Three new cucurbitane-type triterpenoid glycosides from Citrullus colocynthis and their anti-inflammatory activity / 中国中药杂志

Three new cucurbitane-type triterpenoid glycosides were separated from the ethyl acetate extract of Citrullus colocynthis by a variety of chromatographic techniques. According to the data of NMR, HR-ESI-MS, and/or comparison with the reported data, the three novel cucurbitane-type triterpenoid glycosides were identified as colocynthenin E(1), colocynthenin G(2), and colocynthenin H(3). The cell inflammation model was established with RAW264.7 macrophages exposed to lipopolysaccharide and then used to determine the anti-inflammatory activities of the three compounds. Compounds 2 and 3 showed mild anti-inflammatory activities with the IC_(50) of 48.21 and 40.11 μmol·L~(-1), respectively, compared with that(IC_(50)=7.57 μmol·L~(-1)) of the positive control dexamethasone.

Development of novel self-adhesive resin cement with antibacterial and self-healing properties / 华西口腔医学杂志

OBJECTIVE@#This study aimed to develop novel self-adhesive resin cement with antibacterial and self-healing properties. Furthermore, the dentin bonding strength, mechanical properties, self-healing efficiency, and antibacterial property of the developed cement were measured.@*METHODS@#Novel nano-antibacterial inorganic fillers that contain quaternary ammonium salts with long-chain alkyls were synthesized. These fillers were added into self-adhesive resin cement containing self-healing microcapsules at mass fractions of 0, 2.5%, 5.0%, 7.5%, or 10.0%. The dentin shear bonding test was used to test the bonding strength, whereas the flexural test was used to measure the flexural strength and elastic modulus of the cement. The single-edge V-notched beam method was used to measure self-healing efficiency, and human dental plaque microcosm biofilms were chosen to calculate the antibacterial property.@*RESULTS@#The dentin shear bond strength significantly decreased when the mass fraction of the nano-antibacterial inorganic fillers in the novel cement reached 7.5% (P0.1). Resin cement containing 2.5% mass fraction or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilms, indicating strong antibacterial potency (P<0.05).@*CONCLUSIONS@#The novel self-adhesive resin cement exhibited promising antibacterial and self-healing properties, which enable the cement to be used for dental applications.

Application and potential future directions of self-healing polymers in dentistry / 华西口腔医学杂志

Self-healing materials have rapidly developed in recent years to overcome the micro-cracks occurring in the polymer matrix. Self-healing ability offers autonomous crack repairs to prolong the service lives of polymers or polymer composites. As a main approach, extrinsic self-healing materials based on microcapsules have been applied in dentistry recently. This paper comprehensively presented and reviewed the definition and classification of self-healing materials, the synthesis of microcapsules, the calculation of self-healing efficiency, and the application of self-healing materials in dentistry. The future directions of self-healing polymers are also discussed.

Effect of water immersion on a dental self-healing and antibacterial resin composite / 华西口腔医学杂志

OBJECTIVE@#This investigation aimed to develop a novel self-healing and antibacterial dental resin composite. The effects of water immersion on its properties were also evaluated.@*METHODS@#Microcapsules filled with healing agent of triethylene glycol dimethacrylate were synthesized on the basis of previous studies. Antibacterial resin composite contained nano-antibacterial inorganic fillers that were modified by quaternary ammonium salt with long-chain alkyl. Microcapsules were incorporated into antibacterial resin composite at mass fraction of 7.5%. A commercial resin composite named Tetric N-Ceram was used as control. The resin samples were immersed in 37 °C distilled water for different periods. A flexural test was used to measure the mechanical properties of the novel resin composite. A single-edge V-notched beam method was used to measure fracture toughness and self-healing efficiency. A dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony-forming units (CFU) and lactic acid production of biofilm on the novel resin composite were calculated to test the antibacterial property.@*RESULTS@#Mechanical properties and fracture toughness decreased significantly after the composite was immersed in water for 30 days (P0.05). Water immersion did not weaken the self-healing capability of the composite (P>0.05), and self-healing efficiency of 64% could still be obtained even after 270 days. The antibacterial resin composite showed a strong inhibition effect on the biofilm metabolic activity versus water immersion time from 1 day to 270 days. Therefore, the composite could still have a promising antibacterial property even after being immersed in water (P<0.05).@*CONCLUSIONS@#Water immersion could weaken the mechanical properties of the novel self-healing and antibacterial resin composite, but it insignificantly affected the self-healing and antibacterial properties of the composite.

Effect of laser surface hardening technology on the corrosion resistance of dental casting alloy / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of the laser surface hardening technology on the corrosion resistance of dental casting alloy.</p><p><b>METHODS</b>Twenty-three cobalt-chromium alloy specimens were made in this study. Twenty-two specimens were equally divided into two groups randomly. One was experimental group for laser surface hardening processing and the other was control group without any treatment. In each group, ten specimens were used for corrosion analysis by electrochemical method, and one for surface metallographical structure and morphology observation by scanning electron microscope. Remaining one specimen was partially processed on limited area for surface metallographical structure and morphology comparison.</p><p><b>RESULTS</b>Metal grains distributed uniformly and achieved a good refinement with mainly the same size in experimental group. Metal grains in specimen which processed in its partial surface area also achieved a good refinement in the laser processing area. There was statistical difference in electric potential of corrosion and logarithmic value of current of corrosion between experimental group and control group (P < 0.01).</p><p><b>CONCLUSION</b>Laser surface hardening technology has a positive effect in improving the corrosion resistance of dental casting alloy in artificial saliva.</p>

Effect of vacuum deposition technology on the metal-porcelain bond strength of a new type of CO-CR ceramic and framework dental alloy / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of a new engineering technique of vacuum deposition-plasma magnetron reactive sputter deposition technique on the metal-porcelain bond strength of a new type of Co-Cr ceramic and framework dental alloy.</p><p><b>METHODS</b>Before porcelain painted on the specimens, the standardized metal strips made from DA9-4 dental alloy were coated with a thin Al2O3 ceramic film by plasma magnetron reactive sputter deposition technique. The conformation, structure and thickness of the ceramic film were analyzed. The specimens for three-point bending test made from DA9-4 alloy and VMK95 porcelain were used for metal-porcelain bond strength measurement, in the same time the interface of metal-porcelain and element distribution were also observed.</p><p><b>RESULTS</b>The flexural bonding strength of metal-porcelain of sputtering group and control group were (180.55+/-16.45) MPa and (143.80+/-24.49) MPa. The flexural bonding strength of metal-porcelain of sputtering group was higher than control group significantly through statistical analysis (P<0.01).</p><p><b>CONCLUSION</b>The plasma magnetron reactive sputter deposition technique has a positive effect in improving the bonding strength of DA9-4 dental alloy and ceramic.</p>