Amorphous TiO2nano-coating on stainless steel to improve its biological response.

This study delves into the potential of amorphous titanium oxide (aTiO2) nano-coating to enhance various critical aspects of non-Ti-based metallic orthopedic implants. These implants, such as medical-grade stainless steel (SS), are widely used for orthopedic devices that demand high strength and durability. The aTiO2nano-coating, deposited via magnetron sputtering, is a unique attempt to improve the osteogenesis, the inflammatory response, and to reduce bacterial colonization on SS substrates. The study characterized the nanocoated surfaces (SS-a TiO2) in topography, roughness, wettability, and chemical composition. Comparative samples included uncoated SS and sandblasted/acid-etched Ti substrates (Ti). The biological effects were assessed using human mesenchymal stem cells (MSCs) and primary murine macrophages. Bacterial tests were carried out with two aerobic pathogens (S. aureusandS. epidermidis) and an anaerobic bacterial consortium representing an oral dental biofilm. Results from this study provide strong evidence of the positive effects of the aTiO2nano-coating on SS surfaces. The coating enhanced MSC osteoblastic differentiation and exhibited a response similar to that observed on Ti surfaces. Macrophages cultured on aTiO2nano-coating and Ti surfaces showed comparable anti-inflammatory phenotypes. Most significantly, a reduction in bacterial colonization across tested species was observed compared to uncoated SS substrates, further supporting the potential of aTiO2nano-coating in biomedical applications. The findings underscore the potential of magnetron-sputtering deposition of aTiO2nano-coating on non-Ti metallic surfaces such as medical-grade SS as a viable strategy to enhance osteoinductive factors and decrease pathogenic bacterial adhesion. This could significantly improve the performance of metallic-based biomedical devices beyond titanium.

Salivary pellicle modulates biofilm formation on titanium surfaces.

OBJECTIVES: The present study aimed to evaluate the potential of the salivary pellicle (SP) formed on titanium (Ti) surfaces to modulate the formation of a biofilm composed of Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis. MATERIALS AND METHODS: Ti substrates were incubated for 2 h with a pool of saliva samples obtained from 10 systemically and periodontally healthy subjects. Enamel substrates were included as a biological reference. Scanning electron microscopy (SEM) and Raman spectroscopy analysis were used to analyze the formation of the salivary pellicle. After the SP formation, the surfaces were incubated for 12 h with a mix of Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis. The number of bacterial cells attached to each surface was determined by the XTT assay while bacterial viability was analyzed by fluorescence microscopy using the LIVE/DEAD® BacLightTM kit. RESULTS: The SEM and Raman spectroscopy analysis confirmed the presence of a salivary pellicle formed on the tested surfaces. Regarding the biofilm formation, the presence of the SP decreases the number of the bacterial cells detected in the test surfaces, compared with the uncover substrates. Even more, the SP-covered substrates showed similar bacterial counts in both Ti and enamel surfaces, meaning that the physicochemical differences of the substrates were less determinant than the presence of the SP. While on the SP-uncover substrates, differences in the bacterial adhesion patterns were directly related to the physicochemical nature of the substrates. CONCLUSIONS: The salivary pellicle was the main modulator in the development of the biofilm consisting of representative oral bacteria on the Ti substrates. CLINICAL RELEVANCE: The results of this study provide valuable information on the modulatory effect of the salivary pellicle on biofilm formation; such information allows us to understand better the events involved in the formation of oral biofilms on Ti dental implants.

ZnO nanoparticles-modified polycaprolactone-gelatin membranes for guided/bone tissue regeneration, antibacterial and osteogenic differentiation properties.

