bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Liquid/Powder Ratio on the Setting, Handling and Mechanical Properties of Collagen–Apatitic Cements
Authors: Dunne N.J. , O’Hara R. , Buchanan F. , Orr J.
Published: October 2011

Due to their insufficient mechanical stability and brittle nature, calcium phosphate cements (CPCs) have not been used for the treatment of vertebral fractures. Mechanical stability of human bone is provided by a complex interaction of type I collagen fibres and hydroxyapatite crystals. In the present study, fibre reinforcement of an apatitic calcium phosphate prepared at different liquid/powder ratio (LPR) was investigated. Different lengths of type I collagen fibres sourced from bovine Achilles tendon were used. Compressive strength and fracture behaviour were examined. Fibre addition of up to 5 wt.% had a significant influence on the compressive properties of the CPC. The mechanism of fibre reinforcement appeared to be crack bridging. Setting time and injectability of the CPC with fibre reinforcement was also investigated and decreased with fibre volume fraction. Increasing the LPR, improved the injectability and delayed the setting reaction. However, the compressive properties of the hardened cement were reduced as a consequence.
Use of HA–PLLA Composite Screws to Fix Acetabular Bone Graft in Cemented THA: Absorption Pattern of Screws in Six Patients
Authors: Goto Koji , Akiyama Haruhiko , Kawanabe Keiichi , So Kazutaka , Nakamura Takashi
Published: October 2011

We used a composite of uncalcined and unsintered hydroxyapatite (u-HA) particles and poly-l-lactide (PLLA) to fix the acetabular bone graft in total hip arthroplasty (THA) in a clinical trial in six patients, and followed them for over 10 years. The patients were evaluated clinically and radiologically to assess the safety and efficacy of the screws and the characteristics of their absorption. No patient in this series experienced revision or radiographic loosening during the follow-up period. The configurations of the HA–PLLA composite screws were confirmed on early post-operative radiographs in every case, whereas they appeared obscure on radiographs within 5 years after surgery, and only osteosclerotic traces remained in the screw positions at the final follow-up. Some screw heads were covered with bone within 3 months of surgery, and some screw heads migrated laterally with breakage, but were absorbed in situ within 5 years. The screws seemed to have no negative effect on the mid-term clinical results of the THAs.
Simultaneous Implantation of Dental Implants and Autogenous Human Dentin
Authors: Tazaki Junichi , Murata Masaru , Nakanishi Y. , Ochi M. , Hirose Y. , Akazawa T. , Yodogawa S. , Hino J. , Ito K. , Kitajo H. , Arisue M. , Shibata T.
Published: October 2011

In our previous clinical study, autogenous demineralized dentin matrices (DDM) prepared from the functional vital teeth (#38, #41) of thirty-five-year-old female were grafted on the bone defect, using newly developed mill, and then received to the host without troubles. In this study, we implanted the human tooth dentin adjusted previously and the dental implants into the regions of missing tooth simultaneously. Fifty-seven-year-old female presented with missing teeth (#35-#37, #45-#47). First, a non-functional vital tooth (#18) were extracted and cryopreserved immediately. 11 months after extraction, the tooth was crushed by newly developed auto-crash mill using ZrO2 vessel and ZrO2 blade for 1 minute. The crushed granules were demineralized completely in 2% HNO3 solution, rinsed in cold distilled water and lyophilized (granule size: 0.5-2.0mm). The bacteria-free of the DDM were confirmed by the bacteriological examination before use. Drilling of the prospective implant beds were then performed according to the manufacture’s protocol and a screw-type rough surface implants (Nobel Biocare® Mk III) were placed. The adjusted DDM granules were implanted into the bone defect (#45). There are no postoperative complications at 3 years after implantation. This case indicates that the preserved autogenous DDM can be used as collagenous biomaterials with osteoinductive potency.
The Impact of Stirring Rate on the Crystallinity and Bioactivity of 58S Bioactive Glass
Authors: Goudouri Ourania Menti , Perissi Maria , Theodosoglou Eleni , Papadopoulou Lambrini , Chatzistavrou Xanthippi , Kontonasaki Eleana , Koidis Petros , Paraskevopoulos Konstantinos M.
Published: October 2011

In most biphasic composite systems consisting of sol-gel derived bioactive glass and a second system that is usually used as a reinforcing agent, thorough stirring is necessary to prevent the precipitation of the grains of the second system. Consequently, the aim of this work is to investigate the impact of various stirring rates on the crystallinity and bioactivity of a bioactive glass in the system 58S. Sol-gel-derived bioactive glass (58S) was produced as described in literature. During the gelation, stirring rates of 0, 200, 400, 600 and 800 rpms were applied producing, respectively, the corresponding glass powders. The in vitro bioactivity of the powders was tested in Simulated Body Fluid (SBF) for various immersion times, while the solution was renewed after 6h, 24h and then every 2 days. Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffractometry (XRD) were used to characterize all materials before and after immersion in SBF solution. FTIR and XRD measurements of all powders revealed mainly the formation of an amorphous glass, while the main crystalline phase was identified to be Ca2SiO4. After immersion in SBF solution for 12h, SEM microphotographs revealed apatite formation on the surface of all samples, while FTIR and XRD confirmed the aforementioned findings. Furthermore, since EDS analysis proved a mean molar Ca/P ratio of about1.7 after 6 days of immersion of all samples- besides those stirred at 400 and 600rpm- it can be assumed that a thick apatite layer was formed covering the whole surface.
Tribological Characterization of Porous TiO2 Coatings Produced by Electrodeposition
Authors: Santos E. , Camargo S.S. , Soares G.A. , Kuromoto Neide K.
Published: October 2011

