Mechanical properties, surface morphology and stability of a modified commercially pure high strength titanium alloy for dental implants

Recent development and applications of electrodeposition biocoatings on medical titanium for bone repair

Bioactive coatings play a crucial role in enhancing the osseointegration of titanium implants for bone repair. Electrodeposition offers a versatile and efficient technique to deposit uniform coatings onto titanium surfaces, endowing implants with antibacterial properties, controlled drug release, enhanced osteoblast adhesion, and even smart responsiveness. This review summarizes the recent advancements in bioactive coatings for titanium implants used in bone repair, focusing on various electrodeposition strategies based on material-structure synergy. Firstly, it outlines different titanium implant materials and bioactive coating materials suitable for bone repair. Then, it introduces various electrodeposition methods, including electrophoretic deposition, anodization, micro-arc oxidation, electrochemical etching, electrochemical polymerization, and electrochemical deposition, discussing their applications in antibacterial, osteogenic, drug delivery, and smart responsiveness. Finally, it discusses the challenges encountered in the electrodeposition of coatings for titanium implants in bone repair and potential solutions.

Locally released dexamethasone and its effects on osteogenic activity at implant-tissue interface

The osseointegration of titanium implants within the host tissue holds crucial importance. The introduction of functional coatings at tissue-implant interface enhances the bioactivity of titanium implants, improves their therapeutic outcomes, and enhances the effectiveness of treatments. In this study, we focused on enhancing the bioactivity of titanium-based implant materials by coating the titanium surfaces with chitosan microspheres, which are loaded with osseointegration-promoting agent dexamethasone (DEX). Initially, chitosan microspheres were successfully produced, followed by DEX loading through diffusion, resulting in a drug loading efficiency of around 50.2 (wt %). The subsequent drug release profile displayed a 24-hour duration, releasing approximately 32.6 (wt %) of the loaded DEX. In cell proliferation assays using human osteosarcoma (SAOS-2) cells, Ti surfaces coated with DEX-loaded chitosan microspheres initially exhibited lower cell numbers compared with DEX-free ones. This observation was attributed to transient osteogenic differentiation effects of DEX, since a notable increase in cell proliferation was observed on the 7th day. Von Kossa staining revealed mineralization beginning on the 14th day, particularly evident in DEX-loaded samples. Moreover, alkaline phosphatase (ALP) activity displayed a pattern of initial increase and subsequent decrease, with DEX release from chitosan microspheres showing a clear influence on the osteogenic differentiation, especially on the 7th day. These findings align with literature, highlighting DEX's potential to enhance osteogenic differentiation and cellular behavior on chitosan microsphere-coated titanium surfaces. This study emphasizes the promising implications for functionalizing surfaces of implant materials with DEX-loaded chitosan microspheres to improve their biocompatibility and bioactivity.

Controlled Lateral Pressure on Cortical Bone Using Blade-Equipped Implants: An Experimental Study in Rabbits

BACKGROUND

This study aimed to evaluate the biological behavior of a novel implant design incorporating decompressive cervical blades. Hence, the aim of the present study was to evaluate the healing outcomes in cortical regions where decompressive protocols were implemented using implants equipped with blades and installed applying a bicortical anchorage.

MATERIALS AND METHODS

Blades with varying diameters were integrated into the coronal portion of the implant to prepare the cortical region of rabbit tibiae. The blade diameters differed from the implant collar by the following amounts: control group (0 µm), +50 µm, and +200 µm.

RESULTS

No marginal bone loss was detected. Instead, all implants exhibited new bone formation in the coronal region. Complete closure was observed in the CG-0 group, as well as in the TG-50 and TG-200 groups, despite the presence of marginal gaps without primary bone contact at installation. In the apical region, most implants breached the cortical layer. Nevertheless, new bone formation in this region completely closed the osteotomy, effectively isolating the internal environment of the tibia from the external.

CONCLUSIONS

The use of a blade incorporated into the implant body enabled precise preparation of the cortical layer, allowing for controlled decompression in the targeted area. This technique resulted in optimal osseointegration with no loss of marginal bone, and complete restoration of marginal gaps ranging from 0 µm to 200 µm.

An epidemiological qualitative/quantitative SWOT-AHP analysis in order to highlight the positive or critical aspects of dental implants: A pilot study

OBJECTIVES

In recent years, dental implants are increasing in popularity due to their high success rate, demonstrated functionality, and aesthetic treatment results. Scientific research is very active in proposing improvements in the quality and survival of implants, taking into consideration various aspects. The objective of this study was to provide a holistic epidemiologic view of the state of dental implants, using a systematic approach based on a multimethod SWOT (Strengths, Weaknesses, Opportunities, and Threats) analysis and AHP (analytical hierarchical process) qualitative-quantitative analysis to identify the characteristics that can determine their success or failure.

MATERIALS AND METHODS

The study used the hybrid method of SWOT-AHP.

RESULTS

Analysis of the results showed that among strengths, the skill of the dentist was considered the most important factor, followed by the success of dental implants in the old people; among weaknesses, bruxism and chronic diseases were highlighted; for opportunities, biomechanical behavior, in terms of good mechanical strength and good tribological resistance to chemical and physical agents in the oral cavity, were considered the most important factors; finally, among threats, medical liability and biomechanical problems had equal weight.

CONCLUSIONS

This study applied a multimethod SWOT-AHP approach to bring out favorable or critical evidence on the topic of dental implants. In accordance with the result of the strategic vector identified in the Twisting zone Adjustment type section, showed that implant surgery is a widespread technique but always needs improvement to increase the likelihood of success and reduce the complications that can lead to implant failure.

Surface Modification and Functionalities for Titanium Dental Implants

Dental implants have become the mainstream strategy for oral restoration, and implant materials are the most important research hot spot in this field. So far, Ti implants dominate all kinds of implants. The surface properties of the Ti implant play decisive roles in osseointegration and antibacterial performance. Surface modifications can significantly change the surface micro/nanotopography and composition of Ti implants, which will effectively improve their hydrophilicity, mechanical properties, osseointegration performance, antibacterial performance, etc. These optimizations will thus improve implant success and service life. In this paper, the latest surface modification techniques of Ti dental implants are systematically and comprehensively reviewed. The various biomedical functionalities of surface modifications are discussed in-depth. Finally, a profound comment on the challenges and opportunities of this frontier is proposed, and the most promising directions for the future were explored.

Nanotechnology for Dentistry: Prospects and Applications

In the XXI century, application of nanostructures in oral medicine has become common. In oral medicine, using nanostructures for the treatment of dental caries constitutes a great challenge. There are extensive studies on the implementation of nanomaterials to dental composites in order to improve their properties, e.g., their adhesive strength. Moreover, nanostructures are helpful in dental implant applications as well as in maxillofacial surgery for accelerated healing, promoting osseointegration, and others. Dental personal care products are an important part of oral medicine where nanomaterials are increasingly used, e.g., toothpaste for hypersensitivity. Nowadays, nanoparticles such as macrocycles are used in different formulations for early cancer diagnosis in the oral area. Cancer of the oral cavity-human squamous carcinoma-is the sixth leading cause of death. Detection in the early stage offers the best chance at total cure. Along with diagnosis, macrocycles are used for photodynamic mechanism-based treatments, which possess many advantages, such as protecting healthy tissues and producing good cosmetic results. Application of nanostructures in medicine carries potential risks, like long-term influence of toxicity on body, which need to be studied further. The introduction and development of nanotechnologies and nanomaterials are no longer part of a hypothetical future, but an increasingly important element of today's medicine.