Periodontitis is a highly prevalent infectious disease that causes the progressive destruction of the periodontal supporting tissues. If left untreated, it can lead to tooth loss impairing oral function, aesthetics, and the patient's overall quality of life. Guided and Bone Tissue Regeneration (GTR/BTR) are surgical therapies based on the placement of a membrane that prevents epithelial growth into the defect, allowing the periodontal/bone cells (including stem cells) to regenerate or restore the affected tissues. The success of these therapies is commonly affected by the local bacterial colonization of the membrane area and its fast biodegradation, causing postoperative infections and a premature rupture of the membrane limiting the regeneration process. This study presents the antibacterial and osteogenic differentiation properties of polycaprolactone-gelatin (PCL-G) electrospun membranes modified with ZnO nanoparticles (ZnO-NPs). The membranes´ chemical composition, surface roughness, biodegradation, water wettability, and mechanical properties under simulated physiological conditions, were analyzed by the close relationship with their biological properties. The PCL-G membranes modified with 1, 3, and 6% w/w of ZnO-NPs showed a significant reduction in the planktonic and biofilm formation of four clinically relevant bacteria;A. actinomycetemcomitansserotype b, P. gingivalis,E. coli, andS. epidermidis. Additionally, the membranes presented appropriate mechanical properties and biodegradation rates to be potentially used in clinical treatments. Notably, the membranes modified with the lowest concentration of ZnO-NPs (1% w/w) stimulated the production of osteoblast markers and calcium deposits in human bone marrow-derived mesenchymal stem cells (BM-MSC) and were biocompatible to human osteoblasts cells (hFOB). These results suggest that the PCL-G membranes with 1% w/w of ZnO-NPs are high-potential candidates for GTR/BTR treatments, as they were the most effective in terms of better antibacterial effectiveness at a lower NPs-concentration while creating a favorable cellular microenvironment for bone growth.

Effect of Surface Roughness of Deciduous and Permanent Tooth Enamel on Bacterial Adhesion.

The adhesion of some bacteria has been attributed to critical levels of roughness in hard tissues, which increases the risk of developing caries. The objective of this work was to assess the effect of deciduous and permanent tooth enamel surface roughness on bacterial adhesion. One hundred and eight samples of deciduous and permanent enamel were divided into two groups (n = 54). G1_DE deciduous enamel and G2_PE permanent enamel. The surface roughness was measured by profilometry and atomic force microscopy (AFM). Subsequently, the evaluation of bacterial adherence was carried out in triplicate by means of the XTT cell viability test. Additionally, bacterial adhesion was observed using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The average values of the micrometric roughness in both groups were similar; however, in the nanometric scale they presented significant differences. Additionally, the G1_DE group showed the highest amount of adhered S. mutans and S. sanguinis compared to the G2_EP group. Although the roughness of deciduous and permanent enamel showed contrasting results according to the evaluation technique (area and scale of analysis), bacterial adhesion was greater in deciduous enamel; hence, enamel roughness may not be a determining factor in the bacterial adhesion phenomenon.

Degradation Behavior and Mechanical Integrity of a Mg-0.7Zn-0.6Ca (wt.%) Alloy: Effect of Grain Sizes and Crystallographic Texture.

The microstructural characteristics of biodegradable Mg alloys determine their performance and appropriateness for orthopedic fixation applications. In this work, the effect of the annealing treatment of a Mg-0.7Zn-0.6Ca (ZX11) alloy on the mechanical integrity, corrosive behavior, and biocompatibility-osteoinduction was studied considering two annealing temperatures, 350 and 450 °C. The microstructure showed a recrystallized structure, with a lower number of precipitates, grain size, and stronger basal texture for the ZX11-350 condition than the ZX11-450. The characteristics mentioned above induce a higher long-term degradation rate for the ZX11-450 than the ZX11-350 on days 7th and 15th of immersion. In consequence, the mechanical integrity changes within this period. The increased degradation rate of the ZX11-450 condition reduces 40% the elongation at failure, in contrast with the 16% reduction for the ZX11-350 condition. After that period, the mechanical integrity remained unchanged. No cytotoxic effects were observed for both treatments and significant differentiation of mesenchymal stem cells into the osteoblast phenotype was observed.

Roughness and wettability of titanium implant surfaces modify the salivary pellicle composition.

