Iopamidol Abatement from Waters: A Rigorous Approach to Determine Physicochemical Parameters Needed to Scale Up from Batch to Continuous Operation

The abatement of iopamidol (IPM), an X-ray iodinated contrast agent, in aqueous solution using powdered activated carbon (PAC) as a sorbent was investigated in the present work. The material was characterized by various analytical techniques such as thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, dynamic light scattering, and zeta potential measurements. Both thermodynamic and kinetic experiments were conducted in a batch apparatus, and the effects of the initial concentration of IPM, the temperature, and the adsorbent bulk density on the adsorption kinetics were investigated. The adsorption isotherms were interpreted well using the Langmuir model. Moreover, it was demonstrated that IPM adsorption on PAC is spontaneous and exothermic (ΔH0 = -27 kJ mol-1). The adsorption kinetic data were described using a dynamic intraparticle model for fluid-solid adsorption kinetics (ADIM) allowing determination of a surface activation energy Es = 6 ± 1 kJ mol-1. Comparing the experimental results and the model predictions, a good model fit was obtained.

In Situ Hydrogel Formulation for Advanced Wound Dressing: Influence of Co-Solvents and Functional Excipient on Tailored Alginate-Pectin-Chitosan Blend Gelation Kinetics, Adhesiveness, and Performance

Chronic skin wounds affect more than 40 million patients worldwide, representing a huge problem for healthcare systems. This study elucidates the optimization of an in situ gelling polymer blend powder for biomedical applications through the use of co-solvents and functional excipients, underlining the possibility of tailoring microparticulate powder properties to generate, in situ, hydrogels with advanced properties that are able to improve wound management and patient well-being. The blend was composed of alginate, pectin, and chitosan (APC). Various co-solvents (ethanol, isopropanol, and acetone), and salt excipients (sodium bicarbonate and ammonium carbonate) were used to modulate the gelation kinetics, rheology, adhesiveness, and water vapor transmission rate of the gels. The use of co-solvents significantly influenced particle size (mean diameter ranging from 2.91 to 5.05 µm), depending on the solvent removal rate. Hydrogels obtained using ethanol were able to absorb over 15 times their weight in simulated wound fluid within just 5 min, whereas when sodium bicarbonate was used, complete gelation was achieved in less than 30 s. Such improvement was related to the internal microporous network typical of the particle matrix obtained with the use of co-solvents, whereas sodium bicarbonate was able to promote the formation of allowed particles. Specific formulations demonstrated an optimal water vapor transmission rate, enhanced viscoelastic properties, gel stiffness, and adhesiveness (7.7 to 9.9 kPa), facilitating an atraumatic removal post-use with minimized risk of unintended removal. Microscopic analysis unveiled that porous inner structures were influencing fluid uptake, gel formation, and transpiration. In summary, this study provided valuable insights for optimizing tailored APC hydrogels as advanced wound dressings for chronic wounds, including vascular ulcers, pressure ulcers, and partial and full-thickness wounds, characterized by a high production of exudate.

Advances in Transdermal Drug Delivery Systems: A Bibliometric and Patent Analysis

Transdermal drug delivery systems have become an intriguing research topic in healthcare technology and one of the most frequently developed pharmaceutical products in the global market. In recent years, researchers and pharmaceutical companies have made significant progress in developing new solutions in the field. This study sheds light on current trends, collaboration patterns, research hotspots, and emerging frontiers of transdermal drug delivery. Herein, a bibliometric and patent analysis of data recovered from Scopus and The Lens databases, respectively, is reported over the last 20 years. From 2000 to 2022, the annual global publications increased from 131 in 2000 to 659 in 2022. Researchers in the United States, China, and India produced the highest number of publications. Likewise, most patent applications have been filed in the USA, China, and Europe. The recovered patents are 7275, grouped into 2997 patent families, of which 314 were granted. This study could support the work of decision-makers, scientific managers, or scientists to create new business opportunities or save money, time, and intellectual capital, thereby defining when a research or technology project should be a priority or not.