The development of carbohydrate polymer- and protein-based biomaterials and their role in environmental health and hygiene: A review

Biological macromolecules have been significantly used in the medicine due to their certain therapeutic values. Macromolecules have been employed in medical filed in order to enhance, support, and substitute damaged tissues or any other biological function. In the past decade, the biomaterial field has developed considerably because of vast innovations in regenerative medicine, tissue engineering, etc. Different types of biological macromolecules such as natural protein and polysaccharide etc. and synthetic molecules such as metal based, polymer based, and ceramic based etc. have been discussed. These materials can be modified by coatings, fibres, machine parts, films, foams, and fabrics for utilization in biomedical products and other environmental applications. At present, the biological macromolecules can used in different areas like medicine, biology, physics, chemistry, tissue engineering, and materials science. These materials have been used to promote the healing of human tissues, medical implants, bio-sensors and drug delivery, etc. These materials also considered as environmentally sustainable as they are prepared in association with renewable natural resources and living organisms in contrast to non-renewable resources (petrochemicals). In addition, enhanced compatibility, durability and circular economy of biological materials make them highly attractive and innovative for current research.The present review paper summarizes a brief about biological macromolecules, their classification, methods of synthesis, and their role in biomedicine, dyes and herbal products.

Effect of internal design changes on the mechanical properties of laser-sintered cobalt-chromium specimens

STATEMENT OF PROBLEM

Changing the internal design of a metal framework may decrease the manufacturing time, the weight of the restoration, and the amount of alloy powder used, as well as simplify the fabrication process.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of framework internal design changes on the mechanical properties of cobalt-chromium (Co-Cr) specimens manufactured by using direct metal laser sintering (DMLS).

MATERIAL AND METHODS

Dumbbell-shaped test specimens were designed as per the International Organization for Standardization (ISO) 22674(E) standard by using a 3-dimensional software program. A total of 70 dumbbell-shaped specimens were prepared by using Co-Cr alloy powder and DMLS (n=10). The control group specimens were solid with the internal completely filled. For the test groups, the internal design of the dumbbell-shaped specimens was modified. Leaving the outer shell thickness of the specimens at 0.5 mm for all test groups, 6 different internal designs were created, and the specimens were weighed. The tensile strength test was used to evaluate the mean peak strength, elastic modulus, and percentage elongation of the specimens. One-way ANOVA followed by the Dunnett T3 test was used for statistical analysis (α=.05).

RESULTS

A statistically significant difference was found among the groups in terms of bar weight and peak strength (P<.05). The highest values were observed in the control group for all evaluated parameters (mean ±standard deviation bar weight: 1321.3 ±36.6 mg, peak strength: 1045 ±36.7 MPa, elastic modulus: 284.2 ±71.9 GPa, and elongation: 28.7 ±7%). However, no statistically significant difference was observed for elastic modulus or percentage of elongation (P>.05).

CONCLUSIONS

Decreasing the weight of the frameworks by changing the internal design of the specimens also decreased the peak strength. However, it did not affect the elastic modulus or the percentage of elongation.

Osseointegration of Titanium Implants in a Botox-Induced Muscle Paralysis Rat Model Is Sensitive to Surface Topography and Semaphorin 3A Treatment

Reduced skeletal loading associated with many conditions, such as neuromuscular injuries, can lead to bone fragility and may threaten the success of implant therapy. Our group has developed a botulinum toxin A (botox) injection model to imitate disease-reduced skeletal loading and reported that botox dramatically impaired the bone formation and osseointegration of titanium implants. Semaphorin 3A (sema3A) is an osteoprotective factor that increases bone formation and inhibits bone resorption, indicating its potential therapeutic role in improving osseointegration in vivo. We first evaluated the sema3A effect on whole bone morphology following botox injections by delivering sema3A via injection. We then evaluated the sema3A effect on the osseointegration of titanium implants with two different surface topographies by delivering sema3A to cortical bone defect sites prepared for implant insertion and above the implants after insertion using a copper-free click hydrogel that polymerizes rapidly in situ. Implants had hydrophobic smooth surfaces (PT) or multiscale biomimetic micro/nano topography (SLAnano). Sema3A rescued the botox-impaired bone formation. Furthermore, biomimetic Ti implants improved the bone-to-implant contact (BIC) and mechanical properties of the integrated bone in the botox-treated rats, which sema3A enhanced. This study demonstrated the value of biomimetic approaches combining multiscale topography and biologics in improving the clinical outcomes of implant therapy.

Corrosion and wear behavior of Ti-5Cu-xNb biomedical alloy in simulated body fluid for dental implant applications

The present study examined the corrosion and tribological behavior of novel Ti-5Cu-xNb alloy synthesized via powder metallurgy as a new biomedical material in a simulated bodily fluid (SBF) solution. The electrochemical impedance spectroscopy (EIS) study reveals the formation of two protective layers on the surface of alloys during the test. The alloys spontaneously produce a passivating oxide coating on their surfaces, and the breakdown potential (1.14-1.17 V) and re-passivation current density (2.07-3.04 μAcm^-2) were observed during the potentiodynamic polarization test. The highest corrosion resistance was observed for the alloy Ti-5Cu-10Nb (i_corr = 21.44 nA-cm^-2). The SEM and XPS analysis of the corroded surface showed the formation of oxide on the surfaces of the alloys. The samples were tested at 10 N, 15 N, and 20 N loads against the zirconia counterpart to investigate the effect of loading on friction and wear. The lowest coefficient of friction was obtained for Ti-5Cu-5Nb (0.25-0.41) at 20 N loading, while the maximum for Ti-5Cu-10Nb at 15 N load falls in the range of (0.71-0.25). Additionally, they present the wear rate in the range of (5.3 × 10^-8-1.45 × 10^-6 mm³/mm), in accordance with the change in microstructure and mechanical properties. However, the wear rate increases with the addition of niobium and reaches the maximum for Ti-5Cu-15Nb at 20 N loading condition, but it is relatively deficient compared to commonly used implant material. Therefore, it is suggested that this β-type Ti-5Cu-xNb alloy is a promising candidate, more suitable than the commercially used Ti and Ti-6Al-4V for dental applications.

Surface modification of new innocuous Ti-Mo-Zr based alloys for biomedical applications

To address the clinical challenges of modulus mismatch, lack of initial osteointegration and contain toxic elements towards traditional titanium and its alloys with surrounding bone tissue, a new β-type titanium alloy (Ti-12Mo-10Zr) designed by our group will be chosen as dental implant in this proposal due to its excellent properties, e.g. low young's modulus (~ 50.8 GPa) and excellent compressive yield strength (~ 430.89 MPa). A modified hydrothermal and pressure method will be deployed to create tailored micro/nano topography and chemistry (phosphorus) on implant surface with the aim of promoting osteointegration. The formation process and mechanism of micro/nano-scaled hierarchical hybrid coating containing phosphorous will be revealed from the perspective of energetics and crystallography to realize co-design of multiple structure and chemical on Ti-12Mo-10Zr surface. The in vitro cytological performance of this hierarchical hybrid coating containing phosphorous will also be evaluated by co-culturing with rat bone marrow stromal cells This proposal will not only provide guidance and experimental database for next generation potential implant named Ti-12Mo-10Zr, but also display new insights to improve long-lasting stability for dental implant which demonstrate tremendous scientific significance.

