Objective To synthesize nano-hydroxyapatite(nano-HA)and evaluate its effect on the occlusion of dentinal tubules in vitro,and therefore provide evidence for the clinical application.Methods (NH4)2 HPO4 and Ca(NO3)2 were used to form nano-HA,which was characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectrometer (FTIR)and X-ray diffractometer(XRD)respectively.Twenty-four dentin slabs were obtained from 8 healthy third molars and randomly divided into 3 groups,which were control group,casein phosphopetide-amorphous calcium phosphate(CPP-ACP)group,and nano-HA group.After the CPP-ACP and nano-HA were topically applied to the slabs of two study groups twice a day for 7 days,the surface of slab dentin Was observed using SEM.Results SEM,TEM,FTIR,and XRD tests showed that nano-HA was synthesized successfully.SEM observations revealed that the sealing of dentinal tubules of nano-HA group was extremely high when compared with those of control and CPP-ACP group.Conclusions In comparison with CPP-ACP.nano-HA could occlude dentinal tubules more effectively in vitro.

OBJECTIVETo observe the changes of L929 cell membrane with atomic force microscope (AFM) after infrasound exposure and to explore the mechanisms of effect of infrasound on cell membrane.

METHODSAfter primary culture, the L929 cells were exposed to infrasound with intensity output of 130 dB and frequency of 16 Hz 2 hours each day for 3 days. The subsequent changes in the membrane of the control cells and the cells exposed to the infrasound were determined by nano-scale scanning with AFM.

RESULTSAfter infrasound exposure, the normal prominence of the membrane became short and the dent became shallow in the 7.5 microm x 7.5 microm and 4.0 microm x 4.0 microm photographs. The prominence appeared as cobblestones. The surface of the membrane became smooth.

CONCLUSIONThe membrane structure of the L929 cells can be changed by infrasound exposure with intensity of 130 dB and frequency of 16 Hz. The change might be one of the characteristics of effect of infrasound on cell membrane.

Animals ; Cell Membrane ; radiation effects ; ultrastructure ; Cells, Cultured ; Fibroblasts ; radiation effects ; ultrastructure ; Mice ; Microscopy, Atomic Force ; Sound ; adverse effects

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.

OBJECTIVETo investigate the effects of three differently concentrated at-home bleaching agents on the structure and the structure-related mechanical properties of human enamel.

METHODSSixty enamel specimens were randomly divided into four groups and treated with 10% carbamide peroxide (CP), 15% CP, 20% CP and distilled water, respectively. The bleaching process was 8 h/day for 14 consecutive days. Baseline and final atomic force microscopy (AFM) surface detection, Raman spectroscopy, attenuated total reflectance-infrared spectroscopy (ATR-IR), microhardness and fracture toughness (FT) measurements were carried out before and after bleaching experiments.

RESULTSCP didn't change the morphology of enamel. Meanwhile, the three bleached groups and the control group had no significant difference in root mean square detection (P = 0.774), ν(2)CO(3)(2-) : ν(1)ν(3)PO(4)(3-) (P = 0.263) and microhardness (P = 0.829). The percentage of relative Raman intensity in the three bleached groups and the control group were (105.74 ± 11.34)%, (104.46 ± 8.83)%, (99.52 ± 9.32)% and (97.62 ± 7.46)%, respectively. There was no significant difference among them (P = 0.062). However, the percentage of laser-induced fluorescence in the three bleached groups and the control group were (20.86 ± 7.23)%, (22.14 ± 7.34)%, (21.10 ± 7.59)% and (100.78 ± 3.70)%, respectively. There was significant difference between either of the bleached groups and the control group (P < 0.001). Moreover, FT declined significantly in the three groups (P = 0.024, P = 0.005, P = 0.013) when compared with the control group.

CONCLUSIONSUnder in vitro condition, three differently concentrated at-home bleaching agents wouldn't induce the demineralization and the decline of microhardness on enamel. However, the decrease of FT on enamel seemed to be inevitable after bleaching.

Dental Enamel ; drug effects ; Dose-Response Relationship, Drug ; Hardness ; drug effects ; Humans ; Microscopy, Atomic Force ; Peroxides ; administration & dosage ; pharmacology ; Random Allocation ; Spectrophotometry, Infrared ; Spectrum Analysis, Raman ; Surface Properties ; Tooth Bleaching ; Tooth Bleaching Agents ; administration & dosage ; pharmacology ; Tooth Demineralization ; chemically induced ; Urea ; administration & dosage ; analogs & derivatives ; pharmacology

