Relationship between oral microbiota and periodontal disease: a systematic review.

OBJECTIVE: In recent years metagenomic analysis has become more accessible for the characterization of biological specimens. There has been an important increase of studies using this technique for subgingival human samples. To date, there are no updated systematic reviews on the relationship between oral microbiota and periodontal disease. The aim of the present systematic review was to update data about studies concerning the influences of changes in oral microbiota composition on the periodontal status in human subjects. MATERIALS AND METHODS: An electronic search was conducted in four databases (MEDLINE, Scopus, CENTRAL and Web of Science) for articles published in English from January 2014 to April 2018. In vitro or animal studies, case reports, case series, retrospective studies, review articles, abstracts and discussions were excluded. Also, studies that evaluated less than 5 microbial species, only viruses or already known periodontal pathogens were excluded. Two independent researches selected the studies and extracted the data. The quality of evidence was assessed as high, moderate or low for each microorganism. RESULTS: Eight studies and three additional publications recovered from the bibliography search of the selected articles were included in the review. The Bacteria domain was the main detected among the others and it included 53 species. The review confirmed the presence of recognized periodontal pathogens such as the members of the red complex but also identified, with high weight of evidence, the presence of new pathogens. CONCLUSIONS: The results of this systematic review support high evidence for the association of 3 new species/genera with the etiology of periodontitis. Future investigations on the actual role of these new pathogens in the onset and progression of the disease are needed.

Molecular basis of trigeminal nerve disorders and healing.

OBJECTIVE: This review aims to describe trigeminal neuralgia and the molecular basis contributing to the pathophysiology of this condition by focusing on the state of the art. PATIENTS AND METHODS: An electronic search of PubMed was performed using the following keywords: "trigeminal neuralgia" AND "classification", "pathophysiology," "molecular basis" and "mitochondrial role." RESULTS: Mitochondrial abnormality, whether functional or morphological, can contribute to neurological disorders. Additionally, one recent finding showed that gain-of-function mutation in the voltage-gated sodium channel NaV1.6 contributes to the pathophysiology of trigeminal neuralgia by increasing the excitability of trigeminal nerve ganglion neurons. It also exacerbates the pathophysiology of vascular compression. Healing of the trigeminal nerve is controlled by many molecular signaling pathways, including extracellular-signal-regulated kinase, c-Jun, p38, Notch, and mitogen-activated protein kinases. CONCLUSIONS: More investigations regarding the gain-of-function mutation of NaV1.6 sodium channels are essential for the diagnosis and treatment of trigeminal nerve disorders, regardless of whether these are associated with vascular compression or not.

Chitosan-Based Trilayer Scaffold for Multitissue Periodontal Regeneration.

Periodontal regeneration is still a challenge for periodontists and tissue engineers, as it requires the simultaneous restoration of different tissues-namely, cementum, gingiva, bone, and periodontal ligament (PDL). Here, we synthetized a chitosan (CH)-based trilayer porous scaffold to achieve periodontal regeneration driven by multitissue simultaneous healing. We produced 2 porous compartments for bone and gingiva regeneration by cross-linking with genipin either medium molecular weight (MMW) or low molecular weight (LMW) CH and freeze-drying the resulting scaffolds. We synthetized a third compartment for PDL regeneration by CH electrochemical deposition; this allowed us to produce highly oriented microchannels of about 450-µm diameter intended to drive PDL fiber growth toward the dental root. In vitro characterization showed rapid equilibrium water content for MMW-CH and LMW-CH compartments (equilibrium water content after 5 min >85%). The MMW-CH compartment degraded more slowly and provided significantly more resistance to compression (28% ± 1% of weight loss at 4 wk; compression modulus HA = 18 ± 6 kPa) than the LMW-CH compartment (34% ± 1%; 7.7 ± 0.8 kPa) as required to match the physiologic healing rates of bone and gingiva and their mechanical properties. More than 90% of all human primary periodontal cell populations tested on the corresponding compartment survived during cytocompatibility tests, showing active cell metabolism in the alkaline phosphatase and collagen deposition assays. In vivo tests showed high biocompatibility in wild-type mice, tissue ingrowth, and vascularization within the scaffold. Using the periodontal ectopic model in nude mice, we preseeded scaffold compartments with human gingival fibroblasts, osteoblasts, and PDL fibroblasts and found a dense mineralized matrix within the MMW-CH region, with weakly mineralized deposits at the dentin interface. Together, these results support this resorbable trilayer scaffold as a promising candidate for periodontal regeneration.

