Daniel Olmedo - Academia.edu (original) (raw)

Papers by Daniel Olmedo

Implant Dentistry, Mar 1, 2003

Aires performs histologic studies of implants that have failed as a result of mobility, fracture,... more Aires performs histologic studies of implants that have failed as a result of mobility, fracture, and early exposure, among other causes. The implants are received in 20% formalin solution and must be accompanied by the corresponding protocol. The sample is radiographed before processing with histologic analysis (Fig. 1, a and b).

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2022

The surface of a biomedical implant can be a potential endogenous source of release of microparti... more The surface of a biomedical implant can be a potential endogenous source of release of microparticles (MPs) and nanoparticles (NPs) into the biological environment. In addition, titanium particles from exogenous sources can enter the body through inhalation, ingestion, or dermal contact. The aim of this work was to evaluate the biological response of the lung, liver, and kidneys to acute exposure to titanium dioxide (TiO2). Male Wistar rats were intraperitoneally injected with a suspension of 45 μm or 5 nm TiO2 particles. One month post‐exposure, titanium concentration was determined spectrometrically (ICP‐MS) in plasma and target organs. Blood smears and organ tissue samples were examined histopathologically, and oxidative metabolism was analyzed (superoxide anion by nitro blue tetrazolium (NBT) test; superoxide dismutase (SOD) and catalase (CAT); lipid peroxidation; paraoxonase 1). Liver (aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) and kidney (u...

Journal of Trace Elements in Medicine and Biology, 2019

Background: Titanium is widely used in biomedicine. Due to biotribocorrosion, titanium dioxide (T... more Background: Titanium is widely used in biomedicine. Due to biotribocorrosion, titanium dioxide (TiO 2) nanoparticles (NPs) can be released from the titanium implant surface, enter the systemic circulation, and migrate to various organs and tissues including the brain. A previous study showed that 5 nm TiO 2 NPs reached the highest concentration in the brain. Even though TiO 2 NPs are believed to possess low toxicity, little is known about their neurotoxic effects. The aim of the study was to evaluate in vitro the effects of 5 nm TiO 2 NPs on a human neuroblastoma (SH-SY5Y) cell line. Methods: Cell cultures were divided into non-exposed and exposed to TiO 2 NPs for 24 h. The following were evaluated: reactive oxygen species (ROS) generation, apoptosis, cellular antioxidant response, endoplasmic reticulum stress and autophagy. Results: Exposure to TiO 2 NPs induced ROS generation in a dose dependent manner, with values reaching up to 10 fold those of controls (p < 0.001). Nrf2 nuclear localization and autophagy, also increased in a dose dependent manner. Apoptosis increased by 4-to 10-fold compared to the control group, depending on the dose employed. Conclusions: Our results show that TiO 2 NPs cause ROS increase, induction of ER stress, Nrf2 cytoplasmic translocation to the nucleus and apoptosis. Thus, neuroblastoma cell response to TiO 2 NPs may be associated with an imbalance of the oxidative metabolism where endoplasmic reticulum-mediated signal pathway seems to be the main neurotoxic mechanism.

Procedia Materials Science, 2015

The aim of this development is to optimize a bone substitute (BS) for use in tissue engineering. ... more The aim of this development is to optimize a bone substitute (BS) for use in tissue engineering. This is achieved through the combination of three phases in a biocomposite (BCO), in which each is reabsorbed in the site of implantation and replaced by autologous bone (patient's own). The inorganic phases are composed of irregular particles (150-300 microns) obtained by milling and sieving of a biphasic bioceramic (BC) of hydroxyapatite (HA of bovine origin) with 40 % (wt.)-tricalcium phosphate (-TCP, obtained by chemical synthesis) and Bioglass type 45S5 (45SiO 2-24,5CaO-24,5Na2O-6P2O5, in % wt.). Instead, the organic phase consists of collagen extracted from Wharton's jelly (part of the human embryonic tissue) from physical and chemical self-developed process. The BC is produced by mixture of HA and-TCP (< 45 m) and molding by gelcasting with albumin in aqueous solutions, drying and sintering at 1200°C for 2 hours. The BG is obtained from the mixture of the oxides, melting at 1350°C and cast onto metal. Each phase and BCO is subjected to studies by electron microscopy (SEM and EDS), Xray diffraction (DRX) and infrared spectrometry (FT-IR). The biocompatibility is evaluated by in vivo studies using the laminar implant model in Wistar rats (n=40). Histological samples show high biocompatibility and ability to integrate with the bone tissue. 30 days after implantation, the material is completely reabsorbed and the bone regeneration process starts, the primary objective. The process developed allows the synthesis of a new BS with excellent biological properties for clinical use.