This study reports the differences in the protein composition of salivary pellicles formed under in situ conditions on two Titanium (Ti) surfaces, with different roughness and wettability. Smooth pretreatment Ti surfaces (Ti-PT) with an average roughness (Ra) of 0.45 µm and a water contact angle (WCA) of 92.4°, as well as a more rough sandblasted, large grit, acid-etched treatment Ti surfaces (Ti-SLA) with a Ra of 3.3 µm and WCA of 131.8°, were tested. The salivary pellicles were quantitatively analyzed by bicinchoninic acid assays, and the protein identification was performed by Nano-LC-MS/MS (nano mass spectrometry). Protein levels of 2.5, and 9.1 µg/ml were quantified from the detached salivary pellicle formed on the Ti-PT and Ti-SLA surfaces, respectively. Using Nano-LC-MS/MS, a total of 597 proteins were identified on all the substrates tested; 43 proteins were identified only on the Ti-PT, and 226 proteins were adsorbed solely on the Ti-SLA substrates. The physicochemical characteristics of the Ti implant surfaces modified the amount and the identity of the salivary proteome of the pellicles formed, confirming the high selectivity of the protein pellicle formed on a surface once is exposed in the oral cavity.

Antibacterial Activity of Homeopathic Medications Lycopodium clavatum and Arsenicum album Against Periodontal Bacteria / Evaluación antibacteriana de los medicamentos homeopáticos sobre bacterias periodontales

Abstract There are several controversies regarding the efficacy of homeopathic substances; however, these remedies are used in many countries for the treatment of various pathological conditions. The purpose of this study was to evaluate the in vitro antibacterial activity of two homeopathic tinctures Arsenicum album (mineral extract) and Lycopodium clavatum (plant extract) on the periodontal bacteria Actinomyces israelii, Streptococcus sanguinis, Prevotella intermedia, Aggregatibacter actinomycetemcomitans and Phorphyromonas gingivalis (P. gingivalis). Materials and methods: Equal numbers of bacteria were seeded on agar plates containing enriched media with the homeopathic solutions at 1dH and 1cH dilutions. After 7 days of incubation under anaerobic conditions, colony forming units (CFUs) were counted. The antibacterial effect was calculated based on the total number of CFUs observed on non-tincture containing agar, and on the tincture containing plates. Results: No visible growth of any of the strains was observed on the plates containing Arsenicum album at any of the dilutions tested. In contrast, when Lycopodium clavatum at 1cH dilution was tested, only P. gingivalis was susceptible to this compound. Conclusions: The results suggest that the mineral extract tincture had a greater antibacterial activity than the plant extract tincture, also Lycopodium clavatum preparation could be an effective inhibitor of periodontal pathogens bacteria such as P. gingivalis.

Resumen Se necesita un mayor número de estudios in vitro e in vivo para validar estos resultados.

Bacterial adhesion on amorphous and crystalline metal oxide coatings.

Several studies have demonstrated the influence of surface properties (surface energy, composition and topography) of biocompatible materials on the adhesion of cells/bacteria on solid substrates; however, few have provided information about the effect of the atomic arrangement or crystallinity. Using magnetron sputtering deposition, we produced amorphous and crystalline TiO2 and ZrO2 coatings with controlled micro and nanoscale morphology. The effect of the structure on the physical-chemical surface properties was carefully analyzed. Then, we studied how these parameters affect the adhesion of Escherichia coli and Staphylococcus aureus. Our findings demonstrated that the nano-topography and the surface energy were significantly influenced by the coating structure. Bacterial adhesion at micro-rough (2.6 µm) surfaces was independent of the surface composition and structure, contrary to the observation in sub-micron (0.5 µm) rough surfaces, where the crystalline oxides (TiO2>ZrO2) surfaces exhibited higher numbers of attached bacteria. Particularly, crystalline TiO2, which presented a predominant acidic nature, was more attractive for the adhesion of the negatively charged bacteria. The information provided by this study, where surface modifications are introduced by means of the deposition of amorphous or crystalline oxide coatings, offers a route for the rational design of implant surfaces to control or inhibit bacterial adhesion.

Subgingival microbiota of periodontally untreated Mexican subjects with generalized aggressive periodontitis.

