bluuebunny/crossref_metadata_2025 huggingface dataset:
New sustained release dosage form of chlorhexidine for dental use
Authors: Friedman Michael , Golomb Gershon
Published: July 2006

The purpose of this study was to develop a sustained release dosage form of chlorhexidine diacetate for topical use. Cast films of ethyl cellulose with or without polyethylene glycol containing 5, 10, and 20 % of the drug were prepared and exhibited sustained release. Chloroform and ethanol were used as casting solvents. Release rate of chlorhexidine from the film was measured by means of a UV spectrophotometer, and kinetics of release were found to conform to Higuchi's diffusional model. This study demonstrates that by embedding chlorhexidine in polymeric films it is possible to obtain sustained release of the drug for several months.
Effects of topically applied stannous fluoride and acidulated phosphate fluoride alone and in combination on dental plaque
Authors: Yankeli S. L. , Shern R. J. , Stoller N. H. , Green P. A.
Published: July 2006

A five‐day study in 48 subjects, conducted in the absence of customary oral hygiene, measured the effects of a single topical application of stannous fluoride or acidulated phosphate fluoride alone or in a 1:1 combination. All fluoride concentrations were 1.25%. At the end of the study no effects on dental plaque and gingivitis were detected. During the study the flouride treatments, particularly those containing SnF2, temporarily restricted the ability of the saliva to lower the pH of a sucrose solution.
Effects of colchicine on periodontal ligament fibroblasts of the mouse
Authors: Cho Moon Il , Garant Philias R.
Published: July 2006

The effects of colchicine administration on the ultrastructure aad function of periodontal ligament fibroblasts was studied in young mice as a further attempt to document the microtubule‐dependent nature of collagen secretory granule translocation.

Disruption of the normal appearance of the Golgi complex was an early response to colchicine administration. This change was visible at the light microscopic level. At the electron microscopic level it was observed that Golgi saccules were dispersed and that Golgi cisternae were shorter and reduced in number. Microtubules were absent. Dense granules accumulated in a juxtanuclear region of cytoplasm previously occupied by the normal Golgi complex. Lipid droplets and autophagosomes were increased in number. Intermediate filaments (10 nm diameter) formed perinuclear fascicles several hours after colchicine treatment.

These results as well as the recently published report (Cho & Garant 1981d) support the concept that microtubules play an important role in the normal organization of the Golgi complex and in the translocation of secretory granules to the fibroblast cell surface.
Quantitative analysis of connective tissue resorption in the supra‐alveolar region of the mouse incisor ligament
Authors: Schellens J. P. M. , Everts V. , Beertsen W.
Published: July 2006

During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in the occlusal direction and is degraded in the supra‐alveolar region.

In the present study stereologic analysis at the ultrastructural level has shown that significant reduction of the amount of extracellular collagen is confined to the most occlusal region of the ligament, just apically to the functional epithelium. In connection herewith a relatively high amount of homogeneous material of moderate electron density was found in the intercellular space, suggesting a process of extracellular collagen breakdown near the epithelium‐connective tissue interface.

With respect to the distribution of collagen phagocytosis by fibroblasts, it appeared that the volume density of cytoplasmic vacuoles containing collagen fibrils was considerably higher in the supra‐alveolar region of the ligament than in its subcrestal part, particularly in the zone along the tooth surface. This phenomenon is interpreted as being indicative of increased phagocytic activity of fibroblasts leading to the detachment of the periodontal ligament from the cemeatum before it enters the region of final degradation near the apical termination of the junctional epithelium.

In an attempt to identify the cells involved in the degradation of (fragments of) periodontal fibroblasts in the supra‐alveolar region, periodontal ligament cells were labelled with tritiated thymidine at their site of origin. By means of both autoradiography and electron microscopy, it was shown that, following the arrival of Jabelled fibroblasts in the supra‐alveolar region, at least part of the degradation of cellular constituents is accomplished via a process of heterophagocytosis among fibroblasts.
Direct histological comparison of periodontal wound healing in the beagle dog with and without citric acid conditioning
Authors: Nalbandian John , Cote Norman
Published: July 2006

Direct hislological comparison was made of periodontal healing in the beagle dog with and without citric acid conditioning. The acid was applied into one of two small standardized cavities which were prepared on the root surface through a semilunar mucosal incision and a surgically‐created fenestration in the facial alveolar bone. Comparisons were made by general study of serial sections as well as histometric assessments, with particular attention to the formation of cementum. Acid treated cavities exhibited increased cementogenesis as compared to controls. The extent of cementum, its thickness and its area in the sections were, on the average, nearly three times that of the controls. New cementum and connective tissue in the acid treated cavities exhibited minimal artifactual separation from the dentin, whereas in the controls, separation was widespread, signifying that a weaker physical attachment had developed. Differences in the extent of bone formation were not significant. The study confirms a positive effect of citric acid conditioning on cementogenesis and reattachmenl, demonstrating effectiveness with application limited strictly to the root surface.
Immunological and metabolical studies in two siblings with Papillon‐Lefevre syndrome
Authors: Lyberg Torstein
Published: July 2006

Two cases of typical Papillon‐Lefevre syndrome in one family were reported. Neither patient showed evidence of systemic disease as assessed by the medical history and a battery of clinical laboratory tests including a screening system for the detection of inborn errors of metabolism.