In this work, the resistance to scratch and wear (pin-on-flat) tests of five different porous TiO2 films were compared. Such tribological tests were carried out under dry conditions. The coatings were electrodeposited on commercially pure-Ti by anodic oxidation method in different electrolyte solutions at constant voltages. The scratch tests were conducted by applying increasing normal loads up to 400 mN. The coefficient of friction (COF) varied from 0.2 up to 0.5, and increased at larger penetrations depths. When the electrolyte concentration was changed from 0.5 into 1.0M H2SO4, the COF slightly decreased. Scanning electron microscopy indicated that the coatings produced in H2SO4/150V and Na2SO4/100V did not have their substrates revealed. In addition, the samples anodized in H2SO4/150V had the highest elastic recoveries. Therefore, such coatings seem to be more resistant to scratch tests than the others. The wear tests were carried out with Berkovich tip as counter-face under constant normal loads of 10 mN in 10 forward-backward cycles. The coatings deposited in H2SO4/150V had the lowest wear volume rates. The findings suggest that the porous Ti oxide coatings electrodeposited above their rupture voltages are more suitable to both scratch- and wear-resistance compared to those prepared at the lowest voltage (H2SO4/100V).
Effect of XPEED® on Ti Implants with Deep Threads
Authors: Lee Sun Young , Yang Dong Jun , Yeo Shinil , An Hyun Wook , Kim Sung Jun , Choi Won Mi , Park Kwang Bum
Published: October 2011

Calcium-incorporated titanium (Ti) recently reported a large degree of effectiveness in many in vitro and in vivo studies. The implants with the deeper thread provide the higher surface area and will have an advantage in soft bone. We used the Ti implants with deep threads and investigated osseintegration of the implants with resorbable blast media (RBM) surfaces produced by grit-blasting or XPEED surfaces by coating of the nanostrucutred calcium.The Ti implants with deep threads had a thread diameter of 4.0 mm, a length of 5.0 mm and a thread depth of 1.0 mm. The Ti implants with calcium-incorporated surfaces (XPEED surfaces) were hydrothermally prepared from the Ti implants with RBM surfaces in alkaline calcium containing solution. The surface characteristics were evaluated by using scanning electron microscope (SEM) and surface roughness measuring system. Thirty-implants with RBM surfaces and thirty-implants with XPEED surfaces were randomly placed in the proximal tibiae and in the femoral condyles of ten New Zealand White rabbits. The osseointegration was evaluated by removal torque test in the proximal tibiae and histomorphometric analysis in the femoral condyles. The Ti implants with XPEED surfaces showed a similar surface morphology and surface roughness to those of the Ti implants with RBM surfaces. The mean removal torque of the Ti implants with XPEED surfaces was higher than the Ti implants with RBM surfaces (p < 0.05). The percentage of bone-to-implant contact (BIC %) were increased for the Ti implants with XPEED surfaces compared with the Ti implants with RBM surfaces (p < 0.05).The Ti implants with XPEED surfaces significantly enhanced the removal torque and the BIC %. The Ti implants with XPEED surfaces may be shorten healing time of bone by improving osseointegration of Ti implants with deep threads.
Comparative Evaluation of the Bioactive Behavior of HA and ZrO2 Reinforced Coatings
Authors: Theodorou George , Goudouri Ourania Menti , Papadopoulou Lambrini , Kantiranis Nikolaos , Yugeswaran Subramaniam , Kobayashi Akira , Paraskevopoulos Konstantinos M.
Published: October 2011

The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has been widely investigated as the HA coating can achieve the firm and direct biological fixation with the surrounding bone tissue. It is shown in previous studies that the mechanical properties of HA coatings are improved by the addition of ZrO2 particles during the deposition of the coating on the substrate. Subsequently, the cohesive and adhesive strengths of plasma-sprayed hydroxyapatite (HA) coatings were strengthened by the ZrO2 particles addition as a reinforcing agent in the HA coating (HA+ZrO2 composite coating). The aim of the present work is to investigate and evaluate the in vitro bioactivity assessment of HA and HA/ZrO2 coatings, on stainless steel substrate, soaked in c-SBF, in order to study and compare their biological responses. The coatings were produced using vapor plasma spraying (VPS). The characterization of the surface of the coatings before and after soaking in SBF solution was performed using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction analysis (XRD). All samples were smoothed before insertion in the medium and the in vitro bioactivity of all coating samples was tested in conventional Simulated Body Fluid (c-SBF) solution for various immersion times.
Thermal Processing of Calcium Phosphate Coatings on Zirconia Ceramics
Authors: Štefanič Martin , Krnel Kristoffer , Kosmač Tomaz
Published: October 2011

A two-step, biomimetic approach was applied for the rapid deposition of octacalcium phosphate (OCP) coatings on zirconia ceramics (Y-TZP). In the first step, sintered zirconia discs were immersed into a supersaturated Ca-P solution with pH=7.4 (CPS1). In the second step, the substrates were transferred from the CPS1 to another Ca-P solution with a lower pH (CPS2). After 6 hours of immersion in the CPS2, a thick coating consisting of large OCP crystals was obtained. Afterwards, the coated substrates were subjected to a thermal treatment in order to improve the attachment of the coating to the substrate.
Comparison between the SBF Response of Hydroxyapatite Coatings Deposited Using both a Plasma-Spray and a Novel Co-Incident Micro-Blasting Technique
Authors: Barry J.N. , Dowling Denis P.
Published: October 2011

