Influence of Topography and Composition of Commercial Titanium Dental Implants on Cell Adhesion of Human Gingiva-Derived Mesenchymal Stem Cells: An In Vitro Study.

The topography and composition of dental implant surfaces directly impact mesenchymal cell adhesion, proliferation, and differentiation, crucial aspects of achieving osseointegration. However, cell adhesion to biomaterials is considered a key step that drives cell proliferation and differentiation. The aim of this study was to characterize characterize the topography and composition of commercial titanium dental implants manufactured with different surface treatments (two sandblasted/acid-etched (SLA) (INNO Implants, Busan, Republic of Korea; BioHorizonsTM, Oceanside, CA, USA) and two calcium phosphate (CaP) treated (Biounite®, Berazategui, Argentina; Zimmer Biomet, Inc., Warsaw, IN, USA)) and to investigate their influence on the process of cell adhesion in vitro. A smooth surface implant (Zimmer Biomet, Inc.) was used as a control. For that, high-resolution methodologies such as scanning electron microscopy (SEM), X-ray dispersive spectroscopy (EDX), laser scanning confocal microscopy (LSCM), and atomic force microscopy (AFM) were employed. Protein adsorption and retromolar gingival mesenchymal stem cells (GMSCs) adhesion to the implant surfaces were evaluated after 48 h. The adherent cells were examined by SEM and LSCM for morphologic and quantitative analyses. ANOVA and Tukey tests (α = 0.05) were employed to determine statistical significance. SEM revealed that INNO, BioHorizonsTM, and Zimmer implants have an irregular surface, whereas Biounite® has a regular topography consisting of an ordered pattern. EDX confirmed a calcium and phosphate layer on the Biounite® and Zimmer surfaces, and AFM exhibited different roughness parameters. Protein adsorption and cell adhesion were detected on all the implant surfaces studied. However, the Biounite® implant with CaP and regular topography showed the highest protein adsorption capacity and density of adherent GMSCs. Although the Zimmer implant also had a CaP treatment, protein and cell adhesion levels were lower than those observed with Biounite®. Our findings indicated that the surface regularity of the implants is a more determinant factor in the cell adhesion process than the CaP treatment. A regular, nanostructured, hydrophilic, and moderately rough topography generates a higher protein adsorption capacity and thus promotes more efficient cell adhesion.

Interleukin-35 inhibits alveolar bone resorption by modulating the Th17/Treg imbalance during periodontitis.

AIM: T lymphocytes play a central role during the pathogenesis of periodontitis, and the imbalance between the pathogenic T-helper type 17 (Th17) and protective T-regulatory (Treg) lymphocytes determines the tooth-supporting alveolar bone resorption. Interleukin (IL)-35 is a novel anti-inflammatory cytokine with therapeutic properties in diseases whose pathogenesis is associated with the Th17/Treg imbalance; however, its role during periodontitis has not been established yet. This study aimed to elucidate whether IL-35 inhibits the alveolar bone resorption during periodontitis by modulating the Th17/Treg imbalance. MATERIALS AND METHODS: Mice with ligature-induced periodontitis were treated with locally or systemically administrated IL-35. As controls, periodontitis-affected mice without IL-35 treatment and non-ligated mice were used. Alveolar bone resorption was measured by micro-computed tomography and scanning electron microscopy. The Th17/Treg pattern of the immune response was analysed by qPCR, ELISA, and flow cytometry. RESULTS: IL-35 inhibited alveolar bone resorption in periodontitis mice. Besides, IL-35 induced less detection of Th17 lymphocytes and production of Th17-related cytokines, together with higher detection of Treg lymphocytes and production of Treg-related cytokines in periodontitis-affected tissues. CONCLUSION: IL-35 is beneficial in the regulation of periodontitis; particularly, IL-35 inhibited alveolar bone resorption and this inhibition was closely associated with modulation of the periodontal Th17/Treg imbalance.

Protective effect of inactivated blastoconidia in keratinocytes and human reconstituted epithelium against C. albicans infection.

