carbocyanines and Dental-Caries

Despite widespread use of various concentrations of fluoride for the prevention of dental caries, the relationship between fluoride concentration and activity against cariogenic biofilms has not been much studied. Herein we investigated the relationship between fluoride concentration and activity against virulence factors and viability of Streptococcus mutans biofilms. S. mutans biofilms were formed on saliva-coated hydroxyapatite discs. The 70-hour-old biofilms were exposed to 0, 1, 3, 10, 30, 100, 300, 1,000 or 2,000 ppm F(-). The changes of virulence factors and viability of the biofilms were analyzed using biochemical methods and laser scanning confocal fluorescence microscopy. At 1-2,000 ppm F(-), the activity of fluoride against acid production, acid tolerance, and extracellular polysaccharide formation of S. mutans biofilms accurately followed a sigmoidal pattern of concentration dependence (R(2) = 0.94-0.99), with EC50 values ranging from 3.07 to 24.7 ppm F(-). Generally, the activity of fluoride against the virulence factors was concentration-dependently augmented in 10-100 ppm F(-) and did not increase further at concentrations higher than 100 ppm F(-). However, fluoride did not alter glucosyltransferase activity and viability of S. mutans biofilm cells in all concentrations tested. These results can provide a basis for the selection of appropriate fluoride concentrations that reduce the physiological ability of cariogenic biofilms.

Topics: Acids; Adenosine Triphosphatases; Biofilms; Carbocyanines; Cariostatic Agents; Cell Membrane Permeability; Dental Caries; Dental Pellicle; Dose-Response Relationship, Drug; Durapatite; Fluorescent Dyes; Fluorides; Glucosyltransferases; Humans; Hydrogen-Ion Concentration; Microbial Viability; Microscopy, Confocal; Microscopy, Fluorescence; Polysaccharides, Bacterial; Streptococcus mutans; Virulence Factors

There has been controversy about the length and structure of the odontoblast process within dentin since the earliest histologic studies of teeth. Our objective was to use the fluorescent carbocyanine dye Di-I combined with a new gelatin embedment procedure and confocal microscopy to determine the structure and extent of odontoblast processes in developing and mature rat teeth, injured rat molars, reparative dentin, and adult monkey teeth. We found that odontoblast processes do not extend into outer dentin or to the dentin-enamel junction except during early stages of development. Those in innervated regions of crown are long and straight, whereas those in roots are extensively branched and shorter. Cavity injury to crown dentin caused odontoblast fragments to be aspirated into outer dentin. In reparative dentin the odontoblast processes were branched and similar to those in roots. We used photoconversion and electron microscopy to show that Di-I fills the entire odontoblast after gelatin embedment, including the cytoplasm. This is a different type of carbocyanine staining from any previously reported, and it also stains other cells in adjacent hard tissues such as bone and cementum. The Di-I-gelatin method is a new way to use carbocyanine dyes. It has enabled us to solve a long-standing controversy about the histology of teeth, and it should be useful for many other studies of cell structure.

Topics: Animals; Carbocyanines; Dental Caries; Dentin; Dentin, Secondary; Female; Fluorescent Dyes; Gelatin; Incisor; Macaca mulatta; Male; Microscopy, Confocal; Molar; Odontoblasts; Rats; Rats, Sprague-Dawley; Staining and Labeling; Tissue Embedding; Vimentin