A survey of the patients’ immunological status, including lymphocyte transformation tests using mitogens and polymorphonuclear leukocyte chemoiaxis studies, gave no indication of disturbances in immunological functions and host defense mechanisms. Possible pathogenetic mechanisms are discussed.
Polyclonal B‐cell activating capacities of gram‐positive bacteria frequently isolated from periodontally diseased sites
Authors: Dpnaldson S. L. , Bick P. H. , Moore W. E. C. , Ranney R. R. , Burmeister J. A. , Tew J. G.
Published: July 2006

The objective of this study was to determine whether gram‐positive organisms frequently isolated from the periodontium in health and disease contain polyclonal B‐cell activators. Extracts from numerous bacterial strains including Actinomyces viscosus. Actinamyces israelii, Actinomyces NV, Eubacteriun nodatum, Eubacterium brachy, Streptococcus sanguis, Streptococcus anginosus, and Peptostreptococcus micros were tested. All of the organisms contained activity above background, but none of the activators were more potent than pokeweed mitogen, and most were less than half as potent. The aclinomyces appeared to be more active than the eubacteria. streptococci, or peptostreptococci. These PBAs could be significant virulence factors.
Microscopical evaluation of the microflora in relation to necrotizing ulcerative gingivitis in the beagle dog
Authors: Mikx F. H. M. , van Campen G. J.
Published: July 2006

The microflora associated with necrotizing ulcerative gingivitis (NUG) in beagle dogs was investigated in three comparative studies. In the first study beagle dogs were involved harboring different stages of NUG; in the second and third studies the NUG lesions were induced by topical application of debris from a NUG lesion to the gingiva of dogs which had been pretreated with Kenacort A40R.

The microorganisms of diseased and NUG free sites were compared by microscopy in gram‐stained preparations of supra‐ and subgingival samples. Most bacterial types were observed in all dogs, in diseased and NUG free sites. Distinct quantitative differences were observed for the intermediate spirochetes in the supra‐ and subgingival samples of the diseased sites. The other bacterial types were observed in variable numbers. The fusiforms were found in higher numbers in the subgingival samples of the NUG free animals.

A spirillum not described previously was observed especially in relation to inoculated and diseased dogs.

It is concluded that the induction of transmissible lesions in beagle dogs offers the possibility for studying the microbial and host factors related to NUG in an animal model: further investigations will aim at the occurrence of spirochetes and spirillae in relation to necrotizing ulcerating gingivitis.
Aminopeptidase activity of Capnocytophaga
Authors: Nakamura Masakazu , Slots Jøorgen
Published: July 2006

Studies have shown that Capnocytophaga species are unique among the periodonlal microorganisms so far tested in that they produce marked leucine aminopeptidase, valine aminopeptidase, and cystine aminopeptidase activities. In this paper, we used the expanded API ZYMAP (API‐System, La Balme les Grottes, France) system to survey 18 Capnocytophaga strains for their ability to hydrolyze 57 synthetic substrates of β‐naphthylamide derivalives of amino acids, dipeplides, tripeptides, tetrapeptides, and pentapeptides. In general, the study strains exhibited marked hydroiylic activity against all test β‐naphthylamides bearing a free N‐terminal α‐amino group, The hydrolytic activity varied little among the strains. Since aminopeptidases can be involved in bradykinin formation and degradation of collagen fragments and other events ofthe inflammatory process, the Capnocytophaga aminopeptidases may be important virulence factors in Capnocytophaga‐associated periodonial diseases.
An in vitro study of neutrophils obtained from the normal gingival sulcus
Authors: Charon Jacques A. , Metzger Zvi , Terrell Hoffeld J. , Oliver Contance , Gallin John I. , Mergenhagen Stephan E.
Published: July 2006

Neutrophils (PMN) are considered to be key components in the protection of the periodontium against pathogenic bacteria. We therefore compared five of the major characteristics of peripheral blood PMN (PB‐PMN) (adherence, chemotaxis, phagocytosis, oxidaiive metabolism, and lysosomal granules) to those of normal crevicular neutrophils (CR‐PMN) isolated from the same individuals. The data indicate that the presence of Fc and C3b receptors, and the production of superoxide are similar in CR‐PMN and PB‐PMN. In addition, healthy gingival sulci harbor a high percentage of stimulated PMN as determined by the nitroblue tetrazolium (NBT) reduction assay. The percentage of CR‐PMN which phagocytized opsonized red blood cells (RBC) was lower than that of PB‐PMN. The in vitro migration of CR‐PMN was reduced as compared to that of PB‐PMN. Crevicular neutrophils also have a diminished ability to adhere to glass surfaces which may be related to a direct non‐cytotoxic effect of gingival fluid component(s) on CR‐PMN. In addition, morphologic evidence indicates that specific granules are more depleted than azurophil granules in CR‐PMN. Interpretation of studies of neutrophil functions in periodontal diseases must consider the observed differences between normal peripheral blood and crevicular neutrophils.
Mucopolysaccharide localization in gingival epithelium Factors affecting biosynthesis of sulphated proteoglycans in organ cultures of gingival epithelium
Authors: Wiebkin and Ole W. , Thonard John C.
Published: July 2006

