Hypersensitivity to titanium: a less explored area of research

Influence of Connector Design on Displacement and Micromotion in Tooth-Implant Fixed Partial Dentures Using Different Lengths and Diameters: A Three-Dimensional Finite Element Study

The literature presents insufficient data evaluating the displacement and micromotion effects resulting from the combined use of tooth-implant connections in fixed partial dentures. Analyzing the biomechanical behavior of tooth-implant fixed partial denture (FPD) prothesis is vital for achieving an optimum design and successful clinical implementation. The objective of this study was to determine the relative significance of connector design on the displacement and micromotion of tooth-implant-supported fixed dental prostheses under occlusal vertical loading. A unilateral Kennedy class I mandibular model was created using a 3D reconstruction from CT scan data. Eight simulated designs of tooth-implant fixed partial dentures (FPDs) were split into two groups: Group A with rigid connectors and Group B with non-rigid connectors. The models were subjected to a uniform vertical load of 100 N. Displacement, strain, and stress were computed using finite element analysis. The materials were defined as isotropic, homogeneous, and exhibiting linear elastic properties. This study focused on assessing the maximum displacement in various components, including the bridge, mandible, dentin, cementum, periodontal ligament (PDL), and implant. Displacement values were predominantly higher in Group B (non-rigid) compared to Group A (rigid) in all measured components of the tooth-implant FPDs. Accordingly, a statistically significant difference was observed between the two groups at the FPD bridge (p value = 0.021 *), mandible (p value = 0.021 *), dentin (p value = 0.043 *), cementum (p value = 0.043 *), and PDL (p value = 0.043 *). Meanwhile, there was an insignificant increase in displacement values recorded in the distal implant (p value = 0.083). This study highlighted the importance of connector design in the overall stability and performance of the prosthesis. Notably, the 4.7 mm × 10 mm implant in Group B showed a displacement nearly 92 times higher than its rigid counterpart in Group A. Overall, the 5.7 mm × 10 mm combination of implant length and diameter showcased the best performance in both groups. The findings demonstrate that wider implants with a proportional length offer greater resistance to displacement forces. In addition, the use of rigid connection design provides superior biomechanical performance in tooth-implant fixed partial dentures and reduces the risk of micromotion with its associated complications such as ligament overstretching and implant overload, achieving predictable prognosis and enhancing the stability of the protheses.

Influence of Ultrasound on the Characteristics of CaP Coatings Generated Via the Micro-arc Oxidation Process in Relation to Biomedical Engineering

Over the past decade, bone tissue engineering has been at the core of attention because of an increasing number of implant surgeries. The purpose of this study was to obtain coatings on titanium (Ti) implants with improved properties in terms of biomedical applications and to investigate the effect of ultrasound (US) on these properties during the micro-arc oxidation (MAO) process. The influence of various process parameters, such as time and current density, as well as US mode, on the properties of such coatings was evaluated. Novel porous calcium-phosphate-based coatings were obtained on commercially pure Ti. Their microstructure, chemical composition, topography, wettability, nanomechanical properties, thickness, adhesion to the substrate, and corrosion resistance were analyzed. In addition, cytocompatibility evaluation was checked with the human osteoblasts. The properties of the coatings varied significantly, depending on applied process parameters. The US application during the MAO process contributes to the increase of coating thickness, porosity, roughness, and skewness, as well as augmented calcium incorporation. The most advantageous coating was obtained at a current of 136 mA, time 450 s, and unipolar rectangular US, as it exhibits high porosity, adequate wettability, and beneficial skewness, which enabled increased adhesion and proliferation of osteoblasts during in vitro studies. Finally, the conducted research demonstrated the influence of various UMAO process parameters, which allowed for the selection of appropriate Ti implant modification for specific biomedical utilization.

Disruptive Technologies for Learning and Further Investigation of the Potential Toxicity Produced by Titanium in the Human Body during the COVID-19 Pandemic Period

Titanium is considered to be a biocompatible material and is used to a great extent in the pharmaceutical and oral implantology fields. While initially, specialists considered that its use does not cause adverse effects on the human body, as time has gone by, it has become clear that its use can lead to the development of certain diseases. The objective of this study was to identify the way in which digital technologies have the capacity to facilitate information regarding the potential long-term harm caused by titanium device toxicity during the COVID-19 pandemic. In this study, a regression model was developed to identify how a series of independent variables have the ability to influence the dependent variable (respondents' perceptions of how new web technologies have the ability to help future physicians to facilitate information absorption with regard to potential titanium toxicity). The results illustrated that new technologies have the potential to support both the learning process on this topic and the innovation activity by discovering new solutions that will gradually lead to the reduction of the side effects of titanium used in the pharmaceutical and oral implantology fields.

