The inhibitory effect of a novel neem paste against cariogenic bacteria

Dental caries is a major oral health problem, which associates with cariogenic bacteria. Streptococcus mutans and Lactobacillus acidophilus are facultative anaerobic bacteria that are found in tooth decay. Accordingly, neem leaf extract was developed du

Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation

Metal ions originating from mechanical debris and corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+), which is a major component of cobalt–chromium-based implant alloys and a known activator of osteolysis, are incorporated into the mineral phase of bone. We hypothesize that the accumulation of Co2+ in the mineral could directly activate osteolysis by targeting osteoclasts. To test this hypothesis, we coated tissue culture plastic with a thin layer of calcium phosphate (CaP) containing added traces of Co2+, thereby mimicking the bone mineral accumulation of Co2+. Murine bone marrow osteoclasts formed in the presence of M-CSF and RANKL were cultured on these surfaces to examine the effects of Co2+ on osteoclast formation and resorptive activity. Treatment conditions with Co2+ involved incorporation into the CaP layer, adsorption to the mineral surface, or addition to culture media. Micromolar concentrations of Co2+ delivered to developing osteoclast precursors by all 3 routes increased both osteoclast differentiation and resorptive function. Compared to CaP layers without Co2+, we observed a maximal 75% increase in osteoclast numbers and a 2.3- to 2.7-fold increase in mineral resorption from the tissue culture wells containing 0.1 μm Co2+ and 0.1–10 μm Co2+, respectively. These concentrations are well within the range found in peri-implant tissues in vivo. This direct effect of Co2+ on osteoclasts appears to act independently of the particulate phagocytosis/inflammation-mediated pathways, thus enhancing osteolysis and aseptic implant loosening

Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation

Metal ions Originating from mechanical debris and Corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+) which is a major component of cobalt-chromium-based implant alloys and a known activator of osteolysis, are incorporated into the mineral phase of bone. We hypothesize that the accumulation of CO2+ in the mineral could directly activate osteolysis by targeting osteoclasts. To test this hypothesis, we coated tissue culture plastic with a thin layer of calcium phosphate (CaP) containing added traces Co2+ thereby mimicking the bone mineral accumulation of Co2+. Murine bone marrow osteoclasts formed in the presence of M-CSF and RANKL were cultured on these surfaces to examine the effects of Co2+ on osteoclast formation and resorptive activity. Treatment conditions with Co2+ involved incorporation into the Cap layer, adsorption to the mineral Surface, or addition to Culture media. Micromolar concentrations of Co2+ delivered to developing osteoclast Precursors by all 3 routes increased both osteoclast differentiation and resorptive function. Compared to CaP layers without Co2+, we observed a maximal 75% increase in osteoclast numbers and a 2.3- to 2.7-fold increase in mineral resorption from the tissue culture wells containing 0.1 mu m Co2+ and 0.1 - 10 mu m Co2+, respectively. These concentrations are well within the range found in peri-implant tissues in vivo. This direct effect of Co2+ on osteoclasts appears to act independently of the particulate phagocytosis/inflammation-mdiated pathways, thus enhancing osteolysis and aseptic implant loosening. (C) 2008 Elsevier Ltd. All rights reserved

Assessment of Physical/Mechanical Performance of Dental Resin Sealants Containing Sr-Bioactive Glass Nanoparticles and Calcium Phosphate

The aim of this study was to assess the chemical/mechanical properties of ion-releasing dental sealants containing strontium-bioactive glass nanoparticles (Sr-BGNPs) and monocalcium phosphate monohydrate (MCPM). Two experimental sealants, TS1 (10 wt% Sr-BGNPs and 2 wt% MCPM) and TS2 (5 wt% Sr-BGNPs and 4 wt% MCPM), were prepared. Commercial controls were ClinproXT (CP) and BeautiSealant (BT). The monomer conversion (DC) was tested using ATR–FTIR (n = 5). The biaxial flexural strength (BFS) and modulus (BFM) were determined (n = 5) following 24 h and 7 days of immersion in water. The Vickers surface microhardness (SH) after 1 day in acetic acid (conc) versus water was tested (n = 5). The bulk and surface calcium phosphate precipitation in simulated body fluid was examined under SEM-EDX. The ion release at 4 weeks was analyzed using ICP-MS (n = 5). The DC after 40 s of light exposure of TS1 (43%) and TS2 (46%) was significantly lower than that of CP (58%) and BT (61%) (p < 0.05). The average BFS of TS1 (103 MPa), TS2 (123 MPa), and BT (94 MPa) were lower than that of CP (173 MPa). The average BFM and SH of TS1 (2.2 GPa, 19 VHN) and TS2 (2.0 GPa, 16 VHN) were higher than that of CP (1.6 GPa, 11 VHN) and BT (1.3 GPa, 12 VHN). TS1 showed higher Ca, P, and Sr release than TS2. Bulk calcium phosphate precipitation was detected on TS1 and TS2 suggesting some ion exchange. In conclusion, the DC of experimental sealants was lower than that of commercial materials, but their mechanical properties were within the acceptable ranges. The released ions may support remineralizing actions