Hydroxyapatite Coating on Ti-6Al-7Nb Alloy by Plasma Electrolytic Oxidation in Salt-Based Electrolyte

Titanium alloys have good biocompatibility and good mechanical properties, making them particularly suitable for dental and orthopedic implants. Improving their osseointegration with human bones is one of the most essential tasks. This can be achieved by developing hydroxyapatite (HA) on the treating surface using the plasma electrolytic oxidation (PEO) method in molten salt. In this study, a coating of titanium oxide-containing HA nanoparticles was formed on Ti-6Al-7Nb alloy by PEO in molten salt. Then, samples were subjected to hydrothermal treatment (HTT) to form HA crystals sized 0.5 to 1 μm. The effect of the current and voltage frequency for the creation of the coating on the morphology, chemical, and phase composition was studied. The anti-corrosion properties of the samples were studied using the potentiodynamic polarization test (PPT) and electrochemical impedance spectroscopy (EIS). An assessment of the morphology of the sample formed at a frequency of 100 Hz shows that the structure of this coating has a uniform submicron porosity, and its surface shows high hydrophilicity and anti-corrosion properties (4.90 × 10⁶ Ohm·cm²). In this work, for the first time, the process of formation of a bioactive coating consisting of titanium oxides and HA was studied by the PEO method in molten salts.

Fabrication and mechanical properties of different types of carbon fiber reinforced polyetheretherketone: A comparative study

OBJECTIVES

To find alternative non-metallic materials as dental implants for clinical application, different types of carbon fiber reinforced polyetheretherketone were fabricated and investigated.

METHODS

Continuous carbon fiber reinforced polyetheretherketone fabrics were fabricated with polyetheretherketone fibers and carbon fibers. Different kinds of carbon fiber reinforced polyetheretherketone were synthesized by setting specific experiment parameters of injection or hot press molding. Various mechanical tests were performed to determine the mechanical properties of different carbon fiber reinforced polyetheretherketone, pure polyetheretherketone and pure titanium.

RESULTS

Polyetheretherketone composites presented outstanding mechanical and thermal properties after incorporating carbon fiber. The bending and tensile strength of short carbon fiber reinforced polyetheretherketone were close to human bone, and the bending strength of continuous carbon fiber reinforced polyetheretherketone reached 644 MPa, even higher than that of pure titanium.

CONCLUSIONS

The mechanical properties of polyetheretherketone composites are more similar to bone tissue than titanium, and the stress shielding phenomenon may be inhibited. They may become promising materials as substitutions for titanium and prospective materials in bone tissue engineering.

Effects of Different Titanium Surface Treatments on Adhesion, Proliferation and Differentiation of Bone Cells: An In Vitro Study

The objective of this study was to evaluate the impacts of different sandblasting procedures in acid etching of Ti6Al4V surfaces on osteoblast cell behavior, regarding various physicochemical and topographical parameters. Furthermore, differences in osteoblast cell behavior between cpTi and Ti6Al4V SA surfaces were evaluated. Sandblasting and subsequent acid etching of cpTi and Ti6Al4V discs was performed with Al2O3 grains of different sizes and with varying blasting pressures. The micro- and nano-roughness of the experimental SA surfaces were analyzed via confocal, atomic force and scanning electron microscopy. Surface free energy and friction coefficients were determined. hFOB 1.19 cells were seeded to evaluate adhesion, proliferation and osteoblastic differentiation for up to 12 d via crystal violet assays, MTT assays, ALP activity assays and Alizarin Red staining assays. Differences in blasting procedures had significant impacts on surface macro- and micro-topography. The crystal violet assay revealed a significant inverse relationship between blasting grain size and hFOB cell growth after 7 days. This trend was also visible in the Alizarin Red assays staining after 12 d: there was significantly higher biomineralization visible in the group that was sandblasted with smaller grains (F180) when compared to standard-grain-size groups (F70). SA samples treated with reduced blasting pressure exhibited lower hFOB adhesion and growth capabilities at initial (2 h) and later time points for up to 7 days, when compared to the standard SA surface, even though micro-roughness and other relevant surface parameters were similar. Overall, etched-only surfaces consistently exhibited equivalent or higher adhesion, proliferation and differentiation capabilities when compared to all other sandblasted and etched surfaces. No differences were found between cpTi and Ti6Al4V SA surfaces. Subtle modifications in the blasting protocol for Ti6Al4V SA surfaces significantly affect the proliferative and differentiation behavior of human osteoblasts. Surface roughness parameters are not sufficient to predict osteoblast behavior on etched Ti6Al4V surfaces.

Analysis of Torque Maintenance and Fracture Resistance after Fatigue in Retention Screws Made of Different Metals for Screw-Retained Implant-Borne Prosthesis Joints

Purpose

The aim was to evaluate the effect of different metallic alloys used in the manufacture of retention screws for universal cast to long abutment (UCLA) abutments for external hexagon (HE) and Morse taper (MT) connection implants, as well as of mechanical cycling on torque maintenance and fracture resistance through electromechanical fatigue testing by mastication followed by compression testing.

Methods

Sixty implants were used, 30 MT and 30 HE, with their respective titanium UCLA abutments and retention screws of 5 different materials (n = 6): Ti cp grade 2, Ti cp grade 4, Ti cp grade 4 hard, Ti grade 5—Ti6Al4V and surgical steel (DSP® Biomedical). The assemblies were positioned in an electromechanical masticatory fatigue testing machine. The fracture strength test was performed by compression testing in a universal testing machine EMICDL-200.

Results

The cycled screws and new screws of each alloy group for each connection type were evaluated, obtaining the maximum force (FM), in order to verify the effect of mechanical cycling. The data were tabulated and submitted to appropriate statistical analysis (α = 0.05).

Conclusion

It was concluded that for the MT, the alloy with the best performance was steel, both in the maintenance of torque and in the compression test, and cycling negatively influenced the maintenance of preload for this connection. The alloy material did not influence torque maintenance for HE. The new screws that were subjected to EMIC showed higher strength. The alloy with the lowest strength was Ti grade 2.