International journal of oral and maxillofacial surgery, 2008

The aim of this study was to evaluate histologically the biological effect of pitting corrosion a... more The aim of this study was to evaluate histologically the biological effect of pitting corrosion and to contribute clinically relevant data on the permanence of titanium metal structures used in osteosynthesis in the body. Commercially pure titanium laminar implants (control) and commercially pure titanium laminar implants with pitting corrosion (experimental) were implanted in the tibiae of rats. At 14 days post-implantation the animals were killed. The tibiae were resected, fixed, radiographed and processed for embedding in methyl methacrylate. Percentage of bone-implant contact and peri-implant bone volume were evaluated. The histological study of the titanium implants submitted to pitting corrosion showed scarce bone-implant contact, it was only present in the areas with no pitting and/or surface alterations. There was a statistically significant lower percentage of bone-implant contact in the experimental group (6%+/-4) than in the control group (26%+/-6) (p<0.001). Products ...

Journal of Physics: Conference Series, 2007

Commercially Pure Titanium foils, were irradiated using a pulsed Nd:YAG laser under ambient air, ... more Commercially Pure Titanium foils, were irradiated using a pulsed Nd:YAG laser under ambient air, in order to produce and characterize a well controlled surface texture (roughness and waviness) that enhances osseointegration. To study the 'peri-implant' reparative process response, the laser treated Ti foils were implanted in the tibia of 10 male Wistar rats. At 14 days post-implantation, the histological analysis showed a tendency to more bone formation compared to the untreated control implants. The formation of a layer of TiN on the surface and the obtained roughness, have been demonstrated to improve bone response.

Fil: Olmedo, Daniel Gustavo. Universidad de Buenos Aires. Facultad de Odontologia. Catedra de Ana... more Fil: Olmedo, Daniel Gustavo. Universidad de Buenos Aires. Facultad de Odontologia. Catedra de Anatomia Patologica; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Journal of Trace Elements in Medicine and Biology

International Journal of Molecular Sciences

Bone defects have prompted the development of biomaterial-based bone substitutes for restoring th... more Bone defects have prompted the development of biomaterial-based bone substitutes for restoring the affected tissue completely. Although many biomaterials have been designed and evaluated, the combination of properties required in a biomaterial for bone tissue engineering still poses a challenge. In this study, a chitosan–silica-based biocomposite was synthetized, and its physicochemical characteristics and biocompatibility were characterized, with the aim of exploring the advantages and drawbacks of its use in bone tissue engineering. Dynamic light scattering measurements showed that the mean hydrodynamic size of solid silica particles (Sol-Si) was 482 ± 3 nm. Scanning electron microscopy of the biocomposite showed that Sol-Si were homogenously distributed within the chitosan (CS) matrix. The biocomposite swelled rapidly and was observed to have no cytotoxic effect on the [3T3] cell line within 24 h. Biocompatibility was also analyzed in vivo 14 days post-implant using a murine expe...

The American Journal of Surgical Pathology, 1988

Ultrananocrystalline Diamond Coatings for Next-Generation High-Tech and Medical Devices

Nanomaterials, 2022

Implant therapy using osseointegratable titanium (Ti) dental implants has revolutionized clinical... more Implant therapy using osseointegratable titanium (Ti) dental implants has revolutionized clinical dental practice and has shown a high rate of success. However, because a metallic implant is in contact with body tissues and fluids in vivo, ions/particles can be released into the biological milieu as a result of corrosion or biotribocorrosion. Ultrananocrystalline diamond (UNCD) coatings possess a synergistic combination of mechanical, tribological, and chemical properties, which makes UNCD highly biocompatible. In addition, because the UNCD coating is made of carbon (C), a component of human DNA, cells, and molecules, it is potentially a highly biocompatible coating for medical implant devices. The aim of the present research was to evaluate tissue response to UNCD-coated titanium micro-implants using a murine model designed to evaluate biocompatibility. Non-coated (n = 10) and UNCD-coated (n = 10) orthodontic Ti micro-implants were placed in the hematopoietic bone marrow of the tib...

Macromolecular Bioscience, 2022

Synthetic and natural biomaterials are a promising alternative for the treatment of critical-size... more Synthetic and natural biomaterials are a promising alternative for the treatment of critical-sized bone defects. Several parameters such as their porosity, surface, and mechanical properties are extensively pointed out as key points to recapitulate the bone microenvironment. Many biomaterials with this pursuit are employed to provide a matrix, which can supply the specific environment and architecture for an adequate bone growth. Nevertheless, some queries remain unanswered. This review discusses the recent advances achieved by some synthetic and natural biomaterials to mimic the native structure of bone and the manufacturing technology applied to obtain biomaterial candidates. The focus of this review is placed in the recent advances in the development of biomaterial-based therapy for bone defects in different types of bone. In this context, this review gives an overview of the potentialities of synthetic and natural biomaterials: polyurethanes, polyesters, hyaluronic acid, collagen, titanium, and silica as successful candidates for the treatment of bone defects.