The effect of extraneous hyaluronidase, trypsin, hyaluronic acid, chrondroitin sulphate, and commercial heparin on the synthesis and secretion of proteoglycans (mucopolysaccharides) by gingival epithelium in short term incubations was investigated by autoradiography. Small pieces of human gingivae were incubated at 37°C in tissue culture medium (T.C. 199) for 75 min. The first 15 min incubation included a “pulse” of (35S)‐sulphate, after which the radioactive incorporation was “chased” in radioactive free medium. Cryostat sections of these pieces were cut, air dried, slide fixed with cetylpyridinium chloride, and prepared for autoradiography. The effect of the various additives in the “pulse” or the “chase” incubations on the autoradiographic localization of incorporated (35S)‐sulphate in the epithelium was noted.

The responses by the epithelium to the enzymes hyaluronidase and trypsin were different. The former caused marked tissue disruption, probably due in part to degradation of the ground substance. Synthesis and secretion of sulphated macromolecules were evident when the lower concentrations of hyaluronidase were used. Tissue disruption appeared to be less severe. Trypsin in the medium of the gingival incubations appeared to cause both metabolic and secretory disruption. Both the sulphated polyanions, chrondroitin sulphate and heparin, when added to gingival incubations, showed inhibition of localization of (35S)‐sulphate label inlercellularly. Chrondroitin sulphate included in the “chase” incubations alone resulted in the inhibition, while only low concentrations of heparin caused any inhibition. These latter data were curious. The interpretations of a comparison of the data from “pulse” and “chase” additions of the non‐sulphated hyaluronic acid imply that there was an initial inhibitory effect on secretion which in turn resulted in a subsequent regulation of synthesis of the intercellular sulphated macromolecules. These data and those derived from other tissues such as endothelium, cartilage, and chondrocyte cultures are briefly contrasted.
Loss of connective tissue attachment in the marginal periodontium of the mouse following blockage of eruption
Authors: Beertsen Wol'ter , Everts Vincent , Niehof Anneke , Bruins Hubert
Published: July 2006

In an attempt to investigate which factors are involved in modulating the degradation of periodontal ligament carried into the supra‐alveolar region during the eruption of continuously growing teeth, the lower right incisor of the mouse was restrained from erupting by pinning it to its alveolar process. Animals were killed at time intervals varying from one hour up to nine months after pinning and their lower jaws processed for microscopic examination and histometric measurements.

It was observed that, following blockage of eruption, progressive loss of connective tissue attachment occurred in the marginal periodontium throughout the entire experimental period. Loss of attachment and concomitant apical migration of the junctional epithelium apparently were neither related to eruption nor to plaque‐related inflammatory changes. These regressive features were not seen, atleast not to the same extent, in a comparable experiment involving molar teeth which are not subject to a rapid continuous eruption. Although in the latter teeth some lime‐related loss of connective tissue attachment was noted, its overall rate was, on the average, less than one fifth of that calculated for the pinned incisors.

It is concluded that changes of the attachment level in the marginal periodontium of the incisor are caused by local intrinsic factors possibly connected with epithelium‐connective tissue interactions near the apical termination of the junctional epithelium.
Cell turnover in the periodontal ligament determined by continuous infusion of H3‐thymidine using osmotic minipumps
Authors: Gould T. R. L. , Brunette D. M. , Dorey J.
Published: July 2006

Previous methods of determining the labelling index (LI) of periodontal ligament (PDL) over an extended period of time have required multiple injections of isotope or addition of isotope to the animal's drinking water. Problems with these techniques are overcome to a great extent by the use of osmotic minipumps. Male Syrian hamsters had minipumps which had been filled with 2μCiH3‐TdR implanted intraperitoneally. Animals were killed at 2,4,7,21. and 42 days. Specimens were embedded in plastic and 1 μm sections prepared forradioautography. Results show that the LI rose from less than 1% to reach over 50% by the end of the experiment. It is concluded that cells of the PDL are a slowly renewing population.
Collagenase activities in healthy and inflamed gingiva of dogs
Authors: Yanagimura Mitsuhiro , Hara Kohji , Nohara Hiroyoshi
Published: July 2006

The effects of inflammation on collagenase and gelatinase were studied in dog gingiva. Inflammation was induced by the placement of cervical ligatures. Collagenase activity was measured using soluble [14C]‐acetylated collagen with high specific activity as substrate and separating the reaction products by 50% dioxane (Terato et al. 1976). Two forms of collagenase, a soluble enzyme free from the substrate and an insoluble enzyme bound to the substrate, were extracted by neutral salt solution and by sequential sonication in low and high salt buffers, respectively. Treatment with a high concentration of trypsin was necessary for detection of collagenase activities in both extracts. The collagenase activities in the neutral salt extract and the first sonic extract were significantly higher in inflamed gingiva after 1 week of plaque formation than in healthy gingiva, but that in the second sonic extract showed no significant increase. After 3 weeks of plaque formation, the activities in neutral salt extract and the first sonic extract of inflamed gingiva similarly showed significant increases relative to controls. On the other hand, gelatinase activity did not vary significantly with the induction of inflammation.
Diabetes increases collagenase activity in extracts of rat gingiva and skin
Authors: Ramamurthy N. S. , Golub L. M.
Published: July 2006

