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Biomedical subjects

A M Polson

Publications and source records attributed to A M Polson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Periodontal healing after guided tissue regeneration with Atrisorb barriers in beagle dogs.

Periodontal healing after use of Atrisorb barrier material (polylactic acid) for guided tissue regeneration was studied in the premolar and molar teeth of six beagle dogs. Defects studied were surgically induced or were caused by naturally occurring periodontitis. Barriers fragmented and became displaced in 2 to 5 weeks after application. Granulation tissue was sometimes present between the barrier and root surface at 10 days to 4 weeks. Several sites were surgically reentered at 4 months, and new bone covered 60% to 100% of the formerly exposed furcations and root surfaces. Sites obtained for histologic evaluation 9 to 12 months after the baseline surgery showed new connective tissue attachment, cementum, and alveolar bone. Histomorphometric analyses quantitated these tissue changes, and new connective tissue attachment covered 72% of surgically exposed root surfaces and 77% of periodontitis-exposed root surfaces. It was concluded that new periodontal supporting tissues became reconstituted on root and furcation surfaces after use of the Atrisorb barrier material for GTR.

Alveolar Bone Loss↗
PubMed1993

Oriented cell and fiber attachment systems in vivo.

This investigation was undertaken to evaluate whether an oriented cell and fiber attachment system would develop if demineralized dentin surfaces were approximated in vivo. The approximated surfaces consisted of the internal, parallel surfaces of dentin cylinders. The experimental group was demineralized on both the external and internal surfaces of the dentin cylinder with citric acid, pH 1.0, for 3 minutes, but only the external surface of the control dentin cylinder was demineralized. Specimens were implanted transcutaneously into the backs of rats with one end protruding through the surface of the skin. Three specimens in each group were available for analysis at 1 and 10 days after implantation. The groups were compared using histologic and histometric analysis and the following conclusions were made. There were marked differences in the initial cellular response between the groups, and demineralization with citric acid prior to implantation predisposed towards a greater cell attachment at 1 and 10 days. An oriented fiber attachment developed between the demineralized approximated surfaces by 10 days, but did not develop between nondemineralized approximated surfaces. The morphology of the fiber attachment system was structurally similar to a periodontal ligament, with inserting fibers perpendicular to the implant surface. The findings of this study suggest that spatial approximation of appropriate substrates facilitates development of cell and fiber orientation. Thus, to regenerate a functionally oriented attachment system in the clinical setting, it may be beneficial to provide substrates that are appropriately approximated.

Acid Etching, Dental↗
PubMed1993

Healing patterns associated with an Atrisorb barrier in guided tissue regeneration.

The current guided tissue regeneration clinical technique uses synthetic membranes at the time of the surgical procedure to separate the gingival and periodontal tissue components. These membranes are tied to the tooth surface and have to be ++removed during a second surgical procedure. The material Atrisorb is currently under development as a guided tissue regeneration barrier in Class II furcation defects. This material is applied directly over the furcation defect and is not tied to the tooth surface. Because of its biodegradability, Atrisorb does not have to be removed. A case study is presented.

Aged↗
PubMed1992

Effect of metronidazole on experimental periodontitis: cell population characteristics.

Systemic administration of metronidazole during an experimental periodontitis resulted in significantly less active tissue destruction compared to drug-free animals. However, the size of the inflammatory infiltrates in both groups was similar. The present study assessed cell populations within the infiltrates of metronidazole receiving and drug-free animals. In the experimental group, metronidazole was administered orally to 4 squirrel monkeys (100 mg/kg body weight per day) for 17 days. After 3 days, marginal periodontitis was induced around maxillary and mandibular bicuspids and molars by tying silk ligatures at the gingival margins. In 4 monkeys of the drug-free control group, periodontitis was induced around similar teeth. Biopsies of the gingiva representing 3, 7 and 14 days of experimental periodontitis were taken in both groups. The total number of cells and the number of polymorphonuclear leucocytes (PMN's) were counted on one-micron sections. At 3 days after ligature placement, there were numerically less total cells and PMN's in the metronidazole receiving experimental group. At 7 and 14 days the total number of cells and the number of PMN's was significantly greater in the drug-free control group, where more active periodontal breakdown had occurred. These results emphasize the potentially destructive role of PMN's in acute bursts of tissue destruction.

Animals↗
PubMed1991

Histologic studies on the extension of the inflammatory infiltrate in human periodontitis.

