摘要:

Three sequential samples from the distal surface of the upper first premolars of ten 13- to 14-year-old children were collected over a period of 12 weeks. Viable bacterial counts were made on each sample and representative strains of the genera Streptococcus, Actinomyces, Veillonella, Neisseria, Fusobacterium, Rothia, Lactobacillus, Bacterionema, Eubacteria and Arachnia were identified on the basis of morphology, physiological tests, cell wall and acid end product analysis and serology. The qualitative composition of the 58 samples obtained from the 20 sampled areas examined was similar, although some surfaces were consistently free of specific organisms during the test period, this was particularly evident with the lactobacilli. The mean percentages of the predominant genera were Actinomyces 34.92, Streptococcus 22.9, Veillonella 13.07, and ‘bacteroides’ 7.97. Streptococcus mutans mean percentage was 2.17, Strep. sanguis 5.9, Strep. salivarius 0.67, Strep. milleri 0.51, A. israelii 16.5 and A. viscosus together with A. naeslundii 19.05. Consideration of the results indicates that each of the sites represents a distinct ecological niche that should be looked at in isolation, and that the following parameters may be important in relating the bacterial population of a site to the formation of a carious lesion: (a) qualitative composition; (b) persistence of specific bacteria; (c) concentration of specific bacteria, and (d) the stability of the numerical concentration of specific bacte

ISSN:0008-6568    

DOI:10.1159/000260162

出版商:S. Karger AG    

年代:1975

数据来源: Karger

摘要:

Carious dentinal lesions in which a remineralized surface layer covers the decalcified region were subjected to electron-probe and electron microscope studies. The remineralized surface layer contained especially high concentrations of F and K and was composed of crystals which were much larger than the crystals in intact dentine. In the decalcified regions there was a reduction in the concentration of Ca, P, and Mg. The decrease in Mg content seemed to start earlier than that for Ca and P. Although not as prominent as in the remineralized surface layer, crystals in the decalcified region were larger than crystals in intact dentine.

ISSN:0008-6568    

DOI:10.1159/000260163

出版商:S. Karger AG    

年代:1975

数据来源: Karger

ISSN:0008-6568    

DOI:10.1159/000260164

出版商:S. Karger AG    

年代:1975

数据来源: Karger