The connective tissues of diabetic humans and experimental animals exhibit abnormalities in collagen metabolism including an increased production of collagenolytic enzymes by gingival explants in tissue culture. In the current study, gingival tissue and skin were obtained from control and diabetic rats, the latter on the 5th, 10th, 15th, and 22nd day after inducing the disease with streptozotocin. Extracts of the tissues were assessed for collagenase activity using either 14C‐labeled collagen fibrils or Peptide‐P as substrate and by detecting collagenase digestion products by SDS‐polyacrylamide gel electrophoresis. Elastase was measured using the specific substrate, succinyl‐(L‐Alanyl)3‐p‐nitroanilide. Diabetes increased the activity of collagenase in extracts of gingiva and skin; elastase, however, was increased dramatically only in the latter tissue. These findings (1) indicate that diabetes‐induced enhanced gingival collagenase activity occurs in vivo as well as in vitro and (2) explain, at least in part, the greater loss of collagen in skin than in gingiva of the diabetic rat and other complications such as unusually severe periodontal breakdown.
Enhanced synthesis of hyaluronic acid by human gingival fibroblasts exposed to human dental bacterial extract
Authors: Larjava H. , Jalkanen M. , Penttinen R. , Paunio K.
Published: July 2006

Hyaluronic acid synthesis was studied in human gingival fibroblast cultures exposed to human dental bacterial plaque extract. The cells were stimulated to produce large amounts of hyaluronic acid (HA) into the culture medium. The extract did not have any direct effect on the activity of hyaluronic acid synthetase enzyme complex, indicating that the increased hyaluronic acid synthesis was caused by metabolic alterations in gingival cells. Dental plaque extract also decreased the molecular weight of hyaluronic acid. This was obviously caused by the plaque derived hyaluronidase, because denaturation of plaque proteins by heating prevented this degradation. On the other hand, the stimulatory effect on the HA synthesis by the plaque extract was not destroyed by heating. The increased production of low molecular weight HA by gingival fibroblasts after plaque exposure is suggested to have a role in the pathogenesis of chronic periodontal disease in vivo.
Infrequent polysaccharide cohesion among Actinomyces viscosus and Actinomyces naeslundii fresh isolates of human origin
Authors: Ellen Richard P. , Fillery Edward D. , Seckington Kathryn
Published: July 2006

Dextran‐mediated agglutination has been both proposed and opposed as a mechanism for cohesive interactions between Actinomyces viscosus and streptococci in dental plaques. In their Studies, opponents of this mechanism used laboratory strains subcultured in vitro for unknown periods, whereas its proponents had previously shown that laboratory passage of Actinomyces strains weakened this trait. To clarify this issue, eighty‐eight strains of A. viscosus and Actinomyces naeslundii freshly isolated from the human oral cavity and hardly subcultured in vitro, were studied for enhancement of agglutination by commercially obtained polysaccharides including dextran, inulin, agarose, and starch and polysaccharides isolated from sucrose‐grown Streptococcus mutans, Streptococcus sanguis, and Streptococcus salivarius. Few of the strains exhibited higher agglutination scores in buffer containing any of the various polysaccharides than in control buffer free of the polysaccharides. Infrequent polysaccharide agglutinability of these human isolates, even by polysaccharides likely to be encountered in dental plaques, casts doubt on this explanation for Actinomyces’cohesive interactions in plaque formation.
Microbial flora and clinical parameters in phenytoin associated gingival overgrowth
Authors: Smith Q. T. , Wilson Mark M. , Germaine Greg R. , Pihlstrom Bruce L.
Published: July 2006

The effect of phenytoin therapy on periodontal indices, plaque microbiology, and gingival overgrowth was studied. Plaque, gingivitis, and calculus indices and pocket depth were recorded for anterior and posterior teeth of 89 subjects partitioned into 5 groups, a control group, and 4 groups of patients receiving phenytoin therapy with differing severity of gingival overgrowth. A survey of the major oral microorganisms present in marginal plaque was also done. The clinical indices increased with increasing severity of overgrowth. Patients with no or minimal overgrowth had clinical indices equal to or less than those of controls. The proportions of the major oral genera in marginal plaque samples from the groups were similar except for the patients with the most severe gingival overgrowth (mentally retarded and institutionalized). The microbe proportions from neither anterior nor posterior sites had a distinct relationship to severity of gingival overgrowth. Furthermore, no differences were found between clinical parameters or plaque microbiology at the anterior sites of patients who had greater anterior than posterior overgrowth. More frequent Correlations occurred among clinical parameters than among microbial percentages or between microbial percentages and clinical indices. This study does not support a specific marginal plaque etiology for phenytoin associated gingival overgrowth.
The effect of periodontal therapy on lymphocyte blastogenesis to plaque associated microorganisms
Authors: Lopatin D. E. , Smith F. N. , Syed S. A. , Morrison E. C.
Published: July 2006

