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B Mejàre

Publications and source records attributed to B Mejàre.

13 recordsLinked to original sources
PubMed1983

Effects of ammonia and organic acids on the intradental sensory nerve activity.

Ammonia and organic acids constitute a major part of the bacterial metabolites formed in carious decay. The aim of the present study was to investigate their effect on the intradental sensory nerves. Nerve impulse activity was recorded from canine teeth in cats after application of the test solutions in deep dentinal cavities. Ammonia (17-134 mM) consistently generated nerve impulses, whereas organic acids (0.001-1 M) failed to induce any impulse activity. In contrast, acid application resulted in an inhibition of the ongoing nerve activity induced by various stimuli (hypertonic NaCl solution, mechanical pulp exposure, and compound 48/80). However, acid treatment of the cavities resulted in an enhanced neural response to ammonia stimulation. Thus, the present results demonstrate that these bacterial metabolites can influence intradental sensory nerve activity. It is suggested that they may also modulate the symptoms from decayed teeth.

Acetates↗
PubMed1979

Bacteria beneath composite restorations--a culturing and histobacteriological study.

The occurrence, viability and identification of the microbial flora under composite fillings using an anaerobic technique were studied. Class V cavities were prepared on clinically healthy buccal surfaces of 7 contralateral pairs of premolars in children 11--15 years of age. After preparation, rubber dam was applied and one cavity in each pair of teeth was washed with water blasted dry with air and filled with Adaptic. The other cavity was washed with a cavity cleaner (Tubulicid) and a cavity liner (Tubulitec) was applicated prior to filling with Adaptic. The teeth were extracted after 4--6 weeks. Under anerobic conditions the tooth crown was split. From one half samples were taken from the pulpal wall under the filling and cultured on blood agar and in broth medium. The other half was examined with histobacteriological technique. No growth occurred in cultures from lined cavities but in 6 of the 7 unlined cavities. Full agreement was observed between the findings from the culturing and histobacteriological examinations concerning presence or absence of microorganisms at the pulpal wall in all 14 teeth. The flora was mixed. Gram-positive bacteria, mainly Streptococcus and Actinomyces, dominated over gram-negative bacteria including Veillonella, Fusobacterium, Campylobacter and Selenomonas. The composition of the flora was more similar to that observed in dental plaque than that found in carious dentin or in saliva in other studies.

Adolescent↗
PubMed1978

An in vitro study with various vehicles of diffusion of formocresol and its components.

Pulpotomy in primary teeth using the formocresol method results in varying degrees of devitalization of the root pulp. The extent of this devitalization depends on, among other things, the ability of the components of formocresol to leave the dressing. The purpose of this study was to evaluate the rate and duration of diffusion of the components of formocresol when incorporated in different vehicles. The antimicrobial effect of the drugs was used to assess the diffusion of the components of formocresol in blood agar, with a sensitive microorganism as an indicator. Evaluation of the MICs assessed in broth medium for formalin, formocresol and cresol, respectively, and the zone size of growth inhibition on blood agar from these components when incorporated in ZnO or ZnO-eugenol cement, suggested that the initial zone of inhibition from formocresol was due mainly to the diffusion of formaldehyde. Cresol diffused more slowly from the dressing. The presence of eugenol in the dressing, as in ZnO-eugenol cement, gave smaller initial release of formaldehyde, formocresol and cresol compared with the release from ZnO, but more prolonged diffusion. A higher initial release of formaldehyde was obtained when the formocresol was incorporated in ZnO alone compared with ZnO-eugenol cement or Pharmatec.

Agar↗
PubMed1977

Acid production from Lycasin, maltitol, sorbitol and xylitol by oral streptococci and lactobacilli.

The acid production from maltitol was compared with the acid production from hydrogenated starch hydrolysate (Lycasin), sorbitol and xylitol by a number of oral strains and reference strains of Streptococcus mutans, S. sanguis, S. salivarius, S. mitior, S. milleri, S. faecalis, S. faecium, S. avium, Lactobacillus casei and L. salivarius. The polyols were added to a final concentration of 1.0% to two different basal media. Incubation was performed at 37 degrees C for 7 days after which the pH was recorded. Maltitol was fermented only by the lactobacilli (about two thirds of the strains). Lycasin was fermented by all strains of S. faecalis, more than 90% of the lactobacilli, about half of the S. sanguis strains, about one third of the S. mutans strains, and by a few other streptococcal strains. Acid production from sorbitol was observed among more than 80% of the S. mutans strains and the S. faecalis strains and most of the lactobacilli strains. Sorbitol-fermenting strains of S. sanguis and of S. mitior, all isolated from sorbitol-consumers, were observed. No other sorbitol-fermenting streptococci were found. Only the reference strains L. salivarius subsp. salivarius ATCC 11741 and S. avium ATCC 14025 fermented xylitol.

