Bioactivity and Physico-Chemical Properties of Dental Composites Functionalized with Nano- vs. Micro-Sized Bioactive Glass

Bioactive resin composites can contribute to the prevention of secondary caries, which is one of the main reasons for failure of contemporary dental restorations. This study investigated the effect of particle size of bioactive glass 45S5 on chemical and physical composite properties. Four experimental composites were prepared by admixing the following fillers into a commercial flowable composite: (1) 15 wt% of micro-sized bioactive glass, (2) 15 wt% of nano-sized bioactive glass, (3) a combination of micro- (7.5 wt%) and nano-sized (7.5 wt%) bioactive glass, and (4) 15 wt% of micro-sized inert barium glass. Hydroxyapatite precipitation and pH rise in phosphate-buffered saline were evaluated during 28 days. Degree of conversion and Knoop microhardness were measured 24 h after specimen preparation and after 28 days of phosphate-buffered saline immersion. Data were analyzed using non-parametric statistics (Kruskal–Wallis and Wilcoxon tests) at an overall level of significance of 5%. Downsizing the bioactive glass particles from micro- to nano-size considerably improved their capability to increase pH. The effect of nano-sized bioactive glass on degree of conversion and Knoop microhardness was similar to that of micro-sized bioactive glass. Composites containing nano-sized bioactive glass formed a more uniform hydroxyapatite layer after phosphate-buffered saline immersion than composites containing exclusively micro-sized particles. Partial replacement of nano- by micro-sized bioactive glass in the hybrid composite did not impair its reactivity, degree of conversion (p > 0.05), and Knoop microhardness (p > 0.05). It is concluded that downsizing bioactive glass particles to nano-size improves the alkalizing potential of experimental composites with no negative effects on their fundamental properties.

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Polymerization shrinkage behaviour of resin composites functionalized with unsilanized bioactive glass fillers

Scientific Reports ◽

10.1038/s41598-020-72254-6 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Matej Par ◽

Dirk Mohn ◽

Thomas Attin ◽

Zrinka Tarle ◽

Tobias T. Tauböck

Keyword(s):

Bioactive Glass ◽

Degree Of Conversion ◽

Stress Rate ◽

Partial Replacement ◽

Shrinkage Stress ◽

Resin Composites ◽

Dental Resin ◽

Polymerization Shrinkage ◽

Reinforcing Fillers ◽

Shrinkage Behaviour

Abstract Previous work has shown that partial replacement of reinforcing fillers with unsilanized silica particles can diminish polymerization shrinkage stress of dental resin composites. The aim of the present study was to investigate whether such an effect can be attained by using unsilanized bioactive glass (BG). Incorporating BG fillers into resin composites is interesting due to their potential for exerting caries-preventive effects. Experimental light-curable composites with a total filler load of 77 wt% were prepared. Reinforcing fillers were partially replaced with 0–60 wt% of BG 45S5 and an experimental low-sodium fluoride-containing BG. The following properties were investigated: linear shrinkage, degree of conversion, shrinkage stress, maximum shrinkage stress rate, and time to achieve maximum shrinkage stress rate. The diminishing effect of BG 45S5 on shrinkage stress was mediated by a decrease in degree of conversion caused by this BG type. In contrast, as the degree of conversion remained unaffected by the experimental BG, the resulting shrinkage behaviour was governed by the effect of varying amounts of silanized and unsilanized fillers on material’s viscoelastic properties. The replacement of silanized reinforcing fillers with unsilanized BG did not reduce polymerization shrinkage stress unless the reduction was attained indirectly through a diminished degree of conversion.

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Modified gach technique vs critical point drying: Shrinkage analysis for SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012905x ◽

1987 ◽

Vol 45 ◽

pp. 954-955

Author(s):

B. Thompson ◽

N. Sculov ◽

R.E. Crang

Keyword(s):

Critical Point ◽

Calf Serum ◽

Drying Shrinkage ◽

Specimen Preparation ◽

Cell Shrinkage ◽

Whole Cells ◽

Critical Point Drying ◽

Prepared Material ◽

Inverted Microscope ◽

Phosphate Buffered Saline

The use of co-polymerized glutaraldehyde-carbohydrazide (GACH) was proposed for specimen preparation in scanning electron microscopy (SEM) as a means of avoiding dehydration in organic solvents, and to provide dimensionally stable biological specimens through a process of air-drying. It has been assumed that shrinkage of specimens prepared by the GACH technique should be less than that of conventionally-prepared material by critical point drying (CPD). In a previous study, Bell has reported significant shrinkage of whole cells for SEM. This report compares cell shrinkage in GACH and CPD preparations.Fibroblasts from newborn rats were grown on collagen-coated glass cover-slips (with alpha numeric grids etched onto the surface of the coverslips) in Eagle's minimum essential medium + 10% fetal calf serum for 7 d. (3). Using an inverted microscope with phase-contrast optics, micrographs were taken of the cultures in their live state and 1 h. after fixation with 2.5% glutaraldehyde in Dulbecco's phosphate buffered saline (Figs. 1 and 3).