This paper reports on the response of hydroxyapatite (HA) coatings, fabricated using two deposition technologies, to immersion in simulated body fluid (SBF). The deposition methods used were: plasma spray, a commercial standard, and CoBlast, a novel low temperature microblast technique. In the case of the latter, HA coatings are deposited by simultaneous blasting HA and abrasive powders concentrically at a metallic substrate, resulting in a thin layer of HA (approx. 2.5 µm thick). Groups of the CoBlast and plasma spray HA coatings were immersed in 7 ml of SBF solution for 1, 2, 4, 7, 14 and 28 days, and were subsequently removed and examined for any alterations caused by the SBF solution. It was noted from this study that the CoBlast HA coatings appeared to undergo a two step calcium phosphate recrystallisation process; initial homogenous nucleation and subsequent heterogeneous nucleation. Conversely recrystallisation on the plasma spray coatings appeared to proceed largely through a heterogeneous nucleation process. Two factors that may influence the differences in HA recrystallisation is the presence of amorphous HA resulting in rapid dissolution, and/or the significantly lower surface area (roughness) offered to the SBF solution by the CoBlast coatings. The interpretation of recrystallisation mechanisms from this preliminary study is limited however by the differences in coating morphology and thickness (27 versus 2 µm) for the plasma spray and CoBlast HA coatings respectively.
Nano Metallic-Oxides as Antimicrobials for Implant Coatings
Authors: Memarzadeh K. , Vargas M. , Huang Jie , Fan J. , Allaker R.P.
Published: October 2011

The use of metallic nanoparticles in the field of orthopaedics as antimicrobial components of coatings is receiving particular attention. An innovative approach has been developed whereby various metal/metal oxide nanoparticles are used to prevent infection occurring on the surface of prostheses. In this study nano metallic oxides (zinc oxide - ZnO and tungsten oxide - WO3) were used. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of each nanoparticulate were determined against four species of bacteria (Staphylococcus aureus, Escherichia coli, Staphylococcus epidermidis and Pseudomonas aeruginosa). Subsequently the nanoparticles were prepared in a suspension of ethanol and sprayed onto the surface of glass using electrohydrodynamic deposition. Quantitative assessments as regards the antimicrobial properties of these coated samples were carried out. Comparisons of the antibacterial properties demonstrated that 2500 µg/ml or above of the oxides were required to kill the species of bacteria tested. WO3 was the most effective oxide tested in suspension using growth inhibition tests. However, coated samples demonstrated that ZnO was more bactericidal than WO3 under these conditions.
The 1100 C Thermoluminescence Peak as a Probe in Bioactivity Study of the 58S Sol-Gel Bioactive Glass
Authors: Polymeris George S. , Goudouri Ourania Menti , Paraskevopoulos Konstantinos M. , Kitis George
Published: October 2011

Results of the present study provide strong indications towards the effective application of the 110oC Thermoluminescence (TL) peak in discriminating between different bioactive responses for the case of the 58S bioactive glass. The in vitro bioactivity of this glass in the form of powder in SBF solution was tested for various immersion times, ranging between 0 and 6 days. This TL peak is ubiquitously present in all 58S samples, for all immersion times. The intensity of the110oC TL peak was proven to be very sensitive to the different bioactive responses, indicating a strongly decreasing pattern with increasing immersion time in SBF, easily identifying thus the loss of silica. This loss is reflected to the decrease of the 110oC TL peak intensity, which appears to be fast even for the shorter immersion times. The 110oC TL glow peak intensity and sensitization could also be yielding a time scale regarding the beginning of some among the several stages included in the bioactivity sequence.
Spectroscopic Studies of Adsorbed Myoglobin on Hydroxyapatite Surface
Authors: Costa Andrea Machado , Mavropoulos Elena , Mello Alexandre , dos Santos Euler A. , de Oliveira Renata R. , Prado da Silva Marcelo Henrique , Rossi Alexandre
Published: October 2011

In this work myoglobin (Mb) adsorption was carried out in a batch system using hydroxyapatite (HA) powder during 24 hours at 37°C. The HA samples were analyzed after protein adsorption by Fourier Transformed Infrared (FTIR) and UV-Vis Spectroscopy in reflectance mode. UV-Vis analyses showed that Soret and Q bands shifted to lower wavelengths when Mb is associated with HA surface. This result suggests that Mb Heme group is sensitive to the protein adsorption onto HA surface. HA disks coated with myoglobin and cultured with human osteoblastic cells during 7 days showed that cell adhesion and proliferation were not inhibited by the protein coating after 7 days in cell culture.
Organic-Inorganic Hybrids for Bioinert Coating on Implantable Electronic Devices
Authors: Kim Ill Yong , Nomura K. , Kikuta Koichi , Ohta Jun , Tokuda T. , Ohtsuki Chikara
Published: October 2011