Dental Implants and Implant Coatings: A Focus on Their Toxicity and Safety

Dental implants are medical devices that are surgically inserted into the patient's jawbone by an orthodontist to act as roots of missing teeth. After the implantation, the maxilla or mandible integrates with the surface of the dental implant. This process, called "osseointegration," is an important period to ensure the long-term use of dental implants and prevent implant failures. Metal implants are the most used implant materials. However, they have disadvantages such as corrosion, metal ion release from metal implant surfaces and associated toxicity. To avoid these adverse effects and improve osseointegration, alternative dental implant materials such as ceramics, polymers, composites, and novel surface modification technologies have been developed. The safety of these materials are also of concern for toxicologists. This review will give general information about dental implant materials, osseointegration and successful implantation process. Moreover, we will focus on the new surface coatings materials for of dental implants and their toxicity and safety concerns will be discussed.

Development of a novel hybrid Ti6Al4V-ZrO2 surface with high wear resistance by laser and hot pressing techniques for dental implants

The development of implant metal-free surfaces has gained attention since non-benefic results have been reported related to the metallic ions released from metal implants to the human body. Ceramic coatings have been proposed as a possible solution however, the detachment of these coatings, during implantation or even in function, can compromise its function. In order to overcome this problem, this work proposes a novel hybrid Ti6Al4V-ZrO2 surface, starting with laser texturing of the Ti6Al4V substrate by Laser Nd:YV04, followed by the allocation of the zirconia (ZrO2) powder and its subsequent sintering by hot pressing process. Results revealed that zirconia strongly adheres to titanium textured surfaces since no detachment was found under tribological and adhesion scratch tests. Moreover, the tribological results showed that the incorporation of zirconia into textured titanium surface reduces significantly the wear rate of titanium (≈93%), which is a good indicator of low metallic particles/ions released to the body. These results suggest that this novel surface with good aesthetic properties and improved wear resistance (given by zirconia) and mechanical resistance (from titanium) can be a promising solution for dental implants, especially for implant/abutment or abutment/ceramic contact zones, and thus have a huge impact on the long-term performance of implants.

Corrosion Resistance of 3D Printed Ti6Al4V Gyroid Lattices with Varying Porosity

Corrosion of medical implants is a possible failure mode via induced local inflammatory effects, systemic deposition and corrosion related mechanical failure. Cyclic potentiodynamic polarisation (CPP) testing was utilized to evaluate the effect of increased porosity (60% and 80%) and decreased wall thickness in gyroid lattice structures on the electrochemical behaviour of LPBF Ti6Al4V structures. The use of CPP allowed for the landmarks of breakdown potential, resting potential and vertex potential to be analysed, as well as facilitating the construction of Tafel plots and qualitative Goldberg analysis. The results indicated that 60% gyroid samples were most susceptible to the onset of pitting corrosion when compared to 80% gyroid and solid samples. This was shown through decreased breakdown and vertex potentials and were found to correlate to increased lattice surface area to void volume ratio. Tafel plots indicated that despite the earlier onset of pitting corrosion, both gyroid test groups displayed lower rates of corrosion per year, indicating a lower severity of corrosion. This study highlighted inherent tradeoffs between lattice optimisation and corrosion behaviour with a potential parabolic link between void volume, surface area and corrosion being identified. This potential link is supported by 60% gyroid samples having the lowest breakdown potentials, but investigation into other porosity ranges is suggested to support the hypothesis. All 3D printed materials studied here showed breakdown potentials higher than ASTM F2129's suggestion of 800 mV for evaluation within the physiological environment, indicating that under static conditions pitting and crevice corrosion should not initiate within the body.

Biological mechanisms underlying complications related to implant site preparation

Implant site preparation is a critical stage of implant surgery that may underpin various complications related to implant surgery. This review discusses the latest available scientific information on risk factors related to implant site preparation. The role of the drilling process in relation to the density of the available alveolar bone, the effects of insertion torque on peri-implant osseous healing, and implant-related variables such as macrodesign and implant-abutment connection are all factors that can influence implant success. Novel information that links osteotomy characteristics (including methods to improve implant initial stability, the impact of drilling speed, and increase of the implant insertion torque modifying the bone-implant interface) with the appropriate instrumentation techniques will be discussed, as well as interactions at the bone-biomaterial interface that may lead to biologic complications mediated by implant dissolution products.

