Effect of a novel radio-frequency atmospheric-pressure glow discharge plasma jet treatment on crosslinking of dentin collagen / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of a noval radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma jet on crosslinking of dentin collagen.@*METHODS@#(1) Twenty intact third molars were collected. The middle dentin discs were prepared for each tooth by low-speed water-cooled Isomet saw, and then immersed in 10% (mass fraction) H3PO4 solution for 16 h to obtain fully demine-ralized dentin collagen. The twenty dentin discs were then randomly divided into five groups. The control group was untreated while the four experimental groups were treated by plasma jet with gas temperature of 4 ℃ for different times (20 s, 30 s, 40 s, and 50 s). The structure and crosslinking degree of dentin collagen were characterized by attenuated total reflection-Fourier transform infrared spectroscopy. The surface morphology of demineralized dentin was observed by scanning electron microscope, and the microstructure was observed by transmission electron microscope. (2) Fourty non-caries third molars were collected to prepare 5 g fine dentin powder, then completely demineralized with 10% H3PO4 solution. The control group was untreated, while the four experimental groups were treated by plasma jet for 20 s, 30 s, 40 s and 50 s. The crosslinking degree of each group was determined by ninhydrin colorimetric method. (3) Forty intact third molars were collected to obtain dentin strips. Only two central symmetrical dentin strips (nasty 80) were taken from each tooth and immersed in 10% H3PO4 solution for 16 h to obtain fully demineralized dentin collagen. Eighty dentine collagen fiber strips were randomly divided into five groups. The control group was untreated and the axial surfaces of dentin collagen fiber strips in the expe-rimental groups were treated with the plasma jet for 20 s, 30 s, 40 s and 50 s. The ultimate tensile strength of dentin was measured by universal mechanical machine.@*RESULTS@#(1) The surface morphology of demineralized dentin observed by scanning electron microscope showed that the network structure of collagen fibers on the surface of demineralized dentin treated with the plasma jet for 20 s, 30 s and 40 s could maintain the uncollapsed three-dimensional structure, and part of the microstructure was destroyed after plasma jet treated for 50 s. After being treated by plasma jet for 20 s, 30 s and 40 s, the three-dimensional structure was uncollapsed, and the typical periodic transverse pattern of natural type Ⅰ collagen fiber could be seen. The results of infrared spectra showed that the secondary conformation of dentin collagen fibers was the same as that of the control group after being treated with the plasma jet, and the intensity of amide band was significantly increased after being treated for 30 s and 40 s. (2) The results of ninhydrin crosslinking test showed that the crosslinking ratio of dentin collagen treated by plasma jet for 30 s and 40 s was the highest, and the difference was statistically significant (P < 0.05). (3) The results of dentin ultimate tensile strength showed that the control group was (1.67±0.24) MPa, and the plasma jet treated 20 s, 30 s, 40 s and 50 s groups were (4.21±0.15) MPa, (7.06±0.30) MPa, (7.32±0.27) MPa, and (6.87±0.17) MPa, which were significantly different from that of the control group (P < 0.05).@*CONCLUSION@#The novel RF-APGD plasma jet treatment can promote the crosslinking degree of demineralized dentin collagen and improve their ultimate tensile strength.

Esthetic evaluation of conventional and socket shield technique immediate implant restoration / 中华口腔医学杂志