For the purpose of bioinert coating on electronic devices, we developed the non-hydrolytic sol-gel derived organic-inorganic hybrid materials by addition of epoxy groups which can adhere strongly to the surface of electronic silicon device. The adhesion and chemical properties of hybrids were investigated as a function of epoxy group contents. The hybrids were prepared from 3-metacrloxypropyltrimethoxysilane (MPTS) and 3-glycidoxypropyltrimethoxysilane (GPTS) and diphenylsilanediol. The transparent hybrids were obtained after curing by UV irradiation. The adhesion properties of the hybrids were estimated by the maximum load to resist in a scratch test. The adhesion property of the hybrids increased with addition of GPTS and the highest adhesion was obtained from the hybrid with 5-10 mol% of GPTS. From the element analysis, Si concentrations of all the solutions were less than 2 mM after soaking for 7 d. The Si concentrations were not changed with increasing soaking period. The addition of epoxy groups is effective on improvement of adhesion property of the silica-based hybrid without loosening its chemical stability.
Pore Morphology in MAO Produced Oxide Film Modified by Magnesium Integration
Authors: Ungan Guler , Ak Azem F. , Cakir Ahmet
Published: October 2011

Ti6Al4V alloy commonly used in human body for load bearing prosthesis was coated by micro arc oxidation (MAO) with magnesium rich TiO2 oxide. Since the presence of magnesium in bone tissues is known to promote bone formation and proliferation in physiological environment, its integration with TiO2 on implant surface could bring about a bioactivity for a fast bone formation and proliferation. The formation of a composite layer consisting of Mg integrated TiO2 by MAO process was carried out in an electrolyte with different magnesium content. The characterization studies of these coatings were performed by using X-ray diffractometry (XRD), scanning electron microscopy (SEM) coupled with EDS analysis and XP2 surface profilometry.
Ion Release Behavior and Apatite-Forming Ability of Sol-Gel Derived 70S30C Bioactive Glass with Magnesium/Zinc Substitution
Authors: Hamedani A.Ansari , Moztarzadeh F. , Bizari D. , Ashuri Maziar , Tahriri M.
Published: October 2011

Bioactive glasses not only can bond to hard tissues of the body, are also able to release ions that have stimulatory effects on cells and so are regarded as promising candidate materials for gene activating purposes in tissue engineering applications. In this research the effect of co-substitution of Magnesium and Zinc for Calcium on bioactivity of binary sol-gel derived glass 70S30C (70 mol. % SiO2, 30 mol. % CaO) was investigated. Calcium phosphates forming ability tests and investigation of glass degradation products in simulated body fluid (SBF) were performed as follows.After sol-gel synthesis of glass powders of comparable and under 38 μm particle size distributions, their state of being amorphous was investigated using X-ray diffraction. Then for in vitro investigation of bioactivity, ion release, pH change and Calcium phosphate formation during immersion of glass powders in SBF at 37 ͦC up to 2 weeks were studied. Infrared spectroscopy was performed on the reacted glass powders.Results indicate that substitution of Zinc for Calcium suppresses crystalline apatite formation more effectively than substitution of Magnesium for Calcium and help us design modified compositions of magnesium and zinc containing bioactive glasses that can find applications in bone and also cartillage tissue engineering.
Production and Characterization of Bioglass®-Titania Reinforced Hydroxylapatite Composite
Authors: Cetiner Burcu Nilgün , Erkmen E.Z.
Published: October 2011

Hydroxylapatite, titania and Bioglass 45S5 are the components generally used for the production of bioactive biomaterials for years. In literature, although the binary composites with the permutation of three components exist, a ternary composite has not yet been tried. Primarily, Bioglass 45S5 was cast, its thermal analysis (Differential thermal analysis (DTA), dilatometric analysis), phase analysis (X-Ray Diffraction (XRD) ), microstructural characterization (Scanning Electron Microscopy (SEM) ) were performed. Then Bioglass 45S5 powder was ground to fine powder to make its particle size closer to the hydroxylapatite and the titania powders. The particle size of the powders were determined using the laser particle sizer. The DTAs of the 3 components, separately and mixed, were performed. They were then mixed, and ball-milled during 24 hours for a better homogenization. Following drying for 24 hours, pellets of 1 inch diameter were obtained using unaxial manuel press and sintered at 1000, 1100, 1200 °C. Mechanical testing (compression and microhardness), porosity measurement (The Archimèdes Method), phase determination (XRD) and microstructural characterization (SEM) of the composites were then performed. As a conclusion, when sintering temperature was increased, the porosity in the structure was decreased. Between 1100 °C and 1200 °C, a phase transformation occurred. The results of microhardness ( 24.6, 38.99, 316.2 HV (500gf for 15 sec) for the composites sintered at 1000, 1100, 1200 °C, respectively) and subsequent compression tests (93.023±10.5, 298.14±78.074, 371.9684±38.36 MPa, respectively) approved the possible phase transformation between 1100 °C and 1200 °C along with the XRD results.
Mechanical Properties and In Vitro Bioactivity of β-Tri Calcium Phosphate, Merwinite Nanocomposites
Authors: Abbasi-Shahni Marziyeh , Hesaraki Saeed , Behnamghader Ali Asghar , Hafezi-Ardakani Masoud
Published: October 2011

In this study, nanocomposites based on of β-tri calcium phosphate (β-TCP) and 2.5-10 wt% merwinite nanoparticles were prepared and sintered at 1100-1300°c.The mechanical properties were investigated by measuring compressive strength and fracture toughness. Structural properties were evaluated by XRD, TEM and SEM analysis, and the in vitro bioactivity was studied by soaking the samples in simulated body fluid (SBF). The mechanical strength of the sintered samples wereincreased, by increasing the amount of merwinite phase up to 5 wt%, whereas it decreased when the samples were sintered at 1100 and 1200°c. Nanostructured calcium phosphate layer was formed on the surfaces of the nanocomposites within 1 day immersion in simulated body fluid. Because of appropriate mechanical properties the composite is suggested to be used as substitute for hard tissue.
Anterior Single Laminate Veneer Restoration Using CEREC Biogeneric Reference Design Mode: Case Report
Authors: Akgungor G. , Kilincaslan N. , Şen D.
Published: October 2011