Effects of Cold Rolling Deformation and Solution Treatment on Microstructural, Mechanical, and Corrosion Properties of a Biocompatible Ti-Nb-Ta-Zr Alloy

One of the most important requirements for a metallic biomaterial is the mechanical biocompatibility, which means excellent mechanical properties—high strength and fatigue strength, but low elastic modulus, to be mechanically harmonized with hard tissues. In order to improve the mechanical and biocompatible performance of the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy, the influence of cold plastic deformation and solution treatment on its properties were investigated. The Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy was fabricated by melting in a cold crucible furnace (in levitation) and then subjected to several treatment schemes, which include cold rolling and different solution treatments. Microstructural and mechanical characteristics of specimens in as-cast and thermo-mechanically processed condition were determined by SEM microscopy and tensile testing, for different structural states: initial as-cast/as-received, cold rolled and solution treated at different temperatures (800, 900, and 1000 °C) and durations (5, 10, 15, and 20 min), with water quenching. It was concluded that both cold rolling and solution treatment have important positive effects on structural and mechanical properties of the biomaterial, increasing mechanical strength and decreasing the elastic modulus. Samples in different structural states were also corrosion tested and the results provided important information on determining the optimal processing scheme to obtain a high-performance biomaterial. The final processing route chosen consists of a cold rolling deformation with a total deformation degree of 60%, followed by a solution heat treatment at 900 °C with maintenance duration of 5 min and water quenching. By applying this thermo-mechanical processing scheme, the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy showed an elastic modulus of 56 GPa (5% higher than in the as-cast state), an ultimate tensile strength of 1004 MPa (41.8% higher than in the as-cast state), a yield strength of 718 MPa (40.6% higher than in the as-cast state), and increased corrosion resistance (the corrosion rate decreased by 50% compared to the as-cast state).

Tribocorrosion Behavior of NiTi Biomedical Alloy Processed by an Additive Manufacturing Laser Beam Directed Energy Deposition Technique

The purpose of the present study was to experimentally assess the synergistic effects of wear and corrosion on NiTi alloy in comparison with Ti-6Al-4V alloy, the most extensively used titanium alloy in biomedical applications. Both alloys were processed by an additive manufacturing laser beam directed energy deposition (LB-DED) technique, namely laser engineered net shaping (LENS), and analyzed via tribocorrosion tests by using the ball-on-plate configuration. The tests were carried out in phosphate buffered saline solution at 37 °C under open circuit potential (OCP) to simulate the body environment and temperature. The synergistic effect of wear and corrosion was found to result in an improved wear resistance in both materials. It was also observed that, for the process parameters used, the LB-DED NiTi alloy exhibits a lower tendency to corrosion as compared to the LB-DED Ti-6Al-4V alloy. It is expected that, during the service life as an implant, the NiTi alloy is less susceptible to the metallic ions release when compared with the Ti-6Al-4V alloy.

Prevalence of Titanium Hypersensitivity in Patients with Titanium Implants: A Systematic Review and Meta-analysis

BACKGROUND

With increase in exposure to titanium in daily life and its use in medical procedures, there is a greater chance for developing titanium hypersensitivity. Our aim and objective is to examine whether patient patients with titanium implants had a greater incidence of titanium hypersensitivity or not. Titanium is widely considered to have good biocompatibility. A passivating surface layer of TiO₂ is formed when exposed to air which gives it good corrosion resistance. These properties along with its high strength, lightweight, and improvements in smelting technologies have led to its widespread use as an intraosseous and periosteal implant in dentistry and orthopedics.

MATERIALS AND METHODS

Only case-control studies were used for the meta-analysis. Studies with a sample size of <5 were excluded. Cutaneous and epicutaneous tests were used in the study.

RESULTS

Three studies met the inclusion criteria. Titanium hypersensitivity is more prevalent in patients with titanium implants.

CONCLUSIONS

It is also used in a variety of medical devices such as pacemakers and insulin pumps. Moreover, our external exposure to titanium is increasing. It is used in aerospace, chemical, and automobile industries. It is also used in jewelry, home furnishings, and in making sports and marine equipment. Titanium implants increase the possibility of developing titanium hypersensitivity, and thus, it should be considered as a major factor in unexplained implant failure where other causes have been excluded.

Benefits and Biosafety of Use of 3D-Printing Technology for Titanium Biomedical Implants: A Pilot Study in the Rabbit Model

BACKGROUND

Titanium has been used in osteosynthesis for decades and its compatibility and safety is unquestioned. Studies have shown that there is release and collection of titanium in the organ systems with little note of toxicity. The gold standard is considered to be titanium osteosynthesis plate produced by milling methods. The use of customized titanium plates produced with 3D printing, specifically direct metal laser sintering, have found increasing use in recent years. It is unknown how much titanium is released in these printed titanium implants, which is known to be potentially porous, depending on the heat settings of the printer. We hypothesize that the amount of titanium released in printed titanium implants may be potentially more or equal compared to the gold standard, which is the implant produced by milling.

METHODS

We studied the biosafety of this technology and its products by measuring serum and organ titanium levels after implantation of 3D-printed versus traditionally fabrication titanium plates and screws in a pilot study using the rabbit model. A total of nine rabbits were used, with three each in the control, milled and printed titanium group. The animals were euthanized after six months. Serum and organs of the reticuloendothelial system were harvested, digested and assayed for titanium levels.

RESULTS

Organ and serum titanium levels were significantly higher in rabbit subjects implanted with titanium implants (milled and printed) compared to the control group. However, there was no significant difference in organ and serum titanium levels of subjects implanted with milled and traditionally fabricated titanium implants.