A Novel Three-Polysaccharide Blend In Situ Gelling Powder for Wound Healing Applications

In this paper, alginate/pectin and alginate/pectin/chitosan blend particles, in the form of an in situ forming hydrogel, intended for wound repair applications, have been successfully developed. Particles have been used to encapsulate doxycycline in order to control the delivery of the drug, enhance its antimicrobial properties, and the ability to inhibit host matrix metalloproteinases. The presence of chitosan in the particles strongly influenced their size, morphology, and fluid uptake properties, as well as drug encapsulation efficiency and release, due to both chemical interactions between the polymers in the blend and interactions with the drug demonstrated by FTIR studies. In vitro antimicrobial studies highlighted an increase in antibacterial activity related to the chitosan amount in the powders. Moreover, in situ gelling powders are able to induce a higher release of IL-8 from the human keratinocytes that could stimulate the wound healing process in difficult-healing. Interestingly, doxycycline-loaded particles are able to increase drug activity against MMPs, with good activity against MMP-9 even at 0.5 μg/mL over 72 h. Such results suggest that such powders rich in chitosan could be a promising dressing for exudating wounds.

Key Physicochemical Determinants in the Antimicrobial Peptide RiLK1 Promote Amphipathic Structures

Antimicrobial peptides (AMPs) represent a skilled class of new antibiotics, due to their broad range of activity, rapid killing, and low bacterial resistance. Many efforts have been made to discover AMPs with improved performances, i.e., high antimicrobial activity, low cytotoxicity against human cells, stability against proteolytic degradation, and low costs of production. In the design of new AMPs, several physicochemical features, such as hydrophobicity, net positive charge, propensity to assume amphipathic conformation, and self-assembling properties, must be considered. Starting from the sequence of the dodecapeptide 1018-K6, we designed a new 10-aminoacid peptide, namely RiLK1, which is highly effective against both fungi and Gram-positive and -negative bacteria at low micromolar concentrations without causing human cell cytotoxicity. In order to find the structural reasons explaining the improved performance of RiLK1 versus 1018-K6, a comparative analysis of the two peptides was carried out with a combination of CD, NMR, and fluorescence spectroscopies, while their self-assembling properties were analyzed by optical and atomic force microscopies. Interestingly, the different spectroscopic and microscopic profiles exhibited by the two peptides, including the propensity of RiLK1 to adopt helix arrangements in contrast to 1018-K6, could explain the improved bactericidal, antifungal, and anti-biofilm activities shown by the new peptide against a panel of food pathogens.

A Safe and Multitasking Antimicrobial Decapeptide: The Road from De Novo Design to Structural and Functional Characterization

Antimicrobial peptides (AMPs) are excellent candidates to fight multi-resistant pathogens worldwide and are considered promising bio-preservatives to control microbial spoilage through food processing. To date, designing de novo AMPs with high therapeutic indexes, low-cost synthesis, high resistance, and bioavailability, remains a challenge. In this study, a novel decapeptide, named RiLK1, was rationally designed starting from the sequence of the previously characterized AMP 1018-K6, with the aim of developing short peptides, and promoting higher selectivity over mammalian cells, antibacterial activity, and structural resistance under different salt, pH, and temperature conditions. Interestingly, RiLK1 displayed a broad-spectrum of bactericidal activity against Gram-positive and Gram-negative bacteria, including multidrug resistant clinical isolates of Salmonella species, with Minimal Bactericidal Concentration (MBC) values in low micromolar range, and it was effective even against two fungal pathogens with no evidence of cytotoxicity on human keratinocytes and fibroblasts. Moreover, RiLK1-activated polypropylene films were revealed to efficiently prevent the growth of microbial spoilage, possibly improving the shelf life of fresh food products. These results suggested that de novo designed peptide RiLK1 could be the first candidate for the development of a promising class of decameric and multitask antimicrobial agents to overcome drug-resistance phenomena.

