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Biomedical subjects

A M Polson

Publications and source records attributed to A M Polson.

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

Periodontal regeneration via selective cell repopulation.

The purpose of this investigation was to determine the histogenesis of periodontal regeneration using the principle of selective and guided cell repopulation of the root surface. A fenestration model, developed in the squirrel monkey, made it possible to exclude gingival epithelium and connective tissue and promote cell repopulation of the denuded root surface from the periodontal ligament and alveolar bone. Experimental and sham-operated control sites were compared histometrically after 3, 7, 14 and 35 days of healing. The results indicated that new cementum, bone and periodontal ligament formation occurred by the 14th day and that regeneration of the fenestration wound was almost complete by Day 35. Root resorption and ankylosis were observed in both experimental and sham-operated controls. There was significantly more periodontal regeneration in the experimental sites, which favored cell repopulation of the root surface from the periodontal ligament and alveolar bone.

Alveolar Process↗
PubMed1986

The relative importance of plaque and occlusion in periodontal disease.

A series of studies has investigated interactions between periodontal trauma and marginal periodontitis in relation to the initiation, progression and treatment of periodontal disease. Lesions of trauma in the periodontal ligament do not initiate the loss of connective tissue attachment characteristic of marginal periodontitis. Studies conducted in squirrel monkeys and beagle dogs in which jiggling forces were superimposed upon an established marginal periodontitis reported increased loss of alveolar bone, but the accelerated loss of attachment which occurred in the dog model did not occur in the monkey model. In order to clarify the relative importance of inflammation and tooth mobility in the treatment of advanced periodontal disease, periodontal responses were evaluated after removing combinations of traumatic and inflammatory components. Elimination of trauma in the presence of existing marginal inflammation did not reduce tooth mobility or increase bone volume. Osseous regeneration and decreased tooth mobility occurred after resolving both components; however, similar findings occurred after resolving inflammation in the presence of continued tooth mobility. After resolution of inflammation, remaining tooth mobility does not result in increased loss of connective tissue attachment. On a clinical level for periodontal disease treatment, the findings place decreased emphasis upon management of tooth mobility and increased emphasis upon resolution of marginal inflammation.

Animals↗
PubMed1986

Microbial populations and active tissue destruction in experimental periodontitis.

Although specific subgingival microflora are being associated with active tissue destruction in periodontitis, little information exists on the relationship between subgingival flora and histological evidence of tissue destruction. The present study was undertaken to explore these relationships during experimental marginal periodontitis in squirrel monkeys. In 4 squirrel monkeys, experimental periodontitis was induced around bicuspids and molars using silk ligatures. The buccal part of the subgingival ligature was removed for bacterial sampling 3, 7, and 14 days after ligature placement. Dark-field microscopy was used to quantify motile forms, spirochetes, straight and curved rods, filaments, cocci and fusiforms. Subgingival plaque prior to periodontitis induction was dominated by cocci, but fusiforms and straight rods were also present. Spirochetes, filaments, curved rods and motile forms were absent. 3 days after induction of periodontitis, there were marked increases in spirochetes, motile forms, filaments, curved and straight rods. The proportions of coccoids and fusiforms decreased. The bacterial proportions stayed at approximately the same levels through 7 and 14 days. Histometric quantification of periodontal destruction showed loss of connective tissue attachment and crestal alveolar bone. A positive correlation was found between periodontal tissue destruction and both total number of subgingival bacteria and spirochetes.

Alveolar Process↗
PubMed1986

Cell populations associated with interdental gingival bleeding.

The purpose of this study was to characterize the cell populations of the mid-interproximal gingival tissue related to the presence or absence of bleeding. 15 bleeding and 15 non-bleeding interproximal gingival biopsies were obtained from 30 patients and processed for light microscopic evaluation. Morphometric analysis of tissue components revealed that bleeding was associated with an inflammatory lesion located in the mid-interproximal connective tissue. The inflammatory infiltrate was dominated by mononuclear cells of the lymphocyte/macrophage/monocyte group, and the proportions of plasma cells and polymorphonuclear leukocytes were relatively small. The results of this study indicated that interproximal bleeding can be associated with an inflammatory infiltrate not dominated by plasma cells. The rôle of gingival bleeding in the diagnosis of periodontal disease activity is discussed.

Adult↗
PubMed1986

Effect of metronidazole on development of subgingival plaque and experimental periodontitis.

