PubMed Health⌕ Search

Biomedical subjects

A Polson

Publications and source records attributed to A Polson.

At least 19 recordsLinked to original sources
PubMed1992

Guided tissue regeneration in interproximal defects in the monkey.

The potential for guided tissue regeneration was evaluated in one-walled interproximal sites in Macaca fascicularis. Histologic differences were evaluated at 1 and 3 months. Within the experimental (barrier) group, 100% of the root surfaces with potential for regeneration were covered with new cementum, whereas the control specimens had 20% or less new cementum. The amount of regeneration was determined by the position of the barrier membrane; the more coronal the barrier, the greater the regeneration. Observations indicated that the optimal time for barrier removal is between 1 and 3 months.

Animals↗
PubMed1991

Citric acid treatment of periodontitis-affected cementum. A scanning electron microscopic study.

Previous studies have described an inconsistent histological occurrence of a zone of surface demineralization on periodontitis-affected cementum following treatment with citric acid, and a lack of connective tissue attachment to the latter surfaces. In view of these findings, the purpose of the present study was to use scanning electron microscopy to examine the surface morphology of cementum from normal and periodontitis-affected root surfaces following citric acid treatment for differences in the effects of the demineralizing solution on these surfaces. Cementum surfaces were derived from the roots of extracted human teeth from areas beneath attached periodontal ligament fibers (normal) and calculus deposits (periodontitis-affected). 5 specimens were evaluated in both groups. Periodontal ligament fibers were removed from normal root surfaces with a curette, and calculus deposits were removed from periodontitis-affected root surfaces using an ultrasonic scaler. The resultant 5 specimens in each group were then sectioned in half, one-half serving as the untreated control and the other as the experimental, citric acid treated specimen. Experimental specimens were immersed in a saturated solution of citric acid, pH 1 for 3 min and then rinsed in tap water. Both control and experimental specimens were dehydrated in ethanol, critical-point dried, sputter-coated with gold and examined in the scanning electron microscope for morphological characteristics. Citric acid treatment of cementum from normal root surfaces produced an undulating, markedly fibrillar surface morphology which is consistent with the exposure of a fibrillar, collagen substrate. Periodontitis-affected cementum, however, was not appreciably altered in appearance by the citric acid treatment, having only a faint mat-like surface texture. (ABSTRACT TRUNCATED AT 250 WORDS)

Citrates↗
PubMed1990

Cementum thickness and mesial drift.

Cementum thickness increases uniformly with age, and questionably from functional stimulation due to tensional forces. Mesial drift of teeth results in tensional forces on distal root surfaces. This study evaluated whether there was any discernible effect on cementum thickness related to mesial drift in humans. The material consisted of maxillary and mandibular bicuspids and molars with their surrounding periodontia from 5 humans (mean age at death, 48.6 years). The teeth and tissues had been sectioned histologically in a mesio-distal plane, and the analysis for each tooth was done using 3 step-serial sections from the mid-buccolingual region. On the mesial and distal surface of each tooth, cementum thickness was measured in microns at 3 defined locations at a level representing the mid-point of root length for bicuspids and molars. Means from the measurements on mesial and distal surfaces were compared using descriptive and and inferential statistical methods. For each individual tooth analyzed, the cementum was thicker on the distal surface (range greater, 32-107%; mean, 69%). The statistical comparisons showed that cementum thickness on the distal surface was significantly greater for bicuspids (mesial, 135 microns: distal, 216 microns), molars (mesial, 154 microns: distal, 284 microns), and all teeth combined (mesial, 154 microns: distal, 284 microns). The magnitude of this difference became greater with increasing age. It was concluded that cementum thickness was markedly greater on the distal surfaces of teeth from adult humans, and that this may be due to functional stimulation from mesial drift over time.

Adult↗
PubMed1990

Isolation of IgY from the yolks of eggs by a chloroform polyethylene glycol procedure.

By shaking a dilute suspension of egg yolk with chloroform followed by low speed centrifugation (1500 g for 30 min) the water soluble proteins which include chicken IgG (IgY) separate from the emulsion of chloroform and lipophilic substances. The IgY may then be separated from the associated water soluble proteins by precipitation with 12% polyethylene glycol Mr 6000. The method called the chloroform - polyethylene glycol procedure was compared with the polyethylene glycol procedure which is currently being used. It was found that the chloroform - polyethylene glycol method yielded 2.57 times more IgY than the conventional polyethylene glycol method. The ratio of titres of IgY anti Jasus lalandii haemocyanin antibody purified by the two procedures was very nearly 2.57 indicating that the chloroform had no adverse effect on the antibody activity.