Composite Materials for Biomedical Applications

The concepts of composite mechanics have been used to design two materials for potential prosthesis of biomedical interest. They attain specific physical properties and use polymers which show a high degree of biocompatibility.

The materials used were a poly (2-hydroxyethyl-methacrylate) as matrix and polyesther resin as reinforcing fibers.

The mechanical performance of a uniaxially oriented composite has been adjusted to match the behaviour of a human tendon. A laminate composite has been modelled for use in plastic surgery.

Poly(2-hydroxyethyl methacrylate)/Poly(caprolactone) Semi-Interpenetrating Polymer Networks

Semi-interpenetrating polymer networks (semi-IPN's) composed of cross linked poly(2-hydroxyethyl methacrylate) (PHEMA), and linear poly(caprolac tone) (PCL), display improved mechanical properties over pure PHEMA in the water swollen state without covalent bonding between the components.

Preparation and Characterization of a Hydrogel from Low-Molecular Weight Hyaluronic Acid

A relatively low-molecular weight sample of hyaluronic acid (HA) was chemically modified by means of a cross-linking reaction with water-soluble carbodiimide and L-lysine methyl ester to form a chemical hydrogel. FT-IR analysis performed on the precursors and on the cross-linked hydrogel indicated the formation of ester bonds between different HA molecules that led to an intermolecular cross-linking. Hydrogel swelling kinetics as well as equilibrium sorption properties were evaluated. A swelling ratio of 250 was observed after immersion in distilled water for 7 h. Rheological measurements by means of a plate–plate rheometer of the cross-linked sample showed non-Newtonian and pseudoplastic behavior, while the uncross-linked HA showed Newtonian behavior and a viscous characteristic. Morphological analysis of these microstructures by scanning electron microscopy indicated that the freeze-dried crosslinked hydrogel presents a more closed-pore structure and higher density of pores than the freeze-dried original HA.

Water Transport in Hyaluronic Acid Esters

Hyaluronic acid esters belong to a new class of polymers which have been developed in order to overcome water sensitivity displayed by hyaluronic acid. In this paper the effects of the substituting group on the water vapor transport properties were investigated. In particular, water sorption isotherms and kinetics for three types of hyaluronic acid esters (ethyl, dodecyl and benzyl esters) were determined. The type of substituent group has been found to affect polymer hydrophilicity and, consequently, the water swelling properties.

Synthesis and Characterization of Saturated and Unsaturated Poly(Alkylene Tartrate)s and Further Cross-Linking

Saturated and unsaturated polyesters based on l-tartaric acid were prepared and characterized. Two kinds of low molecular weight polyesters were synthesized by the reaction of l-tartaric acid and 1-12 dodecandiol and 1-8 octanediol. Three different kinds of low molecular weight unsaturated polyesters were synthesized by the reaction of l-tartaric acid, 1-12 dodecandiol, and maleic anhydride. The saturated and unsaturated polymers were characterized by means of proton nuclear magnetic resonance (H NMR), infrared analysis (IR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). These functionalized polymers were thermally cross-linked in the presence of a radical initiator and with 2-hydroxyethyl methacrylate (HEMA) and/or polyethylene glycol ethyl ether methacrylate) (PEGEEM) to prepare cross-linked polymers for biomedical applications. The films were characterized by means of DSC, TGA, and FTIR. The glass transition temperatures (Tg) of the polymers increase with increasing alkene group length and for the presence of the double bonds. The transition temperatures of the cross-linked films range from about -50°C, for the films contraining PEGEEM, to about 90°C, for the film containing HEMA.

