Towards a method for determining age ranges from faces of juveniles on photographs.

The steady increase in the distribution of juvenile pornographic material in recent years strongly required valid methods for estimating the age of the victims. At the present in fact forensic experts still commonly use the assessment of sexual characteristics by Tanner staging, although they have proven to be too subjective and deceiving for age estimation. The objective of this study, inspired by a previous EU project involving Italy, Germany and Lithuania, is to verify the applicability of certain anthropometric indices of faces in order to determine age and to create a database of facial measurements on a population of children in order to improve face ageing techniques. In this study, 1924 standardized facial images in frontal view and 1921 in lateral view of individuals from 7 age groups (3-5 years, 6-8 years, 9-11 years, 12-14 years, 15-17 years, 18-20 years, 21-24 years) underwent metric analysis. Individuals were all of Caucasoid ancestry and Italian nationality. Eighteen anthropometric indices in the frontal view and five in the lateral view were then calculated from the obtained measurements. Indices showing a correlation with age were ch-ch/ex-ex, ch-ch/pu-pu, en-en/ch-ch and se-sto/ex-ex in the frontal view, se-prn/se-sn, se-prn/se-sto and se-sn/se-sto in the lateral view. All the indices increased with age except for en-en/ch-ch, without relevant differences between males and females. These results provide an interesting starting point not only for placing a photographed face in an age range but also for refining the techniques of face ageing and personal identification.

Pitfalls at the root of facial assessment on photographs: a quantitative study of accuracy in positioning facial landmarks.

In the last years, facial analysis has gained great interest also for forensic anthropology. The application of facial landmarks may bring about relevant advantages for the analysis of 2D images by measuring distances and extracting quantitative indices. However, this is a complex task which depends upon the variability in positioning facial landmarks. In addition, literature provides only general indications concerning the reliability in positioning facial landmarks on photographic material, and no study is available concerning the specific errors which may be encountered in such an operation. The aim of this study is to analyze the inter- and intra-observer error in defining facial landmarks on photographs by using a software specifically developed for this purpose. Twenty-four operators were requested to define 22 facial landmarks on frontal view photographs and 11 on lateral view images; in addition, three operators repeated the procedure on the same photographs 20 times (at distance of 24 h). In the frontal view, the landmarks with less dispersion were the pupil, cheilion, endocanthion, and stomion (sto), and the landmarks with the highest dispersion were gonion, zygion, frontotemporale, tragion, and selion (se). In the lateral view, the landmarks with the least dispersion were se, pronasale, subnasale, and sto, whereas landmarks with the highest dispersion were gnathion, pogonion, and tragion. Results confirm that few anatomical points can be defined with the highest accuracy and show the importance of the preliminary investigation of reliability in positioning facial landmarks.

Gene delivery systems for gene therapy in tissue engineering and central nervous system applications.

The present review aims to describe the potential applications of gene delivery systems to tissue engineering and central nervous system diseases. Some key experimental work has been done with interesting results, but the subject is far from being fully explored. The combined approach of gene therapy and material science has a huge potential to improve the therapeutic approaches now available for a wide range of medical applications. Focus is given to this multidisciplinary strategy in neurodegenerative pathologies, where the use of polymeric matrices as gene carriers might make a crucial difference.

Engineering injured spinal cord with bone marrow-derived stem cells and hydrogel-based matrices: a glance at the state of the art.

Concerning the broad topic of neural tissue engineering, we present a review relating to the state of the art in spinal cord injury repair strategies. Particular attention is given to spinal cord damage causes and effects, in neural and mesenchymal stem cell therapeutic approaches, in the use of hydrogels as cell carriers and in the mathematical modeling of involved phenomena. High importance is given to multidisciplinary strategies applied to spinal cord repair, since new research frontiers are believed to be now on 3D gel/cells and neuroprotective agent constructs for neural reconstruction purposes.

Nanostructured surfaces for biomedical applications. Part I: nanotopography.