CONCLUSIONS

The biosafety of use of 3D-printed titanium implants and traditionally fabricated titanium implants are comparable. With this in mind, 3D-printed custom implants can not only replace, but will very possibly surpass traditionally fabricated titanium implants in the mode and extent of use.

Will Zirconia Implants Replace Titanium Implants?

This review aims to discuss the advantages and disadvantages of zirconia implants compared with titanium implants. Moreover, it intends to review the relevant available long-term literature of these two materials regarding osteointegration, soft-tissue, microbiota, and peri-implantitis, focusing on clinical results. Briefly, titanium implants are a reliable alternative for missing teeth; however, they are not incapable of failure. In an attempt to provide an alternative implant material, implants made from ceramic-derivate products were developed. Owing to its optimal osseointegration competence, biocompatibility, and esthetic proprieties, zirconium dioxide (ZrO2), also known as zirconia, has gained popularity among researchers and clinicians, being a metal-free alternative for titanium implants with its main use in the anterior esthetic zones. This type of implant may present similar osseointegration as those noted on titanium implants with a greater soft-tissue response. Furthermore, this material does not show corrosion as its titanium analog, and it is less susceptible to bacterial adhesion. Lastly, even presenting a similar inflammatory response to titanium, zirconia implants offer less biofilm formation, suggesting less susceptibility to peri-implantitis. However, it is a relatively new material that has been commercially available for a decade; consequently, the literature still lacks studies with long follow-up periods.

Wettability and in-vitro study of titanium surface profiling prepared by electrolytic plasma processing

Electrolytic plasma processing (EPP) was used to create hydrophilic surface profiles on titanium. The wettability, surface morphology characteristics and chemical composition of the treated samples were studied as a function of EPP processing parameters. The EPP profiled surfaces comprised of a characteristic "hills and valleys" morphology because of continuous surface melting and freezing cycles. A bimodal surface profile was produced with 2-3 μm height hills and valleys with nano-roughness (≤200 nm). The produced profile resulted in a significant contact angle decrease (from 38.7° to 5.4°). Ratios of actual surface area to projection area (r) and fraction of solid surface remaining dry (φ) were obtained from profilometry. The surface characteristics and large r values produced by EPP were able to induce hemi-wicking. Hence, EPP produced superhydrophilic surfaces on Ti. The bioactivity of EPP treated Ti was evaluated using cell free and MC3T3 cells in-vitro studies. The treated Ti surface significantly increased the bioactivity and formed stoichiometric hydroxyapatite after immersion in a bone cell culture medium for 21 days. Cells' attachment and proliferation studies indicated that EPP treated surface significantly enhances the cells' adhesion and growth after 24 and 48 h compared to the untreated surface. The results show that Ti surface profiling by EPP constitutes a promising method to potentially improve bone implant bonding.

Delayed Titanium Hypersensitivity and Retained Foreign Body Causing Late Abdominal Complications

Titanium is a known metal used widely in the medical field and can cause allergic reactions with complications. Our case is about a 28-year-old female presenting with a spectrum of abdominal symptoms with a complicated medical history. The abdominal pain is associated with titanium allergy reaction from previously inserted titanium-based surgical clips. This patient is concurrently found to have a retained pigtail catheter in the cecum discovered incidentally through radiology. We discuss the presentation, investigations, and treatment of this unusual case. The case also unfolds rare differential diagnoses to keep in mind when encountering a patient with abdominal pain and associated nonspecific symptoms.

Antibacterial Layer-by-Layer Coatings for Medical Implants

The widespread occurrence of nosocomial infections and the emergence of new bacterial strands calls for the development of antibacterial coatings with localized antibacterial action that are capable of facing the challenges posed by increasing bacterial resistance to antibiotics. The Layer-by-Layer (LbL) technique, based on the alternating assembly of oppositely charged polyelectrolytes, can be applied for the non-covalent modification of multiple substrates, including medical implants. Polyelectrolyte multilayers fabricated by the LbL technique have been extensively researched for the development of antibacterial coatings as they can be loaded with antibiotics, antibacterial peptides, nanoparticles with bactericide action, in addition to being capable of restricting adhesion of bacteria to surfaces. In this review, the different approaches that apply LbL for antibacterial coatings, emphasizing those that can be applied for implant modification are presented.

Allergies to Titanium Dental Implants: What Do We Really Know about Them? A Scoping Review

Simple Summary

The scientific literature repeatedly insists on the success of titanium implants. Nevertheless, the so-called tribocorrosion process releases titanium ions into the surrounding tissues, which can trigger a cascade of reactions, localized or at a distance, or even systemic reactions. Consequently, guidelines should be drawn up before starting treatment; when a hypersensitivity reaction following titanium dental implant placement occurs, a range of treatment alternatives should be clearly established and made available.

