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The present findings indicate that the second molar is the tooth most severely affected by dental fluorosis and dental caries. Dental caries increased with increasing severity of dental fluorosis, both in moderate- and high-fluoride areas. Thus, a positive relationship between dental caries and dental fluorosis was observed across various tooth types, in both areas.

Bjorvatn K, Selvig KA, Klinge B: Eifect of tetracyeline and SnFa on root resorpdon in replanted incisors in dogs. Scand J Dent Res 1989; 9V: 477-82.Abstract -The present study was made to assess the effect of applying SnF,, tetracycline, or both, to root surfaces of extracted teeth prior to replantation. In five young adult beagles, a total of 18 mandibular incisors were extracted, bench dried for 45 min,. and reimplanted in their respective sockets either after no further treatment or following treatment with 1 % doxycycline HGI for 5 min,, 1% SnEj for 5 min, or 1% SnF, followed by 1% doxycycline HGl. After 4 wk of healing, the relative frequency of root resorption (surface resorption, inflammatorj' resorption and replacement resorption) was approxiniately 27% of the root surface in bench.-dried as well as in doxycycline-treated specimens. By cotitrast, SnFg-treated and SnFg + doxycychne-treated teesh showed less than 1% resorption. In the latter two specimen groups an inflammatory reaction in the periodontal ligament without resorptioti occurred with a frequency of 38.3% and 11.1%, respectively. The results indicate that application of SnF^ to the root surface prior to replantation efieclively reduces resorptive processes during the first postoperative weeks. By subsequently treating the root surface with tetracycline, the adverse effect of SnFj on periodontal connective tissue repair may be reduced.

The present experiment was performed to study how fluoride from krill meal enriched muscle, whole fish and bone of adult Atlantic salmon (Salmo salar) reared in sea water. Atlantic salmon (mean weight 0.5 kg) were divided into four triplicate groups and fed a commercial fish meal based diets with 0, 100, 200 and 300 g krill kg−1 feed, respectively, for 12 weeks. The fluoride concentrations in the experimental feeds were analysed to be 18, 132, 235 and 358 mg kg−1, respectively. Growth, mortality and feed efficiency were recorded through the experiment. Fluoride concentration was measured in muscle, whole‐body, and bone initially and after 12 weeks of feeding. The fluoride concentrations in the samples were determined by alkali fusion and fluoride ion‐selective electrode. Growth, mortality and feed efficiency ratio were not affected by the dietary treatments. The results showed that fluoride concentration in muscle, whole body and bone were not affected by the dietary fluoride level. The fluoride concentration in the tissues showed great variation among replicates of the group given the same diet. Fillets of the fish varied between 0.3 and 1.4 mg fluoride kg−1 wet weight, whereas the whole‐body concentration of fluoride varied between 3.3 and 6.1 mg kg−1 wet weight and the fluoride bone concentration varied between 5.8 and 7.2 mg kg−1 fresh weight. These results suggest that Atlantic salmon are highly tolerant of dietary fluoride given as krill meal with concentration of fluoride up to 350 mg kg−1 diet, and that accumulation of fluoride from feeding diets containing krill meal does not lead to tissue accumulation in the fish, at least over a short period of time.

– The present study was done in order to examine the durability of the tetracycline‐induced antimicrobial capacity, and also to assess the reproducibility of the bacterial growth‐inhibitory assay used. Standardized enamel and dentin specimens were impregnated in aqueous solutions of tetracycline HCl, oxytetracycline HCl or doxycyclinc HCl, rinsed in water, and stored dry for 200 days. Another series of specimens was impregnated in solutions of doxycychne HCl and then rinsed in tap water for varying periods up to 35 days. In addition, drug‐impregnated specimens were used for reproducibility tests without storage or prolonged rinsing. Impregnated specimens were tested for antimicrobial capacity on agar plates seeded with S. sanguis. After 24 h aerobic incubation in 10% CO2 atmosphere, the plates were inspected and the diameter of the bacterial growth inhibition zones measured. The drug‐impregnated enamel and dentin specimens consistently demonstrated growth‐inhibitory capacity. The results of the reproducibility tests showed moderate intrasample and day‐to‐day variation. Two hundred days of dry storage or 35 days soaking in water reduced, but did not eliminate, the bacterial growth‐inhibitory capacity of the impregnated dental specimens. The results show that a short‐term exposure of dental hard tissues to tetracyclines may result in a long‐lasting antibacterial capacity.

Previous studies have indicated that inflammatory resorption and ankylosis, which are frequent sequela after delayed tooth replantation, can be greatly reduced by treating the root surface with 1% solutions of stannous fluoride and tetracycline. However, the SnF2 conditioning leaves a long‐standing inflammatory reaction in the periodontal ligament. To examine whether a more dilute SnF2 solution would reduce postoperative inflammation without jeopardizing any beneficial effects, anterior teeth in three young adult beagles were extracted and allowed to air‐dry for 45 min. They were then immersed in 0.1% SnF2 for 5 min, rinsed in saline, immersed in 1% doxycycline HC1 for 5 min, rinsed, and replanted. Control teeth were air‐dried and replanted without further treatment. Block biopsies were harvested after 4 wk of healing and processed for histometric analysis. In experimental teeth, 85% of the root surface area showed normal healing, compared to 33% in control teeth. Conversely, resorption and ankylosis were more frequent in controls than in experimental teeth. A persisting inflammatory reaction either adjacent to or at a distance from the root surface was seen in limited areas in both experimental and control teeth. Compared to preceding studies, the findings indicate that reducing the strength of the SnF2 solution from 1% to 0.1% may result in less persistent inflammation, at the cost, however, of less complete prevention of inflammatory resorption and ankylosis.

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