Nanogrooves and keratin nanofibers on titanium surfaces aimed at driving gingival fibroblasts alignment and proliferation without increasing bacterial adhesion.

Periimplantitis and epithelial downgrowth are nowadays the main conditions associated to transmucosal dental implants. Gingival fibroblasts can play an important role in periimplantitis because they are the promoters of the inflammatory process and eventual tissue homeostasis and destruction. Moreover, the related inflammatory state is commonly driven also to counteract bacteria implants colonization. In the present research, a new technology based on mechanically produced nanogrooves (0.1-0.2µm) and keratin nanofibers deposited by electrospinning has been proposed in order to obtain titanium surfaces able to drive gingival fibroblasts alignment and proliferation without increasing bacterial adhesion. The prepared surfaces have been characterized for their morphology (FESEM), chemical composition (FTIR, XPS), surface charge (zeta potential) and wettability (contact angle). Afterwards, their performances in terms of cells (human primary gingival fibroblasts) and bacteria (Staphylococcus aureus) adhesion were compared to mirror-like polished titanium surfaces. Results revealed that gingival fibroblasts viability was not negatively affected by the applied surface roughness or by keratin nanofibers. On the opposite, cells adhesion and spread were strongly influenced by surface roughness revealing a significant cell orientation along the produced nanogrooves. However, the keratin influence was clearly predominant with respect to surface topography, thus leading to increased cells proliferation on the surfaces with nanofibers, disregarding the presence of the surfaces grooves. Moreover, nor nanogrooves nor keratin nanofibers increase bacterial biofilm adhesion in comparison with mirror polished surfaces. Thus, the present research represents a promising innovative strategy and technology for a surface modification finalized to match the main requirements for transmucosal dental implants.

How do wettability, zeta potential and hydroxylation degree affect the biological response of biomaterials?

It is well known that composition, electric charge, wettability and roughness of implant surfaces have great influence on their interaction with the biological fluids and tissues, but systematic studies of different materials in the same experimental conditions are still lacking in the scientific literature. The aim of this research is to investigate the correlations between some surface characteristics (wettability, zeta potential and hydroxylation degree) and the biological response (protein adsorption, blood wettability, cell and bacterial adhesion) to some model biomaterials. The resulting knowledge can be applied for the development of future innovative surfaces for implantable biomaterials. Roughness was not considered as a variable because it is a widely explored feature: smooth surfaces prepared by a controlled protocol were compared in order to have no roughness effects. Three oxides (ZrO2, Al2O3, SiO2), three metals (316LSS steel, Ti, Nb) and two polymers (corona treated polystyrene for cell culture and untreated polystyrene for bacteria culture), widely used for biomedical applications, were considered. The surfaces were characterized by contact profilometry, SEM-EDS, XPS, FTIR, zeta potential and wettability with different fluids. Protein adsorption, blood wettability, bacterial and cell adhesion were evaluated in order to investigate the correlations between the surface physiochemical properties and biological responses. From a methodological standpoint, XPS and electrokinetic measurements emerged as the more suitable techniques respectively for the evaluation of hydroxylation degree and surface charge/isoelectric point. Moreover, determination of wettability by blood appeared a specific and crucial test, the results of which are not easily predictable by using other type of tests. Hydroxylation degree resulted correlated to the wettability by water, but not directly to surface charge. Wetting tests with different media showed the possibility to highlight some differences among look-alike materials. A dependence of protein absorption on hydroxylation degree, charge and wettability was evidenced and its maximum was registered for surfaces with low wettability in both water based and protein containing media and a moderate surface charge. As far as bacterial adhesion is concerned, no effect of surface charge or protein adsorption was evidenced, while the presence of a high acid component of the surface energy appeared significant. Finally, the combination of hydroxylation degree, wettability, surface charge and energy (polar component) emerged as a key parameter for cell adhesion and viability.