Animals↗
PubMed1989

Effects of personal oral hygiene and subgingival scaling on bleeding interdental gingiva.

The aim of this study was to determine the effects of personal oral hygiene and subgingival scaling on bleeding interdental gingiva. The Eastman Interdental Bleeding Index (EIBI) was used to clinically evaluate interdental gingival status. Forty-seven bleeding interdental sites in 47 patients were divided into three groups. Sites in Group I bled on stimulation with wooden interdental cleaners. Groups II and III initially bled but were converted to nonbleeding with oral hygiene alone or oral hygiene combined with subgingival scaling, respectively. Interdental gingival biopsies were obtained and subjected to morphometric analysis to compare the three groups. The findings from this study indicated that: (A) personal oral hygiene reduced the magnitude and extent of the interdental inflammatory lesion; (B) subgingival scaling plus oral hygiene decreased the interdental inflammatory lesion to a greater extent than oral hygiene alone; (C) significant repair of the interdental lesion occurred within four weeks; and (D) the EIBI was an effective method for monitoring the effects of therapy directed towards resolution of the interdental inflammatory lesion.

Adult↗
PubMed1989

Steep gradients of inert substances as supports for precipitin reactions.

Precipitin reactions were conducted in the wells of micro titer plates and the light "absorbance" at 405nm plotted as a function of the neg log2 dilutions of the antigens using the Titertek Multiscan apparatus. The procedure followed was to incorporate antibody in 20% sucrose and to diffuse the mixture into serial two-fold dilutions of antigen overlaid on the sugar-antibody columns in the wells. Where the antigen met its antibody in equivalence precipitin bands formed. The bands of precipitates remained suspended. The precipitates formed by mixing the antibody sugar mixture with the serial two-fold dilutions of the antigen were also recorded in the Titertek Multiscan apparatus. Tobacco mosaic virus and its IgY type antibody produced simoidal precipitin curves with the layering as well as the mixing techniques. The haemocyanin of the whelk and its IgY antibody yielded a precipitin diagram with the layering technique which gave evidence to three antigens. The three antigens in the haemocyanin was confirmed by two dimentional Laurell-electrophoresis. Semi-purified human colostral dimeric IgA and its IgY antibody produced a precipitin diagram which showed evidence of four of five antigens. With the mixing technique a single precipitin maximum was obtained preceded by a prozone. Rabbit Ig and its IgY antibody gave a precipitin curve with two maxima. The precipitin curve obtained when the reagents were mixed had one peak preceded by a prozone.

Animals↗
PubMed1989

Eliciting antibodies in chickens to human dimeric IgA removal of factors from human colostrum depressing anti IgA antibody production.

Contrary to expectation chickens did not readily elicit antibodies to IgA dimers when untreated human colostrum was used as antigen. When colostrum was fractionated by means of a column of 8% granulated agarose equilibrated with 10mM phosphate buffer, pH 7.2, a major and a minor fraction were obtained. The major or "1st fraction" consisted of two components with sedimentation coefficients of 10.9 S and 14.1 S, respectively. The minor or "2nd fraction" consisted of components of S values ranging from 2 to 6 and small amounts of 10.9 and 14.1 S material. When chickens were immunized with the "1st fraction" antibodies to dimeric IgA were produced. When the "1st and 2nd fractions" of the column were remixed and used for immunization of chickens, the immune response was poor as when the chickens were injected with untreated colostrum. An immuno-depressing agent in colostrum was indicated. When rabbits were immunized with clarified human colostrum, antibodies against five antigens were elicited, one of the antigens being dimeric IgA. The purified agent suppressed antibody formation in chickens against the haemocyanin of Jasus lalandii. The "activity" is therefore not specific for IgA and the remaining four antigens in human colostrum. The purified component is a glyco-protein with a hexose content in excess of 10%. The derivatized sugars prepared from it were shown by gas liquid chromatography to be an equimolar mixture of galactose, mannose and fucose. The molecular weight (Mr) of the purified component was found to be 72,000 by sedimentation and diffusion and 80,000 by SDS page using Mr reference standards. The properties of the immuno-suppressor strongly suggest that it is the secretory piece of dimeric IgA.

Animals↗
PubMed1988

Cell populations associated with conversion from bleeding to nonbleeding gingiva.