Objective To investigate the ability in diagnosing and reporting brucellosis of primary medical personnel in Suide County of Shaanxi Province,and provide scientific basis for making prevention and control strategies.Methods Convenience sampling method was adopted in October 2016.A questionnaire survey was conducted among the county hospitals,township hospitals,village clinics and individual clinics in Suide County to collect information on the ability in diagnosing and reporting brucellosis of primary medical personnel.The specific content includes the basic information,the awareness of brucellosis diagnosis and reporting capabilities,the situation of brucellosis training,and the views about the diagnosis of brucellosis.SPSS 18.0 software was used to carry out descriptive statistical analysis.Results A total of 77 primary healthcare workers were surveyed.Their average age was (38 ± 9) years old,57.1％ (44/77) workers were undergraduates,and 53.2％ (41/77) were working in county hospitals.9.1％ (7/77) were completely aware of the major infectious diseases,29.9％ (23/77) were fully aware of the transmission mute,28.6％ (22/77) and 66.2％ (51/77) known the high risk population and the epidemiological history of brucellosis.Twenty-six percent (20/77) of the medical staff were thoroughly aware of the main clinical manifestations,68.8％ (53/77) were clearly aware of the clinical stage of brucellosis;24.7％ (19/77) could understand the specificity of the laboratory tests of brucellosis;44.2％ (34/77) had a strong ability in reporting brucellosis.71.4％ (55/77) of the medical staff received the training about the knowledge of brucellosis;49.4％ (38/77) thought that the clinical manifestation was the most difficult to grasp in the criteria about diagnosis of brucellosis.Conclusions The ability of diagnosis and reporting of brucellosis is weak in primary healthcare workers in Suide County,the epidemiology and clinical knowledge of brucellosis are not comprehensive.It is suggested to strengthen the understanding of brucellosis among medical staff,especially in primary healthcare workers.We should carry out the training of disease epidemiology and clinical knowledge of brucellosis and standardize patient management.

Objective To learn the diagnosis and treatment of brucellosis patients in Suide County of Shaanxi Province in 2015,and to provide a scientific basis for making accurate prevention and control measures.Methods All the cases diagnosed as brucellosis in Suide County from January 1 to December 31 in 2015 and lived in this county were retrospectively investigated by case questionnaire survey,including basic information,medical procedures,and epidemiological contacts.Descriptive statistical analysis was performed using SPSS 18.0 software.Results In 2015,75 cases of brucellosis were diagnosed in Suide County,75 questionnaires were distributed,with 53 completed questionnaires returned.The average age of respondents was (49 ± 14) years old,of which 84.9％ (45/53) were male and 94.3％ (50/53) were farmers,except one case was actively monitored by Suide County Centre for Disease Control and Prevention then treated,the rest of the patients were treated after the onset of the disease.Of the 52 patients,one patient was diagnosed after one visit,accounting for 25.0％ (13/52);one patient was diagnosed after at least 4 visits,accounting for 3.8％ (2/52).The cumulative diagnosis rate at provincial-level hospitals was 1/3 and that at disease prevention and control institutions was 92.7％ (51/55),there were no confirmed cases in municipal hospitals,county hospitals,township hospitals,village clinics and individual clinics.For the first reason to see a doctor,65.4％ (34/52) of the patients were fever or accompanied by sweating,fatigue,arthralgia and waist and leg pain.The medians from onset to treatment between the first diagnosis,and 2,3,4 visits were 15,18,27,45 days,respectively;the median from onset to diagnosis was 21 days,ranging from 2 to 182 days.Totally 84.9％ (45/53) patients had a history of exposure to animals,of which 97.8％ (44/45) had contacted the sheep.Conclusions The cases in Suide County are mainly adult male farmers,and the diagnosis rate at hospitals below municipal level is low.It is recommended to strengthen the health intervention of high-risk groups and improve the level of diagnosis and treatment of primary medical staff.

OBJECTIVETo evaluate the microtensile bond strength and bond interface of total-etch or self-etch adhesives to normal dentin and caries-affected dentin.

METHODSA total of 20 molars with occlusal caries lesion were used. The caries-affected dentin was obtained by removing the caries-infected dentin under the guidance of the caries detector. Beyond the level of caries-affected dentin all the enamel and partial dentin were removed. The adhesive systems, two total-etch adhesives (All-Bond 2, Prime&Bond NT) and two self-etch adhesives (Clearfil SE Bond, Xeno III) were applied respectively under the instructions of manufacturers. A block of composite resin was build up superficially. All the teeth were sectioned to obtain bar-shaped specimens with bonded surface area about 0.9 mm x 0.9 mm. The specimens were divided into normal dentin group and caries-affected dentin group via stereomicroscope. The bond strength was tested in a microtensile tester with a crosshead speed of 1 mm/min. The mean values of bond strength were compared using two-way ANOVA. The bonding interface between the dentin and adhesives was qualitatively evaluated under the observation of scanning electron microscope (SEM).

