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Biomedical subjects

R T Zahradnik

Publications and source records attributed to R T Zahradnik.

14 recordsLinked to original sources
PubMed1989

Evaluation of a chairside gingival protease test for use in periodontal diagnosis.

Collagen degradation is a major factor in the destruction of diseased periodontal tissues. Evidence from several investigations indicates that this connective tissue breakdown process may be associated with elevated levels of proteolytic activity in gingival crevicular fluid. A rapid, chairside assay for neutral proteases in biological fluids was evaluated clinically for reproducibility and an indicator of periodontal disease status. This colorimetric test is based on the use of an insoluble, covalently linked dye-collagen substrate. Enzymatic activity is monitored by estimating the production of soluble dye-labeled collagen fragments resulting from the action of sample fluid proteases on the test substrate. Gingival fluid samples were collected on three successive days from 366 interdental sites in 34 volunteers, with and without periodontal disease. Results demonstrate that the assay is reproducible with 98.6% of sampled sites remaining stable throughout the 3-day study. Furthermore, the highest percentage of elevated neutral protease activity (NPA) values and the highest NPA values were found in patients clinically diagnosed as having advanced periodontal disease.

Evaluation Studies as Topic↗
PubMed1979

Demineralization and remineralization of dental enamel.

Experimentation in vitro using organic acid buffers as demineralizing media shows that caries-like lesions can be obtained which are very similar in morphology and developmental stages to early lesions formed naturally under oral conditions. The use of these chemical systems and of mechanistic models advanced to explain the unique histological features of incipient caries have yielded a good understanding of the processes involved in caries formation. The study of natural and induced factors influencing the demineralization process has been greatly facilitated by the use of bacteriological systems in which demineralization is produced by direct colonization of cariogenic microorganisms on the surfaces of extracted teeth. Comparison of results obtained with these latter systems and with chemical systems has allowed us, for example, to elucidate the mechanism by which acquired salivary pellicles and fluoride topical solutions decrease the rate of enamel demineralization. The pellicle retards transport of matter across the enamel surface, whereas the fluoride topical solutions decrease the cariogenicity of the colonizing bacteria.

Acids↗
PubMed1979

Modification by salivary pellicles of in vitro enamel remineralization.

The effectiveness of inorganic calcifying solutions to remineralize enamel with subsurface demineralization decreased with saliva pre-treatments conducive to the formation of enamel pellicles. Greater reductions in remineralization rates occurred with longer pellicle formation times. It is suggested that enamel pellicles may act to control surface deposition and favor subsurface precipitation.

Calcium Phosphates↗
PubMedDate not supplied

Effect of salivary pellicle on enamel subsurface demineralization in vitro.

Diffusion fluxes of two anionic species through hydroxyapatite membranes were found to be reduced up to 50% by the presence of adsorbed salivary pellicles developed on the membrane surfaces. By contrast, water fluxes were only marginally affected, indicating that salivary pellicles display ionic permselectivity. This property is used to explain a remarkable protection of the enamel observed when salivary pellicles were developed on extracted teeth before exposure to acid lactate buffers.

Adolescent↗
PubMedDate not supplied

Effect of fluoride topical solutions on enamel demineralization by lactate buffers and Streptococcus mutans in vitro.

Applications of APF and NaF solutions to extracted human teeth reduced the extent of enamel subsurface demineralization induced by colonization of S. mutans but were ineffective against demineralization by acid lactate buffers. It is concluded that the CaF2 formed on the tooth surface during the treatment is responsible for the protection observed.

Acidulated Phosphate Fluoride↗
PubMedDate not supplied

Effect of salivary pellicle formation time on in vitro attachment and demineralization by Streptococcus mutans.

Enamel subsurface demineralization induced by Streptococcus mutans was significantly reduced by seven-day saliva pre-treatments conducive to the formation of enamel pellicles. A two-hour saliva pre-treatment was ineffective. Results suggest that the protection provided by long-term pellicles may relate to changes in ionic transport rates rather than cell attachment.

Adhesiveness↗