Evaluation of sorption capacity of antibiotics and antibacterial properties of a cyclodextrin-polymer functionalized hydroxyapatite-coated titanium hip prosthesis

Infection still present as one of common complications after total hip replacement (∼2.5%), which may cause serious outcomes. For preventing such risk, loading antibiotics onto implants for increasing local drug concentration at targeted sites could be a solution. This study aims at modifying the surface of hydroxyapatite (HA) coated titanium hip implant material (Ti-HA) with polymer of cyclodextrin (polyCD) for loading antibiotics, to achieve a sustained local drug delivery. Two widely applied antibiotics (tobramycin and rifampicin) in orthopedic surgery were loaded alone or in combination. The drug adsorption isotherm, drug release kinetics and drug's efficacy were thoroughly investigated. The results proved that polyCD coating significantly improved the affinity of both drugs to Ti-HA surface, while the mechanism of drug-polyCD interaction varies from the nature of drug, courtesy of the structural complex of polyCD. The advantage of dual-drug loading was highlighted by its strong efficacy against both Staphylococcus aureus and Enterobacter cloacae, which overcomes the limitation of mono-drug loading for an effective treatment against both bacterial strains. The prolonged antibacterial activity of antibiotic loaded Ti-HA-polyCD samples confirmed that polyCD could be a promising drug-delivery system, for sustained antibiotics release or other potential applications e.g., antimitotic agent release.

Visceral mesh modified with cyclodextrin for the local sustained delivery of ropivacaine

The aim of the study was to develop a polyester visceral implant modified with a cyclodextrin polymer for the local and prolonged delivery of ropivacaine to reduce post operatory pain. Therefore, we applied a coating of an inguinal mesh with a crosslinked polymer of hydroxypropyl-β-cyclodextrin (HPβCD) whose specific host-guest complex forming properties were expected to improve the adsorption capacity of the implant toward anesthetic, and then to release it within a sustained period. The modification reaction of the textile with cyclodextrin was explored through the study of the influence of the pad/dry/cure process parameters and the resulting implant (PET-CD) was characterized by solid state NMR and SEM. Besides, the inclusion complex between ropivacaine and CD was studied by NMR and capillary electrophoresis in PBS medium. Finally, ropivacaine sorption test showed that a maximum of 30 mg/g of ropivacaine could be adsorbed on the functionalized samples. In dynamic batch tests in PBS at pH 7.4, the release could be observed up to 6h. The cytocompatibility of the PET-CD loaded with ropivacaine was also studied and reached 65% cell vitality after 6 days.

Evaluation of a bio-based hydrophobic cellulose laurate film as biomaterial--study on biodegradation and cytocompatibility

The study aims to validate an original bio-based material, obtained by grafting fatty chains, and more especially lauric chains (C12) onto cellulose, for medical applications. The mechanical properties of the synthesized cellulose laurate (C12) are close to those of petrochemical ones such as low density polyethylene. This cellulose-based polymer is transparent, flexible, and hydrophobic. To evaluate the stability of the cellulosic films in biological fluids the samples are soaked in simulated body fluid or blood plasma for a few hours to 6 months, and then submitted to mechanical and chemical analyses. The simultaneously performed cytocompatibility tests were the colony-forming viability, the vitality and cell proliferation tests using NIH 3T3 fibroblasts and MC 3T3 osteoblast-like cells. The results show the stability, the biocompatibility, and the noncytotoxicity of the synthesized cellulose laurate films. This biomaterial may so be considered for surgical applications.

[Bone substitutes: Classification and concerns]

Autograft is considered as the "gold standard" for bone reconstruction. It provides osteoinductive factors, osteogenic cells, and appropriate osteoconductive scaffold. Donor site morbidity is the main limitation of autograft. Donor disease transmission limits the use of allograft. Synthetic bone substitutes still lack osteoinductive or osteogenic properties. Composite bone substitutes combining synthetic scaffold and biochemical substances initiating proliferation and cell differentiation, and possibly osteogenesis. Bone substitutes and grafts intended for clinical use are listed.

Improving endothelial cell adhesion and proliferation on titanium by sol-gel derived oxide coating

In-stent restenosis becomes increasingly prevalent as a difficult-to-treat disease. An alternative therapeutic strategy is enhancing endothelialization on metallic stent surfaces. This study attempted to modify surface chemistry and topography of commercial pure titanium (cp-Ti) by different sol-gel derived oxide coatings (TiO(2), SiO(2), SiO(2)/TiO(2), and Nb(2)O(5)) to improve endothelialization. The physiochemical properties of the modified surfaces were characterized by ellipsometry, atomic force microscope, and sessile-drop method. The cell adhesion/proliferation quantity, cell adhesion morphology, and focal adhesion protein expression were evaluated with human pulmonary microvascular endothelial cell line. The thickness of oxide coatings approximates to 100 nm; significantly rougher nanoporous structure was found in the TiO(2) and Nb(2)O(5) coatings than that of cp-Ti. SiO(2) coating possesses the highest surface energy (75.1 mJ/m(2)) and the lowest was for cp-Ti (45.7 mJ/m(2)). TiO(2) coating showed significantly higher endothelial cell adhesion rate than others; TiO(2), Nb(2)O(5), and TiO(2)/SiO(2) coatings exhibited higher endothelial proliferation in 3-day assays than noncoated Ti. In hemocompatible test, they also showed good hemocompatibility. These results offer the insight into that certain oxide coatings on titanium could significantly improve endothelial cell adhesion and proliferation especially in early period, which will favor reaching the endothelialization rapidly and suitable as matrix for "endothelial seeding" stent.

Polyester vascular prostheses coated with a cyclodextrin polymer and activated with antibiotics: cytotoxicity and microbiological evaluation

Polyester (PET) vascular grafts are used to replace or bypass damaged arteries. To minimize the risk of infection during and after surgical interventions, a PET vascular prosthesis (Polythese) was functionalized with cyclodextrin polymers (PolyCDs) in order to obtain the controlled release of antibiotics (ABs: ciprofloxacin, vancomcyin and rifampicin). An epithelial cell line (L132) was used to determine the viability of the antibiotics, and human pulmonary microvascular endothelial cells (HPMEC) were used for cell proliferation by cell counting and cell vitality with Alamar Blue fluorescent dye. Staphylococcus aureus, Escherichia coli and Enteroccocus sp. were used to determine the antimicrobial activity of AB-loaded virgin and PolyCD-grafted Polythese by the minimum inhibitory concentration method. The spectrophotometric titration results first showed that a larger amount of ABs was sorbed onto PolyCD-coated Polythese compared to virgin Polythese (26.7 vs. 35.3 mg g(-1), 51.1 vs. 72.4 mg g(-1) and 4.1 vs. 21.0 mg g(-1), respectively, for rifampicin, vancomycin and ciprofloxacin). These results were further confirmed by a microbiological test, which showed AB-loaded PolyCD-coated Polythese displayed better antimicrobial activity. The viability test revealed the toxicity of rifampicin (22 mg l(-1)) and ciprofloxacin (35 mg l(-1)), and the absence of toxicity of vancomycin. These tests allow us to further explain the lower vitality and proliferation of HPMEC on the AB-loaded PolyCD-coated Polythese, which was due not to the functionalization process of prostheses but to the cytotoxicity of certain ABs themselves. Moreover, such a property could be exploited to tackle intracellular bacteria, such as in tuberculosis and other diseases, and will not compromise further in vivo applications of our functionalized vascular prostheses.