The effect of clinical treatment on the in vitro lymphocyte blastogenic response to a panel of dental plaque‐associated microorganisms, as well as non‐oral antigens, was assessed longitudinally in a group of twenty‐two patients during treatment for periodontitis. The patients' blastogenic response to the non‐oral antigens remained constant, without, Significant change, throughout the three year study. Following scaling, root planning, and oral hygiene instruction (hygiene phase), an increased blastogenic response to the plaque‐associated Stimulants (except B. gingivalis) was observed. Responses measured after Periodontal Surgery and one year following the hygiene phase (first maintenance year) were lower than pretreatment values. Between the first and second yearly maintenance phase evaluations there was a significant increase in the blastogenic response to A. viscosus, B. gingivalis, and F. nucleatum). Thus, periodontal therapy initially resulted in a reduction of plaque antigen‐induced lymphocyte blastogenesis. However, the responses increased again with time in the absence of deteriorating clinical parameters.
The polymorphonuclear leukocyte chemotactic response to Bacteroides melaninogenicus
Authors: Gale Keith M. , Powell Robin N. , Seymour Gregory J.
Published: July 2006

Neutrophil movement is an important mechanism in the defense against injury or infection. This study examined the in vitro effect of human serum albumin (HSA), normal and heat inactivated foetal calf serum, and Bacteroides melaninogenicus sonicates on human neutrophils using a modified Boyden chamber. The results indicate that sonicates of B. melaninogenicus in the absence of serum or HSA are not either chemotactic or chemokinetic. On the other hand, HSA is chemokinetic, but the addition of B. melaninogenicus sonicates appeared to mask this effect. The results would suggest that the effect of HSA be at least standardized in assessing the presence or absence of in vitro PMN chemotactic anomalies to plaque organisms in relation to periodontal disease.
Lymphocytes from chronically inflamed human gingiva
Authors: Daly C. G. , Cripps A. W. , Clancy R. L.
Published: July 2006

Immunoglobulin production in vitro was investigated for lymphocytes recovered from gingival tissue of 16 patients with chronic marginal gingivitis. Recovered lymphocytes were maintained in culture for 7 days, and the presence of IgG, IgA, and IgM in culture supernatants quantitated using solid‐phase radioimmunoassay. The production of IgG was assessed for 4 patients at days 1, 3, 5, and 7 whilst release of synthesized immunoglobulin due to repeated freeze‐thawing was investigated immediately following cell recovery in 2 patients. The effect of adding pokeweed mitogen (PWM) to gingival cultures was assessed for 8 patients. The concentrations of immunoglobulins found in culture supernatants at 7 days were IgG, 6.6 μg/ml (SD ± 5.7); IgA, 0.8 μg/ml (SD ± 1.0); and IgM, 0.4 μg/ml (SD ± 0.2). Assessment of IgG production over 7 days showed that 56% of the IgG was present by 24 h, 80% by day 3, and 86% by day 5. The amounts of IgG found following repeated freeze‐thawing accounted for 15% of the 7 day total in patient 1 and 38% in patient 2. Addition of PWM to gingival cell cultures at concentrations of 1/50 through to 1/400 had no stimulatory effect on immunoglobulin production. The results indicated that lymphocytes recovered from chronically inflamed gingival tissue secreted immunoglobulin progressively throughout a 7 day culture period. The findings also suggested that gingival B lymphocytes had been highly stimulated in vivo and were actively secreting immunoglobulin at the time of recovery from tissue.
Immunologic observations in macaques with Shigella‐associated periodontal disease
Authors: Armitage G. C. , Banks T. A. , Newbrun E. , Greenspan J. S. , Hoover C. I. , Anderson J. H.
Published: July 2006

The purpose of this study was to determine if macaques with Shigella‐associated periodontal disease (SAPD) were mounting humoral and cellular immunologic responses to Shigella flexneri. Responses to Bacteroides melaninogenicus ss. intermedius, a recognized periodontal pathogen, were also examined. Of the 12 monkeys studied, 4 were uninfected controls, 6 had SAPD, and 2 had been successfully treated for SAPD. At or near the time of immunologic testing, all animals were free of intestinal shigellosis. Antibody titers to the test organisms were determined by direct bacterial agglutination; cellular responses were determined by a serum‐free blast transformation assay. The highest antibody titers and blastogenic responses to both Shigella and Bacteroides antigens were observed in animals from the SAPD group. Monkeys with SAPD gave significantly higher antibody titers to both S. flexneri (p < 0.05) and B. melaninogenicus ss. intermedius (p < 0.01) than did the control monkeys. They also gave significantly higher blastogenic responses to PHA (p < 0.05) and S. flexneri (p < 0.05) than did control monkeys, but did not differ significantly in their blastogenic responses to Bacteroides. These results support the suggestion that Shigella is of etiologic importance in SAPD. They also suggest that a highly virulent microorganism which is a numerically minor component (< 0.1%) of the cultivable flora can elicit significant host responses.
Con A stimulation of collagenase synthesis by human gingival fibroblasts
Authors: Wang H.‐M. , Hurum S. , Sodek J.
Published: July 2006