Synthesis and characterization of electrically conductive polyethylene-supported graphene films

We describe a simple mechanical approach for low-density polyethylene film coating by multilayer graphene. The technique is based on the exfoliation of nanocrystalline graphite (few-layer graphene) by application of shear stress and allows to obtain thin graphene layers on the plastic substrate. We report on the temperature dependence of electrical resistance behaviors in films of different thickness. The experimental results suggest that the semiconducting behavior observed at low temperature can be described in the framework of the Efros-Shklovskii variable-range-hopping model. The obtained films exhibit good electrical conductivity and transparency in the visible spectral region.

PACS

72.80.Vp; 78.67.Wj; 78.66.Qn; 85.40.Hp.

Holographic patterning of graphene-oxide films by light-driven reduction

We report on the patterning and reduction of graphene-oxide films by holographic lithography. Light reduction can be used to engineer low-cost graphene-based devices by performing a local conversion of insulating oxide into the conductive graphene. In this work, computer-generated holograms have been exploited to realize complex graphene patterns in a single shot, different from serial laser writing or mask-based photolithographic processes. The technique has been further improved by achieving speckle noise reduction: submicron and diffraction-limited features have been obtained. In addition we have also demonstrated that the gray-scale lithography capability can be used to obtain different reduction levels in a single exposure.

A simple mechanical technique to obtain carbon nanoscrolls from graphite nanoplatelets

A simple approach for the bulk production of carbon nanoscrolls (CNSs) is described. This method is based on the application of shear-friction forces to convert graphite nanoplatelets into carbon nanoscrolls using a bi-axially oriented polypropylene (BOPP) surface. The combined action of shear and friction forces causes the exfoliation of graphite nanoplatelets and the simultaneous roll-up of graphite layers. Evidence of the CNS formation is given by optical microscopy, scanning electron microscopy, and transmission electron microscopy. These investigations reveal that the CNSs have a long tube-like and fusiform structure with a hollow core surrounded by few layers of graphene. Micro-Raman spectroscopy shows that the produced structures are not defect free, and optical spectroscopy reveals distinctive features due to the presence of two weak absorption bands at 224 and 324 nm.

Graphite nanoplatelet chemical cross-linking by elemental sulfur

Graphite nanoplatelets (GNPs) react with elemental sulfur to provide a mechanically stable, spongy material characterized by good electrical conductivity and high surface development; such unique property combination makes these novel nanostructured materials very useful for applications in different technological fields. The carbon-sulfur reaction can be accurately investigated by thermal analysis (differential scanning calorimetry and thermogravimetric analysis) and energy-dispersive X-ray spectroscopy combined with scanning electron microscopy. The thermal treatment required for the formation of electrically conductive monosulfur connections among the GNP unities has been investigated. PACS: 81.05.Ue, 81.05.Rm, 81.16.Be.

Mechanical properties of low-density polyethylene filled by graphite nanoplatelets

The mechanical properties of GNP/LDPE nanocomposites (graphite nanoplatelets/low density polyethylene) have been investigated, in order to establish the effect of nanoscale reinforcement within the polymer matrix. Results show that the presence of the filler does not involve a change in the microscopic structure of the polymer. However, on a macroscopic scale, GNPs limit the mobility of the polymer chains, resulting in an increase in stiffness for the final composite. Orientation of GNPs within the LDPE matrix is also an important issue that affects mechanical properties and it has been evaluated by testing nanocomposites made by different manufacturing techniques (compression moulding and blown extrusion). The comparison between the experimental data and the Halpin-Tsai model shows that the orientation of GNPs due to the extrusion process leads to values of tensile modulus higher than that obtained with the randomly oriented disposition resulting from the compression moulding technique.