RESULTSTwo-way ANOVA revealed a significant influence of both the type of dentin and the adhesive systems tested on microtensile bond strength values. All the adhesives attained higher strength in normal dentin. In normal dentin, there was no significant difference between total-etch and self-etch adhesives. In caries-affected dentin, bond strength of Xeno III was significantly lower than the others. For SEM, the hybrid layer in caries-affected dentin was thicker but more porous than that in normal dentin. Compared with normal dentin, there was fewer resin tag exhibited in caries-affected dentin and no lateral branches were observed.

CONCLUSIONSThe total-etch adhesive had higher bond strength than self-etch adhesive systems in caries-affected dentin.

Acid Etching, Dental ; Adult ; Dental Caries ; therapy ; Dentin ; ultrastructure ; Dentin-Bonding Agents ; classification ; Humans ; Middle Aged ; Tensile Strength ; Tooth Demineralization ; therapy

Objective To evaluate the association between serum triglyeeride (TG) and the cardiovascular diseases (CVD) risk in Chinese population.Methods A total of 30,378 men and women aged 35-64 years old were recruited in the Chinese-Chinese Multi-provincial Cohort Study (CMCS).The serum TG and other CVD risk factors were measured.All subjects were followed up annually or biannually for acute CVD events from 1992 to 2004.A Cox regression model was established to identify the association between TG and risk of CVD events.Results The accumulative incidence rate of acute coronary heart disease (CHD) events increased from 62.6/100 000 in the low TG groups to 168.4/100 000 in the high TG group divided by the quartile.TG was identified as an independent risk factor for CHD after adjustment for the confounding risk factors by a Cox regression modeL Compared subjects with TG＜0.81 mmol/L,CHD risk increased 81% and 59% in subjects with TG 1.15-1.59 mmol/L and TG≥1.60 mmol/L,respectively (all P＜0.05).There was no significant association between TG level and the risks of hemorrhagic and iachemie stroke events (P＞0.05).Conclusion Serum TG is an independent risk factor for acute CHD events in Chinese population aged 35-64.

OBJECTIVETo observe the risk factors characteristic of patients developing acute coronary syndrome, ischemic or hemorrhagic stroke in a Chinese population aged 35 - 64 (n = 30 378).

METHODThis prospective study was carried out in 11 provinces in China from 1992 to 2003. The association between baseline risk factors and events in the 10-year follow-up period was analyzed.

RESULTS(1) A total of 809 events were recorded during the follow up period and 227 with acute coronary syndrome, 582 with stroke (ischemic 419, hemorrhagic 146, undefined 17) and the 10-year cumulative person-year incidence rates were 114/100,000, 209/100,000 and 73/100,000 for acute coronary syndrome, acute ischemic stroke and acute hemorrhagic stroke, respectively. (2) Rate of having > or = 1 modifiable risk factors was significantly higher in event group than that in subjects without events (89% vs. 64.7%, P < 0.01). (3) Sorted by intensity, the sequence of independently risk factors obtained from multivariate analysis for acute coronary syndrome were hypertension, smoking, hypercholesterolemia and low-HDL-C; for acute ischemic stroke event were hypertension, diabetes, low-HDL-C, smoking and obesity; for acute hemorrhagic stroke was hypertension.

CONCLUSIONThe morbidity for cardiovascular diseases is higher in Chinese population with various traditional risk factors than those without or having fewer traditional risk factors and there are various distinct independent risk factors pattern in patients with different cardiovascular diseases subtypes.

Acute Coronary Syndrome ; epidemiology ; Adult ; China ; epidemiology ; Female ; Humans ; Incidence ; Ischemia ; epidemiology ; Male ; Middle Aged ; Prospective Studies ; Risk Factors ; Stroke ; epidemiology

Objective:By analyzed the transmission patterns of 4 out of the 51 COVID-19 cluster cases in Shaanxi province to provide evidences for the COVID-19 control and prevention.Methods:The epidemiological data of RT-PCR test-confirmed COVID-19 cases were collected. Transmission chain was drawn and the transmission process was analyzed.Results:Cluster case 1 contained 13 cases and was caused by a family of 5 who traveled by car to Wuhan and returned to Shaanxi. Cluster case 2 had 5cases and caused by initial patient who participated family get-together right after back from Wuhan while under incubation period. Cluster case 3 contained 10 cases and could be defined as nosocomial infection. Cluster case 4 contained 4 cases and occurred in work place.Conclusion:Higher contact frequency and smaller places were more likely to cause a small-scale COVID-19 cluster outbreak, with potential longer incubation period. COVID-19 control strategies should turn the attention to infection prevention and control in crowded places, management of enterprise resumption and prevention of nosocomial infection.