Biomechanical and histological evaluation of four different implant macrogeometries in the early osseointegration process: An in vivo animal study

This study aims to evaluate the effects of implant macrogeometry on the early period of the osseointegration process, comparing four different implant models through biomechanical and histological analysis after implantation in rabbit tibiae. Twenty New Zealand rabbits were used, evaluated at two different times (21 and 28 days) after installation of the implant. Eighty implants with different macrogeometries were used, forming four groups (n = 20 per group): cylindrical implants Ø4.1 mm and 8 mm in length (STRc group); cylindrical-conical implants Ø4.1 mm and 8 mm in length (STRt group); tapered implants Ø4.3 mm and 8 mm in length (NOBt group); and tapered implants with healing chambers Ø4.0 mm and 8 mm in length (MAEt group). Ten samples from each group were analyzed at each proposed time. The initial implant stability quotient (ISQ) was measured by resonance frequency analysis, both at the time of installation and at the time of sacrifice. In the histological sections, the percentage of bone-implant contact (BIC%), newly formed bone, osteoid matrix, and medullary spaces were measured in the pre-determined cortical and medullary bone portion for each sample. The three tapered implant groups (STRt, NOBt, and MAEt) showed higher values for the analyzed parameters in the early osseointegration period, in comparison with the cylindrical implant group (STRc). In all parameters, the three tapered groups showed no difference (p > 0.05); however, all three tapered groups presented significant differences, when compared to the cylindrical group (p < 0.05). No correlation was detected between the parameters analyzed. Within the limitations of the present study, in all parameters analyzed, the tapered implants demonstrated greater results when compared to the cylindrical implants.

3D Printed Multifunctional Ti6Al4V-Based Hybrid Scaffold for the Management of Osteosarcoma

Osteosarcoma is a challenging bone disease which is commonly associated with critically sized bone defects and cancer recurrence. Here, we designed and developed a multifunctional, hierarchical structured bone scaffold which can meet the demanding requirements for osteosarcoma management. The 3D printed Ti6Al4V scaffold with hydrothermally induced TiO2/TiP coating can offer a unique photothermal conversion property for in vitro bone cancer ablation. The scaffold is also infused with drug-laden gelatin/hydroxyapatite nanocomposite, which provides the ideal porous structure for cell adhesion/bone ingrowth and promotes bone regeneration. The scaffold has been thoroughly characterized by SEM/EDX, TEM, XPS, XRD, TGA, and UV-vis, and its in vitro bone cancer ablation efficiency has been validated using MG-63 cells. The hybrid scaffold showed excellent biocompatibility, and its osteointegration function has been demonstrated using an animal model.

Immediate soft-tissue adhesion and the mechanical properties of the Ti-6Al-4V alloy after long-term acid treatment

Close attachment of soft tissues onto implantable devices inside the body is regarded as an optimal condition for preventing complications (e.g., infections and abscess formation around implants, and the migration of small injectable devices). We have recently reported that an α-type commercially pure Ti (CpTi) film after a long-term acid treatment and air drying showed a remarkable soft tissue adhesiveness immediately (i.e., within a few seconds) after the attachment onto soft tissues. Herein, we conducted acid treatment for (α + β)-type Ti-6Al-4V alloys and compared their mechanical properties and the immediate soft-tissue adhesiveness with α-type CpTi. The acid treatment for Ti-6Al-4V also promoted immediate soft-tissue adhesion, although the treatment was less effective than for CpTi. The tensile strength of acid-treated Ti-6Al-4V was much higher than that of acid-treated CpTi or human skin tissues, although the degree of hydrogen embrittlement was more severe than that for CpTi. These results suggest that the small amount of Al in the major α phase and/or the minor β phase of Ti-6Al-4V has a significant influence not only on the mechanical properties but also on the immediate soft-tissue adhesiveness of Ti-based solid-state adhesives after the acid treatment.

Johnson-Cook Parameter Identification for Commercially Pure Titanium at Room Temperature under Quasi-Static Strain Rates

BACKGROUND

To simulate mechanical shocks on an intracranial implant called WIMAGINE®, Clinatec chose a Johnson-Cook model to account for the viscoplastic behavior of grade 2 titanium in a dynamic study using Radioss©.

METHODS

Thirty tensile specimens were subjected to tensile tests at room temperature, and the influence of the strain rate (8 × 10-3 and 8 × 10-2 s-1) and sandblasting was analyzed. Relaxations were included in the tests to analyze viscosity phenomena.

RESULTS

A whole set of parameters was identified for the elastic and plastic parts. Strain rate influence on stress was negligible at these strain rates. As expected, the sandblasting hardened the material during the tests by decreasing the hardening parameters, while local necking occurred at an earlier strain.

CONCLUSIONS

This article provides the parameters of a Johnson-Cook model to simulate the elastoplastic behavior of pure titanium (T40, grade 2) in Finite Element Model (FEM) software.

Mechanical strength of stainless steel and titanium alloy mini-implants with different diameters: an experimental laboratory study

BACKGROUND

The mechanical strength of mini-implants is a critical factor due to their small diameters. Currently, it is not possible to state whether there is a relevant difference between the mechanical properties of stainless steel (SS-MIs) and titanium alloy mini-implants (TA-MIs). The objective of this study was to test the null hypothesis that there is no difference in the mechanical strength of SS-MIs and TA-MIs, and to analyze, by scanning electron microscopy (SEM), the SS-MI, and TA-MI threads resistance to morphological damage after insertion.

METHODS

A standardized sample of 504 SS-MIs and TA-MIs with diameters ranging from 1.2 mm to 1.8 mm was used. Torsional fracture was performed in 154 MIs. Flexural strength of 280 MIs was evaluated at 1 mm and 2 mm-deflection. The threads of 70 MIs were morphologically analyzed by scanning electron microscopy (SEM), before and after their insertion in high-density artificial bone blocks. Comparisons between SS-MIs and TA-MIs were performed with t tests or Mann-Whitney U tests. A multiple linear regression analysis was used to evaluate the influence of variables on the ranging of MI mechanical strength.

RESULTS

SS-MIs had higher fracture torque. The mean difference between the SS-MIs and TA-MIs fracture torque was of 4.09 Ncm. The MI diameter explained 90.3% of the total variation in fracture torque, while only 2.2% was explained by the metallic alloy. The SS-MI group presented a higher deformation force during the 1mm and 2mm-deflection. The mean difference between the flexural strength of SS and TA-MIs at 1 mm and 2 mm-deflection was of 18.21 N and 17.55 N, respectively. There was no noticeable morphological damage to the threads of SS-MIs and TA-MIs.

CONCLUSIONS

The null hypothesis was rejected. SS-MIs were 13.2% and 20.2% more resistant to torsional fracture and deflection, respectively. The threads of the SS-MIs and TA-MIs were not damaged during the insertion and removal process. Thus, the use of SS-MI can reduce the fracture risk without increasing the MI diameter.

The unfavorable role of titanium particles released from dental implants

Titanium is considered to be a metal material with the best biological safety. Studies have proved that the titanium implanted in the bone continuously releases titanium particles (Ti particles), significantly increasing the total titanium content in human body. Generally, Ti particles are released slowly without causing a systemic immune response. However, the continuous increased local concentration may result in damage to the intraepithelial homeostasis, aggravation of inflammatory reaction in the surrounding tissues, bone resorption and implant detachment. They also migrate with blood flow and aggregate in the distal organ. The release of Ti particles is affected by the score of the implant surface structure, microenvironment wear and corrosion, medical operation wear, and so on, but the specific mechanism is not clear. Thus, it difficult to prevent the release completely. This paper reviews the causes of the Ti particles formation, the damage to the surrounding tissue, and its mechanism, in particular, methods for reducing the release and toxicity of the Ti particles.

