Ricardo Tejero - Academia.edu (original) (raw)

Papers by Ricardo Tejero

Implant comprising calcium on the surface thereof, and methods for modifying the surface of an implant for providing said surface with calcium

Progress in the Use of Autologous Regenerative Platelet-based Therapies in Implant Dentistry

Current Pharmaceutical Biotechnology, 2016

The field of medicine is rapidly moving towards the development of personalized treatments and no... more The field of medicine is rapidly moving towards the development of personalized treatments and non-invasive tools to achieve a more predictable and optimal tissue regeneration. In this sense, the goal of periodontal healing is to arrest disease progression and functionally regenerate all the tissues that comprise the periodontium. The latter implies a well-orchestrated interaction among oral cells, growth factors and extracellular matrix. Although several procedures are performed in an attempt to regenerate lost periodontal tissue, outcomes are not always predictable. Growth factors represent a class of biologically active polypeptides that have a critical role in the healing process. Their use provides a new paradigm to understand the regenerative medicine. The use of platelet- rich plasma (PRP) products as a local source and delivery system of autologous growth factors has emerged recently. Among them, PRGF stands for its remarkable stimulatory effect on oral tissue regeneration, making it a very safe and successful tool with a great value in Dentistry.

Effects of Calcium Ions on Titanium Surfaces for Bone Regeneration

Colloids and Surfaces B: Biointerfaces, 2015

The chemistry and topography of implant surfaces are of paramount importance for the successful t... more The chemistry and topography of implant surfaces are of paramount importance for the successful tissue integration of load-bearing dental and orthopedic implants. Here we evaluate in vitro and in vivo titanium implant surfaces modified with calcium ions (Ca(2+) surfaces). Calcium ions produce a durable chemical and nano-topographical modification of the titanium oxide interface. Time of flight secondary ion mass spectrometry examination of the outermost surface composition, shows that calcium ions in Ca(2+) surfaces effectively prevent adventitious hydrocarbon passivation of the oxide layer. In aqueous solutions Ca(2+) surfaces release within the first minute, 2/3 of the total measured Ca(2+), the rest is released over the following 85 days. Additionally, Ca(2+) surfaces significantly increase human fetal osteoblasts-like cell adhesion, proliferation and differentiation, as measured by the autocrine synthesis of osteopontin. Relevant for clinical application, after 12 weeks of healing in sheep tibia, microcomputer tomography and histomorphometric analysis show that Ca(2+) surfaces develop significantly more bone contacts and higher bone density in the 1mm region around the implant. Consequently, titanium implants modified with calcium ions represent a valuable tool to improve endosseous integration in the clinical practice.

Journal of biomedical materials research. Part A, 2015

The clinical success of load bearing dental and orthopedic implants relies on adequate osseointeg... more The clinical success of load bearing dental and orthopedic implants relies on adequate osseointegration. Because of its favorable properties, titanium is generally considered as the material of choice. Following implant placement, titanium surfaces establish an ionic equilibrium with the surrounding tissues in which calcium plays major roles. Calcium is a cofactor of the coagulation cascade that mediates plasma protein adsorption and intervenes in a number of other intra and extracellular processes relevant for bone regeneration. In this study, titanium surfaces were modified with calcium ions (Ca(2+) surfaces) and their responses to in vitro and in vivo models were analyzed. Unlike unmodified surfaces, Ca(2+) surfaces were superhydrophilic and induced surface clot formation, platelet adsorption and activation when exposed to blood plasma. Interestingly, in vivo osseointegration using a peri-implant gap model in rabbit demonstrated that Ca(2+) surfaces significantly improved peri-im...

Time-of-flight secondary ion mass spectrometry with principal component analysis of titania-blood plasma interfaces

Langmuir : the ACS journal of surfaces and colloids, Jan 22, 2013

Treatment of osseoimplant surfaces with autologous platelet-rich plasma prepared according to the... more Treatment of osseoimplant surfaces with autologous platelet-rich plasma prepared according to the plasma rich in growth factors (PRGF-Endoret) protocol prior to implantation yields promising results in the clinic. Our objective is to understand the organization of complex interfaces between blood plasma preparations of various compositions and model titania surfaces. Here we present the results of the morphological and chemical characterization of TiO(2) surfaces incubated with four types of blood plasma preparations devoid of leukocytes and red blood cells: either enriched in platelets (PRGF-Endoret) or platelet-depleted, and either activated with CaCl(2) to induce clotting, or not. Chemical characterization was done by time-of-flight secondary ion mass spectrometry with principal component analysis (ToF-SIMS/PCA). The interface morphology was studied with scanning electron and atomic force microscopy. Immunofluorescence microscopy was used to identify platelets and infer their act...

