Comparison between histological and clinical parameters during human experimental gingivitis

The purpose of this investigation was to study stereologically the histopathologic alterations occurring during a human experimental gingivitis, and to establish a relationship between clinical parameters and histologic findings. Eight dental students volunteered for the study. After a prophylaxis they performed optimal oral hygiene for 3-4 weeks to reach mean plaque and gingival indices approaching zero. They then abandoned all oral hygiene procedures for a period of 21 days. At d 0, 4, 7, 14 and 21, Plaque Index (PII), Gingival Index (GI) and Gingival Exudate Flow Rate (GEFR) were assessed, and a buccal biopsy of their gingiva was taken. Point counting procedures were performed at 2 different levels of magnification to estimate the volume densities of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The percentages of polymorphonuclear neutrophilic granulocytes, lymphocytes, plasma cells, macrophages and fibroblasts were estimated by counting the number of profiles of these cells in the connective tissue area close to the apical end of the junctional epithelium. The histological picture during the entire experiment was one of an early lesion (Page & Schroeder 1976). The clinically healthy gingiva did not correspond to a histologically healthy gingiva containing only a few inflammatory cells, probably because the 3-4 wk of perfect oral hygiene were not sufficient to generate histological health. Furthermore, no chronic inflammation of the gingiva, as characterized by a predominance of plasma cells, was observed after 3 wk without oral hygiene. Thus, more than 3 wk of no oral hygiene are necessary to obtain an established gingival lesion. With increasing gingivitis scores between GI = 0 and GI = 2 there was a significant increase in the percentages of lymphocytes and a significant decrease in the percentages of fibroblasts. With increasing GEFR similar trends in percentages were observed for lymphocytes and fibroblasts. It was concluded that GI scores and GEFR reflect histologic changes in tissue and, hence, are valid indicators of gingivitis development.     

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

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

Variability of histologic criteria in clinically healthy human gingiva

After prophylaxis, 5 dental hygienists performed optimal oral hygiene under supervision for 6 months. At months 0, 1, 4 and 6, Plaque Index, Gingival Exudate Flow Rate and Gingival Index were assessed, and a buccal biopsy of their gingiva taken. Point counting procedures were performed at 2 different levels of magnification to estimate the volume densities of epithelium, infiltrated and non-infiltrated connective tissue, and collagen. The percentages of fibroblasts, polymorphonuclear neutrophilic granulocytes, lymphocytes, plasma cells and macrophages were estimated by counting the number of profiles of these cells in the connective tissue area close to the apical end of the junctional epithelium. All the changes inside the tissue occurred slowly. During the 6-month period there was a continuous increase of the volume density of the epithelium in the gingiva. An increase in the percentage of fibroblasts was observed between months 1 and 4 together with a decrease in the percentage of lymphocytes and in the volume density of the infiltrated connective tissue. Between months 4 and 6 an increase of the volume density of the collagen was found together with a further increase in the percentage of fibroblasts and a further decrease in the percentage of lymphocytes. After 6 months of perfect oral hygiene no more plasma cells were visible. This study has shown that, even in presence of clinically healthy gingiva, subclinical changes may take place. It appears realistic to accept the presence of a very mild gingivitis localized in an area adjacent to the attachment as compatible with gingival health.     

Clinical and histologic characteristics of normal gingiva in dogs

The aims of the present study were to establish normal gingiva in dogs, to characterize the clinical conditions prevailing and to stereologically describe the structural composition of the normal gingival tissues. Three beagle dogs were subjected to regular oral hygiene procedures during 15 weeks. Measurements of gingival fluid flow and the amounts of crevicular leukocytes served to clinically assess the gingival conditions. Semi-and ultrathin sections from biopsies of normal buccal gingival tissues from premolars were subjected to stereologic analysis based on morphometric point counting procedures. Gingival normality was achieved in two of the dogs. The normal gingival tissue in these dogs was characterized clinically by abscense of gingival fluid flow and by a minute amount of crevicular leukocytes. A gingival sulcus was most often absent. The junctional epithelium was without rete pegs, and the entire gingival connective tissue was densely filled by homogeneous collagen fiber bundles. A few isolated inflammatory cells were present in the junctional epithelium and the adjacent connective tissue. No clusters of inflammatory cells forming an infiltrate could be observed.
Stereologically, the gingival tissue comprised 48% epithelium and 52% connective tissue. The junctional epithelium occupied 10% of the gingival tissue and included a fraction of 2.8% occupied by leukocytes. The latter by volume comprised 50% neutrophilic granulocytes and mononuclear cells each. The connective tissue was composed of 67% collagen fibers, 14% free cells and 19% residual tissue. The composition of the connective tissue adjacent to the junctional epithelium differed somewhat from that of more central connective tissue fractions.     

