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Biomedical subjects

M C Brecx

Publications and source records attributed to M C Brecx.

12 recordsLinked to original sources
PubMed1992

Microvascular volumes in healthy and inflamed gingiva in humans.

It has been suggested that the vascular alterations found in inflamed gingiva may be of significance in the enhanced extension of the pathological process into the periodontium. The purpose of this investigation was to measured the changes in blood vascular volume occurring in gingiva with the onset of gingivitis and its resolution. Twenty-six individuals participated in this study. Gingival biopsies were taken following a 21-day experimental gingivitis, following resolution of a 21-d experimental gingivitis and during a 6-month experimental gingivitis and a 6-month period of optimal oral hygiene. A total of 126 biopsies was obtained, from which 378 sections were cut at 2 microns for stereological analysis. At low magnification, reference volumes were estimated using point counting procedures and expressed as mm3 of gingiva per mm length of vestibular gingiva, in a vestibulo-lingual plane. At higher magnification the ratio between the volume of vessels and connective tissue was calculated. The final results were expressed as mm3 of vessels per mm length of vestibular gingiva, in a vestibulo-lingual plane. The mean vessel volume expressed per unit length of vestibular gingiva ranged from 0.010 to 0.024 mm3/mm. No statistically significant differences in vascular volumes were found between inflamed and non-inflamed gingiva. It was concluded that the changes in vascular architecture during early gingivitis described in the literature had either taken place in the subjects prior to the time of experimentation or that any vascular changes (cytologic or functional) which had taken place may be compensatory for the changes in architecture described in the literature.

Blood Volume↗
PubMed1989

Histological and clinical parameters of human gingiva following 3 weeks of chemical (chlorhexidine) or mechanical plaque control.

The aim of the present study was to compare stereologically the histopathologic variations following 3 weeks of chemical (chlorhexidine) or mechanical plaque control. 18 students and dental hygienists volunteered for this investigation. After prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching 0. Six of them then performed mechanical plaque control of 3 weeks (control), while the other 12 rinsed 3 times daily with a 0.12% chlorhexidine solution (test). At days 0 and 21, the plaque index (PlI), the gingival index (Gl) and the gingival exudate flow rate (GEFR) were assessed and biopsies were obtained from buccal sites. Point-counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells, macrophages and mast cells were estimated by counting the number of nuclear profiles of these cells in a specific connective tissue area adjacent to the apical termination of the junctional epithelium. After 21 days, the PlIs of the test subjects were significantly higher than the PlIs of the controls, but their Gl were similar. At the end of the experimental period, the various volume fractions and %s of cell profiles remained stable with the exception of an increase in the %s of lymphocytes in the test group. This study has shown that, clinically as well as histologically, the daily use of chlorhexidine for a 3-week period is equally efficient as optimal mechanical tooth cleaning in maintaining a healthy gingiva in the buccal sites investigated.

Chlorhexidine↗
PubMed1988

Observations on the initial stages of healing following human experimental gingivitis. A clinical and morphometric study.

The aim of the present study was to investigate stereologically the histologic alterations occurring during gingival healing after experimental gingivitis and to compare clinical parameters with histological findings. 8 dental students volunteered for the investigation. After a prophylaxis, they performed optimal oral hygiene to reach mean plaque and gingival indices approaching zero. They then abolished all oral hygiene procedures for a period of 21 days. After this experimental gingivitis phase, they again performed optimal oral hygiene for 8 days to restore gingival health. At days 0, 1, 2, 4 and 8 after experimental gingivitis, the plaque index (PlI), the gingival index (GI) and the gingival exudate flow rate (GEFR) were assessed and their buccal gingiva was biopsied. Point counting procedures were performed at 2 different levels of magnification on light microscopic sections to estimate the volume fractions of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The relative numbers of fibroblasts, polymorphonuclear neutrophils, lymphocytes, plasma cells and macrophages were estimated by counting the number of profiles of these cells in a specific connective tissue area adjacent to the apical end of the junctional epithelium. A rapid drop in the PlI was noted with increasing time after oral hygiene, followed by a slower decrease in the GI and GEFR scores. The histological picture during the entire experiment was that of an initial gingival lesion. At day 0, no chronic inflammation of the gingiva characterized by a predominance of plasma cells was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Stereological observations on long-term experimental gingivitis in man.

The purpose of the present investigation was to study stereologically the histopathologic changes in the gingiva during 6 months of abolished oral hygiene and to study the development of chronic gingivitis in man. After a thorough prophylaxis procedure, 5 dental students performed optimal oral hygiene under supervision for a period of 3 weeks. At the end of this pre-experimental phase, they were asked to abolish all oral hygiene procedures for 4 (2 individuals) to 6 months (3 individuals). At day 21, and after 2, 3, 4, 5 and 6 months, the gingival exudate flow rate and the gingival index were assessed, and buccal gingival biopsies taken. Semi-thin histologic sections were stained with basic fuchsine and methylene blue. By point counting at 2 different levels of magnification, the volume densities of epithelium, infiltrated (ICT) and non-infiltrated connective tissue, and collagen were estimated. The %s of fibroblasts, PMN's lymphocytes, plasma cells and macrophages were estimated in a predetermined standardized area close to the apical termination of the junctional epithelium. With increasing time, the volume densities of the ICT rose concomitantly with a decrease in the volume densities of the collagen. In spite of great interindividual variations, a slow shift in the proportions of some cell populations was consistently observed. While the fraction of PMN's, lymphocytes and macrophages remained stable, a decrease of fibro-blasts (57 to 39%) and an increase of plasma cells (0.2 to 10%) was observed. This study has, therefore, demonstrated that, in 6 months of plaque accumulation, a chronic gingivitis with a predominance of PMN's and lymphocytes develops.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

In vivo early human dental plaque formation on different supporting substances. A scanning electron microscopic and bacteriological study.

Different studies have shown that various substances may have an influence on early human dental plaque formation. The purpose of the present study was to compare on tooth substances and supporting prosthetic materials the amount of plaque deposition by SEM and the quantity of selected bacteria using anaerobic culturing techniques. 5 bridges, replacing a missing molar or premolar, were incorporated in 3 patients. In the midbuccal area of each pontic, a semi-precision attachment was placed allowing the insertion of the following test facings: enamel, dentine, non gamma 2-amalgam, alloys of 85% and 55% gold, silver-palladium, chrome-cobalt, chrome-cobalt-titanium, and ceramic. For each material, 2 facings were fabricated. After 4 and 24 hours in situ, bacteriological samples were taken and processed for further identification. After a 2nd period of 4 and 24 hours in situ, the same facings were carefully removed and prepared for SEM-examination. All 4-hour specimens exhibited various areas covered by plaque, the amount of which varied with the different supporting substances. The very smooth surfaces (e.g., gold) harbored sparse deposits, while the rougher (e.g., amalgam) were covered by more plaque. After 24 hours of plaque development, an increase in the number of micro-organisms was noted for all the specimens. After 4 and 24 hours of plaque accumulation, no specific trends suggesting a preferential colonization on the different substances were observed. This study has shown that the amount of early deposits on different substances seems to be related to the degree of their surface roughness, while plaque formation was qualitatively similar.

Adult↗