Non-traumatic implant explantation: a biomechanical and biological analysis in sheep tibia

Journal of Oral Implantology, 2014

Abstract A preclinical research in a sheep tibia model has been conducted to evaluate the underly... more Abstract A preclinical research in a sheep tibia model has been conducted to evaluate the underlying mechanisms of the non-traumatic implant explantation of failed implants, which allow placing a new one in the bone bed. Twelve dental implants were placed in sheep diaphysis tibia and once osseointegrated they were explanted using a non-traumatic implant explantation approach. Implant osseointegration and explantation were monitored by means of frequency resonance, removal torque and angle of rotation measurement. The host bone bed and the explanted implant-surface were analyzed by conventional microscopy and scanning electron microscope. Results show that the osseointegration was broken with an angular displacement of less than 20º. In this situation the implant returns to implant stability quotient values in the same range of their primary stability. Moreover, the explantation technique causes minimal damage to the surrounding bone structure and cellularity. This non-traumatic approach allows the straightforward replacement of failed implants and emerges as a promising strategy to resolve clinically challenging situations.

Progress in Polymer Science, 2014

Replacing malfunctioning tissues with titanium-based implants has become a widespread practice sp... more Replacing malfunctioning tissues with titanium-based implants has become a widespread practice spurred by population aging. Advances in biomaterials, technology and implantation protocols have led to increasing expectations on the applicability and durability of implants. The field has recently moved from a bioinert to a bioactive paradigm due to surface modifications that trigger specific responses on the surrounding tissues. Biopolymeric surface coatings have taken up a central role in these developments. The use of these and other biomimetic strategies on implants provides greater control over material-cell interactions and it is aimed at improving long-term clinical results by replicating some of the structures and mechanisms of living tissues. This review summarizes the state of the art of biomimetic implants and discusses the main directions and challenges of this field toward a more predictable and successful implant osseointegration.

Time-of-Flight Secondary Ion Mass Spectrometry with Principal Component Analysis of Titania–Blood Plasma Interfaces

Langmuir, 2013

Journal of Periodontology, 2013

Background: Alveolar bone loss can be a major clinical concern affecting both functionality and e... more Background: Alveolar bone loss can be a major clinical concern affecting both functionality and esthetics. Osteoblasts are the main cells charged with the repair and regeneration of missing bone tissue. Plasma rich in growth factors (PRGF) allows delivery of a cocktail of proteins and growth factors that promote wound healing and tissue regeneration to the site of injury. This study tests the effect of this endogenous regenerative technology to stimulate alveolar osteoblast bone-forming potential.

Journal of Biomedical Materials Research Part A, 2013

Plasma rich in growth factors (PRGFs) technology is an autologous platelet-rich plasma approach t... more Plasma rich in growth factors (PRGFs) technology is an autologous platelet-rich plasma approach that provides a pool of growth factors and cytokines that have been shown to increase tissue regeneration and accelerate dental implant osseointegration. In this framework, the spatiotemporal release of growth factors and the establishment of a provisional fibrin matrix are likely to be key aspects governing the stimulation of the early phases of tissue regeneration around implants. We investigated the kinetics of growth factor release at implant surfaces functionalized either with PRGFs or platelet-poor plasma and correlated the results obtained with the morphology of the resulting interfaces. Our main finding is that activation and clot formation favors longer residence times of the growth factors at the interfaces studied, probably due to their retention in the adsorbed fibrin matrix. The concentration of the platelet-derived growth factors above the interfaces becomes negligible after 2-4 days and is significantly higher in the case of activated interfaces than in the case of nonactivated ones, whereas that of the plasmatic hepatocyte growth factor is independent of platelet concentration and activation, and remains significant for up to 9 days. Platelet-rich plasma preparations should be activated to permit growth factor release and thereby facilitate implant surface osseointegration. V C 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 00A:000-000, 2012.

Journal of Materials Science: Materials in Medicine, 2010

Glucuronic acid (GlcA) and phosphoserine (pS) carrying acidic functional groups were used as mode... more Glucuronic acid (GlcA) and phosphoserine (pS) carrying acidic functional groups were used as model molecules for glycosaminoglycans and phosphoproteins, respectively to mimic effects of native biomolecules and influence the mineralization behaviour of collagen I. Collagen substrates modified with GlcA showed a stable interaction between GlcA and collagen fibrils. Substrates were mineralized using the electrochemically assisted deposition (ECAD) in a Ca 2? /H x PO 4 (3-x) electrolyte at physiological pH and temperature. During mineralization of collagen-GlcA matrices, crystalline hydroxyapatite (HA) formed earlier with increasing GlcA content of the collagen matrix, while the addition of pS to the electrolyte succeeded in inhibiting the transformation of preformed amorphous calcium phosphate (ACP) to HA. The lower density of the resulting mineralization and the coalesced aggregates formed at a certain pS concentration suggest an interaction between calcium and the phosphate groups of pS involving the formation of complexes. Combining GlcA-modified collagen and pS-modified electrolyte showed dose-dependent cooperative effects.