This study was undertaken to re-examine early and recent morphologic descriptions of gingival and periodontal inflammation based on a study of gingival biopsies and block sections of human jaws. A collection of 350 autopsy and surgically retrieved jaw sections containing multiple teeth and displaying various stages of periodontal inflammation were subjected to routine histologic preparation and analyzed with step serial sections. 105 gingival biopsies, serially sectioned, including 15 clinically normal specimens, were also studied. The results of these investigations suggest that the inflammatory lesion extends into the alveolar process and elicits a response, often before evidence of crestal resorption or connective tissue attachment loss has occurred. Similarly, deep penetrations of inflammatory cells into the alveolar bone, periodontal ligament and periapical tissues, along with fibrosis and enlargement of the marrow spaces, were common findings with advancing disease. More widespread distributions of inflammatory cells than previously described were found in clinically normal gingiva, while in more inflamed gingiva, the inflammatory cell types found and their pattern of distribution varied greatly from individual to individual. These observations cast doubt on the perception of human periodontitis as a localized and marginal disease and suggest that its effects may be much more pervasive than previously thought.

Adult↗
PubMed1991

Correlations between periodontal tissue breakdown and cell populations.

The present study evaluated correlations between periodontal breakdown and cell populations during an experimental periodontitis. Periodontitis was induced by tying plaque retentive silk ligatures at the gingival margins of maxillary and mandibular bicuspids and molars of 4 squirrel monkeys. Periodontal destruction was evaluated at baseline, and 3, 7 and 14 days after ligature placement by measuring loss of connective tissue attachment and crestal alveolar bone. Cell populations were characterized at corresponding time points by counting polymorphonuclear leucocytes (PMNs), plasma cells and the total number of cells. At baseline, levels of connective tissue attachment and crestal alveolar bone were normal. At 3, 7 and 14 days, loss of attachment and loss of bone were statistically significant. At baseline PMNs and plasma cells were sparse. At 3, 7 and 14 days, the total number of cells and PMNs were statistically significantly increased compared to baseline. Periodontal tissue destruction was positively and strongly correlated with the number of PMNs. These correlations emphasize the potential role of PMNs during acute bursts of periodontal tissue destruction.

Animals↗
PubMed1989

Cell and fiber responses to cementum from periodontitis-affected root surfaces after citric acid treatment.

The purpose of this study was to assess connective tissue and epithelial responses to periodontitis-affected cementum (from exposed roots of human teeth) after surface demineralization with citric acid. Cementum specimens were obtained from root surfaces covered by calculus. Each rectangular specimen had a face of cementum and an opposite surface composed of pulpal dentin. One half of the specimens were treated with citric acid (experimental group), 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. 4 specimens in each group were available for examination 1, 3, 5, and 10 days after implantation. Histologic and histometric analyses of the implants included counts of adhering cells, evaluation of attached connective tissue fiber density and diameter, and assessment of epithelial migration. At 1 day, a distinct zone of surface demineralization was not present on the surface of the cementum in the experimental group, although such a zone was present on the dentin surfaces of the same specimens. Histometric comparisons between experimental and control groups at 1 day showed no differences in cell attachment or length of cementum surface within connective tissue. By 10 days, there was a trend for greater cell attachment to demineralized cementum, but the differences were not statistically significant. Although connective tissue fiber attachment has been shown to occur to demineralized dentin and to normal cementum in this model system, fiber attachment did not occur to the cementum in the present study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

A combination of platelet-derived and insulin-like growth factors enhances periodontal regeneration.

The combination of platelet-derived growth factor (PDGF) and insulin-like growth factor one (IGF-1) has previously been shown to enhance repair of soft tissue wounds. Here we report initial observations following application of PDGF and IGF-1 to periodontitis-affected teeth in beagle dogs. 1 micrograms of PDGF and IGF-1 in an aqueous gel was applied to the root surfaces of test teeth following open flap debridement. Control sites received the gel alone. Block biopsies of the teeth and surrounding bone were taken 2 weeks after treatment. Histologic analyses of control specimens revealed a long junctional epithelial attachment, and no new bone or cementum formation. In contrast, growth factor treated sites exhibited significant amounts of new bone and cementum formation. A nearly continuous layer of osteoblasts lined the newly formed bone, and there was a dense cellular "front" at the coronal extent of the new bone. These preliminary results suggest that in vivo application of the combination of PDGF and IGF-1 may enhance regeneration of the periodontal structures.

Alveolar Process↗
PubMed1989

Effects of levamisole on experimental periodontitis.