Osteoblast interaction with DLC-coated Si substrates

Diamond-like carbon (DLC) coating is a convenient means of modifying material surfaces that are sensitive to wear, such as titanium and silica substrates. This work aims to evaluate the osteoblast-like cells' response to DLC-coated Si (Si-DLC), which was treated under different conditions. DLC and deuterated DLC films were deposited by plasma-enhanced chemical vapor deposition to obtain a 200-nm-thick layer on all the samples. Three types of precursor gas were applied for deposition: pure methane (CH(4)), pure deuterated methane (CD(4)) and their half/half mixture. All surface treatments were performed under two different self-bias voltages (V(sb)): -400 and -600V. The modified surfaces were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, Rutherford backscattering spectroscopy, elastic recoil detection analysis, X-ray reflectometry and the sessile-drop method. MC3T3-E1 osteoblasts were cultured on the Si-DLC wafers for 3 and 6 days. Biological tests to measure cell proliferation, cell vitality, cell morphology and cell adhesion were performed. All DLC coatings produced a slightly more hydrophobic state than non-treated Si. Certain types of amorphous DLC coating, such as the surface treated under the V(sb) of -600V in pure methane (600CH(4)) or in pure deuterated methane (600CD(4)), offered a significantly higher cell proliferation rate to Si substrate. Scanning electron microscopy observations confirmed that the optimal cell adhesion behavior, among all the treated surfaces, occurred on the surface of the 600CH(4) and 600CD(4) groups, which showed increased amounts of filopodia and microvilli to enhance cell-environment exchange. In conclusion, DLC coating on Si could produce better surface stability and improved cellular responses.

Osteoblast responses to different oxide coatings produced by the sol-gel process on titanium substrates

In order to improve the osseointegration of endosseous implants made from titanium, the structure and composition of the surface were modified. Mirror-polished commercially pure (cp) titanium substrates were coated by the sol-gel process with different oxides: TiO(2), SiO(2), Nb(2)O(5) and SiO(2)-TiO(2). The coatings were physically and biologically characterized. Infrared spectroscopy confirmed the absence of organic residues. Ellipsometry determined the thickness of layers to be approximately 100nm. High resolution scanning electron microscopy (SEM) and atomice force microscopy revealed a nanoporous structure in the TiO(2) and Nb(2)O(5) layers, whereas the SiO(2) and SiO(2)-TiO(2) layers appeared almost smooth. The R(a) values, as determined by white-light interferometry, ranged from 20 to 50nm. The surface energy determined by the sessile-drop contact angle method revealed the highest polar component for SiO(2) (30.7mJm(-2)) and the lowest for cp-Ti and 316L stainless steel (6.7mJm(-2)). Cytocompatibility of the oxide layers was investigated with MC3T3-E1 osteoblasts in vitro (proliferation, vitality, morphology and cytochemical/immunolabelling of actin and vinculin). Higher cell proliferation rates were found in SiO(2)-TiO(2) and TiO(2), and lower in Nb(2)O(5) and SiO(2); whereas the vitality rates increased for cp-Ti and Nb(2)O(5). Cytochemical assays showed that all substrates induced a normal cytoskeleton and well-developed focal adhesion contacts. SEM revealed good cell attachment for all coating layers. In conclusion, the sol-gel-derived oxide layers were thin, pure and nanostructured; consequent different osteoblast responses to those coatings are explained by the mutual action and coadjustment of different interrelated surface parameters.

Chemical, biological and microbiological evaluation of cyclodextrin finished polyamide inguinal meshes

This study describes the use of cyclodextrins (CDs) as a finishing agent of polyamide (PA) fibers used in order to obtain inguinal meshes with improved antibiotic delivery properties. The finishing process involved polymerization between citric acid and CDs, which yielded a cross-linked polymer that physically adhered to the surface of PA fibers. This permanent functionalization was characterized by evaluating the damping property with a polar liquid (glycerol) via the drop contact angle method for various rates of modification of the fabrics. The biological and microbiological effects of the PA, which were functionalized with hydroxypropylated derivate of gamma-CD (HP-gamma-CDs) and charged with ciprofloxacin (CFX), were evaluated by cell culture assays. We observed a good adhesion and proliferation of fibroblastic cells (NIH3T3) after 3 and 6 days and no detectable toxicity of the modified substrate. The in vitro antibacterial activity of the HP-gamma-CD grafted PA fabrics charged with CFX against the bacteria Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli was greatly superior to that of the virgin sample within a 24h batch experiment in human blood plasma medium. In conclusion, these results from our study offer an insight into the efficient performance of CDs as drug delivery systems for multiple applications in the fields of biomaterials and medical textiles.

Biological behaviour of an endothelial cell line (HPMEC) on vascular prostheses grafted with hydroxypropylgamma-cyclodextrine (HPgamma-CD) and hydroxypropylbeta-cyclodextrine (HPbeta-CD)

The cytocompatibility of cyclodextrins (CDs) grafting on vascular polyester (PET) prostheses for further loading with biomolecules was investigated in this study. Viability tests demonstrated no toxicity of HP-CDs and PolyHP-CDs at 4,000 mg/l with survival rates of 80 to 96%. Proliferation tests using the human pulmonary microvascular endothelial cell line (HPMEC-ST1) revealed an excellent biocompatibility for Melinex (Film form of PET). For Polythese and Polymaille, a good proliferation rate was observed at 3 days (60-80%) but decreased at 6 days (56-73%). For all CD-grafted samples, low proliferation rates were observed after 6 days (35-38%). Vitality tests revealed excellent functional capacities of HPMEC cells after 3 and 6 days for all samples. Adhesion kinetics tests showed a similar adhesion of HPMEC cells on control and Melinex. A low adhesion was observed on Polythese and especially on Polymaille compared to control. After CD grafting, the cell adhesion was decreased. The woven or knitted architecture and CD grafting were the most likely causes of this weak adhesion. The adhesion kinetic test was confirmed by SEM observations and immunocytochemistry. The low proliferation of HPMEC on virgin prostheses and especially on grafted prostheses was not due to a cytotoxic effect, but to the physical surface characteristics of the prostheses.

