone. It can be concluded that all evaluated framework types can be used in the manufacturing of provisional crowns.

Biomechanical effect of implant design on four implants supporting mandibular full-arch fixed dentures: In vitro test and finite element analysis

Impact of the implant shape on the biomechanical performance of all-on-four treatment of dental implant is still unclear. This study evaluated the all-on-four treatment with four osseointegrated implants in terms of the biomechanical effects of implant design and loading position on the implant and surrounding bone by using both invitro strain gauge tests and three-dimensional (3D) finite element (FE) analyses. Both invitro and 3D FE models were constructed with placing NobelSpeedy and NobelActive implants as well as a titanium framework in an edentulous jawbone based on the concept of all-on-four treatment. Three types of loads were applied: at the central incisor area (loading position 1) and at the molar regions with (loading position 2) and without (loading position 3) the denture cantilever. For the invitro tests, the principal bone strains were recorded by rosette strain gauges and statistically evaluated using Wilcoxon's rank-sum test. The 3D FE simulations analyzed the peak von-Mises stresses in the implant and surrounding cortical bone. The peak stress and strain in the surrounding bone were typically 36-62% (3D FE analysis) and 47-57% (invitro test) (p<0.001)higher for loading position 3 than for loading positions 1 and 2. Between those two implant designs, the bone strains and bone stresses did not differ significantly. For all-on-four treatment with four osseointegrated dental implants, altering the implant design does not appear to affect the biomechanical performance of the entire treatment, especially in terms of the stresses and strains in the surrounding bone.

3D Finite Element analysis of patients with full titanium framework on four zygomatic fixtures allows comparison of biomechanical behaviour of the zygomatic implants and of the prosthesis following different techniques of positioning of zygomatic fixtures: A case report

3D Finite Element analysis of patients with full titanium framework on four zygomatic fixtures allows comparison of biomechanical behaviour of the zygomatic implants and of the prosthesis following different techniques of positioning of zygomatic fixtures: A case report