摘要:

Chemical analysis and the appearance of developing enamel from deciduous bovine incisors have distinguished four stages during the process of development: (1) secretion of soft, translucent, partially mineralised enamel; (2) withdrawal of matrix from the soft enamel; (3) secondary mineralisation of the increasingly rigid enamel; (4) emergence of hard, translucent, mature tissue.

ISSN:0008-6568    

DOI:10.1159/000260309

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260358

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260359

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Hydroxyapatite (HA) discs were treated for 1 min with fluoride solutions of varying concentrations and pH. The calcium fluoride and fluoridated hydroxyapatite (FHA) formed were analysed independently of each other following their separation in molar potassium hydroxide. Only the more intimately associated FHA was found to affect the rate of acid dissolution of HA and its level of formation and the reduction in acid dissolution rate of HA were both found to be linearly related to the logarithm of the ionic fluoride level in the treatment solution following 1 min. pretreatment. The benefit of using acidulated fluoride treatment of enamel is questioned as neutral fluoride treatments of enamel mineral resulted in equivalent protection.

ISSN:0008-6568    

DOI:10.1159/000260310

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260361

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Cellular fatty acids and extractable intact lipids of five strains of Streptococcus mutans grown on chemically defined medium were studied. The fatty acids were characterized by the predominance of the C16:0 and C18:1 components as well as traces of cyclopropane acids. The neutral lipids showed the presence of glycerides and the isoprenoids squalene and ficaprenol. The glycolipids consisted mainly of diglucosyldiglycerides accompanied in lesser amounts by the monoglucosyl analog. The phospholipids included, in addition to cardiolipin and phosphatidylglycerol as the major constituents, phosphatidylcholine. This fraction was also found to contain the sugar and sugar phosphate derivatives of ficaprenol.

ISSN:0008-6568    

DOI:10.1159/000260311

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260362

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Sprague-Dawley rats were subjected to a 56-day caries test regimen when they were infected with S. mutans strain 6715 or 10449 at 18, 19, 20, 21, 22, 23 or 24 days of age. Results indicate that there was a decrease in mean caries scores as the age of inoculation increases. Inoculation of animals beyond 22 days of age may not produce caries scores significantly greater than uninoculated animals, suggesting that the time span of maximum caries susceptibility is shorter than previously thought. The two strains of S. mutans produced similar levels of caries. The study suggests that while the strain of microorganism inoculated may account for some of the variability in animal caries studies, the age of inoculation appears to be more important.

ISSN:0008-6568    

DOI:10.1159/000260312

出版商:S. Karger AG    

年代:1978

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260363

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The desirability of developing an experimental technique for the production of secondary caries-like lesions in vitro which will be effective over a wider temperature range than is possible with the previously used acidified gelatin method is discussed. Experiments are described using acidified agar in various concentrations. The results show that this medium at concentrations of 0.6, 0.9 and 1.2% will consistently produce experimental lesions around restorations. The higher concentrations of 1.2% gives a larger number of enamel lesions showing a dark (positively birefringent) zone in quinoline. The results also demonstrate an inverse relationship between the extent of the lesions and the concentration of agar.

ISSN:0008-6568    

DOI:10.1159/000260313

出版商:S. Karger AG    

年代:1978

数据来源: Karger