Although the chemotaxis and efflux of functionally normal polymorphonuclear leukocytes (PMN) into the periodontal sulcus may have a protective role in periodontitis, these cells are also associated with periodontal tissue destruction. The immunomodulating agent, levamisole hydrochloride, is known to enhance PMN chemotaxis. The present study was designed to evaluate the effects of enhanced PMN chemotaxis on the tissue destruction associated with an experimental periodontitis. Levamisole was administered by oro-gastric intubation to 4 squirrel monkeys (experimental) at 3 mg/kg/bw every 2 days for 18 days. After 2 doses of levamisole, marginal periodontitis was induced around maxillary and mandibular bicuspids and the maxillary first molars by tying plaque-retentive ligatures at the gingival margins. Periodontitis was induced around corresponding teeth in 4 animals (control) which had not received levamisole. All animals were killed 2 weeks after induction of periodontitis. Clinically, gingival inflammation was more pronounced in experimental animals at both 7 and 14 days after periodontitis induction. The progression of periodontitis was evaluated histometrically and alterations in the cell populations characterized using step serial sections. The results were analyzed statistically. No significant differences were observed between the groups with respect to areas of infiltrated supracrestal connective tissue and total numbers of cells present, loss of connective tissue attachment and loss of coronal alveolar bone. However, in experimental specimens, a much denser band of inflammatory cells was evident between the apical extent of the bacterial plaque and the gingival sulcular tissues the connective tissue of which contained significantly fewer inflammatory cells and demonstrated more pronounced fibrogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1989

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

The purpose of this study was to assess connective tissue and epithelial responses to cementum (from normal human root surfaces covered by periodontal ligament) after surface demineralization with citric acid. Each rectangular specimen had a face of cementum and an opposite surface composed of pulpal dentin. One half of the specimens were treated with citric acid (experimental group), 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 for examination 1, 3, 5, and 10 days after implantation. Histologic and histometric analyses of the implants included counts of adhering cells, evaluation of attached connective tissue fiber density and diameter, and assessment of epithelial migration. At day 1, a distinct lighter staining zone was present on the surface of both cementum and dentin in the experimental group which corresponded to a zone of surface demineralization produced by the acid treatment. Histometric comparisons between experimental and control groups at 10 days showed a greater number of cells attached to demineralized cementum surfaces. Also, a connective tissue fiber attachment system had developed on these experimental surfaces, but which differed morphologically from periodontal ligament fiber attachment to normal cementum. It was concluded that citric acid treatment can surface demineralize cementum from normal roots, and that the surface demineralization of this cementum facilitated a cell and fiber attachment to the cementum surface.

Animals↗
PubMed1988

Long-term periodontal status after orthodontic treatment.

This study evaluated the clinical periodontal status of persons who had completed orthodontic therapy at least 10 years previously (study) and compared the findings to those of adults with untreated malocclusions (control). Subjects in the study (n = 112; 63 female subjects, 49 male subjects; mean age 29.3 +/- 4.2 [SD] years) and control (n = 111; 62 female subjects, 49 male subjects; mean age 32.9 +/- 6.5 years) populations underwent a comprehensive periodontal examination that consisted of measurements taken at six points around the circumference of each tooth: (1) plaque, (2) visual inflammation, (3) bleeding after probing, (4) pocket depth, (5) gingival recession, and (6) loss of connective tissue attachment. Data from the individual measuring points were organized into 14 different combinations of either tooth types or surface locations; each was subjected to a four-way ANOVA partitioned on group (study vs. control), sex, socioeconomic status, and malocclusion type. The results showed that differences in age distribution within the groups were affecting the comparisons between the groups. Consequently, the groups were balanced for age and analyses were done to investigate group differences by means of multiple regression techniques. The comparisons showed no significant differences between the groups for any of the periodontal variables. It was concluded that orthodontic treatment during adolescence had no discernible effect upon later periodontal health.

Adult↗
PubMed1988

Factors associated with occurrence and reversibility of connective tissue attachment loss.

Marginal periodontitis appears to be site-specific, demonstrates rapid bursts of connective tissue attachment destruction, and may, at times, repair spontaneously. The present study was undertaken to investigate associations between bacterial populations and periodontal destruction parameters within the first 14 days after induction of experimental periodontitis in animals receiving metronidazole. Metronidazole was administered orally to four squirrel monkeys for 17 days at a daily dose of 100 mg/kg body weight. After three days (baseline), marginal periodontitis was induced by tying silk ligatures at the gingival margins of maxillary and mandibular bicuspids and molars. Subgingival bacterial samples were taken and periodontal destruction evaluated at baseline, and 3, 7 and 14 days after ligature placement. Dark-field microscopy was used to quantitate motile forms, spirochetes, straight and curved rods, filaments, cocci and fusiforms. Levels of connective tissue attachment, crestal alveolar bone and the volume of bone were assessed histometrically. Bacterial and histometric parameters were analyzed using analysis of variance. The results indicated that subgingival plaque, prior to induction of periodontitis, consisted primarily of cocci. At three days after ligature placement, cocci were significantly decreased, while straight rods became the predominant bacterial group for the remainder of the study. Spirochetes and motile forms were virtually absent at all time points. Histometric analyses showed significant loss of connective tissue attachment at three and seven days, which was reversed and repaired at 14 days. Factors relating to initiation, potentiation, and reversibility of connective tissue attachment loss are discussed.