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Contributions to the Knowledge of Sandy Soils from Oltenia Plain

Revista de Chimie ◽

10.37358/rc.20.1.7831 ◽

2020 ◽

Vol 71 (1) ◽

pp. 192-200

Author(s):

Anca-Luiza Stanila ◽

Catalin Cristian Simota ◽

Mihail Dumitru

Keyword(s):

Chemical Properties ◽

Soil Formation ◽

Sandy Soils ◽

Physical Geography ◽

Parent Material ◽

Negative Effects ◽

Small Water ◽

Wind Characteristic ◽

The One ◽

Physical And Chemical

Highlighting the sandy soil of Oltenia Plain calls for a better knowledge of their variability their correlation with major natural factors from each physical geography. Pedogenetic processes specific sandy soils are strongly influenced by nature parent material. This leads, on the one hand, climate aridity of the soil due to strong heating and accumulation of small water reserves, consequences emphasizing the moisture deficit in the development of the vegetation and favoring weak deflation, and on the other hand, an increase in mineralization organic matter. Relief under wind characteristic sandy land, soil formation and distribution has some particularly of flat land with the land formed on the loess. The dune ridges are less evolved soils, profile underdeveloped and poorly supplied with nutrients compared to those on the slopes of the dunes and the interdune, whose physical and chemical properties are more favorable to plant growth.Both Romanati Plain and the Blahnita (Mehedinti) Plain and Bailesti Plain, sand wind shaped covering a finer material, loamy sand and even loess (containing up to 26% clay), also rippled with negative effects in terms of overall drainage. Depending on the pedogenetic physical and geographical factors that have contributed to soil cover, in the researched were identified following classes of soils: protisols, cernisols, cambisols, luvisols, hidrisols and antrosols.Obtaining appropriate agricultural production requires some land improvement works (especially fitting for irrigation) and agropedoameliorative works. Particular attention should be paid to preventing and combating wind erosion.

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Characterization of carbon nanotube (MWCNT) containing P(3HB)/bioactive glass composites for tissue engineering applications

Acta Biomaterialia ◽

10.1016/j.actbio.2009.09.023 ◽

2010 ◽

Vol 6 (3) ◽

pp. 735-742 ◽

Cited By ~ 63

Author(s):

Superb K. Misra ◽

F. Ohashi ◽

Sabeel P. Valappil ◽

Jonathan C. Knowles ◽

I. Roy ◽

...

Keyword(s):

Tissue Engineering ◽

Carbon Nanotube ◽

Bioactive Glass ◽

Engineering Applications ◽

Glass Composites

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Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00196-15 ◽

2015 ◽

Vol 59 (12) ◽

pp. 7571-7580 ◽

Cited By ~ 16

Author(s):

Wei-Tao Jia ◽

Qiang Fu ◽

Wen-Hai Huang ◽

Chang-Qing Zhang ◽

Mohamed N. Rahaman

Keyword(s):

Staphylococcus Aureus ◽

Bioactive Glass ◽

Calcium Sulfate ◽

Rabbit Model ◽

Local Delivery ◽

Methicillin Resistant ◽

Content Type ◽

Borate Bioactive Glass ◽

Phosphate Buffered Saline

ABSTRACTThere is growing interest in biomaterials that can cure bone infection and also regenerate bone. In this study, two groups of implants composed of 10% (wt/wt) teicoplanin (TEC)-loaded borate bioactive glass (designated TBG) or calcium sulfate (TCS) were created and evaluated for their ability to release TECin vitroand to cure methicillin-resistantStaphylococcus aureus(MRSA)-induced osteomyelitis in a rabbit model. When immersed in phosphate-buffered saline (PBS), both groups of implants provided a sustained release of TEC at a therapeutic level for up to 3 to 4 weeks while they were gradually degraded and converted to hydroxyapatite. The TBG implants showed a longer duration of TEC release and better retention of strength as a function of immersion time in PBS. Infected rabbit tibiae were treated by debridement, followed by implantation of TBG or TCS pellets or intravenous injection with TEC, or were left untreated. Evaluation at 6 weeks postimplantation showed that the animals implanted with TBG or TCS pellets had significantly lower radiological and histological scores, lower rates of MRSA-positive cultures, and lower bacterial loads than those preoperatively and those of animals treated intravenously. The level of bone regeneration was also higher in the defects treated with the TBG pellets. The results showed that local TEC delivery was more effective than intravenous administration for the treatment of MRSA-induced osteomyelitis. Borate glass has the advantages of better mechanical strength, more desirable kinetics of release of TEC, and a higher osteogenic capacity and thus could be an effective alternative to calcium sulfate for local delivery of TEC.

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Role of the periodic table in discovery of new elements

Proceedings in Radiochemistry ◽

10.1524/rcpr.2011.0000 ◽

2011 ◽

Vol 1 (1) ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

D.C. Hoffman

Keyword(s):

Periodic Table ◽

Predictive Power ◽

Chemical Elements ◽

Chemical Properties ◽

Negative Effects ◽

Current Form ◽

Future Role ◽

History Of ◽

Chemical Techniques

AbstractThis year (2009) marks the 140th Anniversary of Mendeleev's original 1869 periodic table of the elements based on atomic weights. It also marks the 175th anniversary of his birth in Tolbosk, Siberia. The history of the development of periodic tables of the chemical elements is briefly reviewed beginning with the presentation by Dmitri Mendeleev and his associate Nikolai Menshutkin of their original 1869 table based on atomic weights. The value, as well as the sometimes negative effects, of periodic tables in guiding the discovery of new elements based on their predicted chemical properties is assessed. It is noteworthy that the element with Z=101 (mendelevium) was identified in 1955 using chemical techniques. The discoverers proposed the name mendelevium to honor the predictive power of the Mendeleev Periodic Table. Mendelevium still remains the heaviest element to have been identified first by chemical rather than nuclear or physical techniques. The question concerning whether there will be a future role for the current form of the periodic table in predicting chemical properties and aid in the identification of elements beyond those currently known is considered.

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