Synthesis and characterization of soybean-based hydrogels with an intrinsic activity on cell differentiation

The successful regeneration of large defects in traumatized and diseased tissues depends on the availability of biodegradable and bioactive biomaterials able to guide the tissue during its repair by offering both a physical support and a control of its biological mechanisms. Recently, a novel class of natural, biodegradable biomaterials has been obtained by the thermosetting of defatted soy curd. These biomaterials have been shown to regulate the activity of both tissue and inflammatory cells. Here, soybean-based hydrogels with different physicochemical properties and bioactivity have been obtained with a relatively simple and highly reproducible processing method. The content of the different soy components (e.g., the isoflavones) was tuned varying the solvent system during the extraction procedure, while variations in the material crosslinking provided either loose hydrogels or a bioglue. The biomaterials obtained can be used as either bioadhesives or injectable formulations in regenerative medicine as they were shown to stimulate the synthesis of collagen by fibroblasts and the formation of mineralized bone noduli by osteoblasts.

Hyaluronic-acid-based semi-interpenetrating materials

In order to enhance the mechanical performances of hyaluronic acid (HA) without compromising its biological activity, HA has been interpenetrating with a fibrillar collagen scaffold. The semi-interpenetrating materials were obtained by mixing HA with different molecular weight and a pepsin-solubilized collagen (atelocollagen) solution, and then by inducing collagen fibrillogenesis. Results indicate that molecular weight of HA significantly influences the mechanical properties of the semi-interpenetrating materials and more specifically stronger material results from the use of low-molecular-weight (LMW) HA. According to the dynamic mechanical data the composite collagen-LMW HA has a higher elastic modulus than collagen, whereas the opposite is true for the high-molecular-weight (HMW) HA. This result highlights the role of specific interactions that occur between collagen and HA during the gel formation in controlling the network mechanical stability. LMW HA may, probably, interact more strongly with collagen during the fibrillogenesis process than HMW HA due to the higher mobility of the chains and the weaker homologous interactions. Moreover, morphological observations showed that LMW HA is intimately interdispersed within the collagen network and completely coated the fibrils, which act as mechanical support.

Calorimetric and thermomechanical properties of titanium-based orthodontic wires: DSC-DMA relationship to predict the elastic modulus

Orthodontic treatment is strongly dependent on the loads developed by metal wires, and the choice of an orthodontic archwire should be based on its mechanical performance. The desire of both orthodontists and engineers would be to predict the mechanical behavior of archwires. To this aim, Gum Metal (Toyota Central R&L Labs., Inc.), TMA (ORMCO), 35°C Copper NiTi (SDS ORMCO), Thermalloy Plus (Rocky Mountain), Nitinol SE (3M Unitek), and NiTi (SDS ORMCO) were tested according to dynamic mechanical analysis and differential scanning calorimetry. A model was also developed to predict the elastic modulus of superelastic wires. Results from experimental tests have highlighted that superelastic wires are very sensitive to temperature variations occurring in the oral environment, while the proposed model seems to be reliable to predict the Young's modulus allowing to correlate calorimetric and mechanical data. Furthermore, Gum Metal wire behaves as an elastic material with a very low Young's modulus, and it can be particularly useful for the initial stage of orthodontic treatments.

Fast curing of restorative materials through the soft light energy release

OBJECTIVE

The effect of a novel light curing process, namely soft light energy release (SLER), on shrinkage, mechanical strength and residual stress of four dental restorative materials (DEI experience, Gradia Direct, Enamel Plus HFO and Venus) was investigated.

METHODS

Composite specimens were fast cured through high level of power density and soft light energy release. Temperature, linear shrinkage and light power measurements were acquired in parallel in order to assess the effect of light modulation on temperature and shrinkage profiles during the light curing process and the following dark reaction phase. The small punch test and Raman spectroscopy were adopted to investigate the effect of SLER on mechanical strength and on internal stress, respectively.

RESULTS

The soft light energy release photo-polymerization allows to reduce of about 20% the shrinkage rate and to increase the strength of fast light cured specimens. In addition, a more relaxed and homogeneous internal stress distribution was observed.

SIGNIFICANCE

Properties of fast cured restorative materials can be improved by adopting the soft light energy release process.