Periodontology 2000, 2019

The scientific basis of current implantology was established by Per-Ingvar Brånemark. In studies ... more The scientific basis of current implantology was established by Per-Ingvar Brånemark. In studies on the microcirculation of rabbit bone conducted in the 1950s Brånemark discovered that chambers made of the metal titanium became permanently incorporated with bone. The living bone could become so fused with the titanium oxide layer of the implant that the two could not be separated without fracture. 1 Thus, Brånemark introduced the term "osseointegration" to describe this modality for stable fixation between titanium and bone tissue. Since this discovery, osseointegration has become a realized phenomenon of importance not only in dentistry, but also in orthopedic and rehabilitation sciences. 2 Osseointegration was originally defined as a direct structural and functional connection between ordered living bone and the surface of a load-carrying implant. 3 It is now said that an implant is regarded as osseointegrated when there is no progressive relative movement between the implant and the bone with which it is in direct contact. 1 Although the term osseointegration was initially used with reference to titanium metallic implants, the concept currently applies to all biomaterials that have the ability to osseointegrate, such as ceramics used as bone substitutes (Figure 1). The mechanism of osseointegration is closely related to biomaterials, ie, materials designed to be implanted or incorporated into the living system with the aims to substitute for, or regenerate, tissues and tissue functions. Williams 4 defines biomaterials as those used for biomedical devices designed to interact with biological systems. Classically, there are four types of biomaterials: polymers, metals, ceramics, and natural biomaterials. Two different types of biomaterials can be combined to obtain a fifth type of biomaterial known as a composite biomaterial. 5 The discovery of relatively inert metallic and alloy biomaterials has led to their use in the field of biomedical applications, such as orthopedics and dentistry. They are increasingly being used due to their physical-chemical properties and compatibility with the biological surroundings. 6 Similarly, bone substitutes for reconstructive surgery play an important role in modern therapeutics. The use of titanium dental implants has revolutionized oral implantology. Currently, almost 300 000 patients in the United States have dental implants. In the area of orthopedics, replacement hip joints are implanted in more than 200 000 humans each year. 6 Particularly in dentistry, implant procedures are performed worldwide, and the demand for such procedures seems to be growing at a very rapid rate. At present, another branch of medical research that is closely related to the use of biomaterials is tissue engineering. This area combines principles of cell biology, engineering, biochemistry, molecular biology, and biomaterials. Tissue engineering focuses on the development of new procedures aimed at repairing, replacing, maintaining, or optimizing the functioning of damaged organs or tissues. The biomaterials used in the field of bone tissue engineering need to be biocompatible, osteoinductive, osteoconductive, osteopromoting, porous, and mechanically compatible with host bone in order to fulfill their desired role. The materials provide sites for cell anchorage and mechanical stability, and they serve as a structural guide offering an appropriate interface to respond to physiological and biological changes, and to remodel the matrix allowing for integration with the host tissue.

Journal of Periodontology, 2012

Titanium is the most widely used metal in dental implantology. The release of particles from meta... more Titanium is the most widely used metal in dental implantology. The release of particles from metal structures into the biologic milieu may be the result of electrochemical processes (corrosion) and/or mechanical disruption during insertion, abutment connection, or removal of failing implants. The aim of the present study is to evaluate tissue response of human oral mucosa adjacent to titanium cover screws. One hundred fifty-three biopsies of the supra-implant oral mucosa adjacent to the cover screw of submerged dental implants were analyzed. Histologic studies were performed to analyze epithelial and connective tissue as well as the presence of metal particles, which were identified using microchemical analysis. Langerhans cells, macrophages, and T lymphocytes were studied using immunohistochemical techniques. The surface of the cover screws was evaluated by scanning electron microscopy (SEM). Forty-one percent of mucosa biopsies exhibited metal particles in different layers of the section thickness. Particle number and size varied greatly among specimens. Immunohistochemical study confirmed the presence of macrophages and T lymphocytes associated with the metal particles. Microchemical analysis revealed the presence of titanium in the particles. On SEM analysis, the surface of the screws exhibited depressions and irregularities. The biologic effects seen in the mucosa in contact with the cover screws might be associated with the presence of titanium or other elements, such as aluminum or vanadium. The potential long-term biologic effects of particles on soft tissues adjacent to metallic devices should be further investigated because these effects might affect the clinical outcome of the implant.

