The relationship between past caries experience and tooth color determined by an opto-electronic method.

The susceptibility of a tooth to dental caries has been proposed to depend on tooth color. So far there has, however, been no reliable method for tooth color determination. The aims of this study were to evaluate the reliability of an opto-electronic method and to examine the relationship between tooth color and past caries experience. The color of upper right central incisors of 64 school-children was determined using an opto-electronic tri-stimulus color comparator. The intra- and interexaminer reliability of the method was evaluated in vitro and in vivo being 85% and 83%, respectively. To assess the past caries experience the DMFS-index was calculated. Oral hygiene and dietary habits were also assessed. No significant difference in DMFS scores was obtained between the 'white teeth' group and the 'yellow teeth' group. The conclusion is, that the practical importance of possible colorrelated differences in caries resistance is negligible due to the multifaceted nature of dental caries.

Evaluation of a fluoride-containing varnish in children with low caries incidence.

The purpose of the present study was to investigate the caries-preventive effect of four applications during 2 years of the fluoride-containing varnish, Fluor Protector. The final series examined during the 2-year follow-up period comprised 76 girls and 87 boys, whose average age at the onset of the experiment was 12.8 +/- 0.6 years. The test was carried out as a blind study, using a half-month technique. The fluoride content of the surface enamel was measured in 40 children. The results obtained by the conventional fluoride electrode technique were compared with those obtained by the sensitive physical technique based on proton beam bombarding using bovine primary teeth. The teeth were cut longitudinally into two halves; one half was treated with Fluor Protector and the other half served as a control. Clinical examinations of the children showed that the number of carious lesions requiring active treatment was low on both the control and experimental side of the mouth. Varnish treatment did not reduce caries in these children. The fluoride content of the surface enamel was relatively high on the untreated control side, but no increasing trend was observed during the 2-year follow-up period. The fluoride content of the treated teeth was markedly elevated throughout the follow-up period. The in vitro experiments with the bovine teeth showed that etching did not release all the fluoride present in the tooth enamel.

Increment of dental caries among Finnish dental students during a period of 2 years.

The purpose of the study was to estimate the increment of dental caries among dental students in Helsinki, who acquired good knowledge of caries prevention during their studies. The group (59 students) was examined twice with an interval of 20.2 +/- 4.1 months. Clinical findings, augmented with bitewing radiographs and an orthopantomogram, were recorded separately for each tooth surface, and individual DMFS and DS index scores were computed. In addition, the students were interviewed with regard to oral hygiene, topical fluoride application, and dietary habits. The mean DMFS and DS index scores at the first examination were 45.0 and 9.1, respectively. At the second examination, DMFS was 46.4 and the number of new decayed surfaces per student 0.54/year. Both the latter values indicated that caries progression was slow. The increment of dental caries among the dental students was much smaller than that observed earlier among other groups of university students in Finland. Further evidence that caries progression among the dental students was slow was provided by the finding that of the 318 incipient caries lesions recorded at the first examination, no more than 11 had developed into clinical caries by 20 months.

Strontium-90 in deciduous teeth in Finland. A follow-up study.

Deciduous teeth of Finnish children born in 1958-1967 were analysed for strontium-90 by means of Cerenkov radiation. The strontium-90 content was about 9 pCi/gCa in children born in 1963--1964; the values decreased strongly in the subsequent cohorts of children. The strontium-90 content of the deciduous teeth varied in perfect unison with that of cow's milk (r=+0.99). The results confirm that deciduous teeth provide a practical and accurate indicator of the total body burden of bone-seeking environmental pollutants.

Strontium content of deciduous teeth in northern and southern Finland.

A possible connection has been suggested between strontium and a low prevalence of dental caries. An investigation of this subject was initiated by measuring the strontium content of deciduous teeth by atomic absorption spectrophotometry in different regions in Finland. The material analysed consisted of a total of 2,482 tooth crowns and 392 tooth roots. The results showed that the Sr content of the tooth crowns in northern Finland was about two-fold that in the south, about 400 and 200 mug/gCa, respectively. The difference was apparently caused by corresponding differences in dietary strontium. The tooth roots contained much more Sr than the crowns, about 600 and 200 mug/gCa, respectively, in southern Finland, presumably owing to changes occurring in the dietary habits of the child during the development of the crowns and roots of the deciduous teeth.

Localization and activity of various peptidases in germinating barley.

Germinating barley grains contain at least eight different peptidases: three carboxypeptidase (pH optima 4.8, 5.2, and 5.7), three aminopeptidases which act on aminoacyl-ß-naphthylamides (pH opitima in the hydrolysis of di- and tripeptides at pH 5.8-6.5), and two peptidases which hydrolyse Ala-Gly and Leu-Tyr optimally at pH 7.8 and 8.6 respectively. We have determined the activities of these enzymes in the different tissues of non-germinated grains and followed the changes in the activities during a 5-day germination at 16°C.The aleurone layers contain high activities of all three groups of peptidases; there are no changes in the activities of the five aminopeptidases on germination, while the carboxypeptidases exhibit a small increase of activity. The starchy endosperms contain high carboxypeptidase activities, which increase during germination, but are totally devoid of the five aminopeptidases.All the peptidases exhibit high activities in the scutella; the carboxypeptidases and the enzymes acting on Ala-Gly and Leu-Tyr increase in activity during germination, while the "naphthylamidase" activities remain constant.The three peptidase groups occur in the seedling as well, but compared to the other tissues the carboxypeptidase activities are very small and the "naphthylamidase" activities are very high. The last-named enzymes seem to be characteristic for growing tissues.The starchy endosperm contains about two thirds of the total reserve proteins of the grain. Its internal pH during germination is 5.0-5.2, a value at which all the carboxypeptidases are highly active. As these enzymes are present in high concentrations in this tissue, it is probable that they have a central role in the mobilization of the reserve proteins during germination. The high peptidase activities of the scutellum, on the other hand, suggest that some of the hydrolysis products are absorbed as peptides and these are further hydrolysed to amino acids in this tissue.