Superfast Set, Strong and Less Degradable Mineral Trioxide Aggregate Cement

Purpose. Despite the good sealing ability and biocompatibility of mineral trioxide aggregate (MTA), its slow setting, high degradation, and weakness limit its use in surgical endodontics and high stress-bearing areas. This study aimed to develop two new liquids to control these drawbacks. They were prepared from calcium chloride, fumed silica, and hydroxyapatite or calcium phosphate and coded “H” and “P,” respectively. Methods. Portland cement, Grey ProRoot® MTA, and white ProRoot MTA were mixed with distilled water (control) or liquid “H” or “P.” The pH, setting time, degradation rate, leachant/precipitate’ composition, compressive strength, and morphology were assessed. Results. Both liquids maintained MTA’s high alkalinity and reduced the setting time by 1-2 orders of magnitude. Both liquids, H in particular, significantly reduced the degradation rate of Grey ProRoot and White ProRoot MTA®. Calcite has been identified as the main phase of the leachant or precipitate formed during the cement’s degradation. Calcium hydroxide or hydroxyapatite was also identified with Grey ProRoot MTA mixed with H liquid. These liquids also significantly increased the compressive strength with no statistical differences between them; this was associated with the production of dense, consolidated structures. Conclusions. The modified MTA could be used in surgical endodontics and high stress-bearing areas

Antibacterial and Antibiofilm Efficacy of Copper-Doped Phosphate Glass on Pathogenic Bacteria

This study aimed to investigate the antibacterial [minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC)] and antibiofilm activity [log10 colony forming unit/mL (CFU/mL) and biofilm disruption] of copper-doped phosphate glass (CDPG) against Streptococcus oralis, Enterococcus faecalis, Lactobacillus casei, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Methods: the antibacterial activity was determined using microbroth dilution and time-kill assay. The antibiofilm activity was investigated using crystal violet and confocal laser scanning microscopy. Bacteria growing in absence of CDPG were used as controls. Results: the MIC was ≥125 mg of CPDG/mL; the log10 CFU/mL reduction ranged from 2.66–3.14 to 6.23–9.65 after 4 and 24 h respectively. Generally, no growth was observed after 24 h of treatment with CDPG; the MBC was 250 mg/mL for L. casei and S. oralis while 500 mg/mL for the rest of the bacteria. The highest and lowest antibiofilm activity was observed against S. oralis and E. coli respectively. Three patterns of complete biofilm disruption were seen: (i) large areas with E. fecalis and S. oralis, (ii) medium-size pockets with S. aureus and P. aeruginosa, or (iii) small areas with E. coli and L. casei. Conclusion: CDPG can be potentially used as an antibacterial and an antibiofilm agent against oral biofilm-forming bacteria

Control of Surface Free Energy in Titanium Doped Phosphate Based Glasses by Co-Doping With Zinc

To significantly improve the biocompatibility of titanium doped phosphate based glasses, codoping with zinc has been attempted. This study investigated the effect of doping a quaternary 15Na(2)O:30CaO:5TiO(2):50P(2)O(5) glass with zinc oxide (1, 3, and 5 mol %) on bulk, structural, surface, and biological properties; the results were compared with glasses free from ZnO and/or TiO2. ZnO as adjunct to TiO2 was effective in changing density, interchain bond forces, degradation behavior, and ions released from the degrading glasses. Incorporation of both TiO2 and ZnO in T5Z1, T5Z3, and T5Z5 glasses reduced the level of Zn2+ release by two to three orders of magnitude compared with glasses containing ZnO only (Z5). P-31 NMR results for T5Z1, T5Z3, and T5Z5 glasses showed the presence of Q(3) species suggesting that the TiO2 is acting as a network former, and the phosphate network becomes slightly more connected with increasing ZnO incorporation. Regardless of their relative lower hydrophilicity and surface reactivity compared with the control glass free from TiO2 and ZnO (T0Z0), these glasses have significantly higher surface reactivity compared with Thermanox (R). This has been also reflected in the maintenance of >98% viable Osteoblasts, proliferation rate, and expression level of osteoblastic marker genes in a comparable manner to Thermanox (R) and T5 glasses, particularly T5Z1 and T5Z3 glasses. However, T0Z0 and Z5 glasses showed significantly reduced viability compared to Thermanox (R). Therefore, it can be concluded that ZnO doped titanium phosphate glasses, T5Z1 and T5Z3 in particular, can be promising substrates for bone tissue engineering applications. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 89B: 392-407, 200

Physical properties and MAS-NMR studies of titanium phosphate-based glasses

In this study, for a series phosphate-based glasses ((P2O5)(0.45)(CaO)(0.3)(Na2O)(0.25-x)(TiO2)(x) 0 <= x <= 0.15), their degradation, ion release, surface and thermal properties have been determined. The results show that adding TiO2 was associated with a significant increase in density and glass transition temperature, but a decrease in degradation rate and ion release. P-31 solid-state magic-angle-spinning nuclear magnetic resonance (MAS-NMR) showed that the local structure of the glasses changes with increasing TiO2 content. As TiO2 is incorporated into the glass, the phosphate connectivity increases as Q(1) units transform to Q(2), confirming that an increase in the nominal TiO2 content correlates unequivocally with an increase in glass stability. As reported for titania-silica gets, Ti4+ is clearly adopting a network former role in these phosphate-based glasses. Na-23 MAS-NMR results corroborate this phenomenon with a marked upfield trend of the Na-23 isotropic chemical shift suggesting that the local Na-O bond distances are decreasing within a more condensed glass network upon increased incorporation of TiO2. (C) 2009 Elsevier B.V. All rights reserved