Histologic characteristics of experimental gingivitis in the juvenile and adult beagle dog

Abstract An earlier study (Matsson & Attström 1979) revealed an unexplained difference between juvenile and adult dogs in the propensity to develop clinical signs of gingivitis. The aims of the present investigation were to depict the structural composition of clinically normal gingiva and to analyze the histologic changes in the gingiva during plaque development in juvenile and adult dogs. Six beagle dogs were used. Two periods of discontinued oral hygiene were studied, the first at 3 and the second at 12 months of age. Biopsies were sampled on days 0, 4, 7, 14, 21 and 28 of each period. Sections from the biopsies were analyzed at two levels of magnification. Compared to adult dog gingiva, juvenile gingiva seemed to display: 1) a thicker keratinized layer of the oral epithelium, 2) a junctional epithelium that structurally resembles the oral epithelium, 3) a cuticular structure at the surface of the junctional epithelium, 4) a limited mononuclear inflammatory cell response during experimental gingivitis, and 5) a delayed establishment of an infiltrated connective tissue portion during experimental gingivitis. In addition, during experimental gingivitis, subgingival plaque formed along the tooth surfaces to a lesser extent in the juvenile stage compared to adult dogs.     

Expression of ICAM-1/LFA-1 in the pocket area of adult periodontitis]

OBJECTIVE: To study the expression of ICAM-1/LFA-1 in the pocket area of adult periodontitis. METHODS: Expressions of ICAM-1/LFA-1 in adult gingival of periodontitis and healthy subjects were studied by alkaline phosphorylase-antialkaline phosphorylase technique. RESULTS: Junctional epithelium and apical part of sulcus epithelium expressed ICAM-1 in both adult periodontitis and healthy gingiva, showing an ICAM-1 gradient change with maximal staining at tooth aspect and weaker staining in the basal layer of keratinocytes. Significantly more LFA-1 positive leukocytes were observed in connective tissues and within pocket epithelium in adult periodontitis than those in healthy gingiva. CONCLUSION: ICAM-1/LFA-1 may provide important adhesion pathway for leukocytes migration into gingiva sulcus in adult periodontitis lesions.     

Aberrant blastogenic response to LPS in experimental gingivitis of elderly subjects.

The blastogenic response of peripheral blood leukocytes to lipopolysaccharide (LPS), phytohemagglutinin (PHA) and LPS/PHA mixtures was followed over a short course of experimental gingivitis in elderly subjects (65-81 years) who strictly avoided oral hygiene procedures for periods up to 9 d. The leukocytes responded poorly to LPS, PHA and to LPS/PHA combinations. The concomitant heightened sensitivity of the gingiva to dental plaque among the elderly subjects may relate to the altered leukocyte response in this age group.     

Aberrant blastogenic response to LPS in experimental gingivitis of elderly subjects

Abstract – The blastogenic response of peripheral blood leukocytes to lipopolysaccharide (LPS), phytohemagglutinin (PHA) and LPS/PHA mixtures was followed over a short course of experimental gingivitis in elderly subjects (65–81 years) who strictly avoided oral hygiene procedures for periods up to 9 d. The leukocytes responded poorly to LPS, PHA and to LPS/PHA combinations. The concomitant heightened sensitivity of the gingiva to dental plaque among the elderly subjects may relate to the altered leukocyte response in this age group.     