[Influence of inorganic antibacterial agents on the systemic toxicity and cytotoxicity of a self-etching primer]

OBJECTIVE

To evaluate the influence of incorporating inorganic antibacterial agents on the systemic toxicity and cytotoxicity of an experimental self-etching primer (ESP).

METHODS

Six kinds of inorganic agents were incorporated respectively into the primer. Systemic toxicity in vivo tests in rats and direct contact in vitro cytotoxicity tests with NIH fibrohiasts were conducted.

RESULTS

Systemic toxicity tests revealed neither toxic manifestations nor significant differences in body weight gain hetween control and other groups. There were no significant differences between experimental groups and empty control on cell vitality and cell proliferation rates. Toxicity was only observed in areas heneath the specimens and/or in the direct vicinity of the specimen edge. There was no influence on the cell density over the limit of specimens.

CONCLUSION

The incorporation of tested inorganic antibacterial agents with a proper concentration had no significant influence on the systemic toxicity and cytotoxicity of the tested self-etching primer.

Antibacterial functionalization of an experimental self-etching primer by inorganic agents: Microbiological and biocompatibility evaluations

Antibacterial activities have been demonstrated on oral bacteria with inorganic antibacterial agents (ABAs) after their incorporations into an experimental self-etching primer (ESP) before curing. This study was to assess their biocompatibility and antibacterial activity after curing. Six ABAs were incorporated respectively into ESP for treating specimens. After curing, their bactericidal activities on Streptococcus mutans and influences to the early bacterial colonization were assessed by direct contact and viable count. Systemic toxicity in rats after short-term oral exposure and direct contact cytotoxicity with NIH3T3 fibroblasts were tested. Incorporation of ZnOw AT-83, Longbei antibiotic, Antim-AMS2 or IONPURE-H significantly enhanced the antibacterial effect of ESP after curing, even after 1 month aging. Specimens treated by ESP with ZnOw AT-83, Longbei antibiotic or Antim-AMS2 showed slightly less bacterial adhesion than control. Animal experiments revealed neither toxic signs nor significant differences in body weight gain between control and other groups. Cell vitality or proliferation rates were ranged from 76% to 100% with respect to controls. Basic magnesium hypochlorite, ZnOw AT-83 and ZnOw AT-88 were less toxic. Toxicity only observed in areas beneath the specimens and/or in the direct vicinity of the specimen edge. From microbiological and biocompatibility aspects, the tested ABAs can be effectively incorporated in ESP to provide antibacterial activity against S. mutans. ZnOw AT-83 was the most promising one.

Ti-Cp functionalization by deposition of organic/inorganic silica nanoparticles

In orthopaedics and cardiovascular surgery, titanium has become the metal of choice, due to its excellent mechanical properties and biocompatibility. In many surgical operations, chemicals and/or biomolecules (such as antibiotics or growth factors) are used in conjunction with prostheses, so as to avoid or stimulate targeted biological events. Often, immobilization instead of release of such molecules is preferred to optimize their effects, thus avoiding ectopic transformations. A versatile method for the functionalization of pure Ti is shown here, which allows the covalent immobilization of polypeptides. In order to avoid the hydrolysable Ti-O-Si bond found in directly silanized Ti, we use organic/inorganic silica colloids, derived from commercially available 25 nm Ludox silica nanoparticles. Prior to deposition onto Ti-Cp, the silica nanoparticles are functionalized by a propylsemicarbazide moiety by silanization. After spin-coating onto the Ti substrates, the colloids were shown by SEM to form a uniform layer, and to be very strongly adsorbed; the reactivity of the supported semicarbazide (Sc) functionalities being maintained. Chemoselective reaction of semicarbazide groups on the surface with aldehyde moieties present on the polypeptide of interest was chosen in this work due to its efficiency, to its compatibility with the proteinogenic amino acids and in particular cystein and to the use of mild experimental conditions. Aldehyde groups are also easily introduced onto polypeptides by synthesis, oxidation of N-terminal Ser residue or polysaccharide moieties of glycoproteins. Biological assays with MC3T3-E1 osteoblasts revealed an excellent cytocompatibility as shown by the assessment of cell viability, vitality and morphology.

Biological and physico-chemical assessment of hydroxyapatite (HA) with different porosity

HA with specific internal porosities was loaded with different antibiotics (ATBs) and then tested on its microbiological effectiveness. The HA purity was controlled with X-ray diffraction, IR and Raman spectrometry. Varying the sintering temperature and/or adding graphite and PMMA as porogenous agents lead to obtained micro- and meso-porosities. The biological tests concerned cell viability, proliferation and morphology (SEM), and the cytochemical staining of actin and vinculin. The micro- and meso-porous HA samples had an internal pore size of 1-10 microm and 10-50 microm, respectively. X-ray diffraction and FTIR confirmed the high purity of the HA. The cell viability tests with L132 cells confirmed the excellent cytocompatibility of HA, the graphite powder and the ATB vancomycine. Proliferation rate was assessed with MC3T3-E1 osteoblasts. All HA samples produced a higher proliferation than the controls; the micro-porous HA inducing the highest cell growth. The ATB impregnated HA also stimulated cell proliferation but in lower extend. Cytochemical staining of osteoblasts revealed a well-developed cytoskeleton with strong stress fibres. Labelling of the focal adhesion contacts with anti-vinculin showed a less developed adhesion process in the cells on the different HA substrates. It was possible to realize a highly pure hydroxyapatite with different but controlled porosities by varying the sintering temperature and/or addition of a porogenous agents. This purity and the micro-porosity stimulate significantly cell growth.