Bone regeneration potential of a soybean-based filler: experimental study in a rabbit cancellous bone defects

Autologous and allogenic bone grafts are considered as materials of choice for bone reconstructive surgery, but limited availability, risks of transmittable diseases and inconsistent clinical performances have prompted the development of alternative biomaterials. The present work compares the bone regeneration potential of a soybean based bone filler (SB bone filler) in comparison to a commercial 50:50 poly(D: ,L: lactide-glycolide)-based bone graft (Fisiograft((R)) gel) when implanted into a critical size defect (6-mm diameter, 10-mm length) in rabbit distal femurs. The histomorphometric and microhardness analyses of femoral condyles 4, 8, 16 and 24 weeks after surgery showed that no significant difference was found in the percentage of both bone repair and bone in-growth in the external, medium and inner defect areas. The SB filler-treated defects showed significantly higher outer bone formation and microhardness results at 24 weeks than Fisiograft((R)) gel (P < 0.05). Soybean-based biomaterials clearly promoted bone repair through a mechanism of action that is likely to involve both the scaffolding role of the biomaterial for osteoblasts and the induction of their differentiation.

A degradable soybean-based biomaterial used effectively as a bone filler in vivo in a rabbit

The 'gold standard' for bone filling is currently the bone autograft, but its use is limited by material availability and by the possible risks of infection or other donor site morbidity. Materials proposed so far as bone fillers do not show all the characteristics which are desirable. These are (a) osteoconductivity, (b) controlled biodegradation and (c) ease of adaptation to the implantation site. Recently, a new class of biodegradable material based on soybeans has been presented which shows good mechanical properties and an intrinsic bioactivity on inflammatory and tissue cells in vitro. The authors investigated the morphology in vivo of bone response in repairing a surgical lesion in the presence of granules of a novel soybean-based biomaterial (SB), comparing it with a sham-operated contralateral lesion of critical size (non-healing model); 26 operations were performed in New Zealand White rabbits, with back scattered electron microscopy as the analysis technique of choice. Implantation of SB granules over 8 weeks produced bone repair with features distinct from those obtained by healing in a non-treated defect. New and progressively maturing trabeculae appeared in the animal group where SB granules were implanted, while sham operation produced only a rim of pseudo-cortical bone still featuring a large defect. The trabeculae forming in the presence of SB granules had features typical of reticular bone. These findings suggest that the bone regeneration potential of SB granules and their intrinsic bioactivity, combined with their relatively easy and cost-effective preparation procedures, make them suitable candidates as a bone filler in clinical applications.

Effect of light curing and dark reaction phases on the thermomechanical properties of a Bis-GMA based dental restorative material

PURPOSE

The effects of light curing units (LCU) and energy doses on the chemical and physical properties of a dental composite were investigated.

METHODS

The effects on the chemical and physical properties of a bisphenol A diglycidylether methacrylate (Bis-GMA) based dental restorative material were evaluated through photospectrometry, differential scanning calorimetry, and mechanical measurements.

RESULTS

The light curing conditions associated with direct and indirect restorations were replicated in vitro using optical investigation techniques. A slight attenuation resulted independently of the LCU and a strong attenuation was measured for the cement luting a thick inlay, as well as for the deepest layer of a composite filling increment. Calorimetric measurements indicated that the curing degree is very sensitive to the light energy dose rather than to the LCU. Mechanical testing showed a transient phase during which properties increased. The delay of the composite in reaching adequate properties is strongly dependent on the energy dose.

CONCLUSIONS

It is recommended that composites subject to unfavorable light curing conditions undergo a prolonged light curing process.