Bioreactor mechanically guided 3D mesenchymal stem cell chondrogenesis using a biocompatible novel thermo-reversible methylcellulose-based hydrogel.

Autologous chondrocyte implantation for cartilage repair represents a challenge because strongly limited by chondrocytes' poor expansion capacity in vitro. Mesenchymal stem cells (MSCs) can differentiate into chondrocytes, while mechanical loading has been proposed as alternative strategy to induce chondrogenesis excluding the use of exogenous factors. Moreover, MSC supporting material selection is fundamental to allow for an active interaction with cells. Here, we tested a novel thermo-reversible hydrogel composed of 8% w/v methylcellulose (MC) in a 0.05 M Na2SO4 solution. MC hydrogel was obtained by dispersion technique and its thermo-reversibility, mechanical properties, degradation and swelling were investigated, demonstrating a solution-gelation transition between 34 and 37 °C and a low bulk degradation (<20%) after 1 month. The lack of any hydrogel-derived immunoreaction was demonstrated in vivo by mice subcutaneous implantation. To induce in vitro chondrogenesis, MSCs were seeded into MC solution retained within a porous polyurethane (PU) matrix. PU-MC composites were subjected to a combination of compression and shear forces for 21 days in a custom made bioreactor. Mechanical stimulation led to a significant increase in chondrogenic gene expression, while histological analysis detected sulphated glycosaminoglycans and collagen II only in loaded specimens, confirming MC hydrogel suitability to support load induced MSCs chondrogenesis.

Data in support of Gallium (Ga(3+)) antibacterial activities to counteract E. coli and S. epidermidis biofilm formation onto pro-osteointegrative titanium surfaces.

This paper contains original data supporting the antibacterial activities of Gallium (Ga(3+))-doped pro-osteointegrative titanium alloys, obtained via Anodic Spark Deposition (ASD), as described in "The effect of silver or gallium doped titanium against the multidrug resistant Acinetobacter baumannii" (Cochis et al. 2016) [1]. In this article we included an indirect cytocompatibility evaluation towards Saos2 human osteoblasts and extended the microbial evaluation of the Ga(3+) enriched titanium surfaces against the biofilm former Escherichia coli and Staphylococcus epidermidis strains. Cell viability was assayed by the Alamar Blue test, while bacterial viability was evaluated by the metabolic colorimetric 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Finally biofilm morphology was analyzed by Scanning Electron Microscopy (SEM). Data regarding Ga(3+) activity were compared to Silver.

The effect of silver or gallium doped titanium against the multidrug resistant Acinetobacter baumannii.

Implant-related infection of biomaterials is one of the main causes of arthroplasty and osteosynthesis failure. Bacteria, such as the rapidly-emerging Multi Drug Resistant (MDR) pathogen Acinetobacter Baumannii, initiate the infection by adhering to biomaterials and forming a biofilm. Since the implant surface plays a crucial role in early bacterial adhesion phases, titanium was electrochemically modified by an Anodic Spark Deposition (ASD) treatment, developed previously and thought to provide osseo-integrative properties. In this study, the treatment was modified to insert gallium or silver onto the titanium surface, to provide antibacterial properties. The material was characterized morphologically, chemically, and mechanically; biological properties were investigated by direct cytocompatibility assay, Alkaline Phosphatase (ALP) activity, Scanning Electron Microscopy (SEM), and Immunofluorescent (IF) analysis; antibacterial activity was determined by counting Colony Forming Units, and viability assay. The various ASD-treated surfaces showed similar morphology, micrometric pore size, and uniform pore distribution. Of the treatments studied, gallium-doped specimens showed the best ALP synthesis and antibacterial properties. This study demonstrates the possibility of successfully doping the surface of titanium with gallium or silver, using the ASD technique; this approach can provide antibacterial properties and maintain high osseo-integrative potential.