Dental implant-abutment fracture resistance and wear induced by single-unit screw-retained CAD components fabricated by four CAM methods after mechanical cycling

STATEMENT OF PROBLEM

Computer-aided design and computer-aided manufacturing (CAD-CAM) methodologies allow the fabrication of custom dental implant abutments with a variety of materials and techniques. Studies on the mechanical strength of such components and the wear induced at their coupling interface during mechanical cycling are sparse.

PURPOSE

The purpose of this in vitro study was to measure the wear patterns at the hexagonal platform of dental implants induced by the installation and mechanical cycling of custom abutments fabricated by using 4 different CAD-CAM methods and to determine the compressive static resistance of the implant-abutment combinations.

MATERIAL AND METHODS

A CAD software program was used to design a custom abutment for a single-unit screw-retained external hexagon dental implant crown. The same design file was used to manufacture with 4 CAM methods (N=40): milling and sintering of zirconium dioxide (ZO), cobalt-chromium (Co-Cr) sintered by selective laser melting (SLM), fully sintered machined Co-Cr alloy (MM), and machined and sintered agglutinated Co-Cr alloy powder (AM). Prefabricated titanium abutments were used as a control (TI). Each abutment was installed onto a dental implant (4.1×11 mm), and the specimens were mechanically aged (1 million cycles, 2 Hz, 100N, 37 °C). After mechanical cycling, the hexagonal connection of the dental implants was examined with a scanning electron microscope (SEM), and unused dental implants (NI) were examined as a control (n=10). The images were analyzed with a software program to quantify the areas that showed wear. The implant-abutment combinations were reassembled and submitted to a compression test (1mm/min) with a universal testing machine. The data obtained were submitted to 1-way ANOVA (α=.05).

RESULTS

The mean ±standard deviation fracture load (N) of the specimens of each group were 1005 ±187 (ZO), 1074 ±123 (SLM), 1033 ±109 (MM), 1019 ±149 (AM), and 923 ±129 (TI). These values were statistically similar (P=.213). The mean ±standard deviation wear of the implants in squared-pixels were 1.1 ±0.38×10⁵ (ZO), 2.0 ±0.29×10⁵ (SLM), 1.0 ±0.38×10⁵ (MM), 1.1 ±0.27×10⁵ (AM), 1.1 ±0.33×10⁵ (TI), and 0.51 ±0.29×10⁵ (NI). The results indicated that, although significantly higher than those in in the control group (NI), the wear values found in the groups TI, ZO, MM, and AM were significantly lower than in the SLM group (P<.001).

CONCLUSIONS

The CAD-CAM abutments presented the same mechanical fracture load and wear measurements as the TI group, except for the SLM material, which showed increased wear. The failure mode from the load bearing test was the fracture of the abutments for the ZO group. The implants permanently deformed or fractured for the metal abutment groups.

Evaluation of the Influence of Bone Resorption on Dental Implant Systems Using Taguchi Method and Finite Element Analysis

Dental implants are currently the mainstay of dental restoration procedures. They are used to reestablish normal chewing functions for patients. Several studies have reported their high success rate, but post-op bone resorption at the implant site increases the risk of implant fracture, which is especially significant in the posterior mandibular tooth (PMT) area. This study focused on bone resorption at the PMT area to assess and understand the mechanism of implant failure. This study used three implant systems on the posterior mandibular area. Computer tomography (CT) scans and reverse engineering were used to construct mandible and implant systems. The Taguchi method and finite element analysis (FEA) were used to explore the role of biting force on the components of various implant systems in the development of bone resorption. The results of this study found that when the implant site with bone resorption takes a biting force, the stress on the implant is inversely proportional to implant diameter and proportional to its length. For the stress loading, cortical bone thickness does not play a significant role. Instead, the most significant factor is implant diameter, followed by implant length. For better operation outcomes, it is recommended to use implants of larger diameter and less length. Also, it is recommended to avoid the use of implants less than 4.5 mm in diameter, regardless of the implant system, in order to prevent early implant damage or fracture due to bone resorption.

In-vivo comparison of the Ni-free steel X13CrMnMoN18-14-3 and titanium alloy implants in rabbit femora - A promising steel for orthopedic surgery

A variety of metallic biomaterials is used for fracture fixation. Allergic reactions towards nickel-containing steels urge the need for alternatives. The present study investigated the suitability of the nickel-free stainless steel P2000 in comparison to titanium alloy implants for bone surgical applications in a rabbit femora defect model. Thirty-six rabbits received two different cylindrical implants press-fit inserted into the distal femoral metaphysis. At day 0, 28, and 56, implant ingrowth was monitored by radiography; implant stability was assessed by pull-out torque measurements while bone-to-implant contact (BIC) was determined histomorphometrically. Radiography revealed comparable implant ingrowth after 1 and 2 months for both implant materials. The pull-out force of P2000 tended to be higher than that for titanium at day 28 (p = .076) but the values were comparable at day 56 (p = .905). At day 56, implant fixation was significantly increased compared to the day of surgery for both, P2000 (p = .030) and for titanium alloy (p = .026). Microscopic examination revealed that both implant types appeared to be well integrated and firmly anchored in the bone. BIC ratio of titanium alloy tended to be higher at day 28 (p = .079) but they did not differ significantly at day 56 (p = .711). In the present rabbit femora defect model, the nickel-free stainless steel P2000 provides primary stability and osseointegration comparable to that of titanium alloy implants.

Effect of Surgical Instrumentation Variables on the Osseointegration of Narrow- and Wide-Diameter Short Implants

PURPOSE

The aim of the present study was to systematically analyze how a multifactorial surgical instrumentation approach affects osseointegration on both narrow-diameter and wide-diameter short implants.

MATERIALS AND METHODS

Twelve skeletally mature female sheep were used in the study along with 144 plateau-root-form healing chamber titanium (Ti-6Al-4V) implants (Bicon LLC, Boston, MA), evenly distributed between narrow (3.5 mm) and wide (6.0 mm) diameters. The presence or the absence of irrigation, different drilling speeds, and 2 time points quantifying bone-implant contact (BIC) and bone area fraction occupancy (BAFO) to evaluate the osteogenic parameters around the implants.

RESULTS

There were no signs of inflammation, infection, or failure of the implants observed at either healing period. The narrow 3.5-mm implant, at 6 weeks, yielded significant differences in terms of BIC at a drilling speed of 50 rotations per minute (RPM), with higher values of the samples using irrigation (30.6 ± 6.1%) compared with those without (19.7 ± 6.1%). No statistical differences were detected for 500 and 1,000 RPM with or without irrigation. The wide 6-mm diameter implant showed differences with respect to drilling speed, 500 and 1,000 RPM, with higher values associated with samples subjected to irrigation. BAFO results, for both diameters, only detected statistical differences between the 2 times (3 vs 6 weeks); no statistical differences were detected when evaluating as a function of time, drilling speed, and irrigation.

CONCLUSIONS

Surgical instrumentation variables (ie, drilling speed [RPM] and irrigation) yielded to be more of an effect for BIC at longer healing time (6 weeks) for the wider implants. Furthermore, deploying narrow or wide plateau-root-form implants, where conditions allow, has shown to be a safe alternative, considering the high BIC and BAFO values observed, independent of irrigation.