Objective: To evaluate the pink and white esthetics of conventional and socket shield technique (SST) immediate implant restoration. Methods: Thirty volunteers were recruited according to preset criteria, and were assigned to 3 groups. Natural teeth group (ten undergraduates or postgraduates from Peking University School and Hospital of Stomatology in January 2020, n=10): all volunteers' maxillary anterior teeth were natural teeth with healthy gingiva, and none of the teeth were restored by crowns or composite. Conventional group and SST group (patients had a maxillary central incisor immediate implant placed in Department of Prosthodontics, Peking University School and Hospital of Stomatology during October 2016 to January 2021, n=10 for each group): the volunteer had an unrestored natural maxillary central incisor, and the contralateral maxillary central incisor was restored by conventional or SST immediate implant placement, temporization and all ceramic final restoration, photos were taken 12 months post-surgery. Three groups of evaluators namely layperson (staff from Second Clinical Division of Peking University School and Hospital of Stomatology and 2 family members, n=10), dental students (class 2015 undergraduates from Peking University School and Hospital of Stomatology, n=10) and prosthodontists (from Department of Prosthodontics, Peking University School and Hospital of Stomatology, n=10) were invited to assess the esthetics using pink esthetic score (PES) and white esthetic score (WES). The results were statistically analyzed. Results: PES and WES of natural teeth group [9(8, 10) and 8(7, 10)] were significantly higher than conventional group [7(6,8) and 7(6,9)] (H=287.08, 132.79,P<0.01) and SST group [7(6, 9) and 8(7, 9)] (H=216.01, 101.21, P<0.01). SST group yielded higher PES than the conventional group (H=-71.06, P<0.01), yet had similar WES (H=-31.57, P>0.05). Dental students had significant lower PES and WES than prosthodontists (H=-120.90, -218.86, P<0.01) and layperson (H=-109.55, 134.97, P<0.01). Prosthodontists and layperson got similar PES (H=-11.36, P>0.05), however yielded different WES (H=-83.89, P<0.01). Conclusions: SST immediate implant placement obtained better pink esthetics than conventional protocol 12-month after implant surgery, profession may have significant impact on evaluators during pink and white esthetic evaluation.

Effect of a novel cold atmospheric plasma jet treatment with different temperatures on resin-dentin bonding / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of different treatment temperatures of a novel cold atmospheric plasma jet treatment on the resin-dentin bonding.@*METHODS@#(1) Fifty-two freshly extracted, non-carious and intact third molars were collected. The occlusal one-third of the crown was removed by means of a water-cooled low-speed Isomet saw. One dentin disc [(900 ±100) μm] was prepared for each tooth. The fifty-two dentin discs were randomly divided into control group and experimental groups, of which four were in control group, and forty-eight were divided into four experimental groups according to the different treatment temperatures (4 °C, 10 °C, 20 °C and 30 °C) of the novel radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma jet, twelve in each group. Each experimental group was divided into three subgroups according to different treatment time (10 s, 20 s and 30 s), with four in each subgroup. The occlusal one-third of the crown was removed by means of a water-cooled low-speed Isomet saw. The morphology of demineralized dentin surfaces was analyzed using field emission scanning electron microscopy. (2) Twenty unerupted, non-carious and intact third molars were randomly divided into five groups, four in each group: control group, untreated; 4 °C, 10 °C, 20 °C and 30 °C experimental groups, each group was treated with the RF-APGD plasma jet for 20 s. The micro-tensile resin dentin bond strength was tested after 20 s RF-APGD plasma jet treatment with different temperatures, using a universal mechanical machine.@*RESULTS@#(1) The field emission scanning electron microscopy results indicated that when compared with the control group, a 10 s RF-APGD plasma jet treatment with 30 °C and 20 °C collapsed the collagen scaffold. Collagen fibrils maintained an uncollapsed three-dimensional structure after the 4 °C RF-APGD plasma jet treatment for even 30 s treatment. (2) The microtensile resin dentin bond strength results of the 4 °C RF-APGD plasma jet treatment group (57.8±0.7) MPa were significantly higher than that of the control group [(47.4±0.5) MPa] and 10 s, 20 s and 30 s RF-APGD plasma treatment group [(51.9±0.7) MPa,(29.7±1.0) MPa and (22.2±1.5) MPa] with statistically significant difference (P<0.05). Compared with the control group, the micro-tensile bond strength increased about 21.9% and 9.5% after 4 °C and 10 °C RF-APGD plasma jet treatment, respectively.@*CONCLUSION@#Compared with other treatment temperatures, this novel RF-APGD plasma jet treatment with the temperature of 4 °C can preserve the three-dimensional morphology of demineralized dentin better, and can improve the resin-dentin bonding.