Intense Foxp3+ CD25+ regulatory T-cell infiltration is associated with high-grade cutaneous squamous cell carcinoma and counterbalanced by CD8+/Foxp3+ CD25+ ratio.

BACKGROUND: Recent reports have revealed the therapeutic potential of cell-mediated immunity in neoplasms such as cutaneous squamous cell carcinoma (SCC). OBJECTIVES: To define the antigenic coexpression of regulatory T cells (Tregs) and plasmacytoid dendritic cells (pDCs) and assess the CD8(+) /Foxp3(+) CD25(+) cell ratio at peritumoral and intratumoral levels in order to investigate a correlation with the aggressiveness of SCC tumours. METHODS: We evaluated the content and distribution of Foxp3(+) CD25(+) Treg and CD123(+) pDC infiltration and assessed CD8(+) /Foxp3(+) CD25(+) cell ratio at peritumoral and intratumoral levels in 40 SCCs (20 well-differentiated, G1; and 20 moderately to poorly differentiated, G2-G3) to investigate a correlation with their aggressiveness. We determined the profiles of Tregs and CD123(+) cells; immunostained for CD4, CD8, CD123, interleukin (IL)-1 and transforming growth factor (TGF)-ß1; and unequivocally double stained for Foxp3CD25. RESULTS: Peritumorally, CD4, CD8 and Foxp3 expression showed no difference between the two groups. CD123(+) cells were fewer in G2-G3 (P = 0·0005), while Foxp3(+) CD25(+) cells were more numerous (P = 0·0005). The Foxp3(+) CD25(+) /Foxp3(+) ratio was higher in G2-G3 cases (P = 0·0005), confirming the trend in this group of activated T lymphocytes towards total Treg Foxp3(+) cells, while the CD8(+) /Foxp3(+) CD25(+) ratio was higher in G1 (P = 0·0005). Intratumorally, CD4(+) and CD8(+) cells infiltrated G2-G3 (P = 0·048) more than G1 (P = 0·004), whereas almost all cells were CD123 negative. Regarding Foxp3CD25, TGF-ß1 and IL-10, they were less expressed in G1, whereas they were positive in G2-G3 (P < 0·05). The CD8(+) /Foxp3(+) CD25(+) ratio was similar to that observed in peritumoral infiltration. CONCLUSIONS: Our data suggest that intratumoral recruitment of Tregs, high expression of TGF-ß1 and IL-10, almost negative CD123+, and a low CD8(+) /Foxp3(+) CD25(+) T-cell ratio may contribute to the aggressiveness of cutaneous SCC, as already evidenced for other solid tumours.

Three-dimensional cellular distribution in polymeric scaffolds for bone regeneration: a microCT analysis compared to SEM, CLSM and DNA content.

In orthopaedic surgery the tissues damaged by injury or disease could be replaced using constructs based on biocompatible materials, cells and growth factors. Scaffold design, porosity and early colonization are key components for the implant success. From biological point of view, attention may be also given to the number, type and size of seeded cells, as well as the seeding technique and cell morphological and volumetric alterations. This paper describes the use of the microCT approach (to date used principally for mineralized matrix quantification) to observe construct colonization in terms of cell localization, and make a direct comparison of the microtomographic sections with scanning electron microscopy images and confocal laser scanning microscope analysis. Briefly, polycaprolactone scaffolds were seeded at different cell densities with MG63 osteoblastic-like cells. Two different endpoints, 1 and 2 weeks, were selected for the three-dimensional colonization and proliferation analysis of the cells. By observing all images obtained, in addition to a more extensive distribution of cells on scaffolds surfaces than in the deeper layers, cell volume increased at 2 weeks compared to 1 week after seeding. Combining the cell number quantification by deoxyribonucleic acid analysis and the single cell volume changes by confocal laser scanning microscope, we validated the microCT segmentation method by finding no statistical differences in the evaluation of the cell volume fraction of the scaffold. Furthermore, the morphological results of this study suggest that an effective scaffold colonization requires a precise balance between different factors, such as number, type and size of seeded cells in addition to scaffold porosity.