Abstract

The purpose of this scoping review was to describe the current state of knowledge and understanding of allergies to titanium dental implants. A scoping review was conducted following the Prisma Extension for Scoping Reviews checklist. An electronic search was performed in five databases complemented by manual and grey literature searches. Fifty-two relevant papers were included for final review. Titanium particles can be released from the surfaces of dental implants in a process called tribocorrosion, which may contribute to bone loss due to inflammatory reaction. Diverse mechanisms have been described that may trigger allergy to titanium, as well as the clinical signs that manifest as the allergy develops. Allergies to titanium are uncommon but represent a real possibility that should not be overlooked in patients requiring prosthodontic rehabilitation with dental implants. Allergy can trigger a range of symptoms. Patients who have already been diagnosed with allergies to other metals will be more predisposed to suffering an allergy to titanium. Further investigation is needed in order to measure the true scope of these allergies.

Suspected allergy to titanium after anterior cervical discectomy and fusion using a Zero-P device: a case report

Purpose: Cases of allergy to large surgical implants have been reported. However, few studies have reported allergy to small titanium-containing implants (e.g. Zero-P device).Methods: We reported the case of a 51-year old male patient who underwent the anterior cervical discectomy and fusion (ACDF) procedure using a Zero-P device and exhibited allergic symptoms 1 month after the surgery.Results: The allergic symptoms included intermittent tingling and itches in the throat induced by speaking. Systemic rashes over the skin surface and congestion of the eyeball, and dysphagia were also present. Anti-allergic treatment did not resolve the symptoms. Patch tests revealed negative reactions to the rested reagents including titanium. Radiographic results showed solid bone fusion and no signs of chronic inflammation or hypotoxic infection in the surrounding tissues. Upon the patient's request, we removed the titanium screws and plate of the Zero-P device. No allergic reactions were observed after the surgery and at a 6-month follow-up.Conclusions: Even with a small implant such as the Zero-P device, allergy to titanium may still occur. This case demonstrated the need to screen for the presence of allergy to metals including titanium before the surgery.

Influence of the Titanium Implant Surface Treatment on the Surface Roughness and Chemical Composition

The implant surface features affect the osseointegration process. Different surface treatment methods have been applied to improve the surface topography and properties. Trace of different elements may appear on the implant surface, which can modify surface properties and may affect the body’s response. The aim was to evaluate the roughness based on the surface treatment received and the amount and type of trace elements found. Ninety implants (nine different surface treatment) were evaluated. Roughness parameters were measured using white-light-interferometry (WLI). The arithmetical mean for R_a, R_q, R_t, and R_z of each implant system was calculated, and Fisher’s exact test was applied, obtaining R_a values between 0.79 and 2.89 µm. Surface chemical composition was evaluated using X-ray photoelectron spectroscopy (XPS) at two times: as received by the manufacturer (AR) and after sputter-cleaning (SC). Traces of several elements were found in all groups, decreasing in favor of the Ti concentration after the sputter-cleaning. Within the limitations of this study, we can conclude that the surface treatment influences the roughness and the average percentage of the trace elements on the implant surface. The cleaning process at the implant surface should be improved by the manufacturer before assembling the implant.

Type IV Cell-Mediated Hypersensitivity Reaction Caused by Titanium Implant Following Double Calcaneal Osteotomy and First Metatarsal-Cuneiform Arthrodesis: A Case Report and Review of the Literature

Because of their inert character and desired biocompatibility, titanium implants have been universally accepted as safer alternatives to the conventional stainless steel orthopedic implants; however, recent emergence of type IV hypersensitivity reactions to titanium have included eczema, contact dermatitis, a prolonged febrile state, sterile osteonecrosis, and impaired fracture and wound healing. This report presents a patient with postoperative incision dehiscence and devascularization of surfaces in contact with titanium hardware after undergoing a double calcaneal osteotomy and a first metatarsal-cuneiform arthrodesis using titanium alloy implants. Titanium hypersensitivity was confirmed in this case through standard allergy patch testing by a board-certified immunologist. Complete healing occurred after diagnosis of the titanium allergy and hardware explant. To our knowledge, this is one of a few known allergies to titanium implants after foot and ankle surgery.

Positive Material Identification testing of dental implant to correlate their compositions with allergic conditions

BACKGROUND

Rapid increase of products containing titanium leads to the increases in percutaneous and permucosal exposure of populations to the titanium.

PURPOSE

Evaluate the various material compositions in five commercially available dental implant systems and correlate the obtained material contents with allergic conditions seen with implants.

MATERIAL AND METHODS

A total of 25 implant, with 5 samples each in 5 groups of commercially available dental implants (MKIII, Myriad, Nobel Replace, MIS and Alpha Dent) were used in the study. Positive Material Identification (PMI) testing was done to analyse the amount of different metals (percentage by mass) present in the dental implants.

