The level of lead exposure in industrial, urban, and rural populations has been evaluated by sampling permanent teeth gathered from three regions of Belgium. When tooth lead concentrations are plotted against tooth age, a linear function appears to fit the empirical results satisfactorily. On the contrary, comparing only the arithmetical means of the three samples would bring a possible bias of the results because their mean ages are different. The slope of the three best regression lines obtained respectively with data from the three regions increases significantly in the sequence rural < urban < industrial. A simplified mathematical model shows that this slope is directly related to the mean intake of lead under uniform exposure. It is suggested that this slope could be used as an index of the population's exposure to lead.The blood lead (Pb-B) or the free erythrocyte protoporphyrin (FEP) concentrations, or both, are the most commonly used indicators of lead exposure in population surveys. They have both been used to define a "no-effect" lead concentration for children's exposure or a threshold for undue lead absorption. This threshold value has been repeatedly adjusted downwards during the past 20 years as new data have become available on the epidemiology of subclinical effects of low chronic lead exposure.The blood lead concentration is an "instantaneous" indicator that reflects immediate exposure by giving a static picture of a dynamic process that includes intake, excretion, and tissue storage. Changing the conditions of exposure (or intake) leads to a Pb-B variation within about 28 days,' and it is not, therefore, a reliable index of long-term exposure.2 3 The rate at which the free erythrocyte protoporphyrin concentration in blood changes after cessation of exposure is not known.The concentration of lead in teeth, on the contrary, is a cumulative function of earlier exposure. This retrospective look allows the identification of undetected cases of undue lead absorption whenever other indices have returned to normal. In addition, the storage of lead in the teeth of primates has been shown to be dose-dependent.4 Low but continuous lead exposure will thus be shown by the tooth lead Material and methods SAMPLINGSince May 1978 131 permanent teeth, decayed and non-decayed, have been sampled at random from children and adults of both sexes undergoing treatment in private practices or dental schools in Brussels, Hoboken, and Arlon. Clinical data and inquiry cards indicated possible treatments undergone before extraction. Teeth filled with materials suspected to contain lead were discarded. Other information (age, sex, job, home, working or school address, time spent in each place) was noted in order to assess so far as possible sources of lead exposure and their respective contribution to the total exposure of each subject. ANALYSISThe teeth were ashed for 12 hours at 450°C, then crushed. The powders were ashed for a further four hours at the same temperature, then moistened for one hour. Finally, aft...

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This study is aimed at the evaluation of a 1% clindamycin hydrochloride containing gel on the microbial flora of periodontal pockets deeper than 5 mm. In order to achieve that purpose, 20 patients with pocketing in the premolar-molar regions were selected. Active and placebo gel were inserted once during the first 2 weeks of this experimental study. Microbial samplings were performed 1, 2, 4 and 12 weeks after the experiment started. The samples were submitted to microscopic examination and also to culture. Changes in the microbial content of the periodontal pockets treated by subgingival scaling and clindamycin 1% gel were significant, compared with those obtained with subgingival scaling and placebo gel, particularly with respect to anaerobic black-pigmented bacteria and the motile gram-negative flora. However, after 3 months, most of the treated cases were recolonized by the same initial species, though never at pre-clindamycin levels. In the light of this study, it will be concluded that the use of a small amount of clindamycin hydrochloride inserted into a periodontal pocket, once a week for 2 weeks as a complement to periodontal subgingival scaling, is beneficial in the treatment of adult periodontitis, by eliminating more effectively the microbial pocket colonization.

The physiological variations of fibrinolytic activity (FA) in saliva were investigated in a population of 149 healthy volunteers including 12 pregnant women. An increase in FA could be observed with increasing age. Marked variations were observed during daytime with a peak value early in the morning. Higher FA values were observed in males as compared with females in the 20-39 yr age group. A clear decrease in FA was observed during pregnancy. A significant correlation existed between FA and suspended epithelial cell concentration, which seemed responsible for most of the physiological FA variations. It was concluded that age, sex, pregnancy, and the time of the day are important for salivary FA and should be taken into account in any study on salivary FA related to physiological or pathological processes.