Enhanced biological performance of human adipose-derived stem cells cultured on titanium-based biomaterials and silicon carbide sheets for orthopaedic applications.

It is well known that the surface properties of biomaterials may affect bone-healing processes by modulating both cell viability and osteogenic differentiation. In this study we evaluated proliferation and osteogenic differentiation of human adipose-derived stem cells (hASCs) cultured on three prototypes of titanium disks and on thin layers of silicon carbide (SiC-PECVD), a material characterized by a high hardness and wear resistance. Our data indicated that all the tested surfaces supported cell growth, in particular, hASCs seeded on both titanium treated by a double-step etching process (TIT) and titanium modified by two Anodic Spark Deposition processes (TAA) grew better respect to the ones cultured on titanium obtained by KOH alkali etching process on TAA (TAAK). Furthermore, hASCs well colonized SiC-PECVD surface, showing a quite similar viability to cells cultured on plastic (PA). TIT and TAA better supported osteogenic differentiation of hASCs compared to PA, as shown by a marked increase of both alkaline phosphatase activity and calcified extracellular matrix deposition; in contrast TAAK did not positively affect hASCs differentiation. SiC-PECVD did not alter osteogenic differentiation of hASC cells: indeed, ALP and calcium deposition levels were comparable to those of cells cultured on plastic. Furthermore, we observed similar results testing hASCs either pre-differentiated for 14 days in osteogenic medium or directly differentiated on biomaterials. Our study suggests that modifications of titanium surface may improve osteo-integration of implant devices and that SiC-PECVD may represent a valid alternative for the coating of prosthetic devices to reduce wear and metallosis events.

Oral and non oral diseases and conditions associated with bad breath.

AIM: The causes of bad breath are numerous and related to conditions dependent or not on oral and general health. The aim of our observational study is the assessment of the simultaneous relationships between halitosis, oral and/or nonoral diseases, and lifestyles using the principal components analysis of categorical data (CATPCA) to identify the main components involved in the detection of the symptom. METHODS: A sample of 192 patients, who requested general dental examination at the Dental Clinic, participated at the study. Alimentary and voluptuary habits, general health information, drugs assumption, the status of teeth and intraoral medical devices including fillers, lesions of the oral mucosa, tongue coating score (TCS), plaque index (PI), probing bleeding index (PBI) and organoleptic tests were all evaluated. Data were analysed using CATPCA model. RESULTS: A strong relationship between halitosis and plaque, probing bleeding and tongue coating indexes was observed, whereas incongruous fillers, prostheses, systemic pathologies or diet were not clearly associated with halitosis probably because their effects on breath were clinically sheltered by the periodontal condition. CONCLUSION: The data of our observational study confirm that halitosis is more indicative of tongue coating and periodontal disease, rather than other oral and non oral associated conditions, like systemic pathologies or specific habits of life.

Stem cell technologies for tissue regeneration in dentistry.

Embryonal and adult stem cells represent a very interesting research field. Mesenchymal stem cells in particular, derived from different sources, in the last ten years have gained more interest because of their high differentiation potential and their availability. They represent a potential key component in autologos graft for tissue regeneration. Cell-therapy based tissue engineering, even in dentistry field, is based on two approaches: the first is the direct implant of cells in tissues and the second involve the use of a scaffold acting both as a template of tissue and as a carrier of cells. Interest in this technologies continues to increase in dental application as a substitute for traditional treatments and artificial components. Nevertheless, few clinical reports of this topic are available. This review will discuss the current challenges in stem cells field, in particular their differentiation toward oral tissues. Bone marrow, adipose tissues, periodontal ligament and pulp will be described as potential sources of stem cells for oral tissue regeneration.

Ability of polyurethane foams to support cell proliferation and the differentiation of MSCs into osteoblasts.