Cytocompatibility, stability and osteogenic activity of powder metallurgy Ta-xZr alloys as dental implant materials

Tantalum (Ta) and zirconium (Zr) alloys were found to had low elastic modulus and similar biomechanical characteristics as the human bone. However, the biocompatibility and osteogenic potential of Ta-xZr alloyswith different proportions (20, 30, 40 and 50% Zr by atom) remains to be investigated. In this study, the biocompatibility of Ta-xZr alloys and commercially pure titanium (cpTi) was evaluated in vitro by cell counting kit-8 assay. The adhesion of MG63 osteoblasts to the surface of the alloys was observed by fluorescence microscopy, and their morphology was analyzed by scanning electron microscopy (SEM). The expressions of alkaline phosphatase (ALP), Ki67, osteocalcin (OC), collagen-I (Col-I) and Integrin β1 mRNA in the cultured cells were determined by RT-PCR. As a result, Ta-xZr (x = 20, 30, 40 and 50 at%) alloys were non-toxic and supported proliferation of the MG63 cells. The osteoblasts adhered to the Ta-xZr alloys, and subsequently spread and proliferated rapidly. Furthermore, the cells grown on Ta-20Zr and Ta-30Zr expressed high levels of ALP, Col I and OC, indicating that the Ta-xZr alloys can induce osteogenesis. In conclusion, Ta-xZr alloys promoted the adhesion, proliferation and osteogenic differentiation of MG63 cells. The Ta-xZr composites with a higher proportion of Ta exhibited superior osteogenic activity, and Ta-30Zr is therefore a promising alternative for Ti implants.

Surface roughness of titanium disks influences the adhesion, proliferation and differentiation of osteogenic properties derived from human

PURPOSE

The aim of this study was to investigate the response of osteogenic cell lineage and gingival fibroblastic cells to different surface treatments of grade IV commercially pure Titanium (cpTi) disks.

MATERIAL AND METHODS

Grade IV cpTi disks with different surfaces were produced: machined (M), sandblasting (B), sandblasting and acid subtraction (NP), and hydrophilic treatment (ACQ). Surface microtopography characteristics and chemical composition were investigated by scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS). Adhesion and proliferation of SC-EHAD (human surgically-created early healing alveolar defects) and HGF-1 (human gingival fibroblasts) on Ti disks were investigated at 24 and 48 h, and osteogenic differentiation and mineralization were evaluated by assessing alkaline phosphatase (ALP) activity and alizarin red staining, respectively.

RESULTS

No significant differences were found among the various surface treatments for all surface roughness parameters, except for skewness of the assessed profile (Rsk) favoring M (p = 0.035 ANOVA). M disks showed a slightly higher (p > 0.05; Kruskal-Wallis/Dunn) adhesion of HGF-1 (89.43 ± 9.13%) than SC-EHAD cells (57.11 ± 17.72%). ACQ showed a significantly higher percentage of SC-EHAD (100%) than HGF-1 (69.67 ± 13.97%) cells adhered at 24 h. SC-EHAD cells expressed increased ALP activity in osteogenic medium at M (213%) and NP (235.04%) surfaces, but higher mineralization activity on ACQ (54.94 ± 4.80%) at 14 days.

CONCLUSION

These findings suggest that surface treatment influences the chemical composition and the adhesion and differentiation of osteogenic cells in vitro.

CLINICAL RELEVANCE

Hydrophilic surface treatment of grade IV cpTi disks influences osteogenic cell adhesion and differentiation, which might enhance osseointegration.

Influence of Three Dental Implant Surfaces on Cell Viability and Bone Behavior. An In Vitro and a Histometric Study in a Rabbit Model

The chemical composition and the surface characteristics of dental implants are factors that have a decisive effect on the osseointegration process. The surface characterization at the compositional and topographic level of three dental implants available in the market was performed with different surface treatments: (1) sandblasted and acid etched surface (SLA), (2) hydroxyapatite (HA) and tricalcium phosphate (TCP) blasted surface (HA/TCP), and (3) HA-blasted and non-etching acid washed surface (HA + AW). In addition, an in vitro viability study of MG-63 osteoblast cells was performed with a JC-1 test. To complete the study, an in vivo study was conducted in New Zealand rabbits. The study analyzed the histometric characteristics of the bone formed around the implants at the level of area, volume, bone density, accumulated bone density, and bone–implant contact (BIC). The rabbits were sacrificed at 6 weeks after implants were placed in the tibial metaphysis. No statistically significant differences were observed at the level of cell viability or histometric parameters between the different study groups (p > 0.05). SLA and HA/TCP surfaces were the ones that obtained a higher BIC value. Taking into account the limitations of this study, it can be concluded that the different implant surfaces analyzed favor a good bone response.

Physiochemical and biological evaluation of SLM-manufactured Ti-10Ta-2Nb-2Zr alloy for biomedical implant applications

Titanium alloys, such as Ti-10Ta-2Nb-2Zr (TTNZ), are promising biomaterials due to their excellent biocompatibility and low Young's modulus. The TTNZ samples herein were manufactured by selective laser melting and the novel material was evaluated as a dental implant in vitro and in vivo. The microstructure, mechanical properties, electrochemical behaviour, cytotoxicity, haemocompatibility and osteogenic differentiation were systematically investigated. Based on the tensile test results, the as-printed TTNZ samples had an elongation of 20.23% ± 1.95%, an ultimate tensile strength of 646.61 ± 24.96 MPa and a Young's modulus of 23.72 ± 1.18 GPa. According to the biocompatible value, the as-printed TTNZ sample exhibited no cell cytotoxicity and it showed even better cell adhesion ability than that of the as-printed Ti-6Al-4 V and wrought Ti-6Al-4 V samples. The haemolysis percentage of the as-printed TTNZ sample was 0.629% ± 0.363%. Moreover, the as-printed TTNZ sample facilitated protein adsorption and osteogenic differentiation of human osteoblast-like (MG-63) cells in vitro. The in vivo data also demonstrated the histocompatibility of the as-printed TTNZ. In summary, the as-printed TTNZ developed in this study demonstrated good biocompatibility, low stress shielding, excellent ductility and great osteogenic differentiation. These results indicated that as-printed TTNZ alloys can be promising for end-use human biomedical applications.

Customized Therapeutic Surface Coatings for Dental Implants

Dental implants are frequently used to support fixed or removable dental prostheses to replace missing teeth. The clinical success of titanium dental implants is owed to the exceptional biocompatibility and osseointegration with the bone. Therefore, the enhanced therapeutic effectiveness of dental implants had always been preferred. Several concepts for implant coating and local drug delivery had been developed during the last decades. A drug is generally released by diffusion-controlled, solvent-controlled, and chemical controlled methods. Although a range of surface modifications and coatings (antimicrobial, bioactive, therapeutic drugs) have been explored for dental implants, it is still a long way from designing sophisticated therapeutic implant surfaces to achieve the specific needs of dental patients. The present article reviews various interdisciplinary aspects of surface coatings on dental implants from the perspectives of biomaterials, coatings, drug release, and related therapeutic effects. Additionally, the various types of implant coatings, localized drug release from coatings, and how released agents influence the bone–implant surface interface characteristics are discussed. This paper also highlights several strategies for local drug delivery and their limitations in dental implant coatings as some of these concepts are yet to be applied in clinical settings due to the specific requirements of individual patients.

