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Biomedical subjects

D Orstavik

Publications and source records attributed to D Orstavik.

At least 37 records · Page 2Linked to original sources
PubMed1990

Disinfection by endodontic irrigants and dressings of experimentally infected dentinal tubules.

The effect of endodontic irrigants and dressings was tested on bacteria in bovine dentin specimens experimentally infected with Enterococcus faecalis, Streptococcus sanguis, Escherichia coli, or Pseudomonas aeruginosa. Standardized, cylindrical dentin test pieces were prepared and cleaned by ultrasonic treatment with EDTA and sodium hypochlorite. The specimens were infected with the test organism for periods up to 14 days, and the degree of infection into the tubules was monitored using Brown & Brenn stain, scanning electron microscopy, and culturing of dentin dust from sequential bur samples starting from the pulpal side. E. faecalis rapidly infected the whole length of the tubules; S. sanguis required up to 2 weeks for complete infection; E. coli only penetrated to some 600 microns, even after prolonged incubation periods. P. aeruginosa infected dentin quickly, but apparently in very low numbers. E. faecalis persisted for at least 10 d after withdrawal of nutrient support, whereas the other 3 organisms died within 4 to 48 h. Endodontic medicaments were applied to infected specimen for comparison of antibacterial potency. Camphorated p-monochlorophenol was generally more efficient than Calasept, and of the irrigants tested, iodine potassium iodide appeared more potent than sodium hypochlorite or chlorhexidine. The presence of a smear layer delayed, but did not eliminate, the effect of the medicaments.

Animals↗
PubMed1990

Mutans streptococci in plaque from margins of amalgam, composite, and glass-ionomer restorations.

Levels of mutans streptococci in plaque samples from margins of Class II amalgam (Dispersalloy), composite (P-10), and glass-ionomer (Ketac Silver) restorations were compared. Fifty-one children, each having one of the restorations in a permanent first molar, were part of an inter-individual comparison, giving 17 restorations of each material. The age of the children, the age of the restorations, and the salivary levels of mutans streptococci were comparable in the three groups. Another seven children--each having both a composite and a glass-ionomer restoration of the same age placed on contralateral premolar or molar teeth--were part of an intra-individual comparison. The percentage mutans streptococci of total CFU count in plaque was higher on composite (mean 13.7) and amalgam (mean 4.3) than on glass-ionomer (mean 1.1) restorations in the inter-individual comparison, and higher on composite (mean 4.2) than on glass-ionomer (mean 0.4) restorations in the intra-individual comparison. In both comparisons, the differences in values between samples from glass-ionomer restorations and samples from composite or amalgam restorations were statistically significant (p less than 0.05).

Adolescent↗
PubMed1989

Evaluation of alternatives to chloroform in endodontic practice.

Chloroform is used in endodontics for plasticizing gutta-percha points and for facilitating removal of gutta-percha root canal fillings in need of re-treatment. Adverse health effects from exposure to chloroform have been reported, and to improve occupational health, it would be advantageous if a less hazardous solvent could replace chloroform. In this study, methylene chloride, methyl chloroform, tetrahydrofuran, xylol and eucalyptol were tested for their capacity to dissolve or soften gutta-percha points compared with chloroform. The effect of the test solvents was assessed by measuring the depth of penetration of a small indentor of fixed weight and shape into a gutta-percha disk covered with the test solution for various time periods. Chloroform showed the most pronounced effect, followed by methylene chloride, tetrahydrofuran, and methyl chloroform. When both occupational health and gutta-percha solvent capacity were considered, methyl chloroform seemed to be an interesting alternative to chloroform.

Chloroform↗
PubMed1988

Bacterial agglutinins in rat salivary glands: effect of glandular stimulation and calcium dependency.

The secretory pattern of salivary, bacterial agglutinins was studied in the rat. The three major salivary glands were cannulated bilaterally and their secretions collected separately after parasympathomimetic and sympathetic stimulation. The bacterial aggregating activity of the secretions was tested against four strains of bacteria indigenous to the rat. Agglutinin activity was demonstrated in both parasympathomimetic and sympathetic secretions. The parotid glands tended to show the highest total output of agglutinins, with the highest titers found in parotid saliva on sympathetic stimulation. In submandibular and, particularly, parotid saliva, titers tended to increase when stimulation with pilocarpine was followed by sympathetic stimulation. In contrast, titer in sublingual saliva tended to decrease on sympathetic stimulation. When expressed as titer output per minute, sympathetic parotid secretion showed the highest agglutinin activity. Agglutinin activity appeared unrelated to total protein or to duct-derived amidolytic activity. Titers of parotid or submandibular saliva were increased 5- to 10-fold by the presence of 3.3 mM CaCl2 in the reaction mixture. By contrast, the agglutinating activity of sublingual saliva on parasympathomimetic stimulation was unaffected by extraneous CaCl2. Measurements of Ca concentration in similarly obtained rat salivary secretions did not show patterns of Ca concentration that could be related to the varying sensitivity of the agglutinating activity to Ca.

Agglutinins↗
PubMed1988

Reliability of the periapical index scoring system.

Data accumulated in one methodological and two longitudinal clinical studies employing the periapical index (PAI) scoring system were analyzed to assess the usefulness and reliability of the PAI system. More than 93% of pairs of PAI scores were either identical or deviated from each other with one step only for intra- and interexaminer agreement in scoring the same radiograph as well as for intraexaminer agreement in scoring two radiographs of the same root. Untreated roots which on completion of the longitudinal studies were judged to have healthy periapices, were scored as diseased less than 3% of the time during the study. Diseased teeth were scored as healthy less than 7% of the time. The results suggest that the PAI scoring system may be used with a high degree of reliability.

Humans↗
PubMed1987

In vitro infection and disinfection of dentinal tubules.

An in vitro model for dentinal tubule infection of root canals was developed. Cylindrical dentin specimens, 4 mm high with a diameter of 6 mm and a canal 2.3 mm wide, were prepared from freshly extracted bovine incisors. The cementum was removed from all dentin blocks. The tubules were opened by four-minute treatments with 17% EDTA and 5.25% NaOCl before being infected with Enterococcus faecalis ATCC 29212 in yeast extract-glucose broth. Bacteria rapidly invaded the tubules. After three weeks of incubation, a heavy infection was found 400 micron from the canal lumen, and the front of the infection reached 1000 micron in some blocks. Camphorated paramonochlorophenol (CMCP) and a calcium hydroxide compound, Calasept, were tested for their disinfecting efficacy toward E. faecalis-infected dentin. Liquid CMCP rapidly and completely disinfected the dentinal tubules, whereas CMCP in gaseous form disinfected tubules less rapidly. Calasept failed to eliminate, even superficially, E. faecalis in the tubules. The method used in bacteriological sampling allowed for sequential removal of 100-micron-thick zones of dentin from the central canal toward the periphery. Control specimens were uniformly infected and yielded growth in bur samples up to some 500 microns from the surface. The model proved quite sensitive and seems suitable for in vitro testing of root canal medicaments.

Animals↗