The natural cell environment provides a variety of chemical, topographical and mechanical stimuli that contribute in regulating cell behavior and function. If considerable effort has been traditionally dedicated to exploring the chemical side of cell regulation, it was more recently demonstrated that topographic cues might be equally important. Cell substratum interactions are particularly crucial in determining the reaction of cells to biomaterials, which was also shown to be strongly determined by topographical cues. A significant acceleration in investigating this aspect came from the availability of techniques for microstructured surfaces, and is now well known that cells can react to topographical features at their own scale (1-100 micron). Nevertheless, cells possess many nanoscaled features such as filopodia and a cytoskeleton, and the extracellular matrix (ECM) itself possess quite a few nanoscale details. Therefore, the capability of controlling the surface structure of materials in the nanoscale has offered the possibility of adding another level in the hierarchical understanding of cell/biomaterial interactions. Nanofabrication methods, mainly developed out of the semiconductor industries, are a technological driver for addressing the nanotopography related aspects of cell behavior. General concepts regarding some of the more widely utilized techniques that enable the achievement of ordered and well-defined nanoscale features for the investigation of cell reaction to topography are presented together with a few examples of the practical applications available in the literature.

A new chemical etching process to improve endosseous implant osseointegration: in vitro evaluation on human osteoblast-like cells.

The development of novel mechanical and chemical surface modification treatments to improve the osteointegration properties of osseointegrated dental implants is nowadays a topic of great applicative interest. The aim of the present study was to analyse the role of surface topography and chemistry of four different surface treatments on titanium by an in vitro human osteosarcoma immortalised cell line model (MG63). The surface treatments considered were (a) machined titanium, (b) chemical etched on machined titanium, (c) sandblasted titanium and (d) chemical etching on sandblasted titanium. Chemical and physical surface properties were investigated by Scanning Electron Microscopy, Thin Film-X ray Diffraction and by Laser Profilometry. The in vitro biological response was characterised using the MG63 cell line by elution cytotoxicity tests, cell morphology, adhesion, proliferation activity, alkaline phosphatase activity and total DNA content in order to show a relationship between osteoblast response and surface features. Chemical and physical characterisation showed that the considered treatments differently modify the surface morphology in the micro and sub-micrometric scale. Although some differences in alkaline phosphatase activity were observed in the biological characterisation, depending on the specific material's surface finishing, the results showed that cells were well responsive on all the tested materials and grew and differentiated with similar proliferation rate.

Soft tissue response to a new austenitic stainless steel with a negligible nickel content.

This study evaluates the soft tissue response to a new austenitic stainless steel with a low nickel content (P558) in comparison with a conventional stainless steel (SSt)and a titanium alloy (Ti6Al4V). Previous findings showed its in vitro biocompatibility by culturing P558 with healthy and osteoporotic osteoblasts and its in vivo effectiveness as bone implant material. Regarding its use as a material in osteosynthesis,P558 biocompatibility when implanted in soft tissues, as subcutis and muscle, was assessed. Disks and rods of these metals were implanted in rat subcutis and in rabbit muscle, respectively. Four and twelve weeks post surgery implants with surrounding tissue were retrieved for histologic and histomorphometric analysis: fibrous capsule thickness and new vessel formation were measured. Around all implanted materials, light microscopy highlighted a reactive and fibrous capsule formation coupled with ongoing neoangiogenesis both in rats and in rabbits. Histomorphometric measurements revealed a stronger inflammatory response,in terms of capsule thickness,surrounding SSt implants (9.8% Ni content) both in rat subcutis and in rabbit muscle independently of shape and site of implantation. A progressive decrease in capsule thickness around P558 (<0.02% Ni content) and Ti6Al4V, respectively, was seen. Regarding new vessel density, the data showed a different response dependent on the site of implantation. However,in the light of the previous and present studies, P558 is a good material, instead of titanium alloys, in orthopedic research.

Materials characterization of explanted mechanical heart valves and comparison to patients' clinical data.

In the present study, twelve explanted mechanical heart valves (MHVs)with pyrolitic carbon tilting disc and 14 bileaflet MHVs were analyzed to investigate the effects of material properties on valve performance and patients' general health conditions. Optical and scanning electron microscopy was used to investigate material imperfections, wear patterns or damages to housing and occluder components. All analyzed tilting disc valves exhibited wear effects, particularly due to abrasion and impact to both disc and housing. Wear of pyrolitic carbon disc and housing did not influence their in vivo performance. In the bileaflet MHVs, breakaway of the pyrolitic carbon coating sometimes caused malfunctioning and required surgical retrieval of the valve. In all cases, occurrence of clinical symptoms was more likely when wear effects were located in critical areas. The study supports a correlation between the properties of the MHVs material and patients' symptoms.