De Aza P. Can changes in implant macrogeometry accelerate the osseointegration process?: An in vivo experimental biomechanical and histological evaluations

OBJECTIVES

The propose was to compare this new implant macrogeometry with a control implant with a conventional macrogeometry.

MATERIALS AND METHODS

Eighty-six conical implants were divided in two groups (n = 43 per group): group control (group CON) that were used conical implants with a conventional macrogeometry and, group test (group TEST) that were used implants with the new macrogeometry. The new implant macrogeometry show several circular healing cambers between the threads, distributed in the implant body. Three implants of each group were used to scanning electronic microscopy (SEM) analysis and, other eighty samples (n = 40 per group) were inserted the tibia of ten rabbit (n = 2 per tibia), determined by randomization. The animals were sacrificed (n = 5 per time) at 3-weeks (Time 1) and at 4-weeks after the implantations (Time 2). The biomechanical evaluation proposed was the measurement of the implant stability quotient (ISQ) and the removal torque values (RTv). The microscopical analysis was a histomorphometric measurement of the bone to implant contact (%BIC) and the SEM evaluation of the bone adhered on the removed implants.

RESULTS

The results showed that the implants of the group TEST produced a significant enhancement in the osseointegration in comparison with the group CON. The ISQ and RTv tests showed superior values for the group TEST in the both measured times (3- and 4-weeks), with significant differences (p < 0.05). More residual bone in quantity and quality was observed in the samples of the group TEST on the surface of the removed implants. Moreover, the %BIC demonstrated an important increasing for the group TEST in both times, with statistical differences (in Time 1 p = 0.0103 and in Time 2 p < 0.0003).

CONCLUSIONS

Then, we can conclude that the alterations in the implant macrogeometry promote several benefits on the osseointegration process.

Effect of Implant Platform Connection and Abutment Material on Removal Torque and Implant Hexagon Plastic Deformation

Objectives  The aim of this study was to evaluate the plastic deformation of the hexagonal connection, and the removal torque of the implant-abutment joint of two dental implants combined with internal or external hexagonal connection implants after mechanical cycling.

Materials and Methods  Twenty-four dental implants were used in the study. Half of the implants had internal hexagonal connections (IH; Titamax II Plus) and the other half had external hexagonal connections (EH; Titamax Ti Ex). Four groups of two types of dental implant abutments (titanium: Ti, UCLA II Plus and zirconia: Zr, fabricated by CAD/CAM; n = 6) were investigated. The abutments received a metallic crown and the settings were submitted to mechanical cycling (MC; 10 ⁶ cycles, axial load, 120N). The connection surface area was measured by scanning electron microscope (SEM) images. The removal torque was evaluated and the plastic deformation of the hexagonal surface of the implant was measured by comparing the images before and after MC.

Statistical Analysis  Paired- t test was used to analyze the data statistically at a significance level of α = 0.05.

Results  The torque values decreased for all groups after MC, and the hexagonal surface area decreased due to plastic deformation for IH and EH associated with Zr abutments.

Conclusions  Zirconia abutments showed the worst plastic deformation of the implant connection surface and torque loosening when associated with IH implant.

Bioactive Coating on Ti Alloy with High Osseointegration and Antibacterial Ag Nanoparticles

Titanium alloys have advanced mechanical properties jointly with high biocompatibility that make them eminently suitable for biomedical applications such as dental and orthopedic implants. Improvement in their osseointegration with human bone can be achieved by the development of hydroxyapatite (HAp) on a Ti alloy surface using different methods of deposition. However, plasma electrolytic oxidation (PEO) treatment has been found to be one of the most promising techniques, due to the formation of high bonding between the bone and the Ti surface. Along with this high bonding, an antibacterial ability of the surface to prevent bacterial infection is also essential. Silver, which is a widely applicable antibacterial agent, was used in this work. First, a titanium oxide coating containing calcium and phosphorus and Ag nanoparticles was formed by PEO treatment. Then, Ti alloy was subjected to hydrothermal treatment to ensure a crystalline formation of HAp. Morphology and phase composition investigations detected the presence of HAp crystals in the coating along with antibacterial agents of silver nanoparticles. The biocompatibility and bioactivity of the created coating were examined by contact angle (CS) measurement and electrochemical impedance spectroscopy (EIS). It was shown that the coating was extensively grown after exposure of the alloy to simulated body fluid (SBF) solution for 7 days with no effect on the Ag nanoparticles. An antibacterial test using Staphylococcus aureus and Escherichia coli revealed that the coating containing Ag nanoparticles has more significant antibacterial effectiveness compared to a coating that does not contain silver.

Electrochemical methods for fabrication of polymers/calcium phosphates nanocomposites as hard tissue implants

Developing and manipulating new biomaterials is an ongoing topic for their needs in medical uses. The evolution and development of new biomaterials, in both the academic and industrial sectors, have been encouraged due to the dramatic improvement in medicine and medical-related technologies. Due to the drawbacks associated with natural biomaterials, the use of synthetic biomaterials is preferential due to basic and applied aspects. Various techniques are involved in fabricating biomaterials. Among them are the electrochemical-based methods, which include electrodeposition and electrophoretic methods. Although electrospinning and electrospraying are not typical electrochemical methods, they are also reviewed in this article due to their importance. Many remarkable features can be acquired from this technique. Electrodeposition and electrophoretic deposition are exceptional and valuable processes for fabricating thin or thick coated films on a surface of metallic implants. Electrodeposition and electrophoretic deposition have some common positive features. They can be used at low temperatures, do not affect the structure of the implant, and can be applied to complex shapes, and they can produce superior properties, such as quick and uniform coating. Furthermore, they can possibly control the thickness and chemical composition of the coatings. Electrospinning is a potentially emerging and efficient process for producing materials with nanofibrous structures, which have exceptional characteristics such as mechanical properties, pore size, and superior surface area. These specialized characteristics induce these nanostructured materials to be used in different technologies.

Comparative in vivo study of alloy titanium implants with two different surfaces: biomechanical and SEM analysis

OBJECTIVES

The purpose of this study was to evaluate the biomechanical behavior of the interface formed between bone and implants with machined surfaces (MS) and those modified by Al₂O₃ sandblasting and acid etching (SBAS).

MATERIALS AND METHODS

Before surgery, topographic characterization was performed by SEM-EDX and by mean roughness measurements. Ten Albinus rabbits received randomly 20 Ti-6Al-4V implants on its right and left tibiae, with one implant placed in each tibia. After implant insertion, the implant stability quotient (ISQ) was measured by means of resonance frequency analysis (RFA). After 3 and 6 weeks, the ISQ was again measured, followed by torque removal measurements. Analysis of variance and Tukey tests were used to analyze the data. The surface of the implants removed was evaluated by SEM-EDX. Immunohistochemical analysis of osteopontin (OPN) and osteocalcin (OC) protein was performed in bone tissue.