RESULTS

Highest titanium content, 99.47% by mass was found in sample 2 (Myriad) and least, 89.04% by mass in sample 5(Alpha dent). Nickel was found only in sample 5 (Alpha dent) in 0.079% by mass and zinc in sample 4 (MIS) in0.084% by mass, chromium was found in sample 1 (MK III) in 0.263% by mass and in sample 2 in0.273% by mass.

CONCLUSIONS

Implant composition should be made mandatory to be disclosed on the implant packet and before implant placement patch test for the allergen present in the particular implant can be done for the patient's health benefit and long term clinical success of dental implants.

General review of titanium toxicity

Background

Titanium is a commonly used inert bio-implant material within the medical and dental fields. Although the use of titanium is thought to be safe with a high success rate, in some cases, there are rare reports of problems caused by titanium. In most of these problematic reports, only individual reports are dominant and comprehensive reporting has not been performed. This comprehensive article has been prepared to review the toxicity of titanium materials within the medical and dental fields.

Methods

We used online searching tools including MEDLINE (PubMed), Embase, Cochrane Library, and Google Scholar by combining keywords such as “titanium implant toxicity,” “titanium implant corrosion,” “titanium implant allergy,” and “yellow nail syndrome.” Recently updated data has been collected and compiled into one of four categories: “the toxicity of titanium,” “the toxicity of titanium alloys,” “the toxicity of titanium implants,” and “diseases related to titanium.”

Results

Recent studies with regard to titanium toxicity have been increasing and have now expanded to the medical field in addition to the fields of environmental research and basic science. Problems that may arise in titanium-based dental implants include the generation of titanium and titanium alloy particles and ions deposited into surrounding tissues due to the corrosion and wear of implants, resulting in bone loss due to inflammatory reactions, which may lead to osseointegration failure of the dental implant. These titanium ions and particles are systemically deposited and can lead to toxic reactions in other tissues such as yellow nail syndrome. Additionally, implant failure and allergic reactions can occur due to hypersensitivity reactions. Zirconia implants can be considered as an alternative; however, limitations still exist due to a lack of long-term clinical data.

Conclusions

Clinicians should pay attention to the use of titanium dental implants and need to be aware of the problems that may arise from the use of titanium implants and should be able to diagnose them, in spite of very rare occurrence. Within the limitation of this study, it was suggested that we should be aware the rare problems of titanium toxicity.

Association between titanium and silver concentrations in maternal hair and risk of neural tube defects in offspring: A case-control study in north China

Increasing uses of titanium and silver in various products raise concerns for their potential adverse effects on pregnancy outcomes. We aimed to examine the associations between titanium and silver concentrations in maternal hair growing during the periconception period and the risk of neural tube defects (NTDs) in offspring. Our case-control study recruited 191 women with NTD-affected pregnancies and 261 women delivering healthy infants. Metal concentrations in maternal hair were measured by inductively coupled plasma-mass spectrometry. The adjusted odds ratios (AOR) of titanium concentration above the median were 1.46 (95% confidence interval (CI), 0.99-2.13) for total NTDs and 2.10 (95% CI, 1.12-3.94) for anencephaly, while OR of silver wasn't statistically significant. Titanium concentration was positively correlated with consumptions of vegetables and fruits. Maternal exposure to titanium during the periconception period was associated with an increased NTD risk in offspring, which may be partly mediated through maternal dietary habits.

Achieving surface chemical and morphologic alterations on tantalum by plasma electrolytic oxidation

Background

Search for materials that may either replace titanium dental implants or constitute an alternative as a new dental implant material has been widely studied. As well, the search for optimum biocompatible metal surfaces remains crucial. So, the aim of this work is to develop an oxidized surface layer on tantalum using plasma electrolytic oxidation (PEO) similar to those existing on oral implants been marketed today.

Methods

Cleaned tantalum samples were divided into group 1 (control) and groups 2, 3, and 4 (treated by PEO for 1, 3, and 5 min, respectively). An electrolytic solution diluted in 1-L deionized water was used for the anodizing process. Then, samples were washed with anhydrous ethyl alcohol and dried in the open air. For complete anodic treatment disposal, the samples were immersed in acetone altogether, taken to the ultrasonic tank for 10 min, washed again in distilled water, and finally air-dried. For the scanning electron microscopy (SEM) analysis, all samples were previously coated with gold; the salt deposition analysis was conducted with an energy-dispersive X-ray spectroscopy (EDS) system integrated with the SEM unit.

Results

SEM images confirmed the changes on tantalum strips surface according to different exposure times while EDS analysis confirmed increased salt deposition as exposure time to the anodizing process also increased.

Conclusions

PEO was able to produce both surface alteration and salt deposition on tantalum strips similar to those existing on oral implants been marketed today.