On the use of ultrasounds to quantify the longitudinal threshold force to detach osteoblastic cells from a conditioned glass substrate

Cell adhesion on a biomaterial is an important phase of the cell-material interactions and the quality of this phase governs the success of the biomaterial integration. Understanding of the phenomena of cell adhesion and in particular understanding of cell adhesion on biomaterials is of crucial importance for the development of new biomaterials with excellent biocompatibility. One of the physical quantitative indexes to evaluate the quality of cell-material adhesion is its strength. Determining the strength of adhesive bonds requires applying external forces to the cells. Thus, a few methods have been developed to evaluate the strength of cell-material adhesion (micropipette, microplates, microcantilever, ...). These methods apply shear forces on adherent cells. The aim of our work is the development of a new ultrasonic characterization method of cellular adhesion on substrates. With our method, longitudinal acoustic waves are applied on cell culture to impose a longitudinal strain on cells. Only the cells subjected to a sufficient level of strain will be detached from the substrate. The idea is to correlate cell detachment rate to the longitudinal strain threshold supported by cells. From this result, we can deduce the critical force just sufficient to detach the cell. This global method can be adapted for different cell types and for different substrates. This method can provide an evaluation of the effect of functionalization on substrates. The technique is investigated for the 200 kHz ultrasound frequency. An insonificator adapted to the use of cell culture boxes was developed and calibrated. Tests were carried out on a glass substrate with or without biological conditioning. We used the MC3T3-E1 osteoblastic cell line. Our results to date provide the value of the necessary force to detach with reproducibility osteoblastic cells from glass.

Functionalization of PVDF membranes with carbohydrate derivates for the controlled delivery of chlorhexidin

Maltodextrin (MX) was fixed onto PVDF membranes in order to create a drug delivery Guided Tissue Regeneration (GTR) device with controlled drug delivery properties. PVDF microporous membranes were treated by a mixture of MX and citric acid, resulting to an 18 wt% increase of the supports. MX grafted membrane could capture 103 mg/g chlorhexidin digluconate (DigCHX) instead of 1mg/g for a virgin membrane. A neutralization step was performed before the biological tests. Viability tests confirmed the non-toxicity of the MX polymer coating after neutralisation. In vitro release test in human plasma, and microbiological tests showed that membranes grafted with MX were more performing compared to virgin and beta-CD grafted membranes. The antimicrobial activity was effective during more than 72 h.

Antibacterial activation of hydroxyapatite (HA) with controlled porosity by different antibiotics

In order to prevent the increasing frequency of per-operative infections, bioceramics can be loaded with anti-bacterial agents, which will release with respect to their chemical characteristics. A novel hydroxyapatite (HA) was elaborated with specific internal porosities for using as a bone-bioactive antibiotic (ATB) carrier material. UV spectrophotometry and bacteria inhibition tests were performed for testing the ATB adsorption and the microbiological effectiveness after loading with different antibiotics. The impregnation time, ATB impregnating concentration, impregnation condition and other factors, which might influence the ATB loading effect, were studied by exposure to different releasing solvents and different pathogenic bacteria: Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli. It clearly showed that the facility of ATB loading on this porous HA is even possible just under simple non-vacuum impregnation conditions in a not-so-long impregnating interval. The results also showed that, for all three types of ATB (vancomycin, ciprofloxacin and gentamicin), adsorbed amount on the micro-porous HA were hugely higher than that on dense HA. The micro-porosity of test HA had also significantly prolonged the release time of antibiotics even under mimic physiological conditions. Furthermore, it also has primarily proved by a pilot test that the antibacterial efficiency of crude micro-porous HA could be further significantly improved by other methods of functionalization such as cold plasma technique.

Vascular prostheses with controlled release of antibiotics

Vascular prostheses were functionalised with the aim to obtain a slow release of antibiotics in order to reduce postoperative infections. The original process that we present in this paper is based on the use of a family of cage molecules named cyclodextrins (CD). These compounds have the ability to form reversible inclusion complexes with drugs such as antibiotics. The aim of this work was to graft CD onto the prosthesis, so that an antibiotic can be bound on it by this inclusion phenomenon, and then be progressively released over a prolonged period by a complex dissociation mechanism. This paper presents the first part of this research program and concerns mainly the study of the functionalization parameters. It presents surface characterization results of the modified prostheses. The PET prostheses were immersed into a solution containing a cross linking agent, cyclodextrins (beta-CD, gamma-CD, HP-beta-CD and HP-gamma-CD) and a catalyst and were padded. Grafting occurred by the mean of a thermofixation step at a temperature comprised between 140 and 180 degrees C. It was observed that the support was permanently modified when the CD polymer that coated the fibres resisted to the final washing process. Grafting rates of 12 wt% in CD polymer could be reached. It was also observed that the fibre coating reaction induced an increase of the permeability of the grafts.

Vascular prostheses with controlled release of antibiotics

Viability tests by the colony forming method show no toxicity for all CDs (beta-CD, gamma-CD, HPbeta-CD and HPgamma-CD) and their associated polymer. A survival rate of 100% is observed for all CDs at high concentration 400 ppm. Proliferation tests revealed a low proliferation of L132 cells on grafted vascular prostheses and untreated prostheses and good proliferation on Melinex (film form of PET). A proliferation of 17% is observed after 3 days of incubation and decrease at 4% after 6 days on prostheses. Melinex exhibits a proliferation rate as the controls. Vitality tests confirm proliferation tests and show a good vitality of cells even for low cell amounts. From these experiments it becomes obvious that the decreasing proliferation rate is not a cytotoxic effect but is due to the chemical and/or physical surface characteristics. A similar result is obtained for cell adhesion kinetics between grafted vascular prostheses and control. After 2 h adhesion, a lower adhesion is observed on untreated prostheses. Theses results were confirmed by immunochemistry and morphology tests. This cell adhesion inhibiting effect of the PET prostheses contributes to a better "survival" of vascular prostheses without secondary obstruction or stenosis.

Antibacterial activities of inorganic agents on six bacteria associated with oral infections by two susceptibility tests

The antibacterial effects of six inorganic antibacterial agents were assessed using broth dilution and agar dilution tests on six pathogenic bacteria associated with oral infectious diseases: Streptococcus mutans (ATCC 25175), S. mutans (Ingbritt), Actinomyces viscosus (ATCC 15987), Lactobacillus casei (ATCC 393), Staphylococcus aureus (ATCC 29213) and Candida albicans (ATCC 90028). The results of the broth dilution test were significantly lower than those of the agar dilution test (F=38.290; P<0.01). The six inorganic agents notably inhibited the growth of tested common oral bacteria in vitro. Among them, Longbei inorganic antibiotic powder was the strongest antibacterial agent, followed by ZnO whisker antibacterial complex (ZnOw) AT-83, IONPURE-H, basic magnesium hypochlorite, ZnOw AT-88 and Antim-AMS2. The broth dilution test appears to be more suitable for testing insoluble inorganic agents.