BACKGROUND AND AIM: Specific microbial profiles that may distinguish between generalized aggressive-periodontitis (GAgP) and generalized chronic-periodontitis (GCP) have, to date, not been described. The purpose of the present study was to describe the subgingival microbial composition of Mexican subjects with GAgP and compare it with that of individuals with GCP and periodontal health (PH). MATERIAL AND METHODS: Seventy-seven subjects with GAgP (n=19), GCP (n=39) and PH (n=19) were selected. Clinical measurements included plaque accumulation, gingival erythema, bleeding on probing, suppuration, pocket depth and attachment level. Up to 28 subgingival plaque samples were obtained from each subject and analysed using the checkerboard DNA-DNA hybridization technique. RESULTS: GAgP and GCP subjects harboured significantly higher levels and/or proportion of Porphyromonas gingivalis, Tannerella forsythia (levels: p<0.001, proportion: p<0.01), Prevotella nigrescens (p<0.05 levels) and "red" complex species (p<0.001 proportion) than PH subjects. All GAgP subjects were carriers of P. gingivalis and P. nigrescens. No significant differences in any of the 40 microbial species tested were detected between GAgP and GCP subjects. CONCLUSIONS: Our results revealed that the microbial differences between GAgP and GCP subjects were only discrete and none of the bacterial species tested seemed to specifically differentiate the subgingival microbial profile of either periodontitis group.

Proportion of antibiotic resistance in subgingival plaque samples from Mexican subjects.

AIM: To determine the proportion of bacteria resistant to amoxicillin and doxycycline in subgingival plaque samples from Mexican subjects. MATERIALS AND METHODS: Two subgingival plaque samples were taken from 20 Mexican subjects. Samples were dispersed, diluted and plated on non-antibiotic agar plates and on plates containing 0.5, 1, 2, 4, 8 and 16 microg/ml of either amoxicillin or doxycycline. The proportion of resistant bacteria was calculated based on the total number of colony-forming units present in the non-antibiotic containing plates. RESULTS: On average, 0.4-13.4% and 0.9-20.4% of the total cultivable subgingival microbiota was resistant to the concentrations tested of amoxicillin and doxycycline, respectively. The differences between antibiotics were statistically significant for the 0.5, 2 and 4 mug/ml concentrations (p < 0.05, Wilcoxon's test). CONCLUSIONS: Our findings revealed that a relatively small proportion of the total cultivable subgingival microbiota from Mexican subjects was resistant to amoxicillin and doxycycline.

Description of the subgingival microbiota of periodontally untreated Mexican subjects: chronic periodontitis and periodontal health.

BACKGROUND: Recent studies have suggested that changes in the prevalence and/or proportion of distinct microorganisms characterize the subgingival microbial profiles of populations around the world. At present, no information is available on the subgingival microbiota of Mexican subjects. The purpose of the present study was to determine the microbial composition of subgingival plaque in Mexican subjects with untreated chronic periodontitis. METHODS: A total of 44 chronic periodontitis and 20 periodontally healthy subjects (who were currently non-smokers) were selected. Clinical measurements including plaque accumulation, gingival erythema, bleeding on probing, suppuration, probing depth, and attachment level were recorded at six sites of every tooth. Up to 28 subgingival plaque samples were obtained from each subject and individually analyzed to determine the levels, proportion, and prevalence of 40 microbial species using the checkerboard DNA-DNA hybridization technique. RESULTS: Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythensis were the only species that presented higher mean levels in periodontitis subjects. The proportions of P. gingivalis (P<0.001), T. forsythensis (P<0.01), and red complex species (P. gingivalis, T. forsythensis, and T. denticola; P<0.001) as a group were also significantly higher in periodontitis subjects. Periodontally healthy subjects harbored a significantly larger proportion of Actinomyces species (P<0.05). No significant differences were detected in the percentage of carriers of any of the species tested. CONCLUSIONS: Our results revealed that the subgingival microbiota of untreated chronic periodontitis Mexican subjects was characterized by increases in the level, prevalence, and proportion of classic periodontal pathogens. However, the prevalence and proportion of specific microbial species varied significantly from the results of other reports on subjects from different geographical locations.