In bone tissue reconstruction, the use of engineered constructs created by mesenchymal stem cells (MSCs) that differentiate and proliferate into three-dimensional porous scaffolds is an appealing alternative to autologous and heterologous bone grafts. Scaffolds considered in this work are represented by polyurethane (PU) foams. Two PU foams (EC-1 and EC-2) were synthesized and characterized for morphology, mechanical properties and in vitro interaction with the osteoblast-like cell line MG63 and MSCs from human bone marrow. EC-1 and EC-2 showed similar densities (0.20 g cm(-3)) with different morphologies: EC-1 showed a more homogeneous pore size (average Phi = 691 microm) and distribution, with a 35% open porosity, whereas EC-2 evidenced a wide range of pore dimension, with an average pore size of 955 microm and a 74% open porosity. The compressive properties of the two foams were similar in the dry condition and both showed a strong decrease in the wet condition. In vitro tests showed good MG63 cell proliferation, as confirmed by the results of the MTT assay and scanning electron microscopy (SEM) observations, with a higher cell viability on EC-2 foam 7 days post-seeding. In the experiments with MSCs, SEM observations showed the presence of an inorganic phase deposition starting day 7 onto EC-1, day 14 onto EC-2. The inorganic particles (CaP) deposition was much more evident onto the pore surface of both foams at day 30, indicating good differentiation of MSCs into osteoblasts. Both PU foams therefore appeared to stimulate cell adhesion and proliferation in vitro, sustaining the MSCs' growth and differentiation into osteoblasts.

Comparative in vivo evaluation of porous and dense duplex titanium and hydroxyapatite coating with high roughnesses in different implantation environments.

Ti (PG60) and Ti plus HA (HPG60) dense coatings with ultrahigh roughness (Ra: 74 +/- 8 microm and 53 +/- 18 microm, respectively) were compared to high Ti (Ti60) and Ti plus HA (HT60) high roughened porous coatings (Ra: 40 +/- 7 microm and 36 +/- 3 microm, respectively). Surfaces were implanted in cortical and trabecular bone of young adult (YOUNG), aged (AGED) and estrogen-deficient sheep (OVX) and analyzed by means of histology, histomorphometry and push-out tests 3 months after implantation. A significantly lower value in affinity index (AI) of PG60 when compared to TI60 (p < 0.01) was observed in cortical bone. In trabecular bone, lower values in AI were found in TI60 and PG60 when compared to their HA-coated surfaces (p < 0.0005). Bone ingrowth (BI) of TI60 and PG60 was significantly lower than that of the HA-coated surfaces in trabecular bone (p < 0.05). Significantly lower values in BI in OVX sheep in comparison to YOUNG sheep in both cortical and trabecular bone were observed (p < 0.05). Data showed that high roughness and Ti and HA-coated surfaces are suitable for aged and osteoporotic patients. HA coatings represent the most successful strategy in trabecular bone.

Odontogenic tumors in childhood: a retrospective study of 86 treated cases. Importance of a correct histopathologic diagnosis.

The odontogenic tumors are an unusual group of lesions of the jaws derived from embryologic tooth-forming tissues and presenting in a large number of histologic patterns. More common in pediatric age and adolescence than in adult age, the odontogenic tumors can be observed casually or after the appearance of nonspecific symptoms. Because of their slow-growth tendency, usually they do not cause pain. The odontogenic tumors grow in the jaw, through the haversian system, without metastasis but with and high probability of relapse. A retrospective study of 86 cases treated between 1997 and 2005 is reported. The percent of diagnosed cases that were benign was 98.8%, and just one case of malign neoplasm is reported. The most frequent tumor accounted for in the reported sample was odontoma (39.5%) followed by odontogenic fibroma (12.8%). Ameloblastoma and myxoma showed the same incidence (11.6%). Early diagnosis, together with a correct histologic diagnosis, allows a preservative and effective surgical treatment and is necessary to reduce the risk of relapse.

Human adipose-derived stem cells as future tools in tissue regeneration: osteogenic differentiation and cell-scaffold interaction.