Physico-chemical and biological evaluation of excimer laser irradiated polyethylene terephthalate (pet) surfaces

The aim of this work was to investigate the consequences of excimer laser irradiation on the physico-chemical and biological properties of polyethylene terephthalate (PET) films, currently used for medical devices. Three PET films from different origins were studied in the present work, chosen with respect to their chemical and physical properties, which are of high importance for ulterior medical application as vascular prostheses. Multiple assays were carried out to characterize the physical and chemical effects of the laser irradiation: surface morphology tests (light microscopy, Dektak profilometer and confocal laser scanning microscopy) showed the strong transformation of the surface with the laser treatment. Contact angle measurements revealed a significant increase of the surface energy for each PET depending on the applied fluency. Finally XPS characterization of the surface demonstrated the appearance of new chemical species favorable for cell attachment. This aspect had to be strongly considered regarding to the multiple biological effects of laser irradiated surfaces on living cells. Different cell culture experiments were carried out with L132 human epithelial cells after 6-days culture: proliferation and vitality rate, cell adhesion and cell morphology. Results clearly revealed that laser treatment improved cell proliferation (up to 140% with respect to controls), vitality (10% higher than controls), morphology and adhesion kinetics (more than 16% of control). A significant correlation (R2=0.906) was also established on one PET between the fluencies of laser treatment and the cellular response. These results emphasized high importance of the choice of the PET material for a medical application: only one of the three considered PET films showed really improved cellular response.

In vitro studies on the influence of precultural conditioning method on osteoblast reactions of a new type of injectable calcium cement material

A new injectable dicalcium phosphate dehydrate (DCPD)-based cement material "PD" VitalOs Cement was studied to elucidate the process of equilibrium occurring in the early stage of implantation. The present study investigated the pH variations of the cement sample-immersing culture medium at determined intervals, time-dependent calcium/phosphate release, cell proliferation, and vitality in the cells-cement coculture milieu, after different preculture conditionings of the samples. Measurement of pH variation showed that without renewing the medium, pH value of sample lixiviate medium first dropped and, after 70 h, gradually balanced. When medium was renewed each day, pH value of lixiviate medium first descended and, after 24 h, gradually returned to pH 7.2. The cell viability revealed an excellent cytocompatibility of the cement. Both cell proliferation and vitality test showed that the preculture conditioning treatment is important at least for good performance of osteoblasts growing on the surface of calcium phosphate hydraulic cement (CPHC) samples in vitro. The results of calcium and phosphate assays clearly showed that this cement material can continuously dissolve to release calcium and phosphate in the liquid cell culture environment. The decrease of proliferation in some experimental groups with short conditioning is due to an excess of acid, which still can have some influence on cell growth after 24 h, since the biological milieu is not continuously renewed as in in vivo conditions.

Improved drug delivery properties of PVDF membranes functionalized with β-cyclodextrin—Application to guided tissue regeneration in periodontology

The purpose of this study was to develop a membrane for guided tissue regeneration applicable in periodontology that could release antimicrobial agent during the healing period. Our strategy consisted to graft beta-cyclodextrin (beta-CD), a molecule that is known to form inclusion complexes with a large variety of drugs, onto PVDF membranes. Grafting occurred by using citric acid that provoked a crosslinking reaction of beta-CD, and the resulting polymer was imprisoned into the porous structure of the PVDF membrane. The reaction produced a weight increase of the membrane, the range of which depended on the temperature and on the time of curing applied in the process. The biological behavior of the membranes evaluated by proliferation and vitality tests showed good proliferation and improved activity of L132 epithelial cells on the raw and on the grafted membranes. Doxycyclin (DOX) and chlorhexidine (CHX) were used as antimicrobial agents. Their inclusion into the beta-CD cavity in aqueous solutions was confirmed by NMR spectroscopy. After the impregnation of the membranes with DOX and CHX, their release was studied in vitro in batch type experiments and measured by UV spectrophotometry. Low amounts of DOX and CHX were delivered from the raw membranes within the first few hours of tests. Grafted membranes, however, delivered DOX and CHX in larger quantities within 24 h and 10 days respectively.

[Biodegradation of synthetic bioglasses with different crystallinity in vitro]

SG600, SG900 and SG1100 were synthesized by the sol-gel method. Further treatments with increasing temperatures influenced and determined the crystallization degree of the material. Primary cultured osteoclasts were incubated for 4h and 48h on samples. Osteoclast actin labeling was examined by cytochemical staining. The concentrations of Ca and P in culture medium were quantified by colorimetric methods. SEM examined osteoclast morphology and resorption lacuna. Actin staining revealed on all three materials the typical adhesion contact ring. The Ca concentration in the culture medium of SG600 was significantly higher than that in control medium, SG900 and SG1100. Ca and P concentrations were always higher in culture media with the presence of osteoclasts. Morphological studies by scanning electron microsopy(SEM) showed a good adhesion behavior of osteoclasts on all three samples. Well-developed and deep resorption lacunae appearing after the osteoclastic resorption action were detected on all three samples. The synthetic bioglasses with different crystallizations caused different solubility, which seemed to have little effect on the osteoclast resorption behavior. The results of morphological studies on osteoclasts and resorption lacunae clearly demonstrate that the synthetic bioglasses are easily resorbed in vitro by osteoclasts.

Vascular PET Prostheses Surface Modification with Cyclodextrin Coating: Development of a New Drug Delivery System

PURPOSE

Cyclodextrins (CDs) are torus shaped cyclic oligosaccharides with a hydrophobic internal cavity and a hydrophilic external surface. We performed and analysed an antibiotic binding on Dacron (polyethyleneterephtalate, PET) vascular grafts, previously coated with CDs based polymers.

METHODS

The CDs coating process was based on the pad-dry-cure method patented in our laboratory. The Dacron prostheses were immersed into a solution containing a polycarboxylic acid, a cyclodextrin and a catalyst, and placed into a thermofixation oven before impregnation with an antibiotic solution (Vancomycin). Biocompatibility tests were performed with L132 human epithelial cells. The antibiotic release in an aqueous medium was assessed by batch type experiments using UV spectroscopy.

RESULTS

Viability tests confirmed that the CDs polymers coating the Dacron fibers were not toxic towards L132 cell. Cell proliferation was similar on coated and uncoated grafts. A linear release of Vancomycin was observed over 50 days.

CONCLUSION

Our results demonstrate the feasibility of coating CDs onto vascular Dacron grafts. Biological tests show no toxicity of the different cyclodextrins coated. A linear release of antibiotics was depicted over 50 days, demonstrating that cyclodextrin grafting was an efficient drug delivery system.

