Effect of long-term exposure to fluoride in drinking water on risks of bone fractures.

Findings on the risk of bone fractures associated with long-term fluoride exposure from drinking water have been contradictory. The purpose of this study was to determine the prevalence of bone fracture, including hip fracture, in six Chinese populations with water fluoride concentrations ranging from 0.25 to 7.97 parts per million (ppm). A total of 8266 male and female subjects > or =50 years of age were enrolled. Parameters evaluated included fluoride exposure, prevalence of bone fractures, demographics, medical history, physical activity, cigarette smoking, and alcohol consumption. The results confirmed that drinking water was the only major source of fluoride exposure in the study populations. A U-shaped pattern was detected for the relationship between the prevalence of bone fracture and water fluoride level. The prevalence of overall bone fracture was lowest in the population of 1.00-1.06 ppm fluoride in drinking water, which was significantly lower (p < 0.05) than that of the groups exposed to water fluoride levels > or =4.32 and < or =0.34 ppm. The prevalence of hip fractures was highest in the group with the highest water fluoride (4.32-7.97 ppm). The value is significantly higher than the population with 1.00-1.06 ppm water fluoride, which had the lowest prevalence rate. It is concluded that long-term fluoride exposure from drinking water containing > or =4.32 ppm increases the risk of overall fractures as well as hip fractures. Water fluoride levels at 1.00-1.06 ppm decrease the risk of overall fractures relative to negligible fluoride in water; however, there does not appear to be similar protective benefits for the risk of hip fractures.

[Study on the adsorption of collagen onto surfaces with imaging ellipsometry].

The adsorption of collagen onto hydrophilic and hydrophobic surfaces was studied with imaging ellipsometry in different pH, adsorption time, ion strength and BSA existence. The results showed that there was more collagen adsorbed onto hydrophobic surfaces than onto hydrophilic surfaces. The maximum collagen adsorption was observed at pH 7.2. The existence of BSA affected the adsorption of collagen onto hydrophobic surfaces more than that onto hydrophilic surfaces.

[Using self-assembled monolayers to understand the interactions of surfaces with cells].

It is important to understand the interactions of surfaces with cells. Self-assembled monolayers formed on the adsorption of long-chain alkanethiols to the surface of gold or alkylsilanes to hydroxylated surfaces and their patterned surfaces permit of understanding and controlling over the surface-cell interactions at the molecular scale. The present paper reviewed the latest research in using patterned self-assembled monolayers to understand surface-cell interactions.

[Clinical evaluation of manual and ultrasonic subgingival scaling using image analysis]

The objective of this study was to compare the effect of hand and ultrasonic instrumentation in removing subgingival plaque and calculus.In experiment one,forty-eight teeth from patients were randomly assigned to be scaled with curettes or ultrasonic scaler.Probing depth,clinical attachment level and bleeding index were reexamined 2 months latter.The results demonstrated that no significant differences between the two mehtods.In experiment two,seventeen teeth from six patient were also randomly scaled manualty ultrasonic or uninstrumented as a control.All these teeth were extracted immediately after subgingival scaling.The proportion of tooth surfaces covered by residual plaque and calculus(relative to the total surface area of the side of the tooth)was analysed on each tooth using computerized graphic processing.The findings showed the proportional areas of residual plaque and calculus in teeth.But the hand scaled root surface were much smoother than those treated with ultrasonic scaler.