Mechanical properties and in vitro cytocompatibility of dense and porous Ti-6Al-4V ELI manufactured by selective laser melting technology for biomedical applications

A forecasting model for suitable dental implantation in canine mandibular premolar region based on finite element analysis

In recent years, dental implants have become a trend in the treatment of human patients with missing teeth, which may also be an acceptable method for companion animal dentistry. However, there is a gap challenge in determining appropriate implant sizes for different dog breeds and human. In this study, we utilized skull computed tomography data to create three-dimensional models of the mandibles of dogs in different sizes. Subsequently, implants of various sizes were designed and subjected to biomechanical finite element analysis to determine the optimal implant size. Regression models were developed, exploring the relationship between the average weight of dogs and the size of premolar implants. Our results illustrated that the regression equations for mean body weight (x, kg) and second premolar (PM2), third premolar (PM3), and fourth premolar (PM4) implant length (y, mm) in dogs were: y = 0.2785x + 7.8209, y = 0.2544x + 8.9285, and y = 0.2668x + 10.652, respectively; the premolar implant diameter (mm) y = 0.0454x + 3.3506, which may provide a reference for determine suitable clinical implant sizes for dogs.

Biomechanics of Dental Implantation in the Giant Panda (Ailuropoda melanoleuca): A Comparative Study Using Finite Element Analysis

Giant pandas have a high incidence of tooth wear, loss, and fracture since their diet is specifically bamboo. Dental implantation is a common treatment for tooth loss in humans while rarely reported in wild animals. To explore the applicability of dental implantation in giant pandas, this study measured mandible parameters of the giant panda, from an adult skeletal specimen. The mandible bone block model was developed using computer-aided design 3D mechanical drawing software. Implants of different radius and thread types of the third premolar tooth (PM3) were assembled and imported into an analysis software system for finite element analysis. As a result, the reverse buttress implant with a radius of 7.5 mm and 8.3 mm, and a length of 15 mm was found to be the most suitable implant for use in the giant panda PM3. This study provides a reference for appropriate clinical giant panda dental implantation, although, the feasibility of giant panda dental implantation needs to be studied further.

Wear at the implant-framework interface between titanium implant platform and the additively manufactured titanium and cobalt-chromium frameworks

PURPOSE

To measure the wear at the implant interface between the Grade 4 titanium (Ti) of the implant and frameworks fabricated using two additively manufactured alloys (Ti alloy and cobalt-chromium [Co-Cr]) pre- and post-artificial aging.

MATERIAL AND METHODS

Three-unit frameworks supported by two implants were additively manufactured (Atlantis; Dentsply Sirona) using Ti and Co-Cr dental alloys. Two implants (OsseoSpeed EV, Astra Tech; Dentsply Sirona) were torqued on each non-engaging framework. The assembled implant-frameworks were secured into polyurethane foam blocks. Groups were created based on the material and surface assessed: framework (Ti-framework and Co-Cr-framework groups) and implant (Ti-implant group). Two subgroups were created depending on the location: premolar (PM) and molar (M). Computed tomography images were obtained pre- (as manufactured) and post-simulated mastication procedures. The pre- and post-simulated mastication files of each specimen were aligned using the best-fit algorithm using a metrology program. Wear was measured by calculating the volumetric discrepancies at the implant interface on 64 measurement points per area analyzed. Three-way ANOVA and Tukey tests were used to analyze the data (α = 0.05).

RESULTS

The mean volumetric discrepancy values ranged from 0.8 to 3.1 µm among all the subgroups tested. The group (framework vs. implant) (p < 0.001) and tooth location (p < 0.001) were significant factors of the mean volumetric discrepancy values obtained. The framework group presented with significantly lower volumetric discrepancy mean values (1 µm) compared with the implant group (3 µm), whereas the premolar area obtained significantly lower mean volumetric discrepancy values (1.9 µm) compared with the molar location (2.3 µm).

CONCLUSIONS

Volumetric discrepancies were found at the implant-framework interface tested between the pre- and post-artificial aging measurements ranging from 1 to 3 µm after 1,200,000 cyclic loading that simulated approximately 12 months of function.