Surface analyses of micro-arc oxidized and hydrothermally treated titanium and effect on osteoblast behavior

Osteoblast adhesion on the implant material surface is essential for the success of any implant in which osteointegration is required. Surface properties of implant material have a critical role in the cell adhesion progress. Titanium and its alloys are widespread and increasingly used as implant material in dentistry and orthopedics because of their excellent biocompatibility, which is attributed to a passive layer of TiO2 on the surface. In this study, the micro-arc oxidizing (MAO) and hydrothermally synthesizing (HS) methods were used to modify the TiO2 layer on the titanium surface. The surface microstructure was observed by scanning electron microscopy. The surface energy was assessed. The mouse osteoblastic cell line (MC3T3-E1) was seeded on the treated surfaces to evaluate their effect on cell behavior. This included cell adhesion kinetics, cell proliferation, cell morphology, and cytoskeletal organization. The surface structure of MAO samples exhibited micropores with a diameter of 1-3 microm, whereas the MAO-HS-treated samples showed additional multiple crystalline microparticles on the microporous surface. The surface energy of MAO and MAO-HS was higher than that of titanium. The cell adhesion rate was higher on the MAO-HS surface than on the MAO and titanium surface, but without any significant difference between them. After 3 days of culture, cells proliferated significantly more on the MAO and titanium surface than on the MAO-HS surface. The cytoskeletal organization was analyzed by actin and vinculin staining on all the samples. We conclude that the MAO and MAO-HS methods change the surface energy of TiO2 layer on the titanium surface. This may have an influence on the initial cell attachment. Other surface characteristics may be involved in the cell proliferation, which is different from cell attachment on the sample surface. A longer-duration cell experiment should be conducted to see the effect on cell differentiation. Future in vivo evaluation may give further evidence to optimize the surface character of this kind of implant material.

Biological characterization of experimental carbon samples

The use of carbon is widespread in fields as wide as aeronautics, cars, electricity or electronics. The biomedical applications of carbon are also numerous. The purpose of our work is to test four experimental carbon fibers (A, B, C and D; B being the negative control) to determine the best clinical application. Four tests of cytocompatibility are carried out (cell viability, inflammatory test, cell proliferation and cell morphology). Two different cell lines are used: the L132 cell line (epithelial embryonic pulmonary human cell) and the HaCaT line (human normal spontaneously immortalized skin keratinocytes). The results of the biological tests are compared with those of a carbon fiber sample already marketed as a bandage in the treatment of infected wounds: Actisorb "Plus (J2). The various tests show us that only two experimental samples are slightly cytotoxic (A, D). On the other hand, no sample supports cell adherence. A, B, C and D do not have an inflammatory effect. J2 appears at the same time cytotoxic and inflammatory. Consequently, being given the physical presentation and the biological properties of experimental samples (A, C and D), we intend them for an application in the field of wound healing, as a bandage. Also further experimentation is needed.

In vitro MC3T3 osteoblast adhesion with respect to surface roughness of Ti6Al4V substrates

This work investigates the role of the surface roughness of Ti6Al4V on the cell morphology, proliferation and adhesion, and in particular on the variation of the expression of cell adhesion proteins. Standardised test samples with five different surface preparations are used: sandblasted, 80, 1200, and 4000 grade polished, mirror polished. Surface roughness is analysed by Scanning Electron Microscopy and LASER Confocal Microscopy. Cell culture experiments are performed with MC3T3-E1 mouse osteoblasts after 3 days culture: proliferation rate, morphology and adhesion are assessed. The variations of expression of cell adhesion proteins are evidenced by indirect immune fluorescence method: actin from the cytoskeleton, vinculin from the focal adhesion complex, fibronectin and collagen I from the extracellular matrix. The results reveal a clear influence of surface roughness of Ti6Al4V on cell proliferation, morphology and adhesion. A significant correlation is established between surface roughness and cell growth. More the surface is smooth more the osteoblasts proliferate and appear spread out on the test samples. In addition, the expression of adhesion proteins varies with respect to the surface roughness. These results indicate a direct relationship between the decrease of cell adhesion and the increase of cell proliferation on mirror polished materials.

Cells under stress: a non-destructive evaluation of adhesion by ultrasounds

The adhesion process plays a major role in the development of osteoblastic cells on various substrates used in orthopaedic applications such as metals, bioceramics, or glass. High frequency and low power ultrasounds seem to be an appropriate tool for an evaluation of interface mechanical properties. Is it a non-destructive method? We investigated osteoblastic cell cultures, maintained in their medium with high frequency, bulk longitudinal waves. The influence of both acoustical frequency and acoustical power on cell adhesion is evaluated by cell detachment ratio and re-adhesion ratio. We demonstrate the existence of a power threshold depending on the frequency, allowing optimal cellular detachment and re-adhesion. Finally, a qualitative study of the detachment phenomena is performed by use of scanning electron microscopy (SEM), Confocal Laser Scanning Microscopy and cytochemical labelling.

Electrochemical and cytocompatibility assessment of NiTiNOL memory shape alloy for orthodontic use

Orthodontic arcs and wires are mostly realised from alloys and constitute the motor of dental shifting. Ti-base alloys rapidly replaced the formerly used stainless steel wires due to their excellent corrosion resistance, their high mechanical characteristics and their increased biocompatibility. NiTiNOL shape memory alloys add to these advantages their ability of deforming force. NiTiNOL, highly pure Nickel (hp-Ni) and commercially pure titanium (cp-Ti) were tested by electrochemical assays in artificial saliva and in vitro biological tests with L132 cells and HEPM cells. All tests gave concordant results: the electrochemical assays, the proliferation test, the colony forming method, and the inflammatory test clearly show, that nickel is a corrosive and a cytotoxic material. Ti and NiTiNOL are cytocompatible and in particular corrosion resistant. No significant differences are observed for both materials on the electrochemical and the biological level as well. The NiTiNOL shape memory alloy is a master trump for dental practitioners to repair occlusal defects by shifting teeth under optimal biological conditions. In spite of its high Ni-content, it is biocompatible. It considerably reduces the tune of therapeutic treatment, facilitate the occlusal concept and leads to a result of high clinical quality.

Cell orientation and cytoskeleton organisation on ground titanium surfaces

A stable connection between the biomaterial surface and the surrounding tissue is one of the most important prerequisites for the long-term success of implants. Therefore, a strong adhesion of the cells on the biomaterial surface is required. Beside the surface composition the surface topography influences the properties of the adherent cells. The quality of the connection between the cell and the biomaterial is-among other factors-determined by the dimensions of the surface topography. Osteoblasts and fibroblast-like cells in contact with a ground biomaterial surface spread in the direction of the surface structures. These aligned cells provide a more favourable adhesion behaviour than a spherically shaped cell. To determine the influence of the surface structure on the cell alignment and cytoskeleton organisation or arrangement, substrate discs of cp-titanium were ground, producing different roughness of the substrates. The oriented cells had a higher density of focal contacts when they were in contact with the edges of the grooves and showed a better organisation of the cytoskeleton and stronger actin fibres. These changes of the aligned cells depend on the peak to valley height of the surface structures.