Presence of 10–1000 μg/ml of Con A in cultures of human gingival fibroblasts promoted the synthesis and secretion of collagenase. Incubation with Con A for a minimum of 6 hours was required for the effect which could be inhibited over this time period by the addition of α‐methyl mannoside. In the continuous presence of Con A, a latent period of at least 8 hours was required before the stimulating effect was observed. Con A also stimulated the synthesis of a number of other unidentified proteins secreted into the medium. Of other lectins tested, phytohemagglutinin produced a moderate stimulation of collagenase production, but only a small effect was observed with pokeweed mitogen and wheat germ agglutinin. The enzyme, which was detected almost entirely in a latent form, was shown to be a true collagenase through the production of typical 3/4‐ and 1/4‐ fragments from a collagen substrate at neutral pH and the inhibition of activity by sulfhydryl compounds and metal chelators.
Levels of prostaglandin E2, thromboxane, and prostacyclin in periodontal tissues
Authors: Dewhirst Floyd E. , Moss David E. , Offenbacher Steven , Goodson J. Max
Published: July 2006

Prostaglandin E2 (PGE2), thromboxane A2 (TXA2), and prostacyclin (PGI2) are naturally occurring metabolites of arachidonic acid which have been associated with inflammation. To assess the relative importance of these mediators in periodontal diseases, the levels of all three were measured by radioimmunoassay in human tissues removed during surgery. TXA2 and PGI2 were determined as their stable hydrolysis products thromboxane B2 (TXB2) and 6‐keto‐prostaglandin F1α (6‐K‐PGF1α), respectively. Tissues from periodontal pockets were separated into superficial (n = 8) and deep (n = 22) samples. Noninflamed gingival samples (n = 3) were taken from distal wedges with no clinical evidence of periodontal disease. Most of the samples taken from deep sites (73%) had measurable PGE2 with a mean level of 122 pg/mg. Half of these samples also had measurable TXB2 which correlated positively with levels of PGE2. Half of the superficial gingival samples had detectable levels of PGE2, and none had detectable TXB2. 6‐K‐PGF1α was found in virtually all samples but at somewhat lower levels in noninflamed tissue. Neither PGE2 nor TXB2 were detected in noninflamed samples.
Polar and neutral lipid composition of canine gingival specimens in different areas of the mouth
Authors: Rabinowitz Joseph L. , Degroote Carl , Cohen D. Walter
Published: July 2006

Gingiva of the upper buccal, lower buccal, upper front, lower front, lower lingual, and palate regions was removed from the mouth of four young male beagle dogs. The complete polar and neutral lipid composition of these tissues was determined in each of the six regions. There were no observable statistically significant differences between the compositions of the lipid families assayed in relation to the location of the regions of the buccal cavity. The analysis also suggests that the lipid composition of the beagle is unique and different from other species as far as it concerns the neutral and phospholipid family components of the gingiva.
An ultrastructural quantitative study of the significance of microbial multiplication during early dental plaque growth
Authors: Brecx Michel , Theilade Jørgen , Attström Rolf
Published: July 2006

Plaque growth may be a result of proliferation of bacteria already present on the teeth and/or of a continuous deposition of additional salivary bacteria. The purpose of this investigation was to study the relative significance of these two mechanisms.

During 4, 8, or 24 hours, plaque was allowed to form on plastic films placed on the buccal surface of the premolar 14 of subjects with healthy gingiva. In addition plastic films were used to collect plaque for an initial 4 hour period after which a filter was applied to prevent further bacterial aggregation to the deposits. The filter‐covered plastic films remained in situ for another 4 or 20 hours. After removal, the samples were processed for electron microscopy.

After 4 hours, the plastic films were covered by a surface coating of an acellular material in or on which bacteria, epithelial cells, and leukocytes were observed. The 8‐hour samples exhibited the same general morphology, but contained more cellular components. After 24 hours, the plaque consisted mainly of a multilayer of bacteria. The 4‐hour samples which remained in the mouth for an additional 4‐hour period covered by a filter resembled the 8‐hour samples. Furthermore, the samples which were covered by the filter after 4 hours and allowed to remain for another 20 hours in the mouth were very similar to the 24‐hour samples.

Finally, the number of bacteria present in a specified area in the section along the plastic film adjacent to the gingival margin was counted in one section from each sample. These data indicated that the number of bacteria had increased between 4 and 8 hours, but no difference was noted between the number of bacteria originating from the 8‐hour samples with or without filter. For the period between 4 and 24 hours, an obvious increase in bacterial counts was ascertained.

The results indicate that proliferation of bacteria already present on the teeth accounts for the major part of the microbial mass increase during early plaque formation, and that the mean generation time is shorter during the first 8 hours (1–2 hours) than during the following 16 hours (3–7 hours).
Statistical analyses of microbial counts of dental plaque
Authors: Socransky S. S. , Haffajee A. D. , Tanner A. C. R.
Published: July 2006

Samples of bacterial plaque were removed from the mesial surfaces of the upper canine, and upper and lower first molars from 20 young adult subjects with gingivitis but without attachment loss. Absolute counts and proportions of 23 categories of microorganisms were enumerated by darkfield microscopy and on selective and elective media. The differences in means of absolute counts of each microbial group on the tooth surfaces were compared by one‐ and two‐way analysis of variance using untransformed, log and square root transformed values. Data were compared with zero values or with zero values replaced with a minimum threshold of detection values of 105 for microscopic counts and 103 for cultural counts. The untransformed and transformed data with and without minimum thresholds replacing zero were tested for conformity to a normal distribution. Differences in counts of each microbial group on the different tooth surfaces were sought by the nonparametric Kruskal‐Wallis one‐way analysis of variance and the Friedman two‐way analysis of variance. Differences in percentages of each microbial group were also sought using the same analyses on untransformed and arc sine transformed percentages.