Candida albicans is commensal yeast that colonizes skin and mucosa; however, it can become an opportunist pathogen by changing from blastoconidia (commensal form) into hypha (pathogenic form). Each form activates a different cytokines response in epithelial cells. Little is known about the commensal role of C. albicans in the innate immunity. This work studied whether stimulation with C. albicans blastoconidia induces protection in keratinocytes and/or in a reconstituted human epithelium (RHE) infected with C. albicans. For this, inactivated C. albicans blastoconidia was used to stimulate keratinocytes and RHE prior to infection with C. albicans. Blastoconidia induced different cytokine expression profiles; in the case of RHE it decreased interleukin (IL)-1ß and IL-10 and increased IL-8, tumor necrosis factor α (TNF-α), and interferon γ (IFN-γ). A significant increase in the expression of human ß-defensins (HBD) 2 and HBD3 was observed in blastoconidia stimulated keratinocytes and RHE, associated with impaired growth and viability of C. albicans. Additionally, blastoconidia stimulation decreased the expression of virulence factors in C. albicans that are associated with filamentation (EFG1, CPH1 and NRG1), adhesion (ALS5), and invasion (SAP2). Blastoconidia stimulated RHE was significantly less damaged by C. albicans invasion. These results show that the commensal form of C. albicans would exert a protective effect against self-infection.

Multifunctional nanocarriers for the treatment of periodontitis: Immunomodulatory, antimicrobial, and regenerative strategies.

Periodontitis is an inflammatory disease, in which the host immuno-inflammatory response against the dysbiotic subgingival biofilm leads to the breakdown of periodontal tissues. Most of the available treatments seem to be effective in the short-term; nevertheless, permanent periodical controls and patient compliance compromise long-term success. Different strategies have been proposed for the modulation of the host immune response as potential therapeutic tools to take a better care of most susceptible periodontitis patients, such as drug local delivery approaches. Though, maintaining an effective drug concentration for a prolonged period of time has not been achieved yet. In this context, advanced drug delivery strategies using biodegradable nanocarriers have been proposed to avoid toxicity and frequency-related problems of treatment. The versatility of distinct nanocarriers allows the improvement of their loading and release capabilities and could be potentially used for microbiological control, periodontal regeneration, and/or immunomodulation. In the present review, we revise and discuss the most frequent biodegradable nanocarrier strategies proposed for the treatment of periodontitis, including polylactic-co-glycolic acid (PLGA), chitosan, and silica-derived nanoparticles, and further suggest novel therapeutic strategies.

Novel Organic-Inorganic Nanocomposite Hybrids Based on Bioactive Glass Nanoparticles and Their Enhanced Osteoinductive Properties.

Inorganic-organic hybrid biomaterials have been proposed for bone tissue repair, with improved mechanical flexibility compared with scaffolds fabricated from bioceramics. However, obtaining hybrids with osteoinductive properties equivalent to those of bioceramics is still a challenge. In this work, we present for the first time the synthesis of a class II hybrid modified with bioactive glass nanoparticles (nBGs) with osteoinductive properties. The nanocomposite hybrids were produced by incorporating nBGs in situ into a polytetrahydrofuran (PTHF) and silica (SiO2) hybrid synthesis mixture using a combined sol-gel and cationic polymerization method. nBGs ~80 nm in size were synthesized using the sol-gel technique. The structure, composition, morphology, and mechanical properties of the resulting materials were characterized using ATR-FTIR, 29Si MAS NMR, SEM-EDX, AFM, TGA, DSC, mechanical, and DMA testing. The in vitro bioactivity and degradability of the hybrids were assessed in simulated body fluid (SBF) and PBS, respectively. Cytocompatibility with mesenchymal stem cells was assessed using MTS and cell adhesion assays. Osteogenic differentiation was determined using the alkaline phosphatase activity (ALP), as well as the gene expression of Runx2 and Osterix markers. Hybrids loaded with 5, 10, and 15% of nBGs retained the mechanical flexibility of the PTHF-SiO2 matrix and improved its ability to promote the formation of bone-like apatite in SBF. The nBGs did not impair cell viability, increased the ALP activity, and upregulated the expression of Runx2 and Osterix. These results demonstrate that nBGs are an effective osteoinductive nanoadditive for the production of class II hybrid materials with enhanced properties for bone tissue regeneration.