Multiple parameter cytotoxicity index on dental alloys and pure metals

Palladium (Pd) is a metal frequently used for dental alloys. In order to elucidate controversial options about Pd concerning its biological performances, our study consists in the evaluation of commercial and experimental PFM and C&B precious and semi-precious dental alloys. This investigation was also designated to the establishment of a cytotoxicity index (CI) such as it was described for hemocompatibility testing. The following materials were tested: 36 commercial alloys (Au-, Pd- and Ag-base), 14 experimental alloys (Pd-base established by an experience plan) and pure metals (Ag, Au, Cu, Ni, Cr, In, Sn, Pt, Ti, Zn). The cells culture experiments were carried out with epithelial L132 cells and NIH 3T3 fibroblasts. In vitro cell viability tests show that Pt, Sn, In, Ti, Au and Pd have no cytotoxic effect; Cr, Cu and Ag are toxic, Ni, Zn, and Co are highly toxic. An identical ranking was found with the inflammatory and proliferation tests. Toxic and highly toxic metals induced slight or strong prosthetic dental restoration morphological alterations after 3-days cultures and mostly cell death after 6-days cultures. These effects are dependent on the leakage of the element into the culture medium as revealed by ICP. The addition of Au gives benefit to Pd-Ag alloys, but does not produce any major effect on Pd-Cu alloys. This qualitative ranking can quantitatively be confirmed by cytocompatibility testing after application of a CI.

In vitro studies of human and rat osteoclast activity on hydroxyapatite, beta-tricalcium phosphate, calcium carbonate

Investigations on the ceramic degradation caused by osteoclasts are designed to assess osteoclast-ceramic interactions and to determine which ceramics are more suitable for use as bone substitute. This study investigated the resorptive activity of osteoclasts on ceramics presenting different solubility rates. Osteoclasts isolated from new-born rat and from human giant cell tumour were cultured on different bioceramics: hydroxyapatite (HA), beta-tricalcium phosphate (TCP) and calcium carbonate (calcite). Cytoskeletal was revealed by actin labelling and ceramic surfaces were observed by scanning electron microscopy (SEM). On all materials, the distribution of actin in typical ring was revealed. SEM examinations showed a clear difference in the shape and the depth of resorption lacunae on different ceramics. On pure HA, a superficial attack, clearly visible but very little extended. Numerous resorption lacunae, deep and well-delimited were observed on pure beta-TCP, but attacks less punctually were detected too. On pure calcite, an attack with form of spikes, very widespread but superficial was revealed. Degradation measurements revealed a significant increase of P release from the phosphocalcic ceramics and of Ca from all ceramics in the presence of osteoclasts. The both cell models found these characteristics, the rat osteoclasts were also an excellent model to study the ceramic resorption.

[Malignant fibrous histiocytoma of bone 20 years after femoral fracture treated by plate-screw fixation: analysis of corrosion products and their role in malignancy]

We report a case of malignant fibrous histiocytoma of the bone that developed 20 years after a femoral fracture treated by plate-screw fixation. Similar cases reported over the past fifteen years in the literature suggest the possible mechanisms of sarcomatous degeneration. The possible carcinogenic effect of corrosion products is emphasized. Dispersion energy spectrometry of intracellular particles on the periphery and at the center of the tumor demonstrated the presence of chromium, iron and nickel at different concentrations. The association with other elements clearly demonstrates that the corrosion products were metabolized. The presence of metallic components in tumoral cells suggests a possible relationship between metallic implants and malignancy. These observations emphasize the importance of creating a national, or even international, registry of malignant tumors that develop in contact with metallic implants in order to search for a possible cause and effect relationship.

The relative influence of the topography and chemistry of TiAl6V4 surfaces on osteoblastic cell behaviour

Proliferation and adhesion of mouse (MC3T3-E1) osteoblastic cells and primary human osteoblastic cells were carried out on Ti6Al4V titanium alloy samples with varied surface roughnesses. Mechanically or manually polished surfaces were prepared to produce respectively non-oriented or oriented residual polishing grooves. Sand-blasted surfaces were prepared using 500 microm or 3 mm alumina particles. Surface roughness parameters showed a negative correlation in comparison to proliferation and adhesion parameters. X-ray microprobe chemical surface microanalysis showed complete disturbance of the surface element composition of the Ti6Al4V alloy following sand-blasting treatment. An AlOx-enriched layer was observed on sample surfaces. This may lead to the suspicion that the concomittant effect of surface roughness amplitude and AlOx surface concentration has an effect on osteoblastic cell proliferation and adhesion. These findings show the significance of chemical surface analysis after any surface treatment of titanium-based implants before any biological use.

Features of severe periodontal disease in a teenager with Chédiak-Higashi syndrome

BACKGROUND

Chédiak-Higashi syndrome (C-HS) is a rare congenital disease characterized by defective neutrophil function with abnormal lysosomal inclusions, neutropenia, and reduced chemotaxis. The complete syndrome includes oculocutaneous albinism with photophobia, neurologic features, recurrent infections, and enterocolitis.

METHODS

A 14-year-old male C-HS patient was referred to us because of serious periodontal destruction with acute inflamed gingiva and ulcers. Clinical and biological investigations were performed, leading to the diagnosis of C-HS.

RESULTS

Laboratory findings included neutropenia and hypergammaglobulinemia. Peripheral blood smears showed giant granules in neutrophils, eosinophils, and granulocytes. Bone marrow smears showed giant inclusions in leukocyte precursor cells. These granules and inclusions were characteristic of Chédiak-Higashi syndrome. Oral radiographic status showed extensive loss of alveolar bone leading, in most cases, to tooth exfoliation. Bacteria often associated with periodontitis were detected in subgingival plaque samples, including Fusobacterium nucleatum, Campylobacter rectus, Prevotella melaninogenica, Peptostreptococcus anaerobius, and Clostridium sp. Biopsies of periodontal tissues for light and electronic microscopic examinations revealed massive bacterial invasion of the epithelial tissue, epithelial cells, and connective tissue. Ultrastructural observations of periodontal polymorphonuclear leukocytes showed defective granulation, with abnormal granules not discharging their lysosomal content against engulfed bacteria. Viable dividing bacteria were found in the cytoplasm.