Active tissue destruction in experimental periodontitis has been positively correlated with subgingival spirochetes and total number of organisms. The present study was designed to inhibit spirochete populations and evaluate the effect upon periodontal destruction. Metronidazole was administered orally to four squirrel monkeys (100 mg/kg/bwt) for 17 days. After 3 days, marginal periodontitis was induced around bicuspids and molars by tying silk ligatures at the gingival margins. Subgingival plaque samples were taken baseline and 14 days after ligature placement. Dark-field microscopy quantitated motile forms, spirochetes, straight and curved rods, filament, cocci and fusiforms. Periodontal destruction was evaluated at 2 weeks by histometric analysis of connective tissue attachment, crestal alveolar bone and infiltrated connective tissue. Bacterial and histometric comparisons were made with experimental periodontitis data from four animals (control) which had not received metronidazole. Subgingival plaque prior to periodontitis induction was dominated by cocci, but fusiforms and straight rods were also present. Straight rods formed a greater proportion of the plaque which developed in metronidazole-receiving animals. The absence of spirochetes and motile rods contrasted with the control group where spirochetes were the predominant type. The total number of bacteria was also larger in the control animals. Histometric analysis showed that areas of infiltrated supracrestal connective tissue were similar in both groups. Loss of connective tissue attachment and alveolar bone was significantly less in experimental animals, and the latter values did not differ significantly from baseline dimensions. The results indicated that the subgingival bacterial populations which developed during metronidazole administration did not result in an experimental periodontitis.

Animals↗
PubMed1986

Cell and fiber attachment to demineralized dentin from periodontitis-affected root surfaces.

This study assessed connective tissue and epithelial responses to dentin specimens obtained from periodontitis-affected roots of human teeth after surface demineralization. Rectangular dentin specimens with opposite faces of root and pulpal dentin were prepared from beneath root surfaces covered by sheets of calculus. One half of the specimens were treated with citric acid, pH 1, for 3 minutes, while the remainder served as untreated controls. Specimens were implanted vertically into incisional wounds on the dorsal surface of rats with one end of the implant protruding through the skin. Four specimens in each group were available 1, 3, 5 and 10 days after implantation. Histologic and histometric analyses included counts of adhering cells, evaluation of attached connective tissue fiber density and diameter, and assessment of epithelial migration. Analyses within each group comparing root and pulpal surfaces showed no differences between any of the parameters. Comparisons between experimental and control groups showed that demineralized surfaces had a greater number of cells attached, fiber attachment occurred and epithelial downgrowth was inhibited. Surface demineralization of dentin from periodontitis-affected roots predisposed toward a connective tissue attachment.

Animals↗
PubMed1986

Healing after application of tissue-adhesive material to denuded and citric acid-treated root surfaces.

This study was undertaken to evaluate the effects of a commercially available tissue adhesive upon healing of the coronal periodontium. In four squirrel monkeys, 24 teeth were extracted, and the coronal third of the roots planed free of fibers and cementum. Eight teeth were replanted without further alteration and eight were coated with tissue adhesive prior to replantation. In the remaining eight teeth, the planed surface was decalcified, coated with tissue adhesive and replanted. Histological observations were made at 1 and 7 days after replantation. In the teeth replanted after root planing alone and root planing plus tissue adhesive, epithelium migrated apically and was within the ligament space lining the denuded root at 7 days. In contrast, those teeth which were decalcified prior to application of tissue adhesive demonstrated fiber attachment to the planed root surface and little or no epithelial downgrowth.

Animals↗
PubMed1986

The root surface and regeneration; present therapeutic limitations and future biologic potentials.

An ultimate goal of periodontal therapy is predictable regeneration of a periodontium at the site of a previous marginal periodontitis. Current clinical therapeutic techniques result in repair, and not regeneration with formation of a new connective tissue attachment. Studies have indicated that surface demineralization of dentin from root surfaces predisposes toward a new connective tissue attachment, and this attachment may take place in an environment lacking periodontal progenitor cell populations. The rôle of the root surface is considered regarding inhibition and facilitation of these various connective tissue responses.

Animals↗
PubMed1985

Long-term periodontal status of teeth moved into extraction sites.

The present study was undertaken to assess the long-term periodontal status adjacent to teeth that had been moved orthodontically into extraction sites. Twelve persons with a mean age of 29.2 +/- 5.7 (SD) years, who had completed orthodontic therapy at least 10 years previously, were examined. The orthodontic treatment had included bilateral premolar extraction in only the maxilla. Interproximal tooth surfaces in the maxilla adjacent to the extraction sites (study group) were compared to corresponding tooth surfaces in the mandible (control group) with respect to plaque, visual inflammation, bleeding after probing, pocket depth, gingival recession, loss of connective tissue attachment, radiographic bone height, and root resorption. Statistical comparisons were made via analyses of variance and t tests. There were no differences between the groups for any clinical parameter except the presence of less visual inflammation in study subjects. Radiographically, there were no differences in crestal alveolar bone levels measured from the cementoenamel junction. Bone height evaluation by the Bjorn method showed less alveolar support in the study group. However, this was due to the influence of root resorption rather than an effect on crestal height. It was concluded that orthodontic movement of teeth into extraction sites had been without detrimental effect upon the adjacent periodontal status.