None of the untransformed absolute counts conformed to a normal distribution. Log transformation, particularly with minimum threshold values replacing zero, was more successful in fitting the data to a normal distribution than square root transformation. However, few groups conformed to a normal distribution after either transformation. Percentages with or without arc sine transformation in most instances were not normally distributed. Substitution of minimum thresholds for zero values did not markedly alter significance testing, but did help to decrease confidence intervals of the means, particularly of log transformed counts. Significant differences revealed by the nonparametric analyses of absolute counts were most similar to one‐ and two‐way ANOVA of log transformed absolute counts. The use of nonparametric analyses for microbial counts is recommended because of the variability of the count data and the difficulties in interpreting zero values and in transforming the data to a normal distribution.
Clinical and microbiological effects of localized ligature‐induced periodontitis on non‐ligated sites in the cynomolgus monkey
Authors: Kiel Robert A. , Kornman Kenneth S. , Robertson Paul B.
Published: July 2006

The purpose of this study was to examine the clinical and microbiological effects of localized ligature‐induced periodontitis on non‐ligated sites in a monkey model system. Ligature‐induced periodontitis was produced in one quadrant in each of four Macaca fascicularis monkeys. Two additional monkeys without any ligatures served as control. The clinical condition and subgingival microflora of ligated, non‐ligated, and control sites were monitored for 8–11 weeks. Ligated sites demonstrated an initial (1–2 weeks post‐ligation) increase in inflammation, Gram‐negative surface translocating bacteria (STB), and motile rods. Clinical and radiographic evidence of loss of attachment associated with increased proportions of Bacteroides gingivalis was evident 4–6 weeks post‐ligation. No clinical changes were demonstrated in non‐ligated and control sites throughout the experimental period. Non‐ligated sites, however, demonstrated an increase from 4.6% to 13.7% in Gram‐negative STB and motile rods by 4–6 weeks which continued to increase to 20.3%, by 8–11 weeks. Control sites showed no microbiological changes during the experimental period. In a second experiment pure cultures of B. gingivalis were implanted subgingivally at various times in non‐ligated sites. It was only possible to recover increased proportions of B. gingivalis from non‐ligated sites when implantation occurred while proportions of Gram‐negative STB and motile rods were elevated. Loss of attachment in infected non‐ligated sites was not seen within four weeks of implantation.
Variation in collagen expression by cloned periodontal ligament cells
Authors: Limeback H. , Sodek J. , Aubin J. E.
Published: July 2006

Isolation in vitro of clonal populations of fibroblasts from enzyme digested porcine periodontal ligament (PL) has made possible the comparison of collagen synthesis between single colonies of cells. Despite low cloning efficiencies, two independent PL isolations yielded enough clones for detailed analysis. In the first group of clones, the amount of 14C‐labelled collagen synthesized compared to the total protein synthesis varied from 32% to 47%, whereas the values from the second group, with one exception, ranged from 55% to 70%. Each clone synthesized types I, III, and V collagens. However, the relative amounts of these collagens varied from one clone to another in both groups: i. e. the type III collagen synthesis ranged from 10% to 32% of the total collagen in most clones. A single clonal population produced type I collagen almost exclusively and in another collagen synthesis was barely detectable. These results indicate that primary cultures of PL cells contain a heterogenous mixture of cells that not only synthesize different levels of collagen but produce distinctly different ratios of collagen types. These findings further suggest that the PL contains distinct populations of fibroblast‐like cells.
Histopathology of artificial periodontal defects in beagle dogs before and after ligature removal
Authors: Jansen Jan
Published: July 2006

The aim of the resent study was to investigate the histopathological characteristics of artificial periodontal defects before and after removal of ligatures. The defects were created in 12 young adult beagle dogs using cotton floss ligatures. The supracrestal dentogingival fibres were dissected around 6 lower premolars (2P2, 3P3, and 4P4) after which closely adapted copper bands were cemented to the teeth. After 3 weeks these copper bands were replaced by subgingival cotton floss ligatures which were left in place for a further 11 weeks. The placement of ligatures around the different teeth and their removal prior to sacrifice was scheduled to provide histological observations of the periodontal defects both with ligatures in situ, and 1 day and 1, 3, 7, 15, or 31 weeks after their removal.

Defects with ligatures in situ showed histopathological characteristics of advanced chronic periodontitis. Removal of the ligatures and the subsequent production of a notch (to mark the bottom of the pocket) resulted initially in an exacerbation of the inflammatory process but 3 weeks after ligature removal, a distinct decrease in size of the infiltrated connective tissue (I. C. T.) could be observed especially in the deeper part of the lesion. The tissues of the periodontium showed signs of repair whack became more pronounced with time. There was no indication that the lesion had become progressive in the remaining period of 7–31 weeks after ligature removal.