The single anterior tooth replacement remains a complex aesthetic challenge for clinicians and technicians in prosthetic dentistry. Maxillary central incisors are the key point of an esthetic smile and should exhibit a high degree of symmetry across the midline. Matching the shape and contours to the adjacent central incisor is the crucial factor to achieve an esthetic result. The CEREC system is the first to use chairside CAD/CAM system, which allows the dentist to provide ceramic restorations in a single appointment without time consuming laboratory procedures.This clinical report demonstrates the effective usage of CEREC system with the biogeneric reference design mode for designing and milling of a laminate veneer restoration in one appointment.Digital images of the preparation and bite registration were captured using an intraoral camera and virtual models were created. With the biogeneric reference design mode of CEREC 3.0 software, the image of the contralateral central incisor is mirrored, positioned over the preparation, and then refined. Among a variety of ceramic blocs available for CEREC system, the restoration was milled from feldspathic ceramic block.
Surface Morphology of P2O5-CaO-Nb2O5-Na2O Glass-Ceramics after Acid Treatment: SEM and XRD Study
Authors: Stunda Agnese , Jakovlevs Dmitrijs , Poca Lasma , Berzina-Cimdina Liga
Published: October 2011

Modification of surface morphology and composition of niobophosphate glass and glass-ceramic in the system P2O5-CaO-Nb2O5-Na2O was investigated. Amorphous, partly crystalline and crystalline samples were prepared in shape of pellet with diameter 10 mm. Samples were treated in 1 and 5 days in citric acid at 37°C and 3h in boiling HCl. Surface morphology before and after treatment was investigated by scanning electron microscopy (SEM), phase composition by X-ray powder diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Glass sample was smooth, after treatment in citric acid it had cracks and pit-holes on the surface. Partly crystalline sample was smooth and contained inclusions of crystalline Ca3(PO4)2 and Ca2P2O7. Platy crystals of Ca3(PO4)2 dissolved first, than bulky Ca2P2O7. Crystalline samples contained Na4Nb8P4O32 and calcium phosphate phases; surface was rough before and after treatment. EDX showed that amount of phosphorous is proportional to amount of calcium and inversely proportional to amount of sodium and niobium in glass-ceramic samples.
Regeneration of Tooth Enamel by Flexible Hydroxyapatite Sheet
Authors: Hontsu Shigeki , Kato Nobuhiro , Yamamoto Ei , Nishikawa Hiroaki , Kusunoki Masanobu , Hayami Takashi , Yoshikawa Kazushi
Published: October 2011

Before a tooth erupts, the ameloblasts are lost, which means that the tooth enamel does not regenerate itself after tooth eruption. In the present study, we attempt to regenerate the tooth enamel artificially using a flexible hydroxyapatite (HAp) sheet. First, a HAp film was deposited on a soluble substrate by pulsed laser deposition (PLD) using an ArF excimer laser. Next, the HAp film was collected as a freestanding sheet by dissolving the substrate using a solvent. The HAp sheet was adhered to the extracted human teeth using a calcium phosphate solution. The variation of the crystal structure of the HAp sheet with time was investigated by X-ray diffraction analysis. Furthermore, the variation in the mechanical characteristics with time between the HAp sheet and dental enamel were evaluated using tensile and scratch tests. The results suggest that the HAp sheet became fused to the tooth enamel within approximately one week.
Effect of Different Surface Applications and Adhesive Systems on Bond Strength of Porcelain Repair Material
Authors: Tarcin Bilge , Sinmazisik Gulden , Ozer Fusun , Gülmez Turgut
Published: October 2011

The purpose of this study was to evaluate the effect of different surface treatments and adhesive systems on bond strength of composite resin to porcelain when there is need to repair the restoration.Materials and methods: Rectangular discs (10mm x 12mm) with a height of 2mm were prepared from leucite-reinforced feldspathic ceramic CAD/CAM blocks (Vitablocs), embedded in acrylic resin, and bur cut porcelain surfaces were created. The specimens were divided into three groups (n=20) according to the surface treatments: Er:YAG laser at 2W for 20 seconds, air abrasion with 50µm Al2O3 at 2.5 bar for 15 seconds, and the last group left untreated as control. After silane (Monobond S) application on ten specimens from each group, composite rods (Aelite Flo LV) with 4.25mm diameter and 4mm height were bonded to ceramic surfaces with a self-etch adhesive system (All-Bond SE). The remaining ten specimens from each group were etched with 36% orthophosphoric acid (Blue Etch Dental Etching Gel), and after silane and bonding agent (One-Step Plus) application composite rods with the mentioned dimensions were bonded. All groups were stored in distilled water at 37°C for one day before mechanical testing. Shear testing of all groups were performed on a universal testing machine with a load cell of 50kg and at a crosshead speed of 1.5mm/min. Results were statistically analyzed using Mann Whitney U and Kruskall Wallis tests.Results: The bond strength values of the self-etch adhesive system in the lased and control groups were statistically higher in comparison to the other adhesive system (p<0.01, p<0.05, respectively). The highest bond strength values were obtained in the Er:YAG lased and self-etch adhesive applied group.Conclusions: When there is need to repair of a porcelain restoration, a self-etch adhesive application after Er:YAG laser treatment could be the method of choice.
Regulating Protein Adsorption onto Hydroxyapatite: Amino Acid Treatment
Authors: Lee W.H. , Loo C.Y. , Van K.L. , Zavgorodniy A.V. , Rohanizadeh R.
Published: October 2011

