[Study on preparation of breviscapine liposomes and chemicophysical properties].

OBJECTIVE: To prepare breviscapine pro-liposomes and evaluate its properties and stability, as well as its interaction with the mimic-membrane. METHODS: Breviscapine liposomes were prepared by thin film-lyophilization method. Phase inversion temperature was measured by electrical conductance method and coalescence kinetics was studied. Water/n-octanol trans-membrane diffusion model was designed to study the dynamic distribution behavior between two phases, through the determination of diffusion rate of breviscapine and liposomes. RESULTS: The phase inversion temperature was 63 degrees C, the activity energy for coalescence was 14.66 kJ/mol. The results suggested that breviscapine from liposomes staying on the interface were found more than the breviscapine infusion. CONCLUSION: Breviscapine liposomes prepared with thin film-lyophilization method have good physicochemical properties and stability, which is beneficial to treatment.

[The effect of Duraphat varnish on fluoride content of enamel in deciduous teeth].

PURPOSE: The aim of this study was to analyse the fluoride distribution in deciduous teeth enamel after using Duraphat varnish,and to supply the evidence for preventing deciduous caries by using Duraphat varnish. METHODS: After coating Duraphat varnish, the alteration of fluoride distribution in the enamel was observed with electron probe micro-analysis. The result was compared with the control group and NaF solution group. The effect of dose and period of coating Duraphat varnish on fluoride distribution in enamel was evaluated by X-ray photo-electron spectrometer(XPS). The data was analyzed with SPSS17.0 software package. RESULTS: The mean values of fluoride concentration in the control group, NaF group and Duraphat varnish group were(0.0406±0.0234)wt%,(0.1006±0.1040)wt% and (0.1844±0.1293)wt%,respectively.The concentration of fluoride in the Duraphat varnish group was significantly higher than that in the NaF group (P<0.01). In period-dependent test,the mean values of fluoride concentration at 10µm under the enamel surface of short period group and long period group were(0.2407±0.0034)wt%, (0.1434±0.0133)wt%; The concentration of fluoride in the short period group was significantly higher than that in the long period group(P<0.01). In dose-dependent test, the mean values of fluoride concentration at 10µm under the enamel surface in the low-dose group and high-dose group were(0.4417±0.0034)wt%,(0.4413±0.0044)wt%, the concentration of fluoride in the low-dose group and high-dose group had no significant difference(P>0.05). CONCLUSIONS: It is an effective way to increase the concentration of fluoride in enamel by coating Duraphat varnish on the surface of deciduous teeth. Shorten the coating period could increase the concentration of fluoride in enamel effectively but the concentration of fluoride in enamel does not go up along with the coating dose increase.

[In vitro study of the secondary mesiobuccal canal of the maxillary second molar].

OBJECTIVE: To get some anatomical knowledge about the second mesiobuccal canal (MB2) of the maxillary second molar of Shandong region by studying the teeth in vitro. The anatomical knowledge may help us to improve the successful rate of root canal therapy of the maxillary molar. METHODS: 118 maxillary second molars were collected from the different region in Shandong province. Oblique square of pulp opening form was used, then root canals were detected and got through by C-type file. The rate of MB2 detection and getting through was recorded. By taken X-ray, the numbers, the morphologies and classifications of the root canal systems of these molars were recorded. Then the distance between mesiobuccal canal (MB) and MB2 was observed and measured by endodontic operating microscope and digital measurement. At last, we observed the apical foramen from the surfaces of these teeth, and try to analysis the differences between apical foramen and the end points of the roots. RESULTS: The rate of MB2 detection was 49.15%, among them 82.76% could be got through by files. 108 molars had three roots, among them, for the mesiobuccal root canal system, 46.30% were I root canal system, while II and III systems were 12.96% and 31.48%, respectively. The distance between MB and MB2 was 1.26 mm averaged. The distance between anatomical apical holes and the end points of roots was 1.13 mm averaged. CONCLUSION: MB2 can be detected in most of maxillary second molars in Shandong region. The dentists should try to detect MB2 in the root canal therapy, and should judge work length by clinical behavior and apical locator rather than by X-ray alone.

[Measurement and analysis of optical density in dentine of 32 primary teeth].

PURPOSE: To study the optical density (OD) of primary dental dentine and provide data for further research. METHODS: The Digora system of dental digital radiography was used to acquire digital radiographic images of cross sections from 32 deciduous maxillary central incisors, and to measure the OD values of different depth (outer, middle and inner layers) and four sides (mesial, distal, labial and palatal sides) in dentine. The difference was analyzed with one-way ANOVA and SNK using SAS 6.12 software package. RESULTS: The OD value of inner layer dentine was significantly lower than that of outer and middle layers (P=0.002), but there was no significant difference among four sides of dentine (P=0.0997). CONCLUSIONS: OD value is an indirect physical quantity of dental mineralization, it provides a convenient digital indicator for the research of dental hard tissues.