The sources of laser Doppler blood-flow signals recorded from human teeth.

Records of pulpal blood flow obtained from human teeth with a laser Doppler flowmeter include a very large component derived from periodontal and other tissues outside the pulp, but this contamination can be reduced by covering the surrounding tissues with opaque rubber dam. The present experiments were carried out to determine what proportion of the signal obtained with this dam in place is derived from non-pulpal tissues. Recordings were made from 22 healthy, intact upper incisors in 14 individuals (aged 22-40 years) with and without dam under the following conditions: from the intact teeth, after local anaesthesia (LA) and the preparation of a deep cavity in the incisal third of the labial surface of the tooth, and after removal of the pulp and arrest of bleeding. In some cases, a reading was also made after replacing the pulp in the pulp cavity. The rubber dam reduced significantly (P<0.05) the mean blood flow reading from the intact teeth by 73%, from 6.98 arbitrary perfusion units (PU) (+/-1.30 S.D., n=22) to 1.92+/-1.50 PU. After LA and cavity preparation, the mean signal with dam was 1.45+/-0.61 PU (n=16). This fell significantly by 76% to 0.35+/-0.19 PU (n=16) when the pulp was removed but not replaced, and by 43% to 0.98+/-0.36 PU (n=14) when the pulp was removed and replaced in the pulp cavity. The latter condition is thought to reproduce most closely the scattering of light in an intact tooth. The results confirm previous findings that up to 80% of the laser Doppler blood-flow signal recorded from an intact human tooth without rubber dam is of non-pulpal origin. They also show that only approximately 43% of the signal recorded with an opaque rubber dam is from pulp.

Fluoride in water consumed by children in remote areas of Thailand.

The objective of this study was to analyze fluoride content in water for drinking and for use in remote areas of Thailand. Water was sampled from schools and villages along the border by Multiple Stratified Cluster Random Sampling. Fluoride levels of 214 water samples from 48 schools and 48 villages were assessed in triplicate by fluoride ion electrode. The fluoride content in different regions and types of water were statistically analyzed by Kruskal-Wallis test at a significance level of 0.05. Results showed that fluoride in drinking water and water for use from the schools and villages were 0.01-0.37 ppm, 0.01-0.19 ppm, 0.01-0.87 ppm and 0.01-0.92 ppm, respectively. There was no difference in fluoride content in drinking water from various regions (p=0.23). However, there was a statistical difference in fluoride level in water for use (p=0.04, p=0.01) in various regions. The highest fluoride content was found in samples from the central and eastern region (0.19+/-0.24 ppm and 0.29+/-0.28 ppm respectively). When comparing types of water, ie ground water, surface water and rain water, there were differences in fluoride content (p=0.0). Underground water had the highest fluoride content (0.31+/-0.23 ppm).

Dietary fluoride intake of children aged 3-7 years in remote areas of Thailand.

The objectives of this study were to measure dietary fluoride intake in children aged 3-7 years, to correlate dietary fluoride and fluoride content in water for use in schools and to estimate fluoride gained from the daily diet. Fifty food samples were collected in 45 schools under the jurisdiction of the Border Patrol Police Department. The schools were sampled by multiple stratified cluster random sampling. The food samples were weighed, then measured for fluoride content by a microdiffusion method. Statistical analysis was conducted using the Kruskal-Wallis test. Dietary fluoride in each age group was compared by Student's t test. Analysis for the relationship between dietary fluoride and fluoride content in water was done using Kendall's tau-b. Our results showed that the mean of dietary fluoride in lunch was 0.08 +/- 0.1 ppm. There were no differences when comparing dietary fluoride between different regions of Thailand (p = 0.07). No correlation was found between dietary fluoride and fluoride content in water used in different schools (r(tau) = 0.017, p = 0.85). The daily dietary fluoride intake in children aged 3-6 years was 0.002-0.004 mgF/kg bw/day, in children aged 7 years was 0.003-0.004 mgF/kg bw/day in boys and 0.002-0.004 mgF/kg bw/day in girls.

Fluoride analysis of human milk in remote areas of Thailand.

The objective of this study was to measure the fluoride content in human milk collected from mothers living in remote areas of Thailand and to correlate it with fluoride concentrations in drinking water and water for domestic use. Four to five ml of breast milk were sampled from mothers living in villages where schools under the jurisdiction of the Department of Border Patrol Police were located. The schools were sampled by Multiple Stratified Cluster Random Sampling. Fluoride was determined by microdiffusion method. Statistical analysis were made by ANOVA and LSD test. Correlation between fluoride content in milk and water was assessed by Kendall's tau-b. The mean fluoride concentration in breast milk was 0.017+/-0.02 ppm. There was no difference in breast milk fluoride concentration between regions (p=0.6). No correlation was found between breast milk fluoride content and fluoride concentrations in either drinking water or water for domestic use (r(tau) = -0.09, p = 0.32, r(tau) = -0.04, p = 0.65 respectively).