Decreased bacterial adhesion to surface-treated titanium.

Osteointegrative dental implants are widely used in implantology for their well-known excellent performance once implanted in the host. Remarkable bacterial colonization along the transgingival region may result in a progressive loss of adhesion at gum-implant interface and an increase of the bone area exposed to pathogens. This phenomenon may negatively effect the osteointegration process and cause, in the most severe cases, implant failure. The presence of bacteria at implant site affect the growth of new bone tissue and consequently, the achievement of a mechanically stable bone-implant interface, key parameters for a suitable implant osteointegration. In the present work, a novel surface treatment has been developed and optimized in order to convert the amorphous titanium oxide in a crystalline layer enriched in anatase capable of providing not only antibacterial properties but also of stimulating the precipitation of apatite when placed in simulated body fluid. The collected data have shown that the tested treatment results in a crystalline anatase-type titanium oxide layer able to provide a remarkable decrease in bacterial attachment without negatively effecting cell metabolic activity. In conclusion, the surface modification treatment analyzed in the present study might be an elegant way to reduce the risk of bacterial adhesion and increase the lifetime of the transgingival component in the osteointegrated dental implant.

Electrochemical release testing of nickel-titanium orthodontic wires in artificial saliva using thin layer activation.

Alloys based on Ni-Ti intermetallics generally exhibit special shape memory and pseudoelastic properties, which make them desirable for use in the dental field as orthodontic wires. The possibility of nickel release from these materials is of high concern, because the allergenicity of this element. The aim of this study was to test pseudoelastic Ni-Ti wires in simulated physiological conditions, investigating the combined effect of strain and fluoridated media: the wires were examined both under strained (5% tensile strain) and unstrained conditions, in fluoridated artificial saliva at 37 degrees C. Real time electrochemical nickel release testing was performed using a novel application of a radiotracer based method, thin layer activation (TLA). TLA was validated, in unstrained conditions, against adsorptive stripping voltammetry methodology. Control tests were also performed in non-fluoridated artificial saliva. From our research it transpired that the corrosion behaviour of Ni-Ti alloy is highly affected by the fluoride content, showing a release of 4.79+/-0.10 microg/cm2/day, but, differently from other biomaterials, it does not seem to be affected by elastic tensile strain. The application of the TLA method in the biomedical field appears a suitable technique to monitor in real time the corrosion behaviour of biomedical devices.

A new austenitic stainless steel with a negligible amount of nickel: an in vitro study in view of its clinical application in osteoporotic bone.

A biomaterial named P558 is a new austenitic stainless steel (SS) with a negligible amount of Ni (<0.20%). In previous in vitro and in vivo studies it was compared with conventional SS and Ti6Al4V and shown to be a promising material in orthopedics. Because osteoporosis is a type of pathology very often encountered in implanted patients and can be studied with in vitro models, the purpose of the present study was to evaluate P558 in vitro through comparison of normal (nOB) with osteopenic (oOB) bone-derived primary rat osteoblasts. Osteoblasts were cultured directly on P558 and polystyrene as controls for 72 h. Osteoblast proliferation, adhesion, and activity (ALP, OC, TGF-beta1, and IL-6) were evaluated at 24 and 72 h. Results demonstrated that the growth of nOB and oOB cultured on P558 was not affected negatively when compared to control. Cells on P558 did not show any alteration in terms of adhesion, proliferation, and metabolic marker production in nOB and oOB cultures, and a significant increase in ALP, OC, and TGF-beta1 production was observed. SEM images revealed no alteration in cell morphology. The current findings demonstrate that P558 promotes osteoblast proliferation, activation, and differentiation not only in normal bone, but also in osteopenic bone-derived osteoblasts.

Influence of heat treatment on structural, mechanical and wear properties of crosslinked UHMWPE.