Spatial Topological Structure Design of Porous Ti-6Al-4V Alloy with Low Modulus and Magnetic Susceptibility

Ti-6Al-4V alloy is widely used as a biomaterial for hard tissue replacement, but its Young's modulus is still higher than that of human bone tissue, which may cause a "stress shielding" effect and lead to implant loosening. In addition, metal implants with low magnetic susceptibility are beneficial for obtaining minimal artifacts in magnetic resonance imaging. To reduce Young's modulus and magnetic susceptibility of Ti-6Al-4V alloy, a series of irregular prismatic porous structure models were designed based on the Voronoi principle, built by changing the irregularity, prism-diameter-to-initial-seed-spacing ratio, and seed number, and studied using finite-element analysis. Porous samples were prepared by selective laser melting and subjected to a compression test and magnetic susceptibility test. The simulation results show that the prism-diameter-to-initial-seed-spacing ratio has the greatest impact on porosity compared with the irregularity and seed number. The simulation-predicted porosity and compression modulus are highly consistent with the measured ones. The irregular prismatic porous Ti-6Al-4V samples exhibit mechanical properties similar to those of human bones and show a magnetic susceptibility of no more than 50% that of compact Ti-6Al-4V. A regulatable irregular prismatic porous structure is feasible for designing porous implants with desirable properties for biomedical applications.

3D printing for bone regeneration: challenges and opportunities for achieving predictability

3D printing offers attractive opportunities for large-volume bone regeneration in the oro-dental and craniofacial regions. This is enabled by the development of CAD-CAM technologies that support the design and manufacturing of anatomically accurate meshes and scaffolds. This review describes the main 3D-printing technologies utilized for the fabrication of these patient-matched devices, and reports on their pre-clinical and clinical performance including the occurrence of complications for vertical bone augmentation and craniofacial applications. Furthermore, the regulatory pathway for approval of these devices is discussed, highlighting the main hurdles and obstacles. Finally, the review elaborates on a variety of strategies for increasing bone regeneration capacity and explores the future of 4D bioprinting and biodegradable metal 3D printing.

Influence of the roughness of dental implants obtained by additive manufacturing on osteoblastic adhesion and proliferation: A systematic review

Objective

Critically analyzed the existing literature to answer the question "What is the influence of roughness of surfaces for dental implants obtained by additive manufacturing compared to machined on osteoblastic cell adhesion and proliferation?"

Design

This systematic review followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was registered in the Open Science Framework. The personalized search strategy was applied to Embase, Pub Med, Scopus, and Science Direct databases and Google Scholar and ProQuest grey literature. The selection process was carried out in two stages independently by two reviewers according to the eligibility criteria. The risk of bias was analyzed using a checklist of important parameters to be considered.

Results

When applying the search strategy on databases 223 articles were found, after removing the duplicates, 171 were analyzed by title and abstract of which 25 were selected for full reading, of these, 6 met the eligibility criteria. 2 studies were included from the reference list totaling 8 articles included in this systematic review and none were included from the Grey Literature. 7 had a low risk of bias and 1 moderate.

Conclusions

1) Roughness is a property that must be analyzed and correlated with the chemical composition, intrinsic to the alloy and resulting from the surface treatment; morphology of topographic peaks and valleys; printing technique and its parameters; 2) Need for more studies on the biomolecular level to elucidate the mechanism by which the roughness and the morphology of topographical peaks and valleys descriptive of roughness influence osteoblastic adhesion and proliferation.

Numerical Investigation of the Defects Effect in Additive Manufactured Ti-6Al-4V Struts on Deformation Behavior Based on Microtomographic Images

This paper describes the influence of defects occurring in struts under tension, obtained using the additive method of laser powder bed fusion (LPBF), on the stress and strain distributions. The study used struts of different thicknesses separated from Ti-6Al-4V diamond lattice structures. For numerical modeling of stress and strain fields, models that reflect the realistic shape of the tested struts with their imperfections were used. The shape of the diamond structure struts was obtained based on microtomographic measurements. Based on the results obtained, the influence of defects in the material structure on the stress and strain distribution was analyzed. It was observed that the main factor influencing the stress and strain distribution in the struts are micronotches on their external surface. These imperfections have a significantly greater impact on the stress and strain concentration than the micropores inside. Furthermore, the interactions of the imperfections are also important, which in turn affects the stress distributions and the formation of bands of high-stress values inside the material. The relationship between the presence of micropores, the stress–strain curves, and the mechanical properties of the material was also assessed.

Success Factors of Additive Manufactured Root Analogue Implants

Dental implantation is an effective method for the treatment of loose teeth, but the threaded dental implants used in the clinic cannot match with the tooth extraction socket. A root analogue implant (RAI) has the congruence shape, which reduces the damage to bone and soft tissue. Additive manufacturing (AM) technologies have the advantages of high precision, flexibility, and easy operation, becoming the main manufacturing method of RAI in basic research. The purpose of this systematic review is to summarize AM technologies used for RAI manufacturing as well as the factors affecting successful implantation. First, it introduces the AM technologies according to different operating principles and summarizes the advantages and disadvantages of each method. Then the influences of materials, structure design, surface characteristics, implant site, and positioning are discussed, providing reference for designers and dentists. Finally, it addresses the gap between basic research and clinical application for additive manufactured RAIs and discusses the current challenges and future research directions for this field.