Adult↗
PubMed1985

Cell processes in dentin tubules during early phases of attachment to demineralized periodontitis-affected surfaces.

This report details some preliminary observations regarding cell morphology and behavior during early phases of in vivo attachment to demineralized surfaces. Rectangular dentin specimens prepared from beneath calculus-covered areas of root surfaces were treated with citric acid and implanted vertically into the skin of rats such that one end of the implant protruded above the skin. The implants were removed after 1 day and the dentin surface - connective tissue interface examined using scanning electron microscopy. A dynamic series of biological events seemed to be in progress. Numerous cells were attached to the dentinal root surface. Cell processes extended a considerable distance along the root surface and into dentin tubules. Cell processes in dentin tubules are discussed.

Animals↗
PubMed1985

Cell and fiber attachment to demineralized dentin from normal root surfaces.

The study assessed connective tissue and epithelial responses to dentin specimens (obtained from normal roots of human teeth) after surface demineralization. Rectangular dental specimens with opposite faces of root and pulpal dentin were prepared from beneath root surfaces covered by periodontal ligament. One-half of the specimens were treated with citric acid, pH 1, for 3 minutes, while the remainder served as untreated control specimens. Specimens were implanted vertically into incisional wounds on the dorsal surface of rats with one end of the implant protruding through the skin. Four specimens in each group were available 1, 3, 5 and 10 days after implantation. Histologic and histometric analyses included counts of adhering cells, evaluation of connective tissue fiber relationships and assessment of epithelial migration. Analyses within each group comparing root and pulpal surfaces showed no differences between any of the parameters. Comparisons between experimental and control groups showed that demineralized surfaces had a greater number of cells attached, fiber attachment occurred and epithelial downgrowth was inhibited. The fiber attachment to experimental specimens differed morphologically from fiber attachment to normal root surfaces: the number of fibers attached per unit length and the diameter of attached fibers were significantly less on experimental specimens. Demineralized specimens at 10 days had a distinct eosinophilic surface zone. Surface demineralization of dentin predisposed toward a cell and fiber attachment system which inhibited migration of epithelium.

Animals↗
PubMed1985

Gingival wound healing in the presence of plaque-induced inflammation.

An accelerated loss of connective tissue attachment has been reported following surgery in plaque-infected dentitions. It was the purpose of the present study to evaluate histologically the healing of incisional wounds in the gingival supracrestal region in the presence and absence of bacterially induced inflammation. In the experimental group, marginal periodontitis was induced around the teeth by tying plaque-retentive ligatures at the gingival margins and 10 weeks later an incisional wound was made from within the gingival sulcus to the crest of the bone. In the control group, similar incisional wounds were made in normal gingiva. In each group, three specimens were available for histologic and histometric analysis 1, 3, 7 and 21 days after wounding. In the control group, the wound healing sequence in the supracrestal region was similar to that reported following incisional cutaneous wounds. In the experimental group, epithelial continuity across the wound was re-established earlier, and marked invagination of epithelium occurred into the incision. This invagination was significantly greater than in control specimens at all time points. In addition, within the experimental group a second significant epithelial migration into the wound occurred between 7 and 21 days. The epithelial invagination extended through the major portion of the supracrestal area and terminated near the cementum surface. It is conceivable that marked epithelial invagination into a supracrestal wound may predispose to an accelerated loss of connective tissue attachment.

Alveolar Process↗
PubMed1984

Temporomandibular disorders and functional occlusion after orthodontic treatment: results of two long-term studies.

The prevalence of temporomandibular (TM) disorders and the status of the functional occlusion in former orthodontic patients many years after treatment were evaluated in two independent clinical studies. In each study, the former orthodontic patients were compared to similar groups of adults with untreated Class I and Class II malocclusions. Both studies reported similar findings with regard to TM disorders; there was no statistically significant difference (p greater than 0.05) between the orthodontic and control groups in either study. The illinois study found a high prevalence of nonfunctional (balancing) contacts in both groups, while the Eastman study found a somewhat lower prevalence. Differences for most of the occlusal parameters between the orthodontic and control groups were not statistically significant in either study. The findings for these two studies are similar and suggest that orthodontic treatment performed during adolescence does not generally increase or decrease the risk of developing TM disorders in later life.

Adult↗