Hydroxyapatite (HA) has been widely used as bone grafts due to its chemical and structural similarities to the mineral phase of hard tissues. Applying the combination of osteogenic proteins with HA materials can accelerate bone regeneration in defective areas. The aim of the study was investigating the treatment of HA particles with different amino acids such as serine (Ser), asparagine (Asn), aspartic acid (Asp) and arginine (Arg) to enhance the adsorption ability of HA carrier for delivering therapeutic proteins in body. Results: The crystallinity of HA reduced when amino acids were added during HA preparation. Depending on the types of amino acid, the specific surface area of the amino acid-functionalized HA particles varied from 105 to 149 m2/g. Bovine serum albumin (BSA) and lysozyme were used as model proteins for adsorption study. The protein adsorption onto the surface of amino acid-functionalized HA depended on the polarities of HA particles, whereby positively charged Arg-HA had higher affinity towards BSA (0.269 mg/m2) compared to lysozyme (0.133 mg/m2). Alternatively, the binding affinity of lysozyme (0.2 mg/m2) onto the negatively charged Asp-HA was higher compared to BSA (0.129 mg/m2). The amino acids functionalized-HA particles that had higher proteins adsorption demonstrated a lower protein release rate.
Dissolution Medium Responsive Simvastatin Release from Biodegradable Apatite Cements Drug Delivery System - The Therapeutically Effect and their Histology in Osteoporosis Rats -
Authors: Otsuka Makoto , Hamada Hideyuki , Otsuka Kuniko , Ohshima Hiroyuki
Published: October 2011

A biodegradable drug delivery system was established using an apatite cement containing simvastatin. The in-vitro drug release from apatite with lower-crystallinity was investigated under simulated osteoblast and osteoclast conditions (SOB and SOC). Apatite cement containing 6% simvastatin had lower crystallinity as the same as natural bone. In-vitro drug release tests were performed under SOB in simulated body fluid (pH 7.8), and then under SOC in acetate buffer (pH4.5) at 37.0｡C, and the process repeated twice. The device had lower drug release rates under SOB, but significantly higher rates under SOC. The simvastatin release rate was 15 times higher under SOC than SOB. The device showed dissolution medium responsive drug release. After implantation of the APC containing simvastatin in osteoporosis rats, the bone mineral density was evaluated by the X-ray computed tomography. The result indicated that the bone mineral density of APC implanted rat was significantly higher than that of control diseased.
The Effect of Si(IV) Species Derived from Chitosan-Silicate Hydrogels on Osteoblast Behavior
Authors: Shirosaki Yuki , Hayakawa Satoshi , Osaka Akiyoshi
Published: October 2011

Chitosan-GPTMS (γ-Glycidoxypropyltrimethoxysilane) hybrid hydrogels were synthesized with β-glycerophosphate (β-GP) as the additive agent. Chitosan-GPTMS sols were fluid at room temperature and transformed to hydrogel at 36.5°C in several min. The gelation time of the hydrogels was shortened by the addition of GPTMS. From NMR experiments, this gelation behavior depended on some factors, namely, electrostatic interaction between the phosphate groups of β-GP and the amino groups of chitosan chains, crosslinking between the epoxy groups of GPTMS and the amino groups of chitosan, and polycondensation of the methoxy groups of GPTMS. The Si(IV) released from the hydrogels promoted the cell adhesion and ALP activity of osteoblastic cells MG63.
Study of the Cytotoxicity of a Composite of Carboxymethylcellulose (CMC) and a BioCeramic (Biphasic Calcium Phosphate-BCP) Injection for Use in Articular Cartilage Repair
Authors: De Freitas Deny Gomes , Osthues Rachel Mary , da Silva Sidney Nicodemos
Published: October 2011

The failure of organs and tissues caused by trauma and other injuries is one of the most costly of human health problems. It is estimated that 1.6 million people experience work limitations caused by osteoarthritis and related disorders, representing 8.3% of all main conditions. Joint injuries frequently lead to progressive joint degeneration and post-traumatic osteoarthritis. Articular cartilage has only a limited capacity for self-healing, mainly due to the fact that it is avascular; and once seriously damaged, articular cartilage lesions will not regenerate. There is strong evidence that cartilage lesions may lead to osteoarthritis when left untreated. Numerous animal experiments and clinical studies have shown that early biological reconstruction of circumscribed cartilage defects in the knee is superior to conservative or delayed surgical treatment. Tissue engineering has shown promising therapeutic strategies for repair or regeneration of damaged tissues. Currently, ceramic based and polymeric scaffolds have been developed to bring about the restoration of tissue functions. The bioceramics associated with water-soluble polymers have been developed as substitutes for various orthopedic applications. The objectives of this work are the processing and characterization of a composite of carboxymethylcellulose (CMC) and biphasic calcium phosphate (Biphasic Calcium Phosphate - BCP) in the form of a hydrogel, and a study of its cytotoxicity (in vitro), aimed at its application as an injectable biomaterial in order to repair the extracellular matrix of articular cartilage. The CMC and BCP were characterized by Fourier Transform Infrared Spectrometry (FTIR) and X-Ray Diffraction (XRD), X-ray fluorescence (XRF), respectively, and scanning electron microscopy (SEM) of powders and the composite. To evaluate the biological effect of the composite hydrogel, tests of cytotoxicity (MTT) and rheological tests under real conditions of use were performed. The composite of carboxymethylcellulose (CMC) and bioceramics (biphasic calcium phosphate-BCP) in the form of hydrogel showed an adequate injectability in the conditions studied, and a non-toxic response, presenting potential for use as fillers or to stimulate the healing of cartilage defects in the extracellular matrix of articular cartilage.
Injectable Microparticles of Bioceramic for Bone Reconstruction Animal and Human Applications. HYDROS™ Concept
Authors: Daculsi Guy , Briand S. , Goyenvalle E. , Aguado E. , Baroth S.
Published: October 2011

