Objective To investigate the effect of impression of the inherent deformation after adding the circular marker on oral impression. Methods Two metal molds were made by American Dental Association standards. Six metal circular needles were inserted on one of molds. Two groups of impression sample which named A and B were made by two metal molds. Marker line on the impressions were measured and observed by measuring microscope to compare the impressions (group A and B) with the deformation extent and the deformation law. Croup t test method of SAS6.12 software was adopted to analyze the dimensional changes of the samples. Results The deformation range of two. groups( A and B) of alginate impressions was 0.38% ～ 0.58% and 0.43% ～ 0. 66%. Two groups of silicone impressions' deformation range was 0.38% ～ 0.42% and 0.33% ～ 0.49%. There was no significant difference between the two groups (P > 0.05 ). Conclusion The method with adding markers points on the oral impression would the impression of the inherent deformation. This marking method wag feasible.

Objective To investigate the basic data of risk estimation of lung cancer among non-uranium miners in China.Methods 2836 workers from 24 mines in 9 provinces/regions were face-to-face interviewed to collect information including age at exposure,exposure duration,cigarette smoking among others.Results Age of the investigated non-uranium miners ranged from 17 to 72(36.9±8.0)years.The miners received low and poor education,3% of them were illiterate,58% with primary and middle school education,only 7% with junior college and higher education.Seventy-five percent of the uranium miners are migrant rural workers.Ethnic minority miners accoungted for 16% of all the investigated miners.Among the migrant rural workers age at initial exposure was estimated to be 29.6±8.0 years.By the time of the investigation,46.7% of the miners had worked in the mine for five years and longer,working years in the mine was 6.7±6.8 years with a median of 4.1years.3.4% of the non-uranium miners began the initial radon exposure in mines before their 18 years of old.17.5% of the investigated miners reported working more than 8 h every working day.Among the males,58.0% were current smokers with a median of 16 cigarettes per day.Age to begin the cigarette smoking was 20 years on average.Current smoking rate was age-dependent,the rate as high as 69.2% for the males aged 15-19 years.Current smoking rate was significantly statistically lower in coal mines than that in other mines,49.0% vs 62.5%.Compared with other miners,more frequent mechanical ventilations were reported by coal miners,Conclusions In China non-uranium mines,75% were migrant rural workers,by the time of the investigation about half of them had worked in the mines for at least five years.Non-uranium miners began their mining at 30 years on average,with a very small percentage of 3%,exposed to the mining radon before their 18 years.Current cigarette smoking rate in non-uranium male miners was the same as the general male population in China.

Objective To evaluate the cancer risk among the inhabitants around a certain nuclear facility of Gansu Province after operation for nearly 50 years.Methods Specially developed forms were filled by countryside doctors in the villages 30 km on the leeward or at the lower reaches of Yumen City,Gansu Province where a nuclear facility had operated for nearly 50 years,to register the relevant data of those who died of solid cancer and leukemia during the period from 1 January 2004 to 31 December 2008 based on the relevant data and household survey.A town 90 km away from the nuclear facility with 4181 people were regarded as control area.Results The crude mortality and standardized mortality rate(SMR) of cancer were 95.51×10-5 and 93.56×10-5.respectively.The crude mortality and SMR of leukemia were 2.44×10-05 and 2.22×10-05, respectively.and the crude mortality and SMR of cancer were 106.88×10-05, and 89.31×10-5, respectively.The crude mortality and SMR of leukemia were 2.44×10-05 and 2.22×10-5, respectively in the investigated area,and the crude mortality of leukemia was 3.56×10-5 (only one leukemia cage died)in the control area in the same time.The cancer and leukemia mortality rates of the investigated area were similar to those of control area.Conclusions Nuclear facility does not significantly increase the cancer mortality among the residents living nearby.