Optimization by mixture design of chitosan/multi-phase calcium phosphate/BMP-2 biomimetic scaffolds for bone tissue engineering.

The modulation of cell behavior during culture is one of the most important aspects of bone tissue engineering because of the necessity for a complex mechanical and biochemical environment. This study aimed to improve the physicochemical properties of chitosan/multi-phase calcium phosphate (MCaP) scaffolds using an optimized mixture design experiment and evaluate the effect of biofunctionalization of the obtained scaffolds with the bone morphogenetic protein BMP-2 on stem cell behavior. The present study evaluated the compressive strength, elastic modulus, porosity, pore diameter, and degradation in simulated body fluids and integrated these responses using desirability. The properties of the scaffolds with the best desirability (18.4% of MCaP) were: compressive strength of 23 kPa, elastic modulus of 430 kPa, pore diameter of 163 µm, porosity of 92%, and degradation of 20% after 21 days. Proliferation and differentiation experiments were conducted using dental pulp stem cells after grafting BMP-2 onto scaffolds via the carbodiimide route. These experiments showed that MCaP promoted cell proliferation and increased alkaline phosphatase activity, whereas BMP-2 enhanced cell differentiation. This study demonstrates that optimizing the composition of a mixture of chitosan and MCaP improves the physicochemical and biological properties of scaffolds, indicating that this solution is viable for application in bone tissue engineering.

Development of novel antimicrobial acrylic denture modified with copper nanoparticles.

PURPOSE: This study aimed to synthesize heat-cured poly(methyl methacrylate) (PMMA) acrylic formulated with copper nanoparticles (nCu) for producing dentures with antimicrobial properties and ability to prevent denture stomatitis (DS). METHODS: nCu/PMMA nanocomposites were prepared through in situ formation of nCu into methyl methacrylate (MMA). The fabricated material was characterized using scanning electron microscopy, spectroscopy (energy-dispersive X-ray, attenuated total reflectance-Fourier-transform infrared, and X-ray photoelectron spectroscopy), X-ray diffraction analysis, and mechanical flexural tests (ISO 20795-1:2008). Antimicrobial activity against Candida albicans and oral bacteria was determined. MTS assay (ISO 10993-5:2009) and copper release experiments were conducted to assess cytotoxicity. In the clinical trial, participants wearing nCu/PMMA (n=25) and PMMA (n=25) dentures were compared; specifically, DS incidence and severity and Candida species proliferation were assessed for 12 months. Data were analyzed using analysis of variance with Tukey's post hoc test (α=0.05). RESULTS: nCu/PMMA nanocomposite loaded with 0.045% nCu exhibited the maximum antimicrobial activity against C. albicans and other oral bacteria without producing cytotoxicity in the wearer. nCu/PMMA dentures retained their mechanical and aesthetic properties as well as inhibited the growth of Candida species on both denture surface and patient palate. DS incidence and severity were lower in the nCu/PMMA denture group than in the PMMA denture group. CONCLUSIONS: PMMA acrylic produced with copper nanotechnology is antimicrobial, biocompatible, and aesthetic and can reduce DS incidence. Thus, this material may act as a novel preventive alternative for oral infections associated with denture use.

Osteoconductive Effect of a Nanocomposite Membrane Treated with UV Radiation.

Modulation of the bio-regenerative characteristics of materials is an indispensable requirement in tissue engineering. Particularly, in bone tissue engineering, the promotion of the osteoconductive phenomenon determines the elemental property of a material be used therapeutically. In addition to the chemical qualities of the constituent materials, the three-dimensional surface structure plays a fundamental role that various methods are expected to modulate in a number of ways, one most promising of which is the use of different types of radiation. In the present manuscript, we demonstrate in a calvarial defect model, that treatment with ultraviolet irradiation allows modification of the osteoconductive characteristics in a biomaterial formed by gelatin and chitosan, together with the inclusion of hydroxyapatite and titanium oxide nanoparticles.

Nanoparticles of Bioactive Glass Enhance Biodentine Bioactivity on Dental Pulp Stem Cells.