A new biphasic calcium phosphate ceramic material Hydros™ has been developed. The main attractive feature of BCP ceramic is their ability to form a strong direct bond with the host bone resulting in a strong interface. Currently, granules are more and more used in moldable, injectable bone substitutes. However, the biological behaviour of the particles can be influenced not only by chemical composition and crystallinity, but also by several parameters as microporosity and nano-micro sized particles. The aim of the study was to assess, in animal experiment,the role played by an Hydrated Putty Bioceramics (Hydros™), based on specific combination of hydrophilic micro and macrosized BCP particles, to obtain high osteogenic Injectable Bone Substitute. No sign of clinical rejection was noticed. In muscular area, no fibrous encapsulation was observed, degradation of the smaller particles is observed by macrophages and giant cells. At 12 weeks, more of 75% of BCP was resorbed. The biocompatibility and safety in human orthopaedic applications (tibial plateau fracture) has been demonstrated.
Synthesis and Characterization of Nano Crystalline Hydroxyapatite Spheroids Using Anionic Template for Bio Applications
Authors: SL Shanthi P.Michael , Ashok M. , Mangalaraja R.V. , Balasubramanian T.
Published: October 2011

Nano crystalline Hydroxyapatite (HAp) spheroids of uniform size distribution of diameter ~200 nm have been prepared by co-precipitation method at room temperature. The anionic surfactant SDS has been used as the template material. The calcinated samples were subjected to FTIR and XRD characterizations to confirm the phase of HAp. The Ca/P ratio that has been measured from the EDS spectrum 1.69 has good agreement with the theoretical value. The SEM and TEM images reveal the nano spherical nature and narrow size distribution of the HAp particles, which were good candidates for drug delivery applications.
Effect of Silver Concentration on Bioactivity and Antibacterial Properties of SiO2-CaO-P2O5 Sol-Gel Derived Bioactive Glass
Authors: Nezafati Nader , Moztarzadeh F. , Hesaraki Saeed , Mozafari Masoud , Samadikuchaksaraei Ali , Hajibaki Leila , Gholipour Mazaher
Published: October 2011

Human beings are often infected by microorganisms in the living environment. Among various natural and inorganic substances, silver or silver ions have a powerful antibacterial activity. In the present study, the bioactivity and antibacterial activity of the SiO2–CaO–P2O5–Ag2O was compared with that of its ternary counterpart glass system (as a control sample) in vitro. The molar ratio of silver oxide in the bioactive glass composition was considered as different amount (0.5%, 1% and 2%). The surface characterization was evaluated after soaking in simulated body fluid (SBF). The sharpest apatite peak in X-ray diffraction (XRD) analyse after 7 days soaking in SBF was observed for 2% Ag sample (2%Ag-BG). Hence, the antibacterial effects of 2%Ag-BG sample against 2 gram negatives bacterium were examined by agar plate test. The result showed that the amount of silver did not prevent the HAp formation. Also, the antibacterial properties of 2%Ag-BG sample indicated near 100% bactericidal ratio (according to the width of antibacterial halo).
PVP Addition during Hydroxyapatite Synthesis: Effect on Albumin Adsorption
Authors: Fernandes T.J. , Mavropoulos E. , Campos J.B. , Gobbo L.A. , Prado da Silva Marcelo Henrique
Published: October 2011

Hydroxyapatite nanoparticles were synthesized by preparing an aqueous solution comprising 0.5M Ca(OH)2, 0.3M H3PO4 and 1M CH3CHCO2HOH (lactic acid) at pH of 3.7. KOH was added to the solution until pH=12 was reached, to precipitate hydroxyapatite. The incubation time ranged from 24 to 88 hours and the precipitates were then filtered on filter paper with the aid of a vacuum pump. The powders were synthesized with and without PVP addition. The powders were then sintered at 1100°C. Sintered and non sintered powders were characterized by scanning electron microscopy with field emission gun (FEG-SEM) and transmission electron microscopy (TEM) in order to assess particles morphology. Structural characterization was performed by X-ray diffractometry with Rietveld refinement. Albumin adsorption experiments were carried out on the powders with the aid of UV-VIS spectrometry. The results showed that the samples produced in the presence of PVP showed smaller particles when compared to non-dispersed samples. Albumin adsorption was more effective on the powders synthesized with dispersant.
Enhanced Osteoconductivity of Positively Charged Titanium Metal
Authors: Kawai Toshiyuki , Takemoto Mitsuru , Fujibayashi Shunsuke , Neo Masashi , Pattanayak Deepak K. , Doi Kenji , Matsushita Tomiharu , Kokubo Tadashi , Nakamura Takashi
Published: October 2011

