A polarized light microscopic study of progressive stages of enamel caries in vivo.
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Biomedical subjects
Publications and source records attributed to B Ogaard.
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The retention of alkali soluble (CaF2) and alkali insoluble (fluorapatite) fluoride in sound enamel and demineralized enamel 2 wk after application of Duraphat was investigated in a group of orthodontic patients from whom pairs of homolog premolars were to be extracted. Demineralization of the enamel was induced during a 4-wk period prior to application of fluoride by applying orthodontic bands to the premolars. The bands also remained attached to the teeth during and after application of fluoride (2 wk) to maintain a cariogenic environment. Three consecutive enamel layers (approximately 5 microns) were subsequently etched off. A significant uptake of fluoride in the first and second layer of sound enamel and in all the three enamel layers of demineralized enamel was found. More fluoride was found in demineralized enamel and a higher proportion of this fluoride was found to be in an alkali insoluble form compared with the fluoride in sound enamel. The SEM study showed a rough enamel surface after three consecutive acid etchings. The etching pattern differed within the etched area. It was suggested that the variation in etching pattern might be due to differences in orientation of the crystallites and the original surface morphology.
Microbiologic changes during caries development underneath a plaque-retaining band were investigated by the use of selective media for streptococci, Streptococcus mutans, and lactobacilli. The final four-week plaque samples on 16 experimental teeth in six young subjects were assessed. Seven experimental teeth in three other subjects were sampled at baseline and after one, two, and four weeks. All 23 experimental teeth developed a white spot lesion. In the final four-week plaque samples on the lesions, S. mutans accounted for 8% and lactobacilli 0.1% of the total CFU, both being significantly higher than in plaque from unbanded control surfaces. All experimental teeth sampled during lesion formation showed consistently elevated plaque levels of S. mutans and lactobacilli in comparison with baseline and control values at weeks one, two, and four. The results demonstrated a cariogenic environment in the human mouth associated with rapid selection of aciduric bacterial species such as S. mutans and lactobacilli.
Demineralization of enamel was induced by applying orthodontic bands in 15 patients having two of their premolars extracted for orthodontic reasons. After a 4-wk caries induction period, eight patients were instructed to rinse their teeth once daily with a neutral 0.05% NaF solution, whereas seven patients received a single treatment with a neutral 2% NaF solution. The bands were reattached to the teeth during the fluoride treatment period and the teeth were extracted after two more weeks. Three consecutive enamel layers were etched off, and a significant uptake of fluoride in all three layers were found in both treatment groups. A larger part of the deposited fluoride was retained in an alkali insoluble form (i.e. fluorapatite) compared with previous studies of sound enamel. It is suggested that the chemical conditions in the cariogenic milieu were favorable for transformation of the fluoride into a stable apatite structure.
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The present investigation was undertaken to study the plaque-inhibiting effect of a dentifrice containing stannous fluoride/stannous pyrophosphate during treatment with fixed orthodontic appliances. The test toothpaste was compared with sodium monofluorophosphate toothpaste and paste without fluoride and tin. When applied directly on the teeth, the test paste was found to reduce plaque growth significantly for 24 hours (P < 0.001). A double-blind cross-over designed study with twenty-one subjects showed statistically significant plaque inhibition after a 3-week test period on subjects showed statistically significant plaque inhibition after a 3-week test period on subjects showed statistically significant plaque inhibition after a 3-week test period on teeth with the appliances placed more than 1.5 mm. from the gingival margin (P < 0.01). Plaque reduction on teeth with the appliances placed close to the gingival margin was not statistically significant (P > 0.05). No statistically significant improvement in the gingival condition and no side effects were observed. It is concluded that because of its dual action on plaque and teeth stannous fluoride/stannous pyrophosphate toothpaste may be recommended as supplement to and not substitute for other forms of fluoride supplementation in this category of patients.