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Biomedical subjects

F H Mikx

Publications and source records attributed to F H Mikx.

At least 55 records · Page 3Linked to original sources
PubMed1987

Early microbial colonization of permucosal implants in edentulous patients.

In edentulous patients, the microbial colonization of permucosal implants of sintered hydroxyapatite was studied. Samples were taken from mucosa and dentures before insertion of implants and from supra- and subgingival sites two to 10 weeks after insertion. In total, five patients and 10 implants with clinically healthy peri-implant tissues were studied. The samples were investigated by dark-field microscopy and anaerobic culture. The supragingival plaque of the implants was dominated by Gram-positive cocci and rods, the subgingival plaque by Haemophilus spp. and Veillonella parvula. A group of bacteria was found specifically related to the implants: Actinomyces odontolyticus, Peptostreptococcus micros, Haemophilus actinomycetemcomitans, Eikenella corrodens, Capnocytophaga sputigena, and Leptotrichia buccalis. Black-pigmented Bacteroides was not found in any of the examined samples. Spirochetes were observed in denture plaque samples and in supragingival plaque of the implants. It is concluded that bacteria known as potential periodontal pathogens colonize the permucosal implants in the first weeks after insertion. The presence of these species seems to be dependent on the ecological factors provided by the artificial gingival crevice of the permucosal implants in the edentulous mouth.

Actinomyces↗
PubMed1986

The prevalence of spirochetes in the subgingival microbiota of Tanzanian and Dutch children.

The subgingival microflora of 71 Tanzanian and 77 Dutch prepurberty children was analyzed by dark-field microscopy. Spirochetes were observed in almost every Tanzanian child and in 66% of the Dutch children. The predominant spirochetes were small and medium sized; large spirochetes were infrequently observed in the rural Tanzanian children and at the bleeding sites of the Dutch children. Further differences in the %s of cocci, rods and fusiforms indicated that the subgingival microflora of Tanzanian children is different from that of Dutch children. Generally, spirochetes occurred at higher %s and frequency at bleeding sites than at non-bleeding sites in both populations. However, the non-bleeding sites in the Tanzanian children had a higher prevalence of spirochetes than the bleeding sites in Dutch children. It is concluded that spirochetes are members of the normal flora of prepuberty children, that in children gingivitis is associated with increased proportions of spirochetes and that the presence of spirochetes in the gingival crevice is not dependent upon gingival inflammation.

Age Factors↗
PubMed1986

Adherence of oral treponemes and their effect on morphological damage and detachment of epithelial cells in vitro.

The present study shows adherence of Treponema denticola L12D and Treponema vincentii RitzA to guinea pig ear epithelial cells in vitro. The number of adhering organisms was positively related with the treponemal concentration and contact time. Incubation of washed T. denticola L12D and T. vincentii RitzA organisms or their culture supernatants with the epithelial cells induced morphological damage and detachment of these cells. In addition, indications for inhibition of epithelial cell proliferation were found. The activity of the supernatants was dose dependent, heat sensitive, and sensitive to sulfhydryl-containing components, suggesting the presence of enzymatic activity that might be of importance in the pathogenicity of these oral treponemes.

Adhesiveness↗
PubMed1986

Metronidazole concentrations in human plasma, saliva, and gingival crevice fluid after a single dose.

Metronidazole concentrations were estimated in four human volunteers after a single dose of 750 mg taken orally. Samples of blood, saliva, and gingival crevice fluid were collected before intake and during the following 24 hours. The concentrations of metronidazole in plasma and saliva were measured by high-performance liquid chromatography (HPLC). The concentrations in gingival fluid were estimated by a capillary agar-diffusion assay. The results of the metronidazole measurements as obtained by both methods were significantly correlated. The peak concentrations of metronidazole in plasma and saliva were in the same range, 8.7-13.8 micrograms/mL, and similar concentrations were found in the gingival fluid samples. It is concluded that metronidazole taken orally has similar pharmacokinetics in both saliva and plasma, and that a single oral dose of 750 mg metronidazole leads to a concentration of the drug in the gingival crevice fluid that exceeds the minimal inhibitory concentration for most anaerobic oral micro-organisms.

Administration, Oral↗
PubMed1986

The effect of amoxicillin on destructive periodontitis. A case report.