We previously found that a positively charged Ti metal has a higher apatite forming ability in vitro than a non-charged Ti metal. For in vivo analysis using a rabbit model, two types of Ti metal were examined: porous Ti metals heat-treated subsequent to a mixed acid treatment (MHs) and porous Ti metals not heat-treated subsequent to the same mixed acid treatment (MOs). Although MHs and MOs had the same macro- and micro-structure, they had different surface charges. MHs, considered positively charged, had significantly higher bone ingrowth than MOs, considered charged zero. Similarly, MHs had significantly higher percentages of bone–implant contact than MOs at 3- and 6-week. A simple heat treatment made acid-treated porous titanium implants more osteoconductive. These results suggest that a positive charge obtained by a heat treatment enhances bioactivity of acid-treated titanium implants.
Fully-Interconnected Pore Forming Calcium Phosphate Cement
Authors: Kunio Ishikawa , Tsuru Kanji , Pham Trung Kien , Maruta Michito , Matsuya Shigeki
Published: October 2011

Calcium phosphate cement that foams fully-interconnected porous structure along with its gradual replacement to bone may be ideal for bone defect reconstruction. In the present study, α-tricalcium phosphate (αTCP) microspheres were exposed to acidic calcium phosphate solution. It was found that the αTCP microspheres set in approximately 10 min to form fully-interconnected porous structure. The porosity was approximately 50% and the pore size was 300µm. The surface of the porous body was dicalcium phosphate dihydrate whereas the inside was αTCP.
Preparation of Fibrous Scaffolds Containing Calcium and Silicon Species
Authors: Obata Akiko , Ozasa Hiroki , Jones Julian R. , Kasuga Toshihiro
Published: October 2011

Materials for bone defect filling should have 3D macroporous structure and be flexible to be packed into complex defects with limited entrance space. Tissue engineering scaffolds should also mimic the structure and morphology of the host tissue. Electrospinning is a versatile technique to produce materials with micro/nanofibrous structure, large surface area and high porosity. Electrospun materials are very promising for tissue engineering due to the possibility of mimicking the fibrous structure of natural extra cellular matrix (ECM). Siloxane-containing vaterite (SiV)/poly (L-lactic acid) (PLLA) hybrids (SiPVH) with controlled silicate and calcium ions releasing ability has been produced in our group. They have also demonstrated good cell infiltration into the electrospun hybrid materials that had fiber diameters greater than 10 μm. However, these electrospun hybrid materials were planar (2D) and are not suitable for large defect regeneration. In this work, the development of a fabrication technique for the production of 3D cotton wool-like structures with fiber diameter in the range of 10 μm was performed. SiPVH cotton wool-like structure containing 0, 30 and 60 wt % SiV were prepared by blowing air in the direction perpendicular to fiber spinning. Si-vaterite particles and small pores were found on the surface of the fibers. The fiber diameter of the samples were found to be in the range of 10 ~ 20 μm. Stretch tests showed more than 50 % extension for the SiPVH cotton wool-like material containing 30 wt % SiV (SiPVH30). This extension was similar to that observed for the PLLA cotton wool-like material. The results suggest that the SiPVH30 cotton wool-like material are good candidates for bone tissue engineering scaffolds.
SEM Observation of Composite Ceramic Scaffolds’ Surface during Incubation in Culture Medium with or without Human PDL Fibroblasts
Authors: Theocharidou Anna , Tsoptsias K. , Kontonasaki Eleana , Papadopoulou Lambrini , Panayiotou C. , Paraskevopoulos Konstantinos M. , Koidis Petros
Published: October 2011

Chitin is a polysaccharide abundant in nature. Its’ deacetylation product-chitosan- in combination with gelatin (collagen product) is commonly used asbiopolymer scaffold for tissue engineering. The aim of this study was to investigate diffrerences in surface characteristics of chitin (CHN CCS) and chitosan –gelatin (CHS-G CCS) composite ceramic scaffolds (CCS), during their incubation in culture medium (DMEM) with or without human periodontal ligament fibroblasts (HPDLF). CHN CCS and CHS- G CCS, with pore size 70-200μm, were fabricated on the surface of ceramic disks, being coated with a mixture of bioactive glass – ceramic (1:1 wt). Three CCSs of each type were constructed. Each CCS was incubated at 37 °C up to 10 days, either only in DMEM supplemented with 10% FCS or in DMEM with the presence of 105 HPDLF. SEM microphotographs and EDS analysis, before and after incubation, were used to investigate CCSs’ surface alterations. Before incubation, all type of CCSs appeared to be macro porous with high interconnectivity. Exposed to incubation, CHN CCSs’ surface porosity seemed to be rapidly reduced and a rough surface without pores was observed with or without HPDLF. Attached HPDLF were rarely detected. CHS-G CCSs appeared to retain surface porosity in DMEM without cells. In HPDLF culture an almost uniform surface with organic aggregates and attached cells was observed. Until day 10, HPDLF could only be detected at CHS-G CCS’s surface. Conclusion: SEM microphotographs observations indicate that CHN CCSs’ incubation in DMEM led in early and rapid coalescence of surface pores, thus inhibiting HPDLF attachment. HPDLF attachment on CHS-G CCSs confirm the beneficial role of gelatin, while differences in CHS-G CCSs’ surface with and without HPDLF culture indicate that not only sedimentation of medium's ingredients, but cell attachment and function could decrease surface’s porosity, affecting consequently HPDLF proliferation.