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Biomedical subjects

D Orstavik

Publications and source records attributed to D Orstavik.

At least 19 recordsLinked to original sources
PubMed1992

Usage test of four endodontic sealers in Macaca fascicularis monkeys.

Root canals with vital pulps in four Macaca fascicularis monkeys were subjected to pulp extirpation and root filling with gutta-percha and sealer, either AH26, Endomethasone, Kloroperka N-phi, or ProcoSol. Observation periods were 1 and 6 months. The results of treatment were evaluated by radiographic analysis (periapical index scores) and by histopathologic assessment of the remaining pulp and periapical tissues. Sixty roots with acceptable termination (between 0.5 and 3 mm from apex) of the root fillings and adequate histopathologic specimens were available for analysis. These roots were equally distributed in each observation period group and among the four material groups. Radiography indicated periapical pathosis in 6 of the 60 roots--4 at 1 month and 2 at 6 months. Periapical inflammation was observed on histopathologic examination in 17 roots--11 after 1 month and 6 after 6 months. Histologic and radiographic assessment of periapical inflammation was significantly correlated (p less than 0.01, chi 2) at the 6-month observation period. No granuloma or cyst formation was evident on histologic examination. The magnitude of the inflammatory response appeared unrelated to the endodontic sealer used, and several inflammatory foci were not related to foreign bodies in the tissues. Bacteriologic sampling showed growth in thioglycollate broth cultures in 9 of the 60 roots, but the presence of cultivable bacteria by this technique was unrelated to inflammatory changes. Histologic demonstration of bacteria was positive in 4 roots, all of which were associated with inflammatory periapical reactions. The method applied in the present study did not provide a sensitive discrimination among endodontic materials of widely different chemical composition.

Administration, Topical↗
PubMed1991

In vivo and in vitro studies on soft denture materials: microbial adhesion and tests for antibacterial activity.

The microbiological properties of four tissue conditioners, one soft liner, and one acrylic resin were studied. The tissue conditioners showed no or negligible antimicrobial effects toward salivary microorganisms by two different in vitro tests. In in vitro adhesion experiments, more Streptococcus mutans and Candida albicans adhered to the tissue conditioners and the soft liner in comparison with conventional acrylic resin used for denture-base fabrication. No difference in bacterial adhesion was found among the tissue conditioners. The microbial colonization of two tissue conditioners lined on maxillary dentures in three volunteers was followed for 14 days. No difference among the materials was found, but a tendency for subject-dependence in plaque formation on the materials was noted.

Acrylic Resins↗
PubMed1991

Effects of extensive apical reaming and calcium hydroxide dressing on bacterial infection during treatment of apical periodontitis: a pilot study.

An apical dentine sampling technique was applied in order to monitor the bacteriology of the pulp canal and radicular dentine before and during treatment of teeth with chronic apical periodontitis. Twenty-three teeth with a radiographic diagnosis of apical periodontitis were studied. They were subjected to a standardized two-appointment treatment regimen of extensive apical reaming in the absence of antimicrobial agents and 1-week dressing with calcium hydroxide. Bacteriological samples were taken from the root canal at the start, and apical dentine samples at the end, of each sitting. Provision was made to allow growth of anaerobic bacteria. All root canals but one showed growth at the start of treatment. Dentine samples were positive in 14 of the 23 teeth at the end of the first appointment. Eight of the 23 canals had detectable growth from the canal at the start of the second appointment, but in sufficient numbers for quantification in only one root canal. The subsequent dentine samples were otherwise negative at the second appointment. There was a tendency for teeth causing symptoms to harbour more bacteria than symptomless teeth.

Adult↗
PubMed1991

Radiographic evaluation of apical periodontitis and endodontic treatment results: a computer approach.

Chronic apical periodontitis is diagnosed primarily by radiography. Whereas subjective, chairside evaluations of radiographs have serious limitations as regards accuracy of endodontic diagnosis, digitalization of radiological data allows quantification of the information obtained. In clinical practice, digitalization may improve the diagnostic sensitivity and reduce the radiation dose; in clinical endodontic research, digitalization of radiographs provides a means of unbiased and quantitative assessment of apical periodontitis. Automated measurements of the radiographic density of the periapical area have been applied in a study of the effect of different endodontic sealers on the healing of apical periodontitis. Changes in radiographic density could be detected as early as 3 weeks after completion of endodontic treatment, and the computer-based analyses provided numeric values for the progression of the healing process in the periapical region.

Adult↗
PubMed1990

Adhesion of root canal sealers to bovine dentine and gutta-percha.

The adhesive properties of eight root canal sealers, applied as a thin layer between a dentine and a gutta-percha surface, were investigated. Tensile bond strengths ranged from 0.02 MPa (Sealpex) to 2.38 MPa (AH26). Inspection of fractured surfaces indicated failure of adhesion to dentine (Tubli-Seal) and to gutta-percha (AH26, Diaket) as well as failure of cohesion (CRCS, Kloroperka N-O, ProcoSol, rosin chloroform, Sealapex). Pretreatment of the dentine surface with EDTA caused a significant increase in bond strength for ProcoSol, rosin chloroform, Sealapex, and Tubli-Seal.

Adhesiveness↗
PubMed1990

Image analysis of endodontic radiographs: digital subtraction and quantitative densitometry.

In this study computerized image analysis procedures were applied to endodontic radiographs. Kontron IBAS 2000 is a commercially available image analysis system with processing routines applicable to radiograph digitizing and transformations. The system was evaluated for: its ability to harmonize blackening and contrast in endodontic radiographs; its ability to compensate for angulation distortion of sequential exposures of individual teeth; its potential for application of digital subtraction methods; and its use in automated gray-level analyses of diseased and healthy bone areas in endodontic radiographs. The Kontron IBAS 2000 system proved suitable for all applications. However, the specificity of the subtraction procedure was limited by some inherent problems in the harmonization of blackening and in the subtraction process itself. On the other hand, automated gray level measurements proved to be a robust method for unbiased and quantitative assessment of healing of apical periodontitis.

Absorptiometry, Photon↗
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↗