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Biomedical subjects

A Thylstrup

Publications and source records attributed to A Thylstrup.

At least 73 records · Page 4Linked to original sources
PubMed1983

Posteruptive development of isolated and confluent pits in fluorosed enamel in a 6-year-old girl.

A 6-yr-old Danish girl born and reared in a high fluoride area in Kenya was examined for a period of 1 1/2 yr during which a permanent maxillary central incisor erupted. Present primary and permanent teeth showed obvious dental fluorosis with isolated pits on primary molars. At the time of eruption the crown of the permanent central incisor had its normal anatomical shape. Isolated and confluent pits began to develop about the time of complete eruption. The observations thus confirm previous theories suggesting that pits in fluorosed enamel are secondarily produced defects of traumatic origin.

Child↗
PubMed1982

The relationship between water-borne fluoride, dental fluorosis and skeletal development in 11-15 year old Tanzanian girls.

Dental fluorosis was evaluated by a classification system, previously shown to be sensitive, and skeletal changes evaluated by bone maturity and structure. Dental fluorosis was more severe in posterior than in anterior teeth in both jaws irrespective of fluoride concentration of the drinking water. There appeared to be no dependence between fluoride content of the water and skeletal maturity or structure, but there was a definite relationship between the degree of dental fluorosis and skeletal maturity within the high fluoride area. Fluoride concentrations in the drinking water above 3 parts/10(6) seemed to affect all mineralizing tissues under formation. The unique pattern of enamel formation and mineralization renders it the only hard tissue which permits an early diagnosis of the biological effect of even low fluoride doses on the human body.

Adolescent↗
PubMed1982

Development in dental caries among children in 1961-79 in a Danish community with school dental service.

Data on prevalence of dental caries and increment of treated teeth are reported from children receiving dental care from a Public Child Dental Health Service established in 1959. Data are obtained from records in three periods: 1961-63, 1968-70, and 1976-78. The prevalence of dental caries in 8-year-olds (n approximately 300) after initial dental care remained at the same level in 1961 and 1968. In 1976 the prevalence was reduced by 30%. Increments of treated teeth in 8-11-year-old children (n approximately 1600) were reduced by more than 50% from 1961-63 to 1968-70, but remained then at the same level in 1976-78. Increments of restored surfaces of permanent incisor teeth were reduced by 90% in 1968-70 and further by 50% to almost nil in 1976-78. These data suggest a remarkable reduction in caries activity in the population, presumably resulting from the school-based preventive programs introduced in 1960, and widespread use of fluoridated dentifrice in Denmark from 1968. The apparently maintained level of restorative work in the last period is discussed and interpreted in the light of the more favorable dentist to population ratio and the markedly reduced intervals of recall visits in the same period.

Child↗
PubMed1982

Fluoride in mixed human saliva after different topical fluoride treatments and possible relation to caries inhibition.

Fluoride concentrations in mixed saliva were measured at different intervals following topical treatments with various fluoride preparations and procedures such as dentifrice, tablets, mouthrinse and topical solution. The results were related to available caries reduction data from corresponding clinical trials previously published. Salivary fluoride levels varied widely reflecting the different dosages applied, whereas the caries reduction data irrespective of type of treatment appear very similar, with a magnitude of about 30%. When combining salivary fluoride data with recent understanding of enamel-fluoride kinetics it was possible to explain the clinical caries reductions.

Adolescent↗
PubMed1982

Skeletal development and dental fluorosis in 12--14-year-old Danish girls from a fluoride and a non-fluoride community.

The present study has examined the relationship between waterborne fluoride, dental fluorosis and skeletal maturity in two Danish areas containing less than 0.2 and 2.4 parts/10(6) F- in the drinking water. 12--14-year-old girls, 113 from the non-F- area and 122 from the F- area, born and raised in the areas, were examined. No relationship could be found between skeletal maturity and fluoride content of the drinking water. The association between the severity of dental fluorosis and skeletal maturity in the girls from the F- area was not statistically significant, but the tendency followed the same pattern as observed in tropical high and low fluoride areas.

Adolescent↗
PubMed1981

The development of enamel structure in rat incisors as compared to the teeth of monkey and man.