Titanium: a review on exposure, release, penetration, allergy, epidemiology, and clinical reactivity

Exposure to titanium (Ti) from implants and from personal care products as nanoparticles (NPs) is common. This article reviews exposure sources, ion release, skin penetration, allergenic effects, and diagnostic possibilities. We conclude that human exposure to Ti mainly derives from dental and medical implants, personal care products, and foods. Despite being considered to be highly biocompatible relative to other metals, Ti is released in the presence of biological fluids and tissue, especially under certain circumstances, which seem to be more likely with regard to dental implants. Although most of the studies reviewed have important limitations, Ti seems not to penetrate a competent skin barrier, either as pure Ti, alloy, or as Ti oxide NPs. However, there are some indications of Ti penetration through the oral mucosa. We conclude that patch testing with the available Ti preparations for detection of type IV hypersensitivity is currently inadequate for Ti. Although several other methods for contact allergy detection have been suggested, including lymphocyte stimulation tests, none has yet been generally accepted, and the diagnosis of Ti allergy is therefore still based primarily on clinical evaluation. Reports on clinical allergy and adverse events have rarely been published. Whether this is because of unawareness of possible adverse reactions to this specific metal, difficulties in detection methods, or the metal actually being relatively safe to use, is still unresolved.

The effect of plasma surface treatment on the bioactivity of titanium implant materials (in vitro)

BACKGROUND

The surface of an implantable biomaterial plays a very important role in determining the biocompatibility, osteoinduction, and osteointegration of implants because it is in intimate contact with the host bone and soft tissues.

OBJECTIVE

This study was aimed to assess the effect of plasma surface treatment on the bioactivity of titanium alloy (Ti-6Al-4V).

MATERIALS AND METHODS

Fifteen titanium alloy samples were used in this study. The samples were divided into three groups (with five samples in each group). Five samples were kept untreated and served as control (group A). Another five plasma samples were sprayed for nitrogen ion implantation on their surfaces (group B) and the last five samples were pre-etched with acid before plasma treatment (group C). All the investigated samples were immersed for 7 days in Hank's balanced salt solution (HBSS) which was used as a simulating body fluid (SBF) at pH 7.4 and 37°C. HBSS was renewed every 3 days. The different surfaces were characterized by X-ray diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDXA), and Fourier Transformation Infrared Spectroscopy (FTIR).

RESULTS

Nitriding of Ti-alloy samples via plasma nitrogen ion implantation increased the bioactivity of titanium. Moreover, the surface topography affected the chemical structure of the formed apatite. Increasing the surface roughness enhanced the bioactivity of the implant material.

CONCLUSIONS

Nitridation can be exploited as an effective way to promote the formation of bone-like material on the implant surface.

Relevant aspects in the surface properties in titanium dental implants for the cellular viability

Roughness and topographical features are the most relevant of the surface properties for a dental implant for its osseointegration. For that reason, we studied the four surfaces more used in titanium dental implants: machined, sandblasted, acid etching and sandblasted plus acid etching. The roughness and wettability (contact angle and surface free energy) was studied by means 3D-interferometric microscope and sessile drop method. Normal human gingival fibroblasts (HGF) were obtained from small oral mucosa biopsies and were used for cell cultures. To analyze cell integrity, we first quantified the total amount of DNA and LDH released from dead cells to the culture medium. Then, LIVE/DEAD assay was used as a combined method assessing cell integrity and metabolism. All experiments were carried out on each cell type cultured on each Ti material for 24h, 48h and 72h. To evaluate the in vivo cell adhesion capability of each Ti surface, the four types of discs were grafted subcutaneously in 5 Wistar rats. Sandblasted surfaces were significantly rougher than acid etching and machined. Wettability and surface free energy decrease when the roughness increases in sand blasted samples. This fact favors the protein adsorption. The DNA released by cells cultured on the four Ti surfaces did not differ from that of positive control cells (p>0.05). The number of cells per area was significantly lower (p<0.05) in the sand-blasted surface than in the machined and surface for both cell types (7±2 cells for HGF and 10±5 cells for SAOS-2). The surface of the machined-type discs grafted in vivo had a very small area occupied by cells and/or connective tissue (3.5%), whereas 36.6% of the sandblasted plus acid etching surface, 75.9% of sandblasted discs and 59.6% of acid etching discs was covered with cells and connective tissue. Cells cultured on rougher surfaces tended to exhibit attributes of more differentiated osteoblasts than cells cultured on smoother surfaces. These surface properties justify that the sandblasted implants is able to significantly increase bone contact and bone growth with very good osseointegration results in vivo.