The purpose of this study was to observe changes in cell populations of the interdental gingival tissue, which accompanied the conversion of a bleeding to a nonbleeding state induced by scaling and improved oral hygiene. Fifteen bleeding and 18 stopped-bleeding interproximal gingival biopsies were obtained from 33 patients and processed for light microscopic evaluation. The morphometric analysis of eight connective tissue components revealed that the percentage volume density of all inflammatory cells decreased, and the percentage of fibroblasts and collagen increased, when the gingiva changed from a bleeding to a nonbleeding state. Furthermore, the inflammatory cell infiltrate in bleeding and stopped-bleeding specimens was dominated by mononuclear cells of the lymphocyte/macrophage/monocyte group, while plasma cells and polymorphonuclear leukocytes comprised only a small fraction of the inflammatory cells present. Significant repair of gingival connective tissue had occurred in the stopped-bleeding specimens.

Adult↗
PubMed1988

Tissue interactions with dentin specimens after demineralization using tetracycline.

Greater cell attachment to demineralized dentin has been associated with subsequent development of a fiber attachment system. The purpose of this study was to evaluate tissue interactions to dentin demineralized with different concentrations of tetracycline solution. Dentin specimens were obtained from beneath root surfaces covered by periodontal ligament. Each rectangular specimen had a face of root surface dentin and an opposite surface of pulpal dentin. Experimental specimens were treated with a tetracycline solution of either 200 mg/cc or 100 mg/cc for five minutes. The remaining group of specimens served as untreated controls. Specimens were implanted transcutaneously into incisional wounds on the dorsal surface of rats with one end protruding through the skin. Four specimens in each group were available for examination one and ten days after implantation. Histologic and histometric analysis of both root and pulpal surface of implants included counts of adhering cells, assessment of implant length within the connective tissue, and evaluation of connective tissue fiber relationships. In each group, specimens became severely extruded between days one and ten, the number of attached cells decreased, and a fiber attachment system did not develop. Tetracycline-treated surfaces had greater numbers of attached cells at both time points compared to untreated controls. No differences were discernible relating to different tetracycline concentrations. It was concluded that tetracycline-demineralized dentin provided a substrate that increased cell attachment; however, this enhanced response did not result in a connective tissue attachment.

Animals↗
PubMed1988

Associations between bleeding and visual signs of interdental gingival inflammation.

Interdental gingival tissues are designated inflamed on the basis of their color and bleeding after stimulation. Gingival bleeding was previously shown in histological studies to indicate the presence of inflammatory lesions. The present study was undertaken to determine associations between bleeding and visual signs of interdental gingival inflammation. Each interdental site in 82 males, aged 18 to 30, was evaluated for the presence or absence of visual signs of inflammation. The interdental sites on one side of the mouth were evaluated for bleeding tendency using the Papilla Bleeding Index (PBI), while the other half was evaluated using the Eastman Interdental Bleeding Index (EIBI). The percentage of inflamed areas detected with the EIBI and visual method was similar and significantly higher than with the PBI. When the visually noninflamed sites were examined, 38.5% of these areas bled, indicating that interdental inflammatory lesions existed in the absence of visual signs of inflammation. Of the sites that bled but were visually noninflamed, 33.1% were detected using the PBI, while 66.9% were detected using the EIBI. The Eastman Interdental Bleeding Index was a more reliable clinical indicator for detecting interdental inflammatory lesions than the Papilla Bleeding Index.

Adolescent↗
PubMed1988

Effect of personal oral hygiene on bleeding interdental gingiva. Histologic changes.

A previous study demonstrated that the combination of subgingival scaling and improved oral hygiene resulted in a reduction of clinical and histological signs of interdental gingival inflammation, changes that were associated with a cessation of interdental gingival bleeding. The present study compared, histologically, the interdental tissues of bleeding sites with sites that initially bled but had been converted to nonbleeding by an oral hygiene program alone. Morphometric analysis of interdental gingiva demonstrated that conversion from bleeding to nonbleeding was associated with a significant reduction in the inflamed connective tissue component. This study showed that an oral hygiene program consisting of toothbrushing and interdental cleaning could significantly reduce interdental inflammation, and that bleeding determinations monitored the effects of this therapy.

Adult↗
PubMed1987

Orthodontic relapse, apical root resorption, and crestal alveolar bone levels.