The rat incisor is an excellent model system in which to study amelgenesis. However, the information obtained has not been extrapolated to the human because of alleged structural differences between the teeth. The obvious differences include continuous eruption in rat incisors and an enamel rod pattern in rats which seemingly differs from the keyhole pattern of human enamel. A comprehensive analysis was made of those features of enamel structure considered fundamental to the understanding of its formation. This was done by applying the knowledge of amelogenesis obtained in rat incisors to the teeth of monkey and man. The following points of basic similarity were established between these species: (1) Interrod enamel is secreted first. It forms the side walls of cavities which are initially occupied by Tomes' processes. (2) The formation of interrod cavities is followed by deposition of enamel rods within these spaces. (3) The rods conform to the shape of the cavities and are secreted from one surface of Tomes' process. (4) At the initial site of rod deposition its enamel is continuous with the interrod enamel wall. (5) Growth of the rod compresses the process to one side of the cavity resulting in an arcade-shaped "space" between the rod and the remaining interrod walls. This study demonstrates that it is no longer necessary to postulate a keyhole structure for primate enamel, and it has established that a fundamental similarity exists in the basic structure and in the mode of formation of enamel in all three species.

Amelogenesis↗
PubMed1981

Rational use of fluorides in caries prevention. A concept based on possible cariostatic mechanisms.

The aim of this review has been to suggest that future fluoride preventive programs should be based on what is at present known about the possible cariostatic mechanisms of fluoride. The relative role of enamel fluoride in caries prevention has become increasingly questioned during the last two decades. No significant relationship has been demonstrated between caries experience of the individual and fluoride content of the enamel. Furthermore, the fluoride content in surface enamel between teeth developed in low and "optimal" fluoride areas is too small to explain any significant effect on dissolution rate of the enamel. As the major explanation for the cariostatic effect of fluoride must therefore be sought in its local effect on the oral environment, the possible effects on plaque colonization, composition and metabolic activities are discussed. The effect of even low concentrations of fluoride in the liquid phase on enamel dissolution is described, and it is concluded that the major cariostatic effect of water fluoridation, fluoride tooth paste and mouth rinses can probably be ascribed to regular increases in fluoride ion activity in the oral fluids. The effect of high concentrations of topical fluoride solutions is thought to be a result of a slow dissolution of calcium fluoride deposited in initial caries lesions, whereby an increased fluoride ion concentration is maintained locally for longer periods of time. Finally, the clinical consequences of these considerations are described.

Adolescent↗
PubMed1979

Evaluation of a pit- and fissure-sealing program in a public dental health service after 2 years.

The aim of the present study was to test the caries-preventive effect of a bis-GMA type fissure sealant (Concise Enamel Bond System) in a public dental health service for children. The study compared one group of children, in which all sound permanent teeth were sealed, and a control group in which no sealants were placed. During the study period all children received systematic restorative care, while sealing was performed on the basis of diagnoses made at subsequent examinations by one of the authors. After 2 years a total of 187 children were available for re-examination. Sealant retention was comparable to that obtained in previous studies, but no statistically significant reduction in overall caries increment could be demonstrated. Further analysis showed that only 223 sites had been sealed, while the majority of all erupting sites (394) were either carious or filled before they were screened for the purpose of sealing. It is therefore assumed that only teeth less susceptible to occlusal decay were sealed, thereby explaining the lack of benefit derived from the sealing program.

Child, Preschool↗
PubMed1979

Effect of long-term administration of fluoride on plasma fluoride and calcium in relation to forming enamel and dentin in rats.

Three groups of 1-month-old rats were kept on water containing 0.2, 56.5 and 113 parts/10(6) F-, respectively, for a period of 2 months. These groups were set up in order to study the relationship between long-term administration of high doses of waterborne fluoride, plasma values of fluoride and calcium and changes in forming dentin and enamel of the rat incisor. The microradiographic study revealed that increased levels of fluoride caused a delay in mineralization of the enamel. In the 113 parts/10(6) group the radiolucent areas in the enamel exhibited a distinct periodicity along the tooth, a phenomenon which cannot at present be explained. In the dentin the fluoride interfered with the process of mineralization giving rise to radiolucent and radiopaque banding in the experimental groups. With increasing levels of fluoride in the water supply a significant increase of plasma fluoride was recorded. In contrast the serum calcium values in both experimental groups were reduced to the same extent, which differed significantly from that of the control group. It is concluded that the fluoride doses which are needed to create fluorotic changes in rats may interfere with calcium metabolism and basic mineralization processes.

Amelogenesis↗