A histological study of experimental gingivitis in man

Experimental gingivitis was induced in 21 individuals. Oral hygiene was abolished on the buccal and interproximal tooth surfaces of one side of the mouth in the mandibular premolar and molar area. The other tooth surfaces served as controls and were subject to thorough oral hygiene measures. After 15–17 days, when clinically manifest gingivitis had developed in the non-cleansing side of the majority of the subjects, biopsies were obtained from that side as well as from the control side. Histological examination of tissue from the experimental side revealed inflammatory infiltrates largely confined to the connective tissue adjacent to the pocket epithelium. The cells were mainly medium-large and small lymphocytes, macrophages and fibroblasts. A few neutrophilic leukocytes were observed mostly inside the vessels and adjacent to and within the pocket epithelium. Immature and mature plasma cells were seen in the central regions of the connective tissue, but were scant or absent nearer to the pocket epithelium The distribution of the different types of mononuclear cells might be consistent with a transformation of lymphocytes into plasma cells.     

Initial gingivitis in dogs

The gingival characteristics after four days of gingivitis development have been studied in three Beagle dogs. Gingival normality was induced by regular tooth cleaning and gingivitis was provoked by abolishing oral hygiene procedures and giving the animals a soft diet. Measurements of the gingival fluid flow and the amount of crevicular leukocytes served to clinically assess the gingival condition. Semi- and ultra-thin sections from contralateral biopsies of buccal gingival tissues from premolars obtained on day 0 and day 4 respectively were subjected to stereologic analysis based on morphometric point counting procedures. On day 0 of the experiment two dogs revealed minute amounts of gingival fluid and crevicular leukocytes and the gingival tissues of these dogs were normal. The third dog had somewhat higher amounts of the gingival parameters and the connective tissue adjacent to the junctional epithelium harboured a small lymphoid infiltrate occupying 8.3 ± 2.8% of the gingival tissues. On day 4 the gingival fluid flow and the amounts of crevicular leukocytes were increased in all dogs compared to their values on day 0. The coronal con nective tissue in the two dogs with initially normal gingiva revealed on day 4 an infiltrated portion which occupied 6.1 ± 2.4% of the gingival tissues. The infiltrate was predominated by neutrophilic granulocytes, monocytes, macrophages, immunoblasts and small lymphocytes. A 60% loss of the collagen density in the infiltrated fraction was noted between biopsies from day 0 and day 4 in these two dogs. The tissues of the dog which entered the experiment with a preestablished lymphoid infiltrate reacted with similar but more intense inflammatory processes on day 4 than those of the dogs with normal gingiva on day 0. The results indicate that initial gingivitis in dogs is characterized by acute exudative inflammation and immunopathological processes as well as by a marked loss of collagen fibers in the connective tissue located beneath the coronal part of the junctional epithelium. Possible mechanisms responsible for the observed alterations have been discussed.     

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.     

Endothelial cell leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1) expression in gingival tissue during health and experimentally-induced gingivitis

The changes in vascular adhesion molecule expression and numbers of infiltrating leukocytes during a 21-day experimental gingivitis episode were investigated immunohistochemically. Monoclonal antibodies to ELAM-1 (1.2B6), ICAM-1 (6.5B5), CD3 (OKT3-pan-T cell) and neutrophils (PMN-elastase) were used to identify positive vessels and leukocytes within gingival biopsies taken on d 0, 7, 14 and 21. Vascular endothelium expressed ELAM-1 and ICAM-1 both in clinically 'healthy' tissue (d 0) and in experimentally inflamed tissue (d 7 to 21). Positive vessels were found mainly in the connective tissue subjacent to the junctional epithelium where the highest numbers of T cells and neutrophils were also seen. Although T cells were found in all tissue areas studied, neutrophils were largely concentrated in the junctional epithelium and the subjacent connective tissue but were absent from the oral epithelial region. As the experimental gingivitis developed, the number of T cells or neutrophils in the different tissue regions did not change significantly although the most intense vascular ICAM-1 and ELAM-1 staining redistributed to the CT adjacent to the junctional epithelium. A prominent feature was the intense ICAM-1 positive staining of the junctional epithelium and its absence in the closely adjacent oral epithelium, in both clinically 'healthy' and inflamed tissue. The gradient of ICAM-1 in junctional epithelium, with the strongest staining on the crevicular aspect plus the vascular expression of ELAM-1 and ICAM-1 in both clinically 'healthy' and inflamed tissue may be crucial processes which direct leukocyte migration towards the gingival crevice.     