Tissue engineering is now contributing to new developments in several clinical fields, and mesenchymal stem cells derived from adipose tissue (hASCs) may provide a novel opportunity to replace, repair and promote the regeneration of diseased or damaged musculoskeletal tissue. Our interest was to characterize and differentiate hASCs isolated from twenty-three donors. Proliferation, CFU-F, cytofluorimetric and histochemistry analyses were performed. HASCs differentiate into osteogenic, chondrogenic, and adipogenic lineages, as assessed by tissue-specific markers such as alkaline phosphatase, osteopontin expression and deposition of calcium matrix, lipid-vacuoles formation and Glycosaminoglycans production. We also compared osteo-differentiated hASCs cultured on monolayer and loaded on biomaterials routinely used in the clinic, such as hydroxyapatite, cancellous human bone fragments, deproteinized bovine bone granules, and titanium. Scaffolds loaded with pre-differentiated hASCs do not affect cell proliferation and no cellular toxicity was observed. HASCs tightly adhere to scaffolds and differentiated-hASCs on human bone fragments and bovine bone granules produced, respectively, 3.4- and 2.1-fold more calcified matrix than osteo-differentiated hASCs on monolayer. Moreover, both human and deproteinized bovine bone is able to induce osteogenic differentiation of CTRL-hASCs. Although our in vitro results need to be confirmed in in vivo bone regeneration models, our data suggest that hASCs may be considered suitable biological tools for the screening of innovative scaffolds that would be useful in tissue engineering.

Electrochemical surface modification of titanium for implant abutments can affect oral bacteria contamination.

PURPOSE: This research concerns the characterization of an electrochemical surface treatment applied to titanium, focused especially on the treatment of the transmucosal area of dental implants and abutments. The treatment is applied to improve soft tissue adhesion, to control and limit bacteria adhesion and proliferation, and to improve the aesthetic performance through a proper colorization of the metal surface. METHODS: The electrochemical treatment considered, obtained on titanium by Anodic Spark Deposition technique (ASD), was performed in a calcium phosphate enriched solution. The bacteria behaviour was assessed by in vitro and in vivo tests. RESULTS: The investigated ASD treatment showed some antibacterial effect. No negative cytocompatibility effects were found on MG63 - human osteosarcoma cell lines and L929 - murine fibroblasts. CONCLUSIONS: The ASD modified treatment was found capable of modifying the titanium oxide layer providing a prevalent anatase crystalline structure and a microporous morphology, which can play an important role in the tissue integration process. The treatment was found capable of enriching the surface with calcium, providing improved biocompatibility and a light gray colorization. This last point is important for the aesthetic improvement of dental implant systems in the transgingival area.

In vitro and in vivo behaviour of biodegradable and injectable PLA/PGA copolymers related to different matrices.

This study comparatively investigates the in vitro and in vivo behavior of injectable polymeric materials for the treatment of bone defects. The tested materials were three injectable and biodegradable PLA/PGA 50/50 copolymers dispersed in different matrices: Fisograft-gel (GEL) was dispersed in an aqueous matrix of poly-ethyl-glycole (PEG); Slurry2 (SL2) was dispersed in an aqueous matrix of PEG and dextran; and Slurry6 (SL6) was dispersed in a 3% agarose matrix. The biological characterization of these materials was studied by in vitro and in vivo tests: the in vitro test assessed the cellular response in terms of viability, differentiation and synthetic activity, while the in vivo test evaluated the healing capacity of bone defects treated with these biomaterials. GEL and SL2 induced a similar response for viability and differentiation of MG63 osteoblast-like cells after a 7-day culture, while SL6 caused a higher production of both interleukin-6 and type I collagen. Since the results showed that the materials were biocompatible and not cytotoxic in vitro, the in vivo study was carried out: materials were implanted, under general anesthesia, in critical size defects of rabbit femoral condyles; after 4 and 12 weeks, the healing rates and the quality of the regenerated bone were histomorphometrically calculated. The SL2-treated defects healed better at 12 weeks with a more similar microarchitecture of the newly formed bone to normal bone in comparison with other materials, as demonstrated by bone volume fraction and trabecular thickness values.