Long-Term Fever After Hallux Valgus Surgery Secondary to Titanium Allergy: A Case Report and Review of the Literature

We present the case of a patient who had experienced a fever of unknown cause for >7 months after surgical treatment for hallux valgus. A patch test revealed a positive reaction to a titanium alloy. All symptoms subsequently disappeared after we removed the implanted titanium screws. Histopathologic examination of the tissue surrounding the screws showed macrophage infiltration in the tissue. For >1 year after removal of the titanium screws, the patient's body temperature remained <37°C. These results support a diagnosis of titanium allergy in our patient. To the best of our knowledge, a long-term fever caused by an allergic reaction to mini-titanium screws of such a small size has not been reported. A review of 16 cases of titanium allergy reported in the published data confirmed that titanium allergy is extremely rare and that the clinical symptoms can vary. Titanium allergy should be suspected when a patient presents with a fever of unknown cause, delayed wound healing, dermatitis, or impaired fracture healing after internal fixation with titanium materials. A patch test for titanium or the lymphocyte transformation test could offer guidance for the clinical diagnosis of titanium allergy. Finally, we recommend that all patients should be asked whether they have a history of an allergy to any metal before surgery.

Increased frequency of delayed type hypersensitivity to metals in patients with connective tissue disease

BACKGROUND

Connective tissue disease (CTD) is a group of inflammatory disorders of unknown aetiology. Patients with CTD often report hypersensitivity to nickel. We examined the frequency of delayed type hypersensitivity (DTH) (Type IV allergy) to metals in patients with CTD.

METHODS

Thirty-eight patients; 9 with systemic lupus erythematosus (SLE), 16 with rheumatoid arthritis (RA), and 13 with Sjögren's syndrome (SS) and a control group of 43 healthy age- and sex-matched subjects were included in the study. A detailed metal exposure history was collected by questionnaire. Metal hypersensitivity was evaluated using the optimised lymphocyte transformation test LTT-MELISA(®) (Memory Lymphocyte Immuno Stimulation Assay).

RESULTS

In all subjects, the main source of metal exposure was dental metal restorations. The majority of patients (87%) had a positive lymphocyte reaction to at least one metal and 63% reacted to two or more metals tested. Within the control group, 43% of healthy subjects reacted to one metal and only 18% reacted to two or more metals. The increased metal reactivity in the patient group compared with the control group was statistically significant (P<0.0001). The most frequent allergens were nickel, mercury, gold and palladium.

CONCLUSIONS

Patients with SLE, RA and SS have an increased frequency of metal DTH. Metals such as nickel, mercury and gold are present in dental restorative materials, and many adults are therefore continually exposed to metal ions through corrosion of dental alloys. Metal-related DTH will cause inflammation. Since inflammation is a key process in CTDs, it is possible that metal-specific T cell reactivity is an etiological factor in their development. The role of metal-specific lymphocytes in autoimmunity remains an exciting challenge for future studies.

Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite

The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO₂ oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC) solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo properties, electrical semiconductors, stress transfer, additives with low thermal PMC processing and new coating possibilities.

Comparative in vitro study regarding the biocompatibility of titanium-base composites infiltrated with hydroxyapatite or silicatitanate

BACKGROUND

The development of novel biomaterials able to control cell activities and direct their fate is warranted for engineering functional bone tissues. Adding bioactive materials can improve new bone formation and better osseointegration. Three types of titanium (Ti) implants were tested for in vitro biocompatibility in this comparative study: Ti6Al7Nb implants with 25% total porosity used as controls, implants infiltrated using a sol-gel method with hydroxyapatite (Ti HA) and silicatitanate (Ti SiO2). The behavior of human osteoblasts was observed in terms of adhesion, cell growth and differentiation.

RESULTS

The two coating methods have provided different morphological and chemical properties (SEM and EDX analysis). Cell attachment in the first hour was slower on the Ti HA scaffolds when compared to Ti SiO2 and porous uncoated Ti implants. The Alamar blue test and the assessment of total protein content uncovered a peak of metabolic activity at day 8-9 with an advantage for Ti SiO2 implants. Osteoblast differentiation and de novo mineralization, evaluated by osteopontin (OP) expression (ELISA and immnocytochemistry), alkaline phosphatase (ALP) activity, calcium deposition (alizarin red), collagen synthesis (SIRCOL test and immnocytochemical staining) and osteocalcin (OC) expression, highlighted the higher osteoconductive ability of Ti HA implants. Higher soluble collagen levels were found for cells cultured in simple osteogenic differentiation medium on control Ti and Ti SiO2 implants. Osteocalcin (OC), a marker of terminal osteoblastic differentiation, was most strongly expressed in osteoblasts cultivated on Ti SiO2 implants.

CONCLUSIONS

The behavior of osteoblasts depends on the type of implant and culture conditions. Ti SiO2 scaffolds sustain osteoblast adhesion and promote differentiation with increased collagen and non-collagenic proteins (OP and OC) production. Ti HA implants have a lower ability to induce cell adhesion and proliferation but an increased capacity to induce early mineralization. Addition of growth factors BMP-2 and TGFβ1 in differentiation medium did not improve the mineralization process. Both types of infiltrates have their advantages and limitations, which can be exploited depending on local conditions of bone lesions that have to be repaired. These limitations can also be offset through methods of functionalization with biomolecules involved in osteogenesis.