This study aimed to investigate the cytotoxicity and bioactivity of a novel nanocomposite containing nanoparticles of bioactive glass (nBGs) on human dental pulp stem cells (hDPSCs). nBGs were synthesized by the sol-gel method. Biodentine (BD) nanocomposites (nBG/BD) were prepared with 2 and 5% wt of nBG content; unmodified BD and glass ionomer cement were used as references. Cell viability and attachment were evaluated after 3, 7 and 14 days. Odontogenic differentiation was assessed with alkaline phosphatase (ALP) activity after 7 and 14 days of exposure. Cells successfully adhered and proliferated on nBG/BD nanocomposites, cell viability of nanocomposites was comparable with unmodified BD and higher than GIC. nBG/BD nanocomposites were, particularly, more active to promote odontogenic differentiation, expressed as higher ALP activity of hDPSCs after 7 days of exposure, than neat BD or GIC. This novel nanocomposite biomaterial, nBG/BD, allowed hDPSC attachment and proliferation and increased the expression of ALP, upregulated in mineral-producing cells. These findings open opportunities to use nBG/BD in vital pulp therapies.

Preparation and osteogenic properties of nanocomposite hydrogel beads loaded with nanometric bioactive glass particles.

Bone reconstruction in the oral and maxillofacial region presents particular challenges related to the development of biomaterials with osteoinductive properties and suitable physical characteristics for their surgical use in irregular bony defects. In this work, the preparation and bioactivity of chitosan-gelatin (ChG) hydrogel beads loaded with either bioactive glass nanoparticles (nBG) or mesoporous bioactive glass nanospheres (nMBG) were studied.In vitrotesting of the bionanocomposite beads was carried out in simulated body fluid, and through viability and osteogenic differentiation assays using dental pulp stem cells (DPSCs).In vivobone regenerative properties of the biomaterials were assessed using a rat femoral defect model and compared with a traditional maxillary allograft (Puros®). ChG hydrogel beads containing homogeneously distributed BG nanoparticles promoted rapid bone-like apatite mineralization and induced the osteogenic differentiation of DPSCsin vitro. The bionanocomposite beads loaded with either nBG or nMBG also produced a greater bone tissue formationin vivoas compared to Puros® after 8 weeks of implantation. The osteoinductivity capacity of the bionanocomposite hydrogel beads coupled with their physical properties make them promissory for the reconstruction of irregular and less accessible maxillary bone defects.

Effect of Cu- and Zn-Doped Bioactive Glasses on the In Vitro Bioactivity, Mechanical and Degradation Behavior of Biodegradable PDLLA Scaffolds.

Biodegradable polymer scaffolds filled with bioactive glass particles doped with therapeutic metal ions are a novel and promising strategy to repair critical-sized bone defects. In this study, scaffolds based on a poly (D, L-lactide acid) (PDLLA) matrix filled with un-doped and Cu-, Zn- and CuZn-doped bioactive glass particles were produced by freeze-drying and a salt-leaching method. The effects of the doping and content of the glass particles (10 and 30 wt.%) on the morphology, compression properties, apatite formation, and degradation behavior of the scaffolds were evaluated. The scaffolds presented high porosity (~93%) with pores ranged from 100 to 400 µm interconnected by smaller pores and this porosity was kept after the glass particles incorporation. The glass particles reinforced the polymer scaffolds with improvements as high as 130% in elastic moduli, and further promoted the apatite formation on the scaffold surface, both properties depending on the amount and type of filler. The bioactive glass particles boosted the scaffold degradation with the PDLLA/un-doped glass scaffold showing the highest rate, but still retaining structural and dimensional integrity. Our findings show that the incorporation of un-doped and metal-doped bioactive glasses increases the mechanical strength, promotes the bioactivity and modifies the degradation profile of the resulting polymer/glass scaffolds, making them better candidates for bone repair.

Antibacterial activity of a glass ionomer cement doped with copper nanoparticles.