RESULTS

The topographic characterization showed differences between the analyzed surfaces, and the mean roughness values of SBAS group were statistically higher than MS. Overall, higher statistically significant ISQ values were observed in the SBAS group compared to the MS group (p = 0.012). The intra-group comparison of ISQ values in the SBAS group showed statistically significant differences between 0 and 3 weeks (p = 0.032) and 0 and 6 weeks (p = 0.003). The torque removal measurements of group SBAS were statistically higher when compared with the torque removal measurements of group MS in the time intervals of 3 weeks (p = 0.002) and 6 weeks (p < 0.001). SEM-EDX of the implant surfaces removed in SBAS group showed greater bone tissue covering and mean values atomic in percentage of Ca, P, and O statistically superior (p < 0.05) than MS group. Immunohistochemical reactions showed intense OC immunolabeling at 6 weeks postoperative for SBAS group.

CONCLUSIONS

The topographical modifications made in group SBAS allowed a better mechanical interlocking between the implant and bone tissue.

Superficial Characteristics of Titanium after Treatment of Chorreated Surface, Passive Acid, and Decontamination with Argon Plasma

(1) Background. Titanium is characterized by its biocompatibility, resistance to maximum stress, and fatigue and non-toxicity. The composition, surface structure, and roughness of titanium have a key and direct influence on the osseointegration processes when it is used in the form of dental implants. The objective of the present study is to characterize, at chemical, superficial, and biological levels, the result of the application of the sandblasted with large-grit and acid-etched (SLA) treatment consisting of coarse-grained and double-passivated acid blasting with subsequent decontamination with argon plasma on the surface of titanium implants type IV. (2) Methods. Four Oxtein^® dental implants (Zaragoza, Spain) were investigated with the following coding: Code L63713T (titanium grade IV, 3.75 mm in diameter, and 13 mm in length). The surface of the implants was SLA type obtained from coarse-grained, double passivated acid, and decontaminated with argon plasma. The samples were in their sealed packages and were opened in our laboratory. The X-ray photoelectron spectroscopy (XPS) technique was used to characterize the chemical composition of the surface, and the scanning electronic microscope (SEM) technique was used to perform topographic surface evaluation. Cell cultures were also performed on both surfaces. (3) Results. The superficial chemical analysis of the studied samples presented the following components, approximately, expressed in atomic percentage: O: 39%; Ti: 18%; C: 39%; N: 2%; and Si: 1%. In the same way, the topographic analysis values were obtained in the evaluated roughness parameters: R_a: 1.5 μm ± 0.02%; R_q: 1.31 μm ± 0.33; R_z: 8.98 μm ± 0.73; R_p: 5.12 μm ± 0.48; R_v: 3.76 μm ± 0.51; and R_c: 4.92 μm ± 0.24. At a biological level, the expression of osteocalcin was higher (p < 0.05) on the micro-rough surface compared to that machined at 48 and 96 h of culture. (4) Conclusions. The data obtained in our study indicate that the total carbon content, the relative concentration of titanium, and the roughness of the treatment performed on the implants are in agreement with those found in the literature. Further, the roughness of the treatment performed on the implants throws a spongy, three-dimensional surface suitable for bone growth on it. The biological results found are compatible with the clinical use of the surface tested.

Potential Causes of Titanium Particle and Ion Release in Implant Dentistry: A Systematic Review

Implant surface characteristics, as well as physical and mechanical properties, are responsible for the positive interaction between the dental implant, the bone and the surrounding soft tissues. Unfortunately, the dental implant surface does not remain unaltered and changes over time during the life of the implant. If changes occur at the implant surface, mucositis and peri-implantitis processes could be initiated; implant osseointegration might be disrupted and bone resorption phenomena (osteolysis) may lead to implant loss. This systematic review compiled the information related to the potential sources of titanium particle and ions in implant dentistry. Research questions were structured in the Population, Intervention, Comparison, Outcome (PICO) framework. PICO questionnaires were developed and an exhaustive search was performed for all the relevant studies published between 1980 and 2018 involving titanium particles and ions related to implant dentistry procedures. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed for the selection and inclusion of the manuscripts in this review. Titanium particle and ions are released during the implant bed preparation, during the implant insertion and during the implant decontamination. In addition, the implant surfaces and restorations are exposed to the saliva, bacteria and chemicals that can potentially dissolve the titanium oxide layer and, therefore, corrosion cycles can be initiated. Mechanical factors, the micro-gap and fluorides can also influence the proportion of metal particles and ions released from implants and restorations.

Bioactive Sphene-Based Ceramic Coatings on cpTi Substrates for Dental Implants: An In Vitro Study

Titanium implant surface modifications have been widely investigated to favor the process of osseointegration. The present work aimed to evaluate the effect of sphene (CaTiSiO₅) biocoating, on titanium substrates, on the in vitro osteogenic differentiation of Human Adipose-Derived Stem Cells (hADSCs). Sphene bioceramic coatings were prepared using preceramic polymers and nano-sized active fillers and deposited by spray coating. Scanning Electron Microscopy (SEM) analysis, surface roughness measurements and X-ray diffraction analysis were performed. The chemical stability of the coatings in Tris-HCl solution was investigated. In vitro studies were performed by means of proliferation test of hADSCs seeded on coated and uncoated samples after 21 days. Methyl Thiazolyl-Tetrazolium (MTT) test and immunofluorescent staining with phalloidin confirmed the in vitro biocompatibility of both substrates. In vitro osteogenic differentiation of the cells was evaluated using Alizarin Red S staining and quantification assay and real-time PCR (Polymerase Chain Reaction). When hADSCs were cultured in the presence of Osteogenic Differentiation Medium, a significantly higher accumulation of calcium deposits onto the sphene-coated surfaces than on uncoated controls was detected. Osteogenic differentiation on both samples was confirmed by PCR. The proposed coating seems to be promising for dental and orthopedic implants, in terms of composition and deposition technology.

Mechanical strength and fracture point of a dental implant under certification conditions: A numerical approach by finite element analysis

STATEMENT OF PROBLEM

Implant prosthodontics provides high-quality outcomes thanks to recent technological developments and certification procedures such as International Organization for Standardization (ISO) 14801. However, these certification tests are costly, and the result is highly uncertain as the influence of design variables (materials and structure) is still unknown. The design process could be significantly improved if the influence of design parameters were identified.

PURPOSE

The purpose of this in vitro study was to use finite element analysis (FEA) to assess the influence of design parameters on the mechanical performance of an implant in regard to testing conditions of ISO 14801 standard.

MATERIAL AND METHODS

An endosseous dental implant was loaded under ISO 14801 testing conditions by numerical simulation, with 4 parameters evaluated under the following conditions: conditions of the contact surface area between the implant and the loading tool, length of the fixation screw, implant embedding depth, and material used for implant stiffness. FEA was used to compare the force that needed to reach the implant's yield and fracture strength.

RESULTS

A dental implant's fracture point can be increased by 41% by improving the contact surface area, by 20% depending on the type of material, by 4% depending on the length of the fixation screw, and by 1.4% by changing the implant embedding depth.

CONCLUSIONS

FEA made it possible to evaluate 4 performance parameters of a dental implant under ISO 14801 conditions. Under these conditions, the contact surface area was found to be the major parameter influencing implant performance. This observation was validated experimentally in a fatigue test under ISO 14801 conditions.