[Effects of novel bioactive glasses on promoting remineralization of artificial dentin caries].

OBJECTIVE: To investigate the effects of novel bioactive glasses (BG) including PSC with high phosphorus component and FBG with fluorine-doped element on promoting remineralization of artificial dentin caries. METHODS: (1) BGs were used in this study as follows: PSC (10.8%P2O5-54.2%SiO2-35.0%CaO, mol.%) were synthesized using phytic acid as the phosphorus precursor through sol-gel method. FBG (6.1%P2O5-37.0%SiO2-53.9%CaO-3.0%CaF2, mol.%) and 45S5(6.0%P2O5-45.0%SiO2-24.5%CaO-24.5%Na2O, mol.%) were synthesized by traditional melt method. (2) The above BGs were soaked in simulated body fluid (SBF) for 24 hours. Then X-ray diffraction (XRD) was used to analyze the formation of hydroxyapatite (HA) crystals. (3) Prepared 1 mm thick dentin slices were soaked in 17% ethylene diamine tetraacetic acid (EDTA) for 1 week to demineralize the dentin. Then the dentin slices treated by BG were soaked in SBF for 1 week. Field emission scanning electron micro-scopy (FE-SEM) was used to observe the surface morphology of the dentin slices. (4) Four cavities were prepared to 1 mm depth in each 2 mm thick dentin slice, then were treated with lactic acid for 2 weeks to form the artificial dentin caries. Wax, mineral trioxide aggregate (MTA), PSC and FBG were used to fill four cavities as blank control group, MTA group, PSC group and FBG group respectively. Then the spe-cimens were soaked in SBF for 4 weeks. The changes of depth and density of demineralized dentin were analyzed using Micro-CT before filling and after 2 and 4 weeks filling. RESULTS: (1) PSC and FBG promoted mineral formation on the surfaces of the demineralized dentin. And the speed was faster and crystallinity was higher in PSC group than the FBG and 45S5 groups. (2) The increased mineral density of artificial dentin caries in PSC group were (185.98 ± 55.66) mg/cm3 and (213.64 ± 36.01) mg/cm3 2 and 4 weeks after filling respectively, which were significantly higher than the control group [(20.38 ± 7.55) mg/cm3, P=0.006; (36.46 ± 10.79) mg/cm3, P=0.001]. At meanwhile, PSC group was also higher than MTA group [(57.29 ± 10.09) mg/cm3; (111.02 ± 22.06) mg/cm3], and it had statistical difference (P=0.015; P=0.006). The depth of remineralized dentin in PSC group were (40.0 ± 16.9) µm and (54.5 ± 17.8) µm 2 and 4 weeks respectively, which were also statistically different from the control group (P =0.010;P=0.001). There were no statistical differences between the control group and MTA group. The above effects of FBG group were between PSC and MTA. CONCLUSION: PSC has advantages in the speed, quality and depth of mineral deposition in the demineralized layer of artificial dentin caries. It would be expected to be an ideal material to promote the remineralization of dentin caries.

[Clinical efficacy observation of direct pulp capping using iRoot BP Plus therapy in mature permanent teeth with carious pulp exposure].

Objective: To evaluate the clinical efficacy and influence factors of direct pulp capping using a bioactive ceramic in mature permanent teeth with carious pulp exposure, in order to explore the feasibility and indications of vital pulp therapy for such teeth. Methods: From January 2016 to September 2017, 57 patients (57 teeth) with carious pulp exposure in mature permanent teeth were selected from the Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology. All the teeth were preoperatively diagnosed as deep caries with normal pulp or reversible pulpitis. After rubber dam isolation, all the carious dentin was removed and the exposed pulp tissue was observed under microscope. Hemostasis should be achieved within 3 min by using 2.5% sodium hypochlorite cotton pellets with a gently press. A resin composite restoration was performed immediately or 2 weeks later after direct pulp capping by using a bioceramic material (iRoot BP Plus). The patients were re-examined 12 to 50 months after operation (average 30 months) and the outcomes were evaluated by symptoms, clinical examination and X-ray. Kaplan-Meier survival analysis was used to calculate the success rate and influence factors were analyzed by Log-Rank test. Results: Totally 50 patients [age (32±13) years old (13-68 years old), 12 males and 38 females] received the follow-up examination more than one year. The overall success rate was 90% (45/50) and the success rates at 1 year, 2 years, 3 years and more were 98%, 89% and 81%, respectively. Age, gender, symptom, tooth and cavity type, pulpal exposure size and coronal restoration material had no significant correlations with the treatment outcome (P>0.05). Conclusions: Direct pulp capping of mature permanent teeth with carious pulp exposure by using iRoot BP Plus might have high success rate. There's no significant correlations between the major clinical factors and the treatment outcome.

[Physical and chemical properties of pulp capping materials based on bioactive glass].

