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Objective: To compare ProTaper Universal(PU),ProTaper Next(PN),WaveOne(WO) and M3 in the preparation of simulated curved canals. Methods: 40 simulated root canals were made from translucent resin and randomly divided into 4 groups(n = 10),the canals were prepared by PU,PN,WO and M3 respectively. The efficacy of canal preparation was analyzed. The pre-instrumentation and post-instrumentation images were recorded and the assessment of the canal shape was completed with Photoshop cs6 and Image Pro Plus6. 0. The apical transportation indexes and the amounts of apically extruded debris were measured. Results: WO was the most time-saving in mean working time(P ＜ 0. 05). PN and M3 took less time than PU in shaping the canals at the most levels(P ＜ 0. 05; PN vs M3,P＞ 0. 05). The amounts of apically extruded debris by PN was less than by PU,WO and M3(P ＜ 0. 05). The apical transportation by PN and M3 was less than that by PU and WO(P ＜ 0. 05). Conclusion: WaveOne is the most time-saving in shaping root canals. ProTaper Next and M3 are more effective and time-saving than ProTaper Universal in shaping root canals. ProTaper Next and M3 are comparable for optimally enlarge root canal.
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Objective To evaluate the shaping ability of ProTaper Universal (PU), ProTaper Next (PN) and M3 in preparation of curved root canals by CBCT (cone-beam computed tomography). Methods Sixty extracted maxillary first premolars were divided into two groups according to the canal curvature:10°-25° group and 26°-75°group. Then, each group was divided into PU group, PN group and M3 group and prepared with three instruments respectively. Canals were scanned by CBCT scanner before and after preparation. The efficacy of canal preparation was analyzed. The width of dentine removed was measured at three points (2 mm, 5 mm and 8 mm to root tip). The apical transportation indexes and the centring ratio values were recorded. Results PN group and M3 group needed less time in preparation and showed more efficiency than those of PU group in 26°-75° groups. One of root canals in PU group appeared deformation, neither PN group nor M3 group appeared deformation after 5 root canal preparations in average. None instrument was broken in three groups. PU group removed more materials at internal walls than PN group and M3 group at internal walls of root canals in 5 mm from the apex. There was no difference in the offset of the external walls of root canals. Compared with the offset of the internal and external walls of root canals in 2 mm from the apex, the apical transportations prepared by the PN group were less than those of M3 group and PU group in 26°-75° groups. Compared with the offset of the internal and external walls of root canals in 5 mm from the apex, the apical transportations prepared by the PN group and M3 group were less than those of PU group, and their centring ratio values were greater than those of PU group in 26°-75°groups. Conclusion ProTaper Next and M3 tested in this study are effective and time-saving in shaping curved root canals. The results indicate that both ProTaper Next and M 3are comparable to optimally enlarge root canal.
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Objective:To observe the effect of storage period of three experimental dentin self-etching primers on the shear bond strength.Methods:Three experimental primers with 2-hydroxyethyl methacrylate (HEMA)or N-methacryloyl glycine (NMGly)as a hydrophilic monomer and 1 0-methacryloxydecyl dihydrogen phosphate(MDP)or N-methacryloyl-2-aminoethylphosphonic acid (NMEP) as an acid monomer,were designed.Immediately after preparation of the samples of MDP-HEMA,MDP-NMGly and NMEP-NMGly, the primers were stored at 40 ℃for 0,6 and 1 4 weeks.At the end of each storage period,the shear bond strength of resin to dentin(n=1 4)and the pH value of the primers were measured.Results:After storage at 40 ℃ for 1 4 weeks,the shear bond strength of MDP-HEMA decreased from (1 7.61 ±1 .56)MPa to (7.53 ±1 .76)MPa;however the bond strenth of MDP-NMGly and NMEP-NMGly did not decrease;most of the specimens of MDP-HEMA and MDP-NMGly exhibited an interfacial failure of the resin from the dentin sur-face;however NMEP-NMGly exhibited a cohesional failure of the dentin and/or resin.The SEMimages showed a separation of resin and dentin of MDP-HEMA and MDP-NMGly had storaged at 40 ℃for 1 4 weeks;while the interface of NMEP-NMGly did not change.Con-clusion:The NMEP-NMGly primer has noticeably higher hydrolytic stability than the MDP-HEMA and MDP-NMGly primers.
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<p><b>OBJECTIVE</b>To study the community characteristics of Acanthopanax giraldii and its role and adaptability in the community.</p><p><b>METHOD</b>The methods of community ecology were used to investigate vegetation composition in different sample plots and the number of the clumps and clonal ramets. The importance value of species and biodiversity index of each plot was calculated. The life form spectra in different community were counted. The chi-square test was applied to analyze the dependence degree of A. giraldii to other main shrub species in the community.</p><p><b>RESULT</b>The investigation had showed that A. giraldii community could be divided into three types. The number of A. giraldii population in each type had great difference. Statistical analysis had shown that there's no correlation between the growth of A. giraldii with biodiversity and no significant interspecific association between A. giraldii and other main shrub species in the community yet.</p><p><b>CONCLUSION</b>The population growth of A. giraldii was sensitive to Sunshine. A. giraldii maybe has the biological characteristics for artificial planting as a single population.</p>
Subject(s)
China , Ecosystem , Eleutherococcus , ClassificationABSTRACT
<p><b>OBJECTIVE</b>To study age structure and medicinal parts biomass accumulation of Acanthopanax giraldii population in West Sichuan Plateau.</p><p><b>METHOD</b>The methods of plant population ecology were applied to the study. The ramets of A. giraldii were collected in sample plot, survey the age, height, basal diameter and biomass of ramets,and also survey the number,stem bark height and length of the one-year-shoot growing in clonal ramets. Then statistically analyzed the survey data.</p><p><b>RESULT</b>The article revealed growth rule of A. giraldii population. The mortality rate of clonal ramets reached a peak after six years growth. The power exponential fuction could reflect the correlation of age to the height, basal diameter and biomass of ramets. The production of medicinal parts was stable between two to six years growth of clonal ramets.</p><p><b>CONCLUSION</b>Suggested to harvest medicinal parts after three years growth of the clonal ramets. The study could provide biologic basis to population management and sustainable harvest of A. giraldii.</p>
Subject(s)
Biomass , Ecosystem , Eleutherococcus , Chemistry , Plant Extracts , Time FactorsABSTRACT
Objective To explore the protective affect of individual earmuffs in microtia reconstruction using tissue expander.Methods 95 patients performed the implantation of tissue expander had been grouped into the experimental group(49 cases)and the control group(46 cases).Patients in the experimental group wore individual earmuffs,whereas patients in the control group wore traditional earmuffs.The survey including the information of patients' experience in wearing the earmuffs was carried out on the day when patients were given auricular reconstruction.Data collected from the two groups were analyzed to evaluate the aspects of permeability and safety.Results Patients in the experimental group complained less discomfort in sultry in permeability and tinnitus than patients in the control group.From the perspective of safety,there was no complaints of mosquitoes climbing into the earmuffs from the two groups.Because of the good adhesiveness of the individual earmuffs to the skin,the incidence of redness of skin in the experimen tal group was significantly lower than that in the control group.Conclusions Individual earmuff is a safe and comfortable nursing appliance which is practical for clinical application because of its good permeability,adhesiveness and less incidence of redness of skin.
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The present study is conducted to review and analyze the postgraduate education on clinical medicine in Xinjiang Medical University from 1998-2008. The results indicate that there is still room to make progress in terms of guaranteeing the quality of the newly-en-rolled students,promoting the training of minority postgraduates,the development of clinical training base,and in terms of clinical ability assessment.