Prediction of Antiviral and Anti-inflammatory Mechanisms of Major Compounds from Flowers of Trollius Chinensis Based on Molecular Docking Technology / 中国中医药信息杂志

Objective To predict the antiviral and anti-inflammatory mechanisms of major compounds from the flowers of Trollius chinensis, namely, vitexin, orientin, 2"-O-β-L-galactopyranosylvitexin, 2"-O-β-L-galactopyranosylorientin, veratric acid, and trolline, by using the molecular docking technique. Methods Discovery Studio 2.5 software and Chinese Medicine Chemistry Database were employed for docking between the ligands including 6 compounds and the proteins including Toll-like receptors (TLRs) and neuraminidase (NA). The docking results and interactions of their functional domains were obtained by simulation analysis. Results Vitexin, orientin, 2"-O-β-L-galactopyranosylvitexin, veratric acid, and trolline were applied to one or more TLR, whereas 2"-O-β-L-galactopyranosylorientin could interact with neither of the proteins investigated. Flavonoids, namely vitexin, orientin, 2"-O-β-L-galactopyranosylvitexin and 2"-O-β-L-galactopyranosylorientin were applied to NA, whereas veratric acid and trolline could not interact with NA. Conclusion Five out of the 6 compounds have influence on the signaling pathways mediated by TLRs, and TLR3, 4, and 7 are their potential targets for antivirus and anti-inflammation. Four flavonoids can affect the activity of influenza virus by interacting with NA. This study can provide a basis for the investigation of the antiviral and anti-inflammatory effective compounds of the flowers of Trollius chinensis and the further development.

Biological evaluation of a novel chitosan-PVA-based local delivery system for treatment of periodontitis.

In the study, we intend to design a suitable localized drug delivery system (LDDS) with chitosan and poly vinyl alcohol (PVA) for treating serve periodontitis. For that, a novel formulation based on the incorporation of chitosan-based microspheres into PVA film was prepared. As the core parts of the novel formulation, chitosan-based microspheres were prepared form chitosan and/or carboxymethyl-chitosan (CM-chitosan) by using water-in-oil emulsification method. Then basic in vitro and in vivo experiments focusing on biocompatibility and biodegradability of the two chitosan-based microspheres were carried out to evaluate the feasibility of the novel LDDS. In vitro tests, besides having no hemolysis, chitosan microsphere (Cs1-Ms), and CM-chitosan microsphere (Cs2-Ms) have adsorbed little proteins on their surfaces. Moreover, plasma proteins adsorbed on Cs2-Ms, most of which can easily desorbed, are much less than that adsorbed on Cs1-Ms. This indicates that Cs2-Ms perhaps has better biocompatibility than Cs1-Ms. In vivo tests, Cs1-Ms and Cs2-Ms were subcutaneously implanted in rat to investigate the host tissue inflammatory response. Implantations of Cs1-Ms and Cs2-Ms induced a little more severe inflammation when compared with the implantation of PVA film. However, the difference on in vivo biocompatibility between Cs1-Ms and Cs2-Ms could not be confirmed by the implantation model of our experiments. Both Cs1-Ms and Cs2-Ms had suffered bioerosion when they were subcutaneously implanted. The hard and compact matrixes of Cs1-Ms were degraded very slowly, and only some trifling degradation had been found until 4 weeks of implantation. In contrast, Cs2-Ms is soft and more hydrophilic, and can be quickly degraded in a form of diffluence by the physiological circumstance. All these results suggested that Cs2-Ms had better potentials used as core parts of the novel designed LDDS in the future developments.

High nitrogen removal from wastewater with several new aerobic bacteria isolated from diverse ecosystems.

Three new bacteria HS-03, HS-043 and HS-047 isolated from different ecosystems were found capable of aerobic denitrification. The potential application of these strains in wastewater treatment under aerobic conditions was investigated. These three bacteria all presented high nitrogen removal from wastewater that more than 98% of 10 mmol/L nitrate could be removed in 12-24 h by adding cheap external carbon source and low concentration of iron as well as molybdate. The mechanism at molecular level was analyzed. The success of this aerobic denitrification applied to wastewater treatment may serve as an alternative to enhance the practical nitrogen removal from wastewater. Main biochemical and physiological features of these strains were characterized. The 16S rDNA sequences were compared with the published data in GenBank by using BLAST. The results of phenotype and genotype proved that strain HS-03 and HS-047 belonged to Pseudomonas stutzeri and Pseudomonas pseudoalcaligenes respectively. Strain HS-043 was identified as Delftia acidovorans of which denitrifying activity has not previously been explored.