Copper nanoparticles (NCu) were synthetized and added to commercial glass ionomer cement, to evaluate in vitro its antibacterial activity against oral cavity strains. The NCu were synthesized by copper acetate reduction with L-ascorbic acid and characterized by FTIR, Raman, XPS, XRD and TEM. Then, commercial glass ionomer cement (GIC) was modified (MGIC) with various concentrations of NCu and physicochemically characterized. Cell viability was tested against human dental pulp fibroblasts (HDPFs) by Alamar-Blue assay and antibacterial test was performed against S. mutans and S. sanguinis by colony forming unit (CFU) growth method. Synthesized NCu rendered a mixture of both metallic copper and cuprous oxide (Cu2O). HDPF viability reduces with exposure time to the extracts (68-72% viability) and MGIC with 2-4 wt% NCu showed antimicrobial activity against the two tested strains.

In situ preparation and osteogenic properties of bionanocomposite scaffolds based on aliphatic polyurethane and bioactive glass nanoparticles.

Bionanocomposite scaffolds based on aliphatic polyurethane (PU) and bioactive glass nanoparticles were produced by using a one-step in situ polymerization method. Bioactive glass nanoparticles (nBG) or mesoporous BG nanospheres (nMBG) were incorporated during the polymerization reaction to produce simultaneous formation and foaming of porous nanocomposite scaffolds. The in vitro bioactivity of the scaffolds was assessed in simulated body fluid (SBF), and through cytocompatibility and osteogenic differentiation assays with stem cells. Bone regeneration properties of the scaffold materials were in vivo assessed by using a critical-sized femoral defect model in rat. The scaffold nanocomposites showed excellent cytocompatibility and ability to accelerate the crystallization of bone-like apatite in vitro. nBG/PU bionanocomposite scaffold exhibited the higher capacity to stimulate osteogenic cell differentiation as judged by an increased ALP activity and the presence of mineralized nodules associated with the stem cells. nBG (5%)/PU scaffold significantly also produces in vivo a denser and more significant amount of new bone after 8 weeks of implantation, which is attributed to the more rapid dissolution rate of nBG into osteogenic ionic products compared to nMBG. The results of this work show that the in situ polymerization method combined with the use of nanodimensional BG particles enable the production of PU - based scaffolds with enhanced bioactive properties to stimulate the bone tissue regeneration.

Synthesis of hybrid copper-chitosan nanoparticles with antibacterial activity against cariogenic Streptococcus mutans.

Hybrid nanoparticles (CuChNP) comprising of copper nanoparticles with a chitosan shell were synthesized. Antimicrobial properties of CuChNP were assessed against Streptococcus mutans (S. mutans), one of the main bacterium that causes tooth decay. Antibacterial activity of CuChNP against S. mutans was comparable to that of oral antimicrobial agents, such as chlorhexidine, and cetylpyridinium chloride. Particularly, CuChNP exhibited superior capacity to prevent the S. mutans growth on human tooth surface as well as disrupt and kill the bacterial cells in an established dental biofilm. Chitosan may interact with both tooth hydroxyapatite and bacterial cell wall, which improves the adherence of copper to the tooth surface and potentiates their anti-biofilm action. The antimicrobial properties exhibited by CuChNP could be useful for the future development of more effective treatments for the control of dental plaque biofilms.

Bionanocomposite scaffolds based on chitosan-gelatin and nanodimensional bioactive glass particles: In vitro properties and in vivo bone regeneration.

Bone repair bionanocomposite scaffolds were produced by incorporating dense bioactive glass nanoparticles or mesoporous bioactive glass nanospheres into a chitosan-gelatin polymer blend. The in vitro bioactivity of the scaffolds was assessed in simulated body fluid, and cell viability and osteogenic differentiation assays were performed with dental pulp stem cells. Bone regeneration properties of the scaffold materials were in vivo assessed by using a critical-sized femoral defect model in rat. The scaffold nanocomposites showed excellent cytocompatibility and ability to accelerate the crystallization of bone-like apatite in vitro. Bionanocomposites prepared with bioactive glass nanoparticles were particularly more active to promote the osteogenic differentiation of dental pulp stem cells as judged by the higher activity of alkaline phosphatase. This result is attributed to the faster dissolution of bioactive glass nanoparticles into osteogenic ionic products compared to mesoporous bioactive glass nanospheres. In vivo experiments demonstrated that bioactive glass nanoparticles (5%)/chitosan-gelatin bionanocomposite significantly produces the highest amount of new bone (∼80%) in the defect area after eight weeks of implantation. The bone regeneration capacity exhibited by the scaffolds formulated with nanodimensional bioactive glass particles make them attractive for bone reconstruction applications.