New crosslinked ultra high molecular weight polyethylenes (UHMWPEs) have recently been developed, characterized and introduced in clinical applications. UHMWPE cross-linking treatments are very promising for reducing osteolysis induced by wear debris. The irradiation type, gamma or beta, the dosage and the thermal treatment performed during or following the irradiation process are all factors affecting polyethylene wear resistance. Thermal stabilization treatments performed after or during the irradiation process at a temperature above melting point (i.e. >130 degrees C) have been proven to effectively remove the free radicals generated during irradiation from UHMWPE, but their effect on the mechanical properties of UHMWPE are not completely clear. In addition to wear rate reduction, maintaining good mechanical properties is fundamental aspect in designing the new generation of crosslinked UHMWPE for artificial load bearing materials, especially considering the application in total knee replacements. In this study, we investigated the influence of different stabilization treatments, performed after gamma irradiation, on structural, wear and mechanical properties of UHMWPE. We performed four different stabilization treatments, with different temperatures and cooling rates, on 100 kGy gamma irradiated UHMWPE. Structural properties of UHMWPE were assessed by differential scanning calorimetry (DSC). To assess the mechanical performance of the materials, uni-axial tensile tests were performed according to the ASTM D638 standard, bi-axial tension performance was evaluated by small punch tests (ASTM F2183-02), toughness resistance was evaluated by the Izod method (ASTM F648), and cold flow resistance was analysed by a dynamic compressive test. Evaluation of wear resistance was by a multidirectional pin-on-disk screening machine. Materials considered were in ""aged"" and ""non-aged"" conditions. Results confirmed that cross-linking greatly enhances UHMWPE wear resistance, but introduces some detrimental effects on the mechanical properties. In this study, we found that the negative ef-fects on the mechanical properties of crosslinked UHMWPE can be modulated, to some extent, by choosing a thermal stabiliza-tion treatment at a correct temperature and cooling rate. (Journal of Applied Biomaterials & Biomechanics 2004; 2: 20-8).

A new austenitic stainless steel with negligible nickel content: an in vitro and in vivo comparative investigation.

New nickel (Ni)-reduced stainless-steel metals have recently been developed to avoid sensitivity to Ni. In the present study, an austenitic Ni-reduced SSt named P558 (P558, Böhler, Milan, Italy) was studied in vitro on primary osteoblasts and in vivo after bone implantation in the sheep tibia, and was compared to ISO 5832-9 SSt (SSt) and Ti6Al4V. Cells were cultured directly on P558 and Ti6Al4V. Cells cultured on polystyrene were used as controls. Osteoblast proliferation, viability and synthetic activity were evaluated at 72 h by assaying WST1, alkaline phosphatase activity (ALP), nitric oxide, pro-collagen I (PICP), osteocalcin (OC), transforming growth factor-beta1 (TGFbeta-1) and interleukin-6 (IL-6) after 1.25(OH)2D3 stimulation. Under general anaesthesia, four sheep were submitted for bilateral tibial implantation of P558, SSt and Ti6Al4V rods. In vitro results demonstrated that the effect of P558 on osteoblast viability, PICP, TGF beta-1, tumor necrosis factor-alpha production did not significantly differ from that exerted by Ti6Al4V and controls. Furthermore, P558 enhanced osteoblast differentiation, as confirmed by ALP and OC levels, and reduced IL-6 production. At 26 weeks, the bone-to-implant contact was higher in P558 than in SSt (28%, p<0.005) and Ti6Al4V (4%, p<0.05), and was higher in Ti6Al4V than in SSt (22%, p<0.005). The tested materials did not affect bone microhardness in pre-existing host bone as evidenced by the measurements taken at 1000 microm from the bone-biomaterial interface (F=1.89, ns). At the bone-biomaterial interface the lowest HV value was found for SSt, whereas no differences in HV were observed between materials (F=1.55, ns). The current findings demonstrate P558 biocompatibility both in vitro and in vivo, and osteointegration processes are shown to be significantly improved by P558 as compared to the other materials tested.

Histomorphometric and microhardness assessments of sheep cortical bone surrounding titanium implants with different surface treatments.