Histopathology of initial gingivitis in humans

Abstract The present study concerns the inflammatory alterations in the gingival margin during initial gingivitis in 11–13 year old human subjects. At day 0 of the experiment, all participants had clean teeth and healthy gingiva. All active oral hygiene measures were excluded for 4 days. From upper and lower premolars, which were extracted for orthodontic reasons, contralateral gingival biopsies, including the tooth and the adjacent gingiva, were obtained on days 0 and 4. The presence of inflammatory cells in the junctional epithelium and the adjacent connective tissue was determined quantitatively in semi-thin sections. The collagen content of the gingival margin was also determined. From day 0 to day 4 there was only a slight increase in the number of neutrophilic granulocytes in the junctional epithelium and adjacent connective tissue, while a more pronounced increase was found in the number of mononuclear leukocytes. A loss of collagen was noticed in 4 of the subjects, while 2 did not show any changes in collagen content. The inflammatory reaction seen in the present study differs somewhat from that observed in adult humans and adult dogs. The results correspond more to the reaction seen in juvenile dogs.     

The effect of topical application of dextran on the gingiva of the beagle dog.

Dextrans derived from Leuconostoc mesenteroides were placed on clinically healthy gingiva of Beagle dogs once a day for 21 days. Control gingival tissues received saline. Both healthy controls and dextran-treated tissues were brushed daily. Inflamed control tissues were obtained by allowing plaque to accumulate for 21 days. Tissues receiving daily application of dextran solutions developed chronic gingival inflammation but displayed no clinical signs of gingivitis. Healthy control gingival tissues showed no clinical signs of gingivitis and minor histologic inflammatory changes. Tissues exposed to dental plaque showed the typical clinical and histological inflammatory changes of gingivitis. Thus dextran, a substance similar to the extracellular polysaccharide found in dental plaque, was able to penetrate the sulcular epithelium, enter healthy gingival connective tissue and cause chronic inflammation. This connective tissue inflammation occurred without inducing any of the clinical signs of gingivitis. Therefore, it is concluded that dextran produced one component of the gingivitis response, chronic histologic inflammation, independent of another major component of the disease, clinical inflammation.     

Increasing expression of tissue plasminogen activator and plasminogen activator inhibitor type 2 in dog gingival tissues with progressive inflammation

Urokinase and tissue-type plasminogen activators (u--PA and t--PA) are serine proteases that convert plasminogen into plasmin, which degrades matrix proteins and activates metalloproteinases. The PAs are balanced by specific inhibitors (PAI--1 and PAI--2). Local production of t--PA and PAI--2 was recently demonstrated in human gingival tissues. The aim now was to investigate the production and localization of t--PA and PAI--2 in gingival tissues from dogs in three well-defined periodontal conditions; clinically healthy gingiva, chronic gingivitis and an initial stage of ligature-induced loss of attachment. At the start of the experiment the gingiva showed clear signs of inflammation. Clinically healthy gingiva were obtained after 21 days period of intense oral hygiene. Attachment loss was induced by placing rubber ligatures around the neck of some teeth. Biopsies were taken from areas representing the different conditions and prepared for in situ hybridization and immunohistochemistry. In clinically healthy gingiva both t--PA mRNA and antigen were expressed in a thin outer layer of the sulcular and junctional epithelia. No t--PA signals or staining were seen in connective tissue. Both mRNA signaling and immunostaining for t--PA were stronger in chronic gingivitis. In areas with loss of attachment, t--PA mRNA as well as antigen were found in the sulcular and junctional epithelia to a similar degree as in gingivitis. Occasionally the connective tissue was involved, especially in connection with vessels. PAI--2 mRNA was seen in a thin outer layer of the sulcular and junctional epithelia in clinically healthy gingiva, but no signals were seen in connective tissue. PAI--2 antigen was found primarily in the outer layer of the sulcular and junctional epithelia. Some cells in the connective tissue were stained. In gingivitis, PAI--2 signals were mainly found in the same locations, but more intense and extending towards the connective tissue. Immunostaining was seen in the outer half of the sulcular and junctional epithelia as well as in the upper part of the connective tissue, close to the sulcular epithelium. In sites with loss of attachment, PAI--2 mRNA was found throughout the sulcular and junctional epithelia, as was the antigen, which stained intensely. No PAI--2 mRNA was seen in connective tissue; the antigen was found scattered, especially near vessels. This study shows that the expression of both t--PA and PAI--2 increases with experimental gingival inflammation in the dog, and furthermore, the two techniques demonstrate a strong correlation between the topographical distribution of the site of protein synthesis and the tissue location of the antigens for both t--PA and PAI--2. The distribution correlates well with previous findings in humans.     