Animals↗
PubMed1988

Initial wound healing attachments to demineralized dentin.

This report describes the initial in vivo wound healing response of connective tissue components and cells to demineralized and nondemineralized dentin surfaces. Rectangular dentin specimens were prepared from beneath root surfaces covered by periodontal ligament. One group of six specimens were treated with citric acid, while another six specimens served as untreated controls. Specimens were implanted vertically into the skin of rats such that one end of the implant protruded above the skin. After one day, the implants were removed, and the dentin surface-connective tissue interface was examined using scanning electron microscopic methods. The surface of the nondemineralized dentin implants had the morphological characteristics of a surface smear layer. Cells that were present on these nondemineralized surfaces were rounded in shape with few processes or extensions to the dentin surface or to other cells. The surfaces of the demineralized dentin implants were fibrillar in appearance and were usually covered by a layer that had many globular and fibrillar structures attached. Cells that were present on these demineralized surfaces exhibited marked bipolarity with distinct attachments to the dentin surface. Cell processes often extended into the openings of demineralized dentin tubules. It was concluded that an established cellular and connective tissue response to demineralized dentin occurred within the first 24 hours of wound healing, and that this response differed markedly from that associated with nondermineralized dentin surfaces.

Animals↗
PubMed1988

Tetracycline therapy in patients with early juvenile periodontitis.

Tetracycline therapy, when used in conjunction with surgery or root planing, has been shown to be effective in controlling the progression of juvenile periodontitis. However, the ability of tetracycline alone to control the disease has not been assessed. The present study evaluated the effects of tetracycline therapy, with supragingival plaque control, on clinical attachment levels and radiographic bone height in patients with clinical and radiographic evidence of juvenile periodontitis. The four patients (mean age 15.2 +/- 0.3 yrs) each demonstrated loss of attachment of greater than or equal to 2 mm at one or more probing sites and had accompanying radiographic evidence of early localized bone loss. Following an initial clinical evaluation consisting of pocket depths, attachment levels and standardized radiographs, the patients received systemic tetracycline therapy (1 gm/day for three to six weeks) and oral hygiene instruction. At the completion of antibiotic therapy, patients received a supragingival professional prophylaxis every two weeks for three months, whereupon the initial evaluation was repeated. On comparing the initial and three-month clinical and radiographic data, there were significant decreases in clinical and radiographic measurements. For a total of 85 affected probing sites around 26 teeth, 79% decreased in pocket depth by greater than or equal to 2 mm (with no sites increasing in pocket depth) and 69% gained clinical attachment (with only one site losing attachment of 1 mm). Radiographic measurements revealed an increase in both the height and area of coronal alveolar bone. The findings indicated that six weeks of systemic tetracycline therapy combined with supragingival plaque control was effective in the initial control of early juvenile periodontitis.

Adolescent↗
PubMed1987

Cell and fiber attachment to demineralized dentin. A comparison between normal and periodontitis-affected root surfaces.

The purpose of the present study was to compare and contrast cellular, connective tissue, and epithelial responses to dentin specimens derived from the roots of either normal or periodontitis-affected human teeth after surface demineralization. Rectangular dentin specimens, with opposite faces of root and pulpal dentin, were derived from beneath root surfaces covered by periodontal ligament (normal) or calculus-covered areas of periodontitis-affected teeth. In each of the groups, the specimens were treated with citric acid (pH 1 for 3 min), whereupon they were implanted transcutaneously into incisional wounds on the dorsal surface of rats with one end of the implant protruding through the skin. 4 specimens were available in each group at 10 days after implantation. Histologic and histometric analyses of the root surfaces of the implants included counts of adhering cells, evaluation of connective tissue fiber relationships, and assessment of epithelial migration. New connective tissue attachment with inhibition of epithelial migration occurred in both groups. Cementum formation was not present. Comparisons between the groups showed no significant differences regarding length of implant surface adjacent to connective tissue, number of attached cells, or density and diameter of attached fibers. The fiber attachment system which had developed on these demineralized surfaces seemed intrinsic to the connective tissue location, and differed morphologically from corresponding fibers attaching the root surface in a normal periodontium. It was concluded that there were no observable differences between the new connective tissue attachment systems which developed on demineralized dentin from either normal or periodontitis-affected root surfaces.

Animals↗