Process-structure Relationships in PCL Foaming

The foaming behavior of poly(ε-caprolactone) (PCL) with nitrogen as the foaming agent has been investigated. By using a uniquely designed and instrumented batch foaming apparatus it is possible to study the correlation between the foam structure (i.e., foam density and mean cell diameter) and the main processing variables (i.e., foaming temperature, foaming agent concentration, and pressure drop rate). A narrow experimental range has been used to describe the complex dependencies by a simple model. In particular, linear algebraic functions have been used to describe the effect of the processing variables on both the foam density and the mean cell diameter. With the aim to better depict these relationships, 3D graphs are also reported. This visualization/ parametrization allows the rapid selection of the proper process parameters to obtain PCL foams with the desired density and morphology.

A new class of bioactive and biodegradable soybean-based bone fillers

The reconstruction of large bone defects in periodontal, maxillofacial, and orthopedic surgery relies on the implantation of biomaterials able to support the growth of new tissue. None of the materials currently available is able to combine all the properties required, which are (i) easy handling, (ii) biodegradation, (iii) low immunogenicity, and more importantly, (iv) induction of tissue regeneration. A new class of biodegradable biomaterials has been obtained by simple thermosetting of defatted soybean curd. The final material can be processed into films, porous scaffolds, and granules for different surgical needs. When incubated in physiological solutions the material shows water uptake of 80%, elongation at break of 0.9 mm/mm, and 25% (w/w) degradation in 7 days. Soybean-based biomaterial granules are shown to reduce the activity of the monocytes/macrophages and of the osteoclasts and to induce osteoblast differentiation in vitro, thus demonstrating a bone regeneration potential suitable for many clinical applications.

Effects of polymer amount and processing conditions on the in vitro behaviour of hybrid titanium dioxide/polycaprolactone composites

Titanium dioxide (TiO(2)) and TiO(2) glasses containing poly(epsilon-caprolactone) (PCL) up to 24% by weight were obtained by the sol-gel process. Powder compaction was achieved providing heat and pressure. Properties were evaluated through compression and bending tests assisted by X-ray micro-computed tomography imaging. The effects of compaction conditions (i.e. temperature, pressure and duration) on mechanical properties of inorganic/organic composites were investigated. Biocompatibility tests on organic/inorganic composites were carried out using human cells and the MTT assay to determine viability. Results indicated that the mechanical properties (i.e. Young's modulus and maximum strength), in both compression and bending, were a function of the compression moulding conditions. Highest mechanical properties were measured using a compaction pressure of 1500 MPa acting for 90 min at a die temperature of 100 degrees C. The results, however, also suggest that mechanical properties can be tailored by varying the amount of PCL to TiO(2). Strength and stiffness spanned between the properties of spongy and cortical bone. Young's modulus in both compression and bending were higher for PCL amounts of 6%. Instead, higher bending strength values were measured for PCL amounts of 12%. These weight amounts of PCL also provide higher average density values, thus suggesting that the polymeric phase is effective in toughening TiO(2)-based materials. The investigated materials also showed a very good cytocompatibility as indicated by the MTT assay results.

Biomechanical effects of titanium implants with full arch bridge rehabilitation on a synthetic model of the human jaw

A composite model of the mandible, constituted by an inner polymeric core and a glass fibre reinforced outer shell, has been developed and equipped with six ITI titanium implants and a full gold alloy arch bridge prosthesis. The effects of this oral rehabilitation on the biomechanics of the mandible are investigated through a simulation of the lateral component of the pterygoid muscles. These muscles are involved as the mouth is opened and closed, hence their activity is very frequent. An increase of the mandible stiffness due to the prosthesis is observed; moreover, the coupling of the relatively stiff rehabilitation devices with the natural tissue analogue leads to stress-shielding and stress-concentration in the incisal and molar regions, respectively. Although the amplitude of the force generated by pterygoid muscles is quite small, high strains over the incisal region are measured. A stress-shielding effect, of about 20%, is observed at the symphysis as the full arch bridge prosthesis is fixed on the implants. Therefore, the presence of the prosthesis leads to significant modification of the stress field experienced by the mandible, and this may be relevant in relation to the biomechanics of mandibular bone remodelling.