The interdental gingivae

Material from 20 young rhesus monkeys was prepared for study of the interdental gingival epithelium. An additional four young monkeys were injected with tritiated thymidine and radioautographs prepared for analysis of cell turnover.
It was found that the interdental gingiva between recently erupted teeth in proximal contact has a col form. The appearance of the col can be simulated by vertical sections close to the roots of single teeth. Analysis of sections through the actual col showed that it is always lined by squamous epithelium, five or more cell-layers thick, without any recognizable ameloblasts. The radioautographs showed consistent evidence of thymidine uptake, indicating cell-division, in all epithelia lining the col. It was concluded that the histological features and turnover-rate of epithelium in the interdental region are closely analogous to those of epithelium on other aspects of the teeth.
Clinical studies of the presence and amount of plaque and gingivitis in 1,075 intact interdental areas in 48 young adults showed a high degree of correlation between the presence and amount of plaque and the presence and severity of gingivitis, and lend support to the hypothesis that gingivitis starts interdentally because plaque accumulates there.     

Different distribution of immunocompetent cells in the dentogingival junction during root formation in rat molars

The distribution of immunocompetent cells in the dentogingival junction of rat molars during root formation was investigated by immunocytochemistry using antibodies to class II major histocompatibility complex (MHC) molecules (OX6-antibody) and monocyte/macrophage lineage cells (ED1-antibody) as well as by histochemical reaction for periodic acid-Schiff (PAS). Two portions (the junctional epithelium in the mesial gingiva of the first molar, and the interdental gingiva between the first and second molars) were selected for observations. At the eruption stage of the first molar (16-18 days after birth), OX6-positive cells, dendritic or oval in shape, were abundantly distributed in the connective tissue between the oral epithelium and tooth germ. Positive cells with slender cell processes were also found beneath the ameloblast layer. At the commencement stage of the first molar occlusion (24-28 days after birth), numerous OX6-positive cells displaying a dendritic fashion existed preferentially in the mesial gingiva, but were fewer in the interdental gingiva. In contrast, the interdental gingiva showed a denser distribution of ED1-positive cells and PAS-reactive polymorphonuclear leukocytes (PMLs) than the mesial gingiva. At the completion stage of root formation (100-120 days after birth), the OX6-immunopositive cells invaded the deeper position of the mesial gingiva with the downgrowth of the epithelium; they had a considerably higher cell density compared with those in the interdental gingiva where PAS-reactive PMLs persisted. These findings indicated that the immunocompetent cells showed a region-specific distribution and cell density by their roles in immune response.     

Experimental gingivitis in young and elderly individuals

Abstract The development of experimental gingivitis was studied in young and elderly humans during a 21-d period of oral hygiene abstention. The state of the gingiva was assessed by the Gingival Index and by measurements of the amount of gingival exudate on filter paper strips placed at the entrance of the gingival sulcus of the lower lateral incisors and cuspids. Soft deposits were assessed by the Plaque Index and by differential counts of microorganisms in gram stained smears of dento-gingival plaque. At the end of the plaque growth period, the patients were given a thorough dental prophylaxis. Gingival condition and plaque were assessed at regular intervals during a subsequent period of controlled oral hygiene. The development of gingivitis during the oral hygiene abstention period was more rapid and more severe in old than in young individuals. Plaque accumulation was greater in the older persons. A definite difference in plaque consistency was also observed. However, microscopic counts of various types of microorganisms did not reveal any differences throughout the period of plaque accumulation. When active oral hygiene was reinstituted, the state of the gingiva rapidly returned to pre-experimental levels in both groups. The findings of this study indicate that with age there is an altered host response to the microorganisms of the plaque.     

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.