Journal of Biomedical Materials Research Part A, 2013

Due to corrosion, a titanium implant surface can be a potential source for the release of micro (... more Due to corrosion, a titanium implant surface can be a potential source for the release of micro (MPs) and nanosized particles (NPs) into the biological environment. This work sought to evaluate the biokinetics of different sized titanium dioxide particles (TiO 2) and their potential to cause cell damage. Wistar rats were intraperitoneally injected with 150 nm, 10 nm, or 5nm TiO 2 particles. The presence of TiO 2 particles was evaluated in histologic sections of the liver, lung, and kidney and in blood cells at 3 and 12 months. Ultrastructural analysis of liver and lung tissue was performed by TEM, deposit concentration in tissues was determined spectroscopically, and oxidative metabolism was assessed by determining oxidative membrane damage, generation of superoxide anion (O 2-), and enzymatic and non-enzymatic antioxidants. TiO 2 particles were observed inside mononuclear blood cells and in organ parenchyma at 3 and 12 months. TiO 2 deposits were consistently larger in liver than in lung tissue. Alveolar macrophage O 2 generation and average particle size correlated negatively (p < 0.05). NPs were more reactive and biopersistent in lung tissue than MPs. Antioxidant activity, particularly in the case of 5 nm particles, failed to compensate for membrane damage in liver cells; the damage was consistent with histological evidence of necrosis.

Journal of Periodontology, 2013

Aim: Titanium implants are commonly used as replacement therapy for lost teeth and much current r... more Aim: Titanium implants are commonly used as replacement therapy for lost teeth and much current research is focusing on the improvement of the chemical and physical properties of their surfaces in order to improve the osseointegration process. TiO 2 , when it is deposited in the form of pillar array nanometric structures, has photocatalytic properties and wet surface control, which, together with UV irradiation, provide it with superhydrophilic surfaces, which may be of interest for improving cell adhesion on the peri-implant surface. In this article, we address the influence of this type of surface treatment on type IV and type V titanium discs on their surface energy and cell growth on them. Materials and methods: Samples from titanium rods used for making dental implants were used. There were two types of samples: grade IV and grade V. In turn, within each grade, two types of samples were differentiated: untreated and treated with sand blasting and subjected to double acid etching. Synthesis of the film consisting of titanium oxide pillar array structures was carried out using plasma-enhanced chemical vapor deposition equipment. The plasma was generated in a quartz vessel by an external SLAN-1 microwave source with a frequency of 2.45 GHz. Five specimens from each group were used (40 discs in total). On the surfaces to be studied, the following determinations were carried out: (a) X-ray photoelectron spectroscopy, (b) scanning electron microscopy, (c) energy dispersive X-ray spectroscopy, (d) profilometry, (e) contact angle measurement or surface wettability, (f) progression of contact angle on applying ultraviolet irradiation, and (g) a biocompatibility test and cytotoxicity with cell cultures. Results: The application of ultraviolet light decreased the hydrophobicity of all the surfaces studied, although it did so to a greater extent on the surfaces with the studied modification applied, this being more evident in samples manufactured in grade V titanium. In samples made in grade IV titanium, this difference was less evident, and even in the sample manufactured with grade IV and SLA treatment, the application of the nanometric modification of the surface made the surface optically less active. Regarding cell growth, all the surfaces studied, grouped in relation to the presence or not of the nanometric treatment, showed similar growth. Conclusions. Treatment of titanium oxide surfaces with ultraviolet irradiation made them change temporarily into superhydrophilic ones, which confirms that their biocompatibility could be improved in this way, or at least be maintained.

Journal of Materials Science: Materials in Medicine, 2003

Acta odontologica latinoamericana : AOL, 2009

Pure titanium or titanium alloys, and to a lesser extent, zirconium, are metals that are often us... more Pure titanium or titanium alloys, and to a lesser extent, zirconium, are metals that are often used in direct contact with host tissues. These metallic biomaterials are highly reactive, and on exposure to fluid media or air, quickly develop a layer of titanium dioxide (TiO2) or zirconium dioxide (ZrO2). This layer of dioxide forms a boundary at the interface between the biological medium and the metal structure, determining the degree of biocompatibility and the biological response of the implant. Corrosion is the deterioration a metal undergoes as a result of the surrounding medium (electrochemical attack), which causes the release of ions into the microenvironment. No metal or alloy is entirely inert in vivo. Corrosion phenomena at the interlace are particularly important in the evolution of both dental and orthopedic implants and one of the possible causes of implant failure after initial success. This paper comprises a review of literature and presents results of our laboratory ...