摘要:

The prevalence and distribution of dental caries was studied in 820 Nigerians aged 15, 19, 20 or 21 years from Lagos educational establishments. In contrast with observations in most Western countries, caries experience in Lagos was observed to be low, the mean DMF value being less than 2 at all ages. Irrespective of age, sex, tribe or social class, the ratio of DFS to DFT was constant at about 1.3, while the mean DMF value remained constant at between 3 and 4 in those persons with at least one tooth decayed, missing or filled. Furthermore, the caries vulnerability difference between first and second permanent molars was independent of the jaw affected or social class.

ISSN:0008-6568    

DOI:10.1159/000260407

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

A highly reproducible seeded growth method has been used to study the mineralization of calcium phosphate on human enamel and hydroxyapatite seed crystals at a pH of 7.4 and at 37 °C in stable supersaturated solutions of calcium phosphate containing various concentrations of fluoride ion. The pH and pF values were maintained constant potentiometrically by the addition of potassium hydroxide and potassium fluoride, respectively, and the grown material was characterized chemically, by infrared spectroscopy, by scanning electron microscopy and by subsequent dissolution kinetic experiments. Low concentrations of fluoride (∼ 0.15 ppm) reduce the rate of crystallization in the initial stages, but an enhancement of calcium phosphate mineralization is observed in the presence of higher fluoride concentrations (1–5 ppm). Whereas the stoichiometry of the first-formed surface phase corresponds to that of octacalcium phosphate in the absence of fluoride, higher molar calcium/phosphate ratios are indicated in its pres

ISSN:0008-6568    

DOI:10.1159/000260408

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Fluoride has been shown to be an effective agent for prevention of dental caries. It has also been shown that a major portion of this fluoride deposited onto the enamel by topical treatments is rapidly leached away. This in vitro study suggests that fluorosilanes enhance retention and improve penetration of fluoride in enamel. The efficacy of this treatment seems to lie in its ability to utilize the enamel organic network as a conduit. This network increases the enamel prism surface area accessible to reaction with fluoride. This study demonstrates the effectiveness of silanes as a vehicle to transport fluoride via the organic network to loci best suited for therapeutic effectiveness.

ISSN:0008-6568    

DOI:10.1159/000260409

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

In 1969, a caries preventive program was initiated in a part of Denmark where parents of infants were offered prescriptions for fluoride tablets for daily use. When requested new prescriptions were supplied free of charge by the County Dental Officer. In 1976, samples of children about 7 years of age who had received a total of 0, 1–800, 800–1,600 and more than 1,600 0.25 mg F tablets were examined. A positive association between number of tablets prescribed and dental fluorosis was found in erupted permanent teeth. The frequency of localized enamel opacities was similar in the four study groups. A significant inhibition of dental caries in the primary dentition was recorded only for those, who in total received more than 1,600 tablets and used them continuously through the years. No difference in caries was observed in the permanent dentition. The findings indicate in accordance with current theories that topical effects of fluoride rather than the systemic effects have prevented dental car

ISSN:0008-6568    

DOI:10.1159/000260410

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

High resolution TEM made it possible to study acid dissolution of biological and synthetic apatite crystals at the lattice pattern level. It was shown that acid dissolution starts at the dislocation level and proceeds more frequently according to lattice families with large d spacings, i.e., (100), (110), (101) and equivalents. Acid dissolution is preferential according to the c axis, due to the existence of dislocations and probably to variations occurring in the composition and organization of the solid phase. It was hypothesized that Mg ions could help organizing a nucleation phase remaining in the central part of mature crystallites and that incorporation of fluoride ions to the lattice, related to dislocations, could stop diffusion process and progress of dissolution.

ISSN:0008-6568    

DOI:10.1159/000260411

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

In this study, Knoop hardness experiments on artificial carious enamel (pH 5.0, 4.5 and 4.0) are presented with the load perpendicular to the subsurface lesion. The results show that for human and bovine enamel the indentation length is proportional to the square root of the load. The proportionality constant is numerically estimated for all pH values for human and bovine enamel. The indentation measurements reflect the decalcification despite the presence of surface layer covering the lesion.

ISSN:0008-6568    

DOI:10.1159/000260412

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260413

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260414

出版商:S. Karger AG    

年代:1979

数据来源: Karger