OBJECTIVE: To investigate the physical and chemical properties of pulp capping materials based on bioactive glass (BG). METHODS: Novel BG pulp capping materials were composed of powder and fluid. The powder was BG (82.36% SiO2, 15.36% CaO, and 2.28% P2O5) synthesized by using the sol-gel method combined with template technology. Two kinds of fluid were provided: (1) phosphate buffer (PB) solution and (2) phosphate buffer solution with 1% sodium alginate (SA) addition. After mixing the powder and fluid, BG-PB and BG-PB-SA were prepared. Setting time and compressive strength of the BG pulp capping materials were tested by setting time loading system and mechanical testing machine. Statistical analysis was performed using the independent sample t-test, with the significance set at 0.05. pH meters was used to test the pH of the BG pulp capping materials and mineral trioxide aggregate (MTA). The sealing ability of the BG pulp capping materials and MTA was tested by methylene blue dye leakage model. Statistical analysis was performed using one-way ANOVA analysis and LSD multiple comparison, with the significance set at 0.05. RESULTS: (1) Setting time: the initial and final setting time of BG-PB were (7.2±0.3) min and (12.7±0.9) min, respectively. And the initial and final setting time of BG-PB-SA was (7.5±0.3) min and (13.6±1.6) min. There was no significant difference between BG-PB and BG-PB-SA groups (P>0.05). (2) Compressive strength: the compressive strength of BG-PB was (16.5±1.8) MPa at 1 day and (14.1±3.7) MPa at the end of 28 days. However, the compressive strength of BG-PB-SA was (26.6±6.3) MPa on day 1 and (21.6±5.6) MPa on day 28, which was significantly higher than that of BG-PB (P<0.05). (3) pH: the pH of BG pulp capping materials' bulk immersed in simulated body fluid (SBF) went up to 8.06, and the highest pH of MTA was 8.47. Significant difference was observed between the BG pulp capping materials and MTA (P<0.05). (4) Sealing ability: the optical density (D) in positive control group was significantly higher than ln BG-PB, BG-PB-SA and MTA groups (P<0.05). And BG-PB and BG-PB-SA showed the similar favorable sealing ability with MTA, and no significant difference was observed among the three groups (P>0.05). CONCLUSION: The novel BG pulp capping materials showed good physical properties, especially BG's setting time was short; BG pulp capping materials are promising.

[Progress of different drug delivery route of vancomycin for the treatment of chronic osteomyelitis].

Chronic osteomyelitis (COM) is an infectious disease caused by methicillin-resistant Staphylococcus aureus (MRSA), the main characteristics of COM including local dead bone formation, soft tissue infection, and repeatedly attacks. As a sensitive antibiotic, vancomycin plays an important role in the therapy of COM caused by MRSA. Currently, drug treatment is divided into systemic and topical, systemic medication is given priority to intravenous drug delivery; local drug application including local delivery device and local antibiotics lavage and regional arterial perfusion. In practice, its validity depends on whether free drug concentration of vancomycin has riched the effective concentration in the organization. Nevertheless, low concentration lead to treatment failure and even induce drug-resistance bacteria, meanwhile high concentration may cause acute renal failure. So when using vancomycin for the treatment of chronic osteomyelitis, both drug resistance and renal toxicity is as the same important as the effectiveness. Systemic administration is a targeting weak way and has many complications; topical medicate effect on the lesion can be targeted, it would be an effective way in the future treatment of COM. Different methods of delivering vancomycin have great influence on local drug concentration, which makes it become the most important factor on local drug concentration of COM.

In situ precision electrospinning as an effective delivery technique for cyanoacrylate medical glue with high efficiency and low toxicity.

The side effects or toxicity of cyanoacrylate used in vivo have been argued since its first application in wound closure. We propose an airflow-assisted in situ precision electrospinning apparatus as an applicator and make a detailed comparison with traditional spraying via in vitro and in vivo experiments. This novel method can not only improve operational performance and safety by precisely depositing cyanoacrylate fibers onto a wound, but significantly reduce the dosage of cyanoacrylate by almost 80%. A white blood cell count, liver function test and histological analysis prove that the in situ precision electrospinning applicator produces a better postoperative outcome, e.g., minor hepatocyte injury, moderate inflammation and the significant ability for liver regeneration. This in situ precision electrospinning method may thus dramatically broaden both civilian and military applications of cyanoacrylates.

Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning.

La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

Low-temperature electronic transport in single K(0.27)MnO(2)·0.5H(2)O nanowires: enhanced electron-electron interaction.

The current-voltage (I-V) characteristics and electrical resistivity of isolated potassium manganese oxide (K(0.27)MnO(2)·0.5H(2)O) nanowires prepared by a simple hydrothermal method were investigated over a wide temperature range from 300 to 4 K. With lowering temperature, a transition from linear to nonlinear I-V curves was observed around 50 K, and a clear zero bias anomaly (i.e., Coulomb gap-like structure) appeared on the differential conductance (dI/dV) curves, possibly due to enhanced electron-electron interaction at low temperatures. The temperature dependence of resistivity, [Formula: see text], follows the Efros-Shklovskii (ES) law, as expected in the presence of a Coulomb gap. Here we note that both the ES law and Coulomb blockade can in principle lead to a reduced zero bias conductance at low temperatures; in this study we cannot exclude the possibility of Coulomb-blockade transport in the measured nanowires, especially in the low-temperature range. It is still an open question how to pin down the origin of the observed reduction to a Coulomb gap (ES law) or Coulomb blockade.