RESUMO
This study evaluated the effects of sodium hypochlorite (NaOC1) with different concentrations and exposure time on the structural,compositional and mechanical properties of human dentin in vitro.Sixty dentin slabs were obtained from freshly extracted premolars,randomly distributed into four groups (n=15),and treated with 1％,5％,10％ NaOC1 and distilled water (control group),respectively,for a total of 60 min.Attenuated total reflection infrared (ATR-IR) spectroscopy,Raman spectroscopy and X-ray diffraction (XRD) were carried out before,10 min and 60 min after the treatment.Scanning electron microscopy (SEM) and flexural strength test were conducted as well.The results showed that dentins experienced morphological alterations in the NaOC1 groups,but not in the control group.Two-way repeated-measures analysis of variance revealed that the carbonate:mineral ratio (C:M),Raman relative intensity (RRI),a-axis,c-axis length and full width at half maximum (FWHM) with the increase of time and concentration in the NaOC1 groups were not significantly different from those in the control group (P＞0.05).Nevertheless,the mineral:matrix ratio (M:M) increased and the flexural strength declined with the increase of concentration and the extension of time in the NaOC1 groups (P＜0.05).Additionally,it was found that the M:M and the flexural strength remained unchanged after 1％ NaOCl treatment (P＞0.05),and the morphology changes were unnoticeable within 10 min in 1％ NaOC1 group.These results indicated that NaOC1 has no significant effects on the inorganic mineral of human dentin;but it undermines and eliminates the organic content concentration-and time-dependently,which in turn influences the flexural strength and toughness of dentins.In addition,an irrigation of 1％NaOCl within 10 min can minimize the effects of NaOC1 on the structural and mechanical properties of dentin during root canal treatment.
RESUMO
China implemented the public hospital reform in 2012.This study utilized bootstrapping data envelopment analysis (DEA) to evaluate the technical efficiency (TE) and productivity of county public hospitals in Eastern,Central,and Western China after the 2012 public hospital reform.Data from 127 county public hospitals (39,45,and 43 in Eastern,Central,and Western China,respectively) were collected during 2012-2015.Changes of TE and productivity over time were estimated by bootstrapping DEA and bootstrapping Malmquist.The disparities in TE and productivity among public hospitals in the three regions of China were compared by Kruskal-Wallis H test and Mann-Whitney U test.The average bias-corrected TE values for the four-year period were 0.6442,0.5785,0.6099,and 0.6094 in Eastern,Central,and Western China,and the entire country respectively,with average non-technical efficiency,low pure technical efficiency (PTE),and high scale efficiency found.Productivity increased by 8.12％,0.25％,12.11％,and 11.58％ in China and its three regions during 2012-2015,and such increase in productivity resulted from progressive technological changes by 16.42％,6.32％,21.08％,and 21.42％,respectively.The TE and PTE of the county hospitals significantly differed among the three regions of China.Eastern and Western China showed significantly higher TE and PTE than Central China.More than 60％ of county public hospitals in China and its three areas operated at decreasing return scales.There was a considerable space for TE improvement in county hospitals in China and its three regions.During 2012-2015,the hospitals experienced progressive productivity;however,the PTE changed adversely.Moreover,Central China continuously achieved a significantly lower efficiency score than Eastern and Westem China.Decision makers and administrators in China should identify the causes of the observed inefficiencies and take appropriate measures to increase the efficiency of county public hospitals in the three areas of China,especially in Central China.