Acids↗
PubMed1975

Streptococcus salivarius, Streptococcus sanguis and Streptococcus "mitis" as indicators of contamination of root canal cultures.

Small samples were taken from the first drop of saliva entering an operation field for root canal treatment isolated by rubber dam, which was intentionally leaky. The samples were primarly cultured in TAS- and BLH-medium and on MS-agar aerobically. The culture media were inoculated directly and via transport medium (VMG III). The cultures were analysed for Strep. salivarius, Strep. sanguis and/or Strep. "mitis" after subculture on MS-agar as soon as visible growth had appeared in the broth media and again after a further 2 days. The following observations were made: 1. Strep. salivarius was almost regularly found in either or both of TAS- and BLH-medium at primary culture of the samples contaminated with saliva. The result was the same whether these broth media were inoculated directly or via VMG III. 2. Strep. salivarius was always found in mixed cultures and was nearly always accompanied by Strep. sanguis and/or Strep. "mitis". 3. Strep. salivarius as well as Strep. sanguis survived two days after visible growth significantly more oftern in BLH-medium than in TAS-medium. The findings lend support to the hypothesis based on clinical studies that when present in root canal cultures Strep. salivarius is ascribable to contamination with saliva.

Adolescent↗
PubMed1975

Characteristics of Streptococcus milleri and Streptococcus mitior from infected dental root canals.

Morphological and physiological characteristics of 103 streptococcal isolates obtained from positive routine cultures of material from dental root canals at filling, were studied. The majority of the isolates were those which at a primary identification not fullfilled the criteria of enterococci, Strep. sanguis, Strep. mutans or Strep. salivarius. Only a few representative strains of the latter types were included in the study as a control of the method. The resemblance of the 103 isolates to 38 reference strains were assessed with numerical methods. The isolates formed 9 clusters with reference strains occurring in all but one. Of the isolates which it was intended to identify and characterize with numerical taxonomic analysis, all but one joined one of 3 clusters and were identified as Strep. milleri or Strep. mitior (mitis). The most useful cultural characteristics to dfferentiate the two species were growth on the sulphonamide containing MC-agar and 7.5% bile blood agar by Strep. milleri and production of hydrogen peroxide by Strep. mitior. The characteristics of the strains in the nine 80-phenons are given in Table 2. Other characteristics that appeared to be of interest for differentiating Strep. milleri from Strep. mitior and these two species from other viridans streptococci are underlined in Table 2. Strep. milleri seems not earlier to have been reported to occur in infected root canals. The occurrence of Strep. milleri is in agreement with the data given on serological groups found among streptococcal isolates from routine root canal cultures. Little is known about the occurrence and distribution of Strep. milleri in the human oral cavity, which therefore warrant further investigations.

Dental Pulp Cavity↗
PubMed1975

Streptococcus faecalis and Streptococcus faecium in infected dental root canals at filling and their susceptibility to azidocillin and some comparable antibiotics.

The study was performed on 612 routine cultures of material obtained from root canals of teeth at the time of filling (r-cultures) by students at the Department of Endodontics during a continuous period of one year. Twenty-nine isolates from 27 (29.3%) of the 92 positive cultures filled the criteria of enterococci (Sherman, 1937) and had demonstrable group D-antigen. With a set of tests these isolates were identified as follows: Strep. faecalis subsp. faecalis (10), Strep. faecalis subsp. zymogenes (3), Strep. faecalis subsp. liquefaciens (8), atypical variants of Strep. faecalis (6), Strep. faecium var. faecium (1) and Strep. faecium var. durans (1). Five tests in the present study clearly differentiated Strep. faecalis from Strep. faecium i.e. fermentation of sorbitol, glycerol (anaerobic) and melezitose, tolerance to potassium tellurite (0.1%) (positive for Strep. faecalis) and production of hydrogen peroxide (positive for Strep. faecium). In the inocula 10(3) or more colony forming units of enterococci were found more often of other identified microorganisms. This means that enterococci are of special interest in studies on the influence of infection at the time of filling of root canals on the prognosis of root canal therapy. The isolates were also tested for susceptibility to azidocillin, ampicillin, penicillin-G, penicillin-V and erythromycin with the paper disc method. All the isolates were susceptible to azidocillin and ampicillin (sensitivity group I), while the majority of the isolates showed a lower susceptibility to the other three antibiotics (sensitivity group II). The significance of these findings in the choice of prophylactic antibiotic to prevent bacterial endocarditis in patients with a history of rheumatic or congenital heart disease are discussed, when bacteremia from dental procedures may be expected.

Ampicillin↗