Several factors influence the healing process and the long-term mechanical stability of cementless fixed implants, such as bone remodeling and mineralization processes. Histomorphometric and bone hardness measurements were taken in implants inserted in sheep femoral cortical bone at different times to compare the in vivo osseointegration of titanium screws (diam.; 3.5 x 7 mm length) with the following surface treatments: machined (Ti-MA); acid-etched (Ti-HF); HA vacuum plasma spray (Ti-HA); and Ca-P anodization followed by a hydrothermal treatment (Ti-AM/HA). Ti-MA and Ti-AM/HA implants presented the lowest (Ra = 0.20 +/- 0.01 microm) and highest (Ra = 1.97 +/- 0.64 microm) significant (p < 0.0005) roughness value, respectively. Bone-to-implant contact of Ti-HF was lower than that of the other surface treatments at both experimental times (8 weeks: -20%, ns; 12 weeks: -30%, p < 0.01). Significant differences in MAR (mineral apposition rate) were also found between the different experimental times for Ti-MA (115%, p < 0.01) and Ti-HF (57%, p < 0.01), demonstrating that bone growth had slowed inside the screw threads of Ti-HA and Ti-AM/HA after 12 weeks. No bone microhardness changes in preexisting host bone were found, while Ti-MA showed the lowest value for the inner thread area at 8 weeks (HV(200 microm)= 49.8 +/- 3.8 HV). These findings confirm that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as Ca-P anodization followed by a hydrothermal treatment, which enhance bone interlocking and mineralization.

A novel biomimetic treatment for an improved osteointegration of titanium.

Direct osteointegration of titanium and titanium alloys implants is one of the main goals of biomaterials research for dental and orthopedic applications. Chemical, mechanical or biological treatments are investigated searching for fast and durable implant to bone bonding. The aim of the present work is to assess the in vitro mineralisation capabilities and to investigate the mechanical and physico-chemical properties of a new biomimetic treatment on titanium. The new surface treatment was obtained using Anodic Spark Deposition technique, and consists of a first ASD treatment performed in solutions containing phosphate ions followed by a second ASD treatment in a solution rich in calcium ions. The resulting surface is finally treated by alkali etching. The physio-chemical and mechanical properties of this material are analyzed and the mineralization potential is considered by surface analysis after soaking it in different solutions of simulated body fluid (SBF). The developed biomimetic treatment was then compared to other treatments from the literature. The proposed treatment was found to possess a very high mineralization capaci-ty, that makes its application very interesting in terms of speed and strength of direct implant osteointegration. (Journal of Ap-plied Biomaterials & Biomechanics 2003; 1: 33-42).

Screening of stabilized crosslinked polyethylene using a novel wear tester.

A novel pin-on-disk type wear tester is described allowing a rapid screening of different types of polyethylene under both unidirectional and multidirectional sliding motion. The wear of four polyethylene materials sliding against a roughened CoCrMo alloy was evaluated: a non-irradiated UHMWPE, a UHMWPE irradiated with a dose of 25 kGy in air, and two types of crosslinked UHMWPE (100 kGy, air), which were subjected to a stabilization heat treatment in nitrogen at 155 degrees C for 72 hours (XLPE I) and in water at 130 degrees C for 72 hours (XLPE II), respectively.Under multidirectional sliding conditions both types of XLPE exhibited significantly less wear with respect to the 25 kGy irradiated UHMWPE and the non-irradiated UHMWPE, even under the rough counterface conditions applied. Under unidirectional sliding motion both types of XLPE exhibited the highest wear of all materials tested, because the orientation hardening effect acting under linear lubricated condition is less pronounced for crosslinked polyethylene.

Enhanced wear performance of highly crosslinked UHMWPE for artificial joints.

It is well known that osteolysis induced by polyethylene wear debris is the main cause of long-term failure of hip and knee prostheses. We developed a treatment of medical-grade ultra-high molecular-weight polyethylene (UHMWPE) in order to improve its tribologic properties and reduce its wear. Medical-grade UHMWPE was irradiated with a 200 kGy dose of radiation, thermally stabilized at a temperature close to the melting point, and then sterilized with ethylene oxide. The irradiation treatment was performed to crosslink the UHMWPE. The thermal stabilization treatment, contributing to the reaction between the free radicals generated by the irradiation process, was chosen to enhance crosslinking and to prevent oxidation and the shortening of chains. The non-invasive sterilization process with ethylene oxide was chosen to prevent the re-formation of free radicals. The wear performance of this material was compared to UHMWPE, untreated or treated with different sterilization techniques, using gamma and beta irradiation. Insoluble crosslinked constituents were measured with an extraction method. Wear was evaluated using a flat-on-ring wear test machine. While small differences were found among the different sterilization processes, 200 kGy-irradiated UHMWPE followed by thermal treatment and sterilization with ethylene oxide had the least wear and the greatest amount of crosslinking.