This investigation examined the relationship of postorthodontic treatment relapse to crestal alveolar bone support and root resorption. Thirty-six persons having completed the retention phase of orthodontics at least 10 years earlier were divided into two groups based on the amount of relapse crowding of the mandibular anterior teeth. Eighteen subjects (relapse group) exhibited 2 mm or more of mandibular anterior relapse crowding and 18 subjects (nonrelapse group) exhibited no mandibular anterior relapse crowding. At time of recall, full-mouth series of periapical and bitewing radiographs were obtained as well as lateral cephalometric films to allow comparison with similar lateral cephalometric films obtained at pretreatment and retention time points. The radiographs were examined to assess three parameters: root resorption, crestal alveolar bone levels, and changes in the position and angulation of the maxillary incisors. The subjects in the relapse group had undergone longer periods of treatment and exhibited a greater prevalence of root resorption; they also displayed significantly greater crestal alveolar bone level distances, indicating greater loss of bone support than that observed in the nonrelapse group. The distances that teeth were translated seemed to affect the extent of root resorption and crestal bone loss with smaller amounts of tooth translation seemingly more prone to demonstrate tissue loss. The findings of this investigation suggest there may be a relationship between orthodontic relapse and the parameters of increased root resorption and decreased crestal alveolar bone levels.

Adult↗
PubMed1987

A novel method of electrophoresis for the separation of individual human serum glycoproteins.

A method for the isolation of protein components by a combination of polyacrylamide gel electrophoresis and electro-extraction of slices of gel contained in cellophane dialysis tubing, using the H tube electrophoresis apparatus, is described. The method was applied to the purification of individual human serum glycoproteins. Although the glycoproteins have widely differing electrophoretic mobilities, they appeared to be antigenically interrelated judging from their complex "spurring" in Ouchterlony double gel diffusion tests.

Blood Protein Electrophoresis↗
PubMed1986

Preparation of agarose with low net negative charge density using an inexpensive anion exchanger.

A method of preparing agarose of low net negative charge density by the use of Chromium tanned gelatin is described. Using commercial agarose (agarose c) as standard of comparison the product has a sulphate content approximately 0.1 that of agarose c and its pyruvate content was reduced to zero as shown by NMR in DMSO. The product was still able to adsorb and desorb serum glycoproteins similar to agarose c indicating that charge on the agarose c gel particles played a minor role if any on the binding of the serum glycoproteins.

Adsorption↗
PubMed1986

Interproximal gingival inflammation related to the conversion of a bleeding to a nonbleeding state.

Elimination of gingival bleeding has been related to a reduction in inflammation; however, histologic data are not available to support this association. The purpose of this study was to characterize the histology of interproximal gingiva that was converted from a bleeding to a nonbleeding state. An interproximal gingival biopsy was obtained from each of 32 patients, 15 of whom bled upon stimulation with a soft wooden interdental cleaner. The remaining 17 biopsies were obtained from sites which initially bled, but were converted to nonbleeding by scaling and interproximal plaque control. Specimens were processed for light microscopic evaluation and subjected to a morphometric analysis for various tissue components. Data from bleeding and "stopped bleeding" specimens were compared using analysis of covariance. The results indicated that "stopped bleeding" specimens had significantly less inflamed connective tissue. It was concluded that the conversion of a bleeding to a nonbleeding state corresponds with a histological reduction in the magnitude of the interproximal inflammatory lesion and provides a rationale, therefore, for the use of bleeding to monitor the effects of therapeutic methods.

Adult↗
PubMed1985

An apparatus for the concentration of large volumes of dilute protein solutions to a predetermined volume.

An apparatus was designed and manufactured that can be used for the concentration of large quantities of dilute protein solutions to a predetermined volume. The method is based on the osmotic transfer of water to a concentrated hydrophilic polymer (poly ethylene glycol, PEG) through a protein-stopping dialysis membrane and is a refinement of a method previously reported by van Oss. The apparatus is made of perspex. Concentration takes place through a commercially available dialysis tube and is aided by a 40% polyethylene glycol solution. Large volumes (5l) of dilute protein solution could be reduced to 50 ml at a rate of 30 ml per hour with no significant loss in biological activity.

Animals↗
PubMed1985

Microscopic monitoring of pathogens associated with periodontal diseases. A review.

Microscopic monitoring of the subgingival microbiota to detect pathogens associated with periodontal diseases has been an active area of investigation. Researchers have demonstrated that plaque samples obtained at diseased sites contain more motile bacteria and less coccoid forms than healthy sites. Therapy at diseased locations has resulted in a shift in the microbiota to one that resembles healthy sites. However, the ability to predict disease activity based on morphotype counts still remains unverified. The current literature addressing chairside microscopic assessments as a diagnostic parameter is reviewed and discussed.

Bacteria↗