In a 22-year-old female patient, advanced localized periodontal destruction was observed. The planned treatment consisted of oral hygiene instructions, professional plaque control, deep scaling and root planning and finally modified Widman flap surgery. One molar had to be extracted but was left untreated initially as a control. During the treatment period of 9 months and during 1 year thereafter, samples were taken of the subgingival plaque for dark-field microscopy. The unplanned use of amoxicillin by the patient for a middle ear infection resulted in a suppression below detection level of spirochetes at the investigated sites. At the nontreated control site, the absence of spirochetes was accompanied by a 3-mm reduction of pocket depth and a 2-mm gain in clinical probing attachment, while some formation of new alveolar bone was observed. At the treated sites, clinical improvement was observed. However, a distinction between the effect of the periodontal therapy and the nonscheduled use of amoxicillin could not be made at the treated sites. It is concluded that a single course of systematically administered amoxicillin changed the composition of the subgingival microflora over a long period of time (17 months) and had a beneficial effect upon the status of the periodontium.

Adult↗
PubMed1985

Antibiotypes of Bacteroides gingivalis assessed by antimicrobial disks and multivariate analysis.

Antibiograms with 20 different antimicrobial disks were studied for antibiotyping of Bacteroides gingivalis isolates. The stability of the antibiotypes was tested by passage in mice. Several B. gingivalis isolates of the same subject were used to investigate the presence of different antibiotypes in one individual, while isolates from different subjects were used to investigate individual differences. The antibiotypes were found to remain stable after animal passage. All tested strains of different origin represented different antibiotypes. The isolates from one subject all belonged to the same antibiotype. Principal component analysis of the data showed that two factors were important in the discrimination of the strains of B. gingivalis. One included beta-lactam antimicrobial agents that affect the cell wall. The other included antimicrobial agents that inhibit synthesis of protein and nucleic acid. Both principal component analysis and discriminant analysis proved to be of great use in the reduction of the amount of data and the visualization of the relations between different antibiotypes of B. gingivalis in a linear map. Among the investigated subjects, different antibiotypes of B. gingivalis were found, indicating that in the mouth of an individual, one antibiotype of B. gingivalis predominates and that different persons harbor different antibiotypes of B. gingivalis.

Analysis of Variance↗
PubMed1984

Effect of splint placement on black-pigmented Bacteroides and spirochetes in the dental plaque of beagle dogs.

The gingival microbiota in beagle dogs was investigated during a period of 42 days after the placement of continuous wire and arch bar splints. The splints were found to induce an increase in helicoidal-shaped micro-organisms and black-pigmented Bacteroides. Two different asaccharolytic Bacteroides types were isolated and tentatively identified as B. gingivalis and B. asaccharolyticus. In addition, B. intermedius-like organisms were isolated. The last two species were observed only after splint placement. The local accumulation of helicoidal-shaped micro-organisms in the epithelial tissue rather than in the micro-ulcerations was regarded as an indication of an active role for these spirochetes in the disease process. The observed shift toward tissue-invading and potentially pathogenic micro-organisms after splinting stresses the need for antimicrobial measures during splint placement in order to minimize periodontal destruction.

Animals↗
PubMed1979

Effect of bacteriocin production by Streptococcus mutans on the plaque of gnotobiotic rats.

The effect of bacteriocins produced by strains of Streptococcus mutans on the microbial composition of dental plaque was studied in gnotobiotic rats. In one set of tests, using S. mutans strains T2 and SW31, rats were simultaneously infected with the bacteriocinogenic parent (bac(+)) and corresponding bac(-) mutants, and the relative proportions of each strain present in three different tooth sites were determined at various time intervals after inoculation. Some animals were monoinfected with bac(+) and bac(-) strains, and in vivo properties, such as plaque fermentation end products, amount of plaque formed, and cariogenicity, were measured. In another series of tests with strains T2 bac(+) and T2 bac(-), animals were sequentially inoculated with a time interval of 1 week. On simultaneous inoculation, the bac(-) mutant, which was sensitive in vitro to the bacteriocin produced by the parent, was totally unable to establish in a plaque consisting of the bac(+) strain even when the challenging dose was increased 100-fold. In contrast, the bac(+) strain was successful not only in invading an established bac(-) plaque but also in eventually almost eliminating the mutant. In monoinfected animals, there were no significant differences in plaque-forming ability, fermentation end products, or cariogenicity between the two strains. Also, bacteriocin activity was detected in plaque harboring the bac(+) but not the bac(-) strain. The results not only indicate that bacteriocin activity can occur in vivo but also suggest that bacteriocinogeny might confer an ecological advantage upon a strain attempting to establish itself in an ecosystem.

Acetates↗