It is concluded that the maintenance of the established lesion is dependent on the persistence of subgingival plaque containing ligatures.
Loss of connective tissue attachment in the marginal periodontium of the mouse following blockage of eruption
Authors: Beertsen Wouter , Everts Vincent , Hoeben Kees
Published: July 2006

Following blockage of eruption of continuously erupting teeth in rodents, regressive changes occur in the marginal periodontium resulting in detachment of periodontal ligament from the root surface and concomitant apical migration of the functional epithelium. In the present investigation we attempted to identify the mechanisms that are possibly responsible for these changes which occur in the absence of dental plaque.

Mice were killed at time intervals varying from one hour up to nine months following pinning their lower right incisor to the surrounding alveolar bone. Stereologic analysis of ultrathin sections revealed that, on the pinned side, the collagen content of the periodontal ligament adjacent to the apical termination of the functional epithelium was substantially less as compared with the ligament at more apical levels. The low volume density of collagen close to the functional epithelium was accompanied by a relatively high amount of phagocytosed collagen in fibroblasts. The volume density of collagen‐containing vacuoles in these cells correlated well with the rate at which the periodontal ligament was detached from the tooth, thereby suggesting that collagen degradation in this area is likely to be performed by connective tissue cells. In addition, it was observed that layers of afibrillar cementum were deposited against the root surface. This would seam to suggest a local disturbance in the incorporation of periodontal ligament fibers in the cementum and could possibly facilitate therapid apical progression of the junctional epithelium during the course of the experiment.
Periodontal bone loss in ovalbumin sensitized germfree rats fed antigen‐free diet with ovalbumin
Authors: Taubman Martin A. , Buckelew Julia M. , Ebersole Jeffrey L. , Smith Daniel J.
Published: July 2006

The cellular and humoral responses in ovalbumin (OVA) presensitized germfree rats fed OVA (SAF), in an otherwise antigen‐free diet, were compared to sham‐sensitized animals that were also fed OVA (SSAF). Sensitized animals demonstrated relatively more lymphocytes in their gingival tissues. An initial predominance of T lymphocytes gave way to a predominance of B‐lymphocytes. Splenic lymphocytes from presensitized animals showed significant blastogenesis at the time antigen feeding was initiated. Sensitized animals showed elevated blastogenesis throughout the feeding period whereas the sham‐sensitized animals showed some elevated responses only after 38 days of antigen feeding. The plasma IgG response to OVA was markedly elevated in the sensitized animals, in contrast to a low or nonexistent IgG antibody response in the sham‐sensitized rats. On the other hand, IgA anti‐OVA responses in intestinal perfusates were elevated in the SAF group for the first 14 to 21 days of feeding. Early salivary IgA responses (0 to 21 days) were essentially the same between the groups, but later (38 to 84 days) both IgA and IgG responses in saliva were elevated in the SAF group. Sensitized animals demonstrated significantly elevated periodontal bone loss after 84 or 128 days of OVA feeding. The potential effects of “mixed” hypersensitivity on periodontal disease in the rat are discussed.
Short team implantation studies of periodontal dressings
Authors: Wennberg Alf , Mjör Ivar A.
Published: July 2006

A modified implantation technique was used to study the early tissue reactions to three periodontal dressings (Coe‐pak, Peripac, and Wondrpak). The dressings were placed in contact with an intact non‐epithelialized tissue surface for 15 minutes and 3 days. The tissue reactions were assessed by histochemical and histological techniques. After 15 minutes of tissue‐material contact, the most severe tissue reactions were caused by Wondrpak. When the contact period was increased to 3 days, Peripac generally showed a more severe tissue response than Wondrpak. At both contact periods Coe‐pak had caused the mildest reactions.
An attempt to simulate junctional epithelium of human gingiva in vitro
Authors: Salonen J. , Santti R.
Published: July 2006

Pieces of human masticator mucosa were maintained in a Trowell‐type organ culture. The explants were placed on their side on either microporous filters or decalcified dentin matrix slices. The presence of serum in the culture medium enhanced epithelial outgrowth (epibolus) from the explants. The epibolus grew longer in contact with the substratum than along the free connective tissue surface of the explant.

When grown on microporous filters, the flow of migrating cells was directed between the explant and substratum. As a sign of epithelial attachment to the filter, a structure morphologically similar to basal lamina and hemidesmosomes was seen. The decalcified dentin matrix, however, caused the epithelial cells to migrate outwards from the explant. The explants became loosely attached to the matrix. Although some electron‐dense material was secreted into the contact area, a typical basal lamina was not seen.
Neuraminidase activity in human crevicular fluid
Authors: Kitawaki Masaki , Iijima Ken‐ichi , Nakashizuka Tadashi , Hayakawa Taro
Published: July 2006

Neuraminidase activity in human crevicular fluid by an improved assay procedure was initially demonstrated. The mean values of the activity in periodontally healthy and diseased patients were 11–12 and 144–155 a units per total fluid collected for 10 min, respectively. The activity showed significant correlations (p<0.01) with clinical findings, that is, Debris Index, Calculus, Index, Gingival Index, and pocket depth.