Enhanced bioactive properties of BiodentineTM modified with bioactive glass nanoparticles.

OBJECTIVE: To prepare nanocomposite cements based on the incorporation of bioactive glass nanoparticles (nBGs) into BiodentineTM (BD, Septodent, Saint-Maur-des-Fosses Cedex, France) and to assess their bioactive properties. MATERIAL AND METHODS: nBGs were synthesised by the sol-gel method. BD nanocomposites (nBG/BD) were prepared with 1 and 2% nBGs by weight; unmodified BD and GC Fuji IX (GIC, GC Corporation, Tokyo, Japan) were used as references. The in vitro ability of the materials to induce apatite formation was assessed in SBF by X-ray diffraction (XRD), attenuated total reflectance with Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. BD and nBG/BD were also applied to dentine discs for seven days; the morphology and elemental composition of the dentine-cement interface were analysed using SEM-EDX. RESULTS: One and two percent nBG/BD composites accelerated apatite formation on the disc surface after short-term immersion in SBF. Apatite was detected on the nBG/BD nanocomposites after three days, compared with seven days for unmodified BD. No apatite formation was detected on the GIC surface. nBG/BD formed a wider interfacial area with dentine than BD, showing blockage of dentine tubules and Si incorporation, suggesting intratubular precipitation. CONCLUSIONS: The incorporation of nBGs into BD improves its in vitro bioactivity, accelerating the formation of a crystalline apatite layer on its surface after immersion in SBF. Compared with unmodified BD, nBG/BD showed a wider interfacial area with greater Si incorporation and intratubular precipitation of deposits when immersed in SBF.

Differential Antifungal Activity of Human and Cryptococcal Melanins with Structural Discrepancies.

Melanin is a pigment found in all biological kingdoms, and plays a key role in protection against ultraviolet radiation, oxidizing agents, and ionizing radiation damage. Melanin exerts an antimicrobial activity against bacteria, fungi, and parasites. We demonstrated an antifungal activity of synthetic and human melanin against Candida sp. The members of the Cryptococcus neoformans and C. gattii species complexes are capsulated yeasts, which cause cryptococcosis. For both species melanin is an important virulence factor. To evaluate if cryptococcal and human melanins have antifungal activity against Cryptococcus species they both were assayed for their antifungal properties and physico-chemical characters. Melanin extracts from human hair and different strains of C. neoformans (n = 4) and C. gattii (n = 4) were investigated. The following minimum inhibitory concentrations were found for different melanins against C. neoformans and C. gattii were (average/range): 13.7/(7.8-15.6) and 19.5/(15.6-31.2) µg/mL, respectively, for human melanin; 273.4/(125->500) and 367.2/(125.5->500) µg/mL for C. neoformans melanin and 125/(62.5-250) and 156.2/(62-250) µg/mL for C. gattii melanin. Using Scanning Electron Microscopy we observed that human melanin showed a compact conformation and cryptococcal melanins exposed an amorphous conformation. Infrared spectroscopy (FTIR) showed some differences in the signals related to C-C bonds of the aromatic ring of the melanin monomers. High Performance Liquid Chromatography established differences in the chromatograms of fungal melanins extracts in comparison with human and synthetic melanin, particularly in the retention time of the main compound of fungal melanin extracts and also in the presence of minor unknown compounds. On the other hand, MALDI-TOF-MS analysis showed slight differences in the spectra, specifically the presence of a minor intensity ion in synthetic and human melanin, as well as in some fungal melanin extracts. We conclude that human melanin is more active than the two fungal melanins against Cryptococcus. Although some physico-chemical differences were found, they do not explain the differences in the antifungal activity against Cryptococcus of human and cryptococcal melanins. More detailed studies on the structure should be considered to associate structure and antifungal activity.