CONCLUSIONS

In this case, early-onset periodontitis seems to be the expression of C-HS granulocyte deficiency. Periodontal treatment of these patients is often unsuccessful. This case report illustrates the importance of the dentist in initiating clinical and biological investigations in such early aggressive periodontitis in young patients.

Adsorption and release of insulin-like growth factor-I on porous tricalcium phosphate implant

In order to develop bone substitutes, the design of biomaterials like calcium phosphate ceramic loaded with bone growth factor are of great interest. However, it is necessary to control the amount of growth factor adsorbed onto ceramics and the kinetics of its release. Radiolabeling of insulin-like growth factor-I (IGF-I) with 125-iodine ([(125)I]-IGF-I) and its adsorption onto porous tricalcium phosphate (TCP) cylinders enabled us to establish the time-adsorption and time-release curves using various concentrations of IGF-I. The adsorption curve increased rapidly and then flattened out at 72 h; 90% of the maximum was already reached at 24 h; and 20% of the adsorbed IGF-I was released in water within 4 days. In human serum the release was faster at 82% within 4 days. In vivo evaluation on an animal model was then performed. Rabbits' bilateral femoral cylindrical bone defects were filled with the TCP cylinders, which were either carrying IGF-I or implanted alone as a control in each rabbit. Bone turnover and ceramic resorption were stimulated by IGF-I loaded TCP according to standard radiography, dual-energy X-ray absorptiometry, histology, and histomorphometry.

Evaluation of human recombinant bone morphogenetic protein-2-loaded tricalcium phosphate implants in rabbits' bone defects

Porous beta-tricalcium phosphate (betaTCP) has osteoconductive properties. The adsorption of human recombinant bone morphogenetic protein-2 (rhBMP-2) onto TCP could realize an osteoinductive bone substitute. We evaluated it on an animal model using dual-energy X-ray absorptiometry (DEXA) and solid-state 31P nuclear magnetic resonance (NMR) spectroscopy. BetaTCP cylinders loaded with rhBMP-2 were implanted into rabbits' femoral condyle bone defects, and betaTCP alone as control into the contralateral femur. We studied two different doses of rhBMP-2 (10 and 40 microg) on two groups of four animals. Evaluation consisted in radiography, histology, and histomorphometry, DEXA, and NMR spectroscopy using an original method of quantification. With both doses of rhBMP-2, we observed on radiographs an increase of trabecular bone around implants. Histology showed resorption of the ceramic, trabecular bone with osteoblasts and osteoid substance around the implants, and colonization inside the porous betaTCP by new bone formed. Histomorphometry showed that the osteoid surface (OS/BS) was greatest with the high dose of rhBMP-2. The difference was slight between the low dose of rhBMP-2 and control. DEXA showed a dose-dependent increase of bone mineral density of rhBMP-2-loaded betaTCP vs. control. NMR spectroscopy confirmed that the amount of new bone formed in betaTCP was greater when betaTCP carried rhBMP-2, and increased with the dose of rhBMP-2 used. We showed that betaTCP was a good matrix for rhBMP-2, which gave it osteoinductive properties in an orthotopic site, in a dose-dependent manner. Thus, such composite biomaterial seems to be of great interest in reconstructive bone surgery. Further studies are needed in clinical practice to determine optimal doses.

Potentialities of ultrasounds for the nondestructive evaluation of cell adhesion

The aim of this paper is to present the potentialities of ultrasounds to investigate the mechanical properties of a cell/substrate interface. The adhesion process plays a major role in the development of osteoblastic cells on various substrates used in orthopedic applications such as metals, bioceramics, etc. Particularly, cell adherence appears to be a critical factor in the colonization process. High-frequency and low-power ultrasounds seem to be an appropriate tool for a nondestructive evaluation of interface properties. First, we present the results obtained with bulk longitudinal and shear waves under an arbitrary incidence over an aluminum-adhesive interface. This study was performed for an industrial application of bonding. The results clearly show the sensitivity of shear waves for the evaluation of the adhesion quality owing to the shear solicitations at the interface they induce. A model of ultrasound interactions with a boundary subject to varying degrees of adhesion has been developed and compared to the experiments. Second, we investigated osteoblastic cell cultures with a high-frequency acoustic microscope working at 50 MHz. The images obtained in the shear mode reveal a better contrast than those obtained in the longitudinal mode. For the time being, these results are qualitative, and theoretical models have to be developed according to the point of view of biologists.

[The in vitro biological behavior of TiNb30 alloy treated with hydroxyapatite and tricalcium phosphates]

An in vitro study has been carried out in different cell systems to determine the biological response of TiNb30 alloy before and after a surface treatment with hydroxyapatite (HA) and tricalcium phosphate (TCP) by the sol-gel method. TiNb30 pure Ti induce favorable cell viability with respect to pure Ni showing a high cytotoxic effect. After surface treatment with HA or HA-TCP mixtures, no difference in cell proliferation can be observed between amorphous and cristalline forms. However, HA decreases (75 +/- 15%) and HA-TCP mixtures increase (133 +/- 11%) significantly cell proliferation compared with controls.

[In vitro and in vivo biocompatibility of stainless steel as a function of surface treatments: roughness and surfacing with hydroxyapatite]

The in vitro tests on cell viability reveal a favorable position for steel and hydroxyapatite (HA)? However, the roughness induces a negative effect on cell proliferation. Sandblasting of the stainless steel considerably decreased cell number compared with the polished substrate. HA showed a better percentage of proliferation in spite of the surface effect compared with controls. For in vivo biocompatibility, intramuscular implants revealed localized inflammatory reactions for the HA treated stainless steel but nor for the untreated alloy.

[Cytocompatibility of dental alloys containing palladium]

The cytoxicity and the 50% lethal concentration (LC50) has been assessed in vitro by the colony forming method in extracts of 5 precious or semiprecious alloys and of oxides and chlorides of the metal contained in these alloys: Pd, Ag, Cu, Zn, Sn, In and Ga. All alloy extracts in culture medium induced cell death depending on their composition. In, Ga and Sn compounds showed the most favorable cell viability, Cu and Ag salts induced the lowest survival rate.

[The electrochemical behavior of TiTa30 and TiNb30 alloys for implantology]

The electrochemical behavior in artificial saliva of TiNb30 and TiTa30 alloys were compared with that of commercial pure titanium. The anodic potential, the current density, the passivation potential and the galvanic corrosion vs. Au were determined. Both alloys have a similar behavior to that of pure titanium. Crevace corrosion, which is very weak in pure Ti, is completely inhibited by the addition of Nb or Ta.