[Study on hepatitis B virus in saliva of dental patients].

PURPOSE: To compare the detection rate of HBV antigens in different samples, and to explore the significance of saliva transmission in the spread of HBV. METHODS: Eight hundred and ninety-one ordinary saliva samples, 578 bloody saliva samples and 450 serum samples of dental patients were collected from Shanghai Sixth People's Hospital and Dahua Hospital, and HBsAg, HBsAb, HBeAg, HBeAb and HBcAb were detected by ELISA method. SPSS19.0 software package was used for chi-square test. RESULTS: There was no significant difference in gender, age and household registration between three types of saliva sample: ordinary saliva, bloody saliva and serum (P>0.05). Eight, 11 and 12 of HBV-M combination modes were detected from the above three samples. Six "HHAs" were detected from the normal saliva samples (0.67%), and the detection rate was similar to bloody saliva samples (0.87%) and serum samples (1.56%) (P>0.05). HBsAg detection rate in serum samples was significantly higher than bloody saliva and ordinary saliva (P<0.001). The difference between ordinary saliva and bloody saliva and between different age-group, sex-group, and census register group in serum samples was of no significant difference (P>0.05), and so was HBeAg. CONCLUSIONS: Saliva is an important transmission route of hepatitis B, and should be taken seriously. When the infectivity is strong, the virus content in saliva is high. Hepatitis B virus in saliva may come from other than sources except blood.

[Effect of different surface treatments on the bond strength of fiber posts to resin cement].

PURPOSE: To evaluate the effects of five different surface treatments on the bond strength between fiber posts and resin cement. METHODS: Fifty fiber posts were randomly divided into 5 groups for different surface treatments. Group A was treated with silane coupling agent (Clearfil Porcelain Bond Activator,Kuraray); Group B was treated with silane coupling agent and then coated with dentin bonding agent (Clearfil SE Bond,Kuraray); Group C was immersed in 30% H(2)O(2); Group D was immersed in 30 % H(2)O(2) and then treated with silane coupling agent; Group E received no surface treatment (control group). After bonding to resin cement, each group was then divided into 2 subgroups equally, while one group was stored in sodium chloride for 24 h at 37 degrees centigrade, and the other group was stored in sodium chloride for 24 h at 37 degrees centigrade and then subjected to thermal cycling for 10000 times. Microtensile bond strengths were tested and the data was statistically analyzed using SPSS17.0 software package. RESULTS: The microtensile bond strength before thermal cycling was (6.7±0.7) MPa for group A,(14.4±1.1) MPa for group B,(10.7±0.9) MPa for group C,(16.0±1.0) MPa for group D and (6.7±1.0) MPa for group E. After thermal cycling, the microtensile bond strength was (6.7±0.7) MPa for group A, (13.1±0.7) MPa for group B, (9.0±0.7) MPa for group C, (15.0±0.9) MPa for group D and (5.6±0.7) MPa for group E. The results showed that surface treatments had significant impact on the bond strength (P<0.05). There was no significant difference between group A and group E. Group D had the highest bond strength compared with the other groups. Microtensile bond strengths were significantly different before and after thermalcycling treatment in each group (P<0.05). CONCLUSIONS: Thermocycling treatment decreases the bond strength of fiber posts to resin cement with these 5 surface treatments. Coupled with 30 % H(2)O(2) solution and silanization, the bonding strength of fiber posts to resin cement can increase significantly.

[Investigation on noncarious hard tissue lesions of teeth in teachers of one university in Shanghai municipality].

PURPOSE: To investigate the condition of four kinds of noncarious hard tissue lesions of the teeth in teachers of one university in Shanghai municipality and provide guidance about oral health care. METHODS: The table and the standard on oral health survey authorized by WHO were adopted, condition of four kinds of noncarious hard tissue lesions of teeth in 776 teachers of East China University of Science was investigated and analyzed using SPSS16.0 software package. RESULTS: The average wedge-shaped defect teeth was 5.54±3.87, the incidence was 30.41%, caries incidence of the first bicuspid was the highest(29.52%). The incidence of tetracycline pigmentation teeth was 3.09%, the incidence of enamel hypoplasia was 2.06%, and the incidence of dental fluorosis was 1.55%. CONCLUSIONS: The average wedge-shaped defect teeth is higher than the data over the country, the incidence of dental textural anomaly is lower. The behaviors of oral health care of university teachers in Shanghai municipality remains to be further strengthened.

[Clinical survey of the association between age and maturation of cervical vertebra in 216 adolescents in Shanghai municipality].

PURPOSE: To investigate the relationship between age and maturation of cervical vertebra in 216 adolescents in Shanghai municipality. METHODS: 216 adolescents from 10 to 20 years old were investigated by lateral cephalometric radiographs. The growth status and the relationship of C2- C5 cervical vertebra were evaluated by SAS 6.12 software package with Fisher's test. RESULTS: The shapes of cervical vertebra bodies varied in regular manner. Although female went into the young quick growing period 2 years earlier than male, the shape changes had no significant difference between gender.The beginning and the peak of the puberty spurt was with great individual diversity. CONCLUSION: The morphological variation of cervical vertebra can be used as an indicator of skeletal age to determine adolescents' growth and development status.

An improved straight-line fitting method for analyzing pumping test recovery data.

Theis (1935) derived an exact solution for the residual drawdown in a well after the cessation of a pumping test by summing two drawdowns: one (s1), caused by imaginary continuation of the original pumping and the other (s2), due to an imaginary injection at the same constant rate. We approximated the Theis solution to obtain a simple linear relation for determining the transmissivity and storage coefficient from recovery data. Unlike other existing straight-line fitting methods, in our method, we applied different approximations to the well functions in the solutions of s1 and s2. We used the well-known Cooper-Jacob approximation for s1, truncating the expansion of the well function in s2 to its first three terms. For the same level of truncation errors, while the Cooper-Jacob approximation requires the argument u1