A comparative study on the microstructural and antibacterial properties of Laser - textured and SLA dental implants

ABSTRACT: Objective: To compare the structural and antibacterial properties of a Laser - treated commercial dental implant (No-Itis®) with those of a traditional sandblasted and acid-etched (SLA) implant. Materials and Methods: Surface topography and elemental composition of the implant surfaces were analyzed by using scanning electron microscopy (SEM) coupled to dispersive X - ray spectrometry (EDX). The antibacterial properties of the implants were tested against Aggregatibacter actinomycetemcomitans. Protein adsorption capacity and bioactivity in simulated body fluid (SBF) of the implant surfaces were also analyzed. Results: The Laser - treated implant presents a topography constituted by smooth and uniform concavities of ~ 30 µm in diameter, free of Laser - induced alterations, and impurity elements. The Laser - textured surface demonstrated to significantly (p = 0.0132) reduce by up to around 61% the bacterial growth as compared with the SLA implant, which was found to be associated to a reduced adhesion of proteins on the Laser surface. No apatite - related mineral deposits were detected on the SBF - incubated surfaces. Conclusion: The smooth Laser - designed surface exhibits an antimicrobial effect that decreases the growth of bacterial biofilm on its surface, which could contribute to reduce the risk of peri-implantitis.

Alendronate Functionalized Mesoporous Bioactive Glass Nanospheres.

In this work we synthesized mesoporous bioactive glass nanospheres (nMBG) with the aim to utilize them as substrates for loading one of the most potent amino-bisphosphonates, alendronate (AL). The results of the chemical and structural characterization show that the nMBG display a relatively high surface area (528 m²/g) and a mean pore volume of 0.63 cm³/g, both of which decrease on increasing alendronate content. It is possible to modulate the amount of AL loaded into the nanospheres up to a maximum value of about 17 wt %. In vitro tests were performed using a human osteosarcoma cell line (MG63) and a murine monocyte/macrophage cell line as osteoclast model (RAW 264.7). The results indicate that even the lower concentration of alendronate provokes decreased tumor cell viability, and that osteoclast activity exhibits an alendronate dose-dependent inhibition. The data suggest that nMBG can act as a suitable support for the local delivery of alendronate, and that the antiresorptive and antitumor properties of the functionalized mesoporous nanospheres can be modulated by varying the amount of alendronate loading.

Preparation and bioactive properties of nano bioactive glass and segmented polyurethane composites.

Composites of glutamine-based segmented polyurethanes with 5 to 25 wt.% bioactive glass nanoparticles were prepared, characterized, and their mineralization potential was evaluated in simulated body fluid. Biocompatibility with dental pulp stem cells was assessed by MTS to an extended range of compositions (1 to 25 wt.% of bioactive glass nanoparticles). Physicochemical characterization showed that composites retained many of the matrix properties, i.e. those corresponding to semicrystalline elastomeric polymers as they exhibited a glass transition temperature (Tg) between -41 and -36℃ and a melting temperature (Tm) between 46 and 49℃ in agreement with X-ray reflections at 23.6° and 21.3°. However, with bioactive glass nanoparticles addition, tensile strength and strain were reduced from 22.2 to 12.2 MPa and 667.2 to 457.8%, respectively with 25 wt.% of bioactive glass nanoparticles. Although Fourier transform infrared spectroscopy did not show evidence of mineralization after conditioning of these composites in simulated body fluid, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray microanalysis showed the formation of an apatite layer on the surface which increased with higher bioactive glass concentrations and longer conditioning time. Dental pulp stem cells proliferation at day 5 was improved in bioactive glass nanoparticles composites containing lower amounts of the filler (1-2.5 wt.%) but it was compromised at day 9 in composites containing high contents of nBG (5, 15, 25 wt.%). However, Runx2 gene expression was particularly upregulated for the dental pulp stem cells cultured with composites loaded with 15 and 25 wt.% of bioactive glass nanoparticles. In conclusion, low content bioactive glass nanoparticles and segmented polyurethanes composites deserve further investigation for applications such as guided bone regeneration membranes, where osteoconductivity is desirable but not a demanding mechanical performance.