Development of experimental gingivitis in the juvenile and adult beagle dog

Abstract. In a previous paper a lower tendency to develop gingivitis was reported among preschool children compared to adults. The aim of the present study was to clarify if the same age-dependent difference exists in dogs.
Six beagle dogs from the same litter were used. two periods of discontinued oral hygiene were studied, one period when the dogs were 3 months old and the other at 12 months. Prior to and between the experimental periods the animals were subjected to meticulous toothcleaning. During the experimental periods the Gingival and Plaque Index scores as well as the amounts of gingival exudate and crevicular leukocytes were determined on days 0, 4, 7, 14, 21 and 28.
During the juvenile period the development of dental plaque was lower compared with the adult period. The frequency of gingival units with high Gingival Index scores was lower at every registration interval during the juvenile period. The amounts of gingival exudate and crevicular leukocytes increased to high values during the adult stage but only small increments were found in the juvenile stage. An intraindividual comparison of the increase in the amount of gingival exudate from day 0 to day 28 in areas with the same amount of dental plaque accumulation showed a lower increase in gingival exudate during the juvenile stage in all dogs.     

Extracellular neutrophil traps in periodontitis

Background and Objective:  Chronic periodontitis, the chronic inflammatory disease of the periodontium, is caused by bacteria and is characterized by an influx of neutrophils into the gingival crevice. Recently, a 'new' extracellular neutrophil defense mechanism – neutrophil extracellular traps – has been described. However, their role in periodontitis has not yet been investigated.
Material and Methods:  Clinical examinations, transmission and scanning electron microscopy, as well as cytology and confocal laser-scanning microscopy, were employed to analyze gingiva biopsies and crevicular exudate from patients with chronic periodontitis.
Results:  An abundance of neutrophil extracellular traps and some phagocytic neutrophils was found on the gingival pocket surface and in the purulent crevicular exudate. Finding neutrophil extracellular traps in the spontaneously effused purulent crevicular exudate clearly indicated that they are flushed from the pocket by the crevicular exudate. In cases of dispersal of subgingival plaque bacteria, their trapping by neutrophil extracellular traps in purulent crevicular exudate and on the gingival surface was demonstrated.
Conclusion:  Trapping the crevicular bacteria prevents their adhesion to and invasion of the gingiva. The combination of neutrophil extracellular traps and crevicular exudate outflow appears to be a 'novel' defense mechanism for the clearance of crevicular bacteria in chronic periodontitis.     

Development of gingivitis in pre-school children and young adults

Earlier studies suggest that children and adults differ in the propensity to develop gingivitis when oral hygiene is abandoned. To confirm the existence of such a difference, a comparative study of pre-school children and young adults was made with objective registration methods. The author performed all registrations. After a period of intensive oral hygiene, all cleaning of teeth was discontinued for 21 days. The amount of bacterial plaque, the amount of gingival exudate and crevicular leukocytes and the bleeding tendency were registered on days 0, 7, 14 and 21. During the experiment the amount of bacterial plaque increased continously in both groups. The amount of gingival exudate and the tendency to gingival bleeding increased to high values in the adults, while only a small rise was seen in the children. The amount of crevicular leukocytes increased in both groups, but the increment was greater in the adults. A comparison concerning differences in gingival exudate and bleeding tendency between pre-school children and adults was undertaken for gingival units that showed a similar plaque development. Under these statistically acceptable prerequisites, it was shown that there is a real difference in the tendency to develop gingivitis between pre-school children and adults.     

Development of gingivitis around different types of composite resin

Earlier studies have demonstrated signs of gingivitis around conventional composite resin restorations. Newly developed resin types differ considerably in composition and surface characteristics. The purpose of this study was to compare the initiation of gingival inflammation around aged restorations of 3 types of composite resins and around enamel, during a 7-day period of experimental gingivitis. Plaque index, gingival index and crevicular exudate were registered at days 0 and 7. There was significantly less exudate around the intact enamel surfaces than around the composite fillings at both registration times. The plaque and gingival indices showed no significant differences among the composite resins and enamel. The results indicate that differences among the resins with regard to surface roughness and composition did not result in clinically measurable differences in the development of plaque and gingivitis.     

Experimental gingivitis around deciduous teeth in children with Down's syndrome

Abstract. Epidemiological studies have shown that there is a high prevalence and rapid progression of periodontal disease in children with Down's Syndrome (DS). In this respect, DS children exhibit a markedly different response compared with healthy children. In order to understand the reasons for this difference, a controlled study was set up to determine the extent and the quality of the differences in the early periodontal tissue response towards dental plaque in the deciduous dentition of DS children and matched control children. In a preliminary investigation, the gingival health was estimated by determining the bleeding tendency. 9 healthy children were selected from a group of 14 and matched with 9 DS children with respect to plaque development, sulcus depth and age. The DS children had a higher bleeding tendency than the matched controls. In the DS children, moreover, a correlation was found between bleeding tendency and age. No such correlation was found in the controls. After a period of intensive oral hygiene, all cleaning of teeth was discontinued for 21 days. The amount of plaque according to the plaque index, the gingival health according to the gingival index, and the amount of crevicular leucocytes and gingival exudate were assessed at days 0, 7, 14 and 21. During the experimental phase of the study, the amount of plaque increased at a similar rate in both groups. In the DS children, the development of gingival inflammation started earlier and was more extensive. It increased after day 14, whereas in the control children, the gingival inflammation seemed to stabilize at this time. The results of the present experimental study thus confirm earlier results from epidemiological studies. The amount of gingival exudate was very low in both groups, but in the DS group it increased after day 14. In contrast to the DS children, the amount of crevicular leukocytes increased significantly in the control children from day 0 to day 21, the highest score being found on day 14. On day 7, a significantly larger amount of crevicular leucocytes was found in the DS children than in the controls. The findings of this study suggest that DS children have a different leucocyte response together with a more extensive gingival inflammation than normal children.     

Presence of leukocytes wuthin the gingival crevices during developing gingivities in dogs

The presence of leukocytes in the cellular exudates within the gingival crevices during developing gingivitis has been studied in dogs. Repeated sampling was performed over a period of 35 days. An increase in the amount of leukocytes within the crevices was observed. The relative proportions of the various leukocytes in the crevicular exudates remained unaltered throughout the experimental period, showing 95–98% neutrophils, 1.2% lymphocytes and 1.3% monocytes. Experiments on cellular emigration, utilizing the skin window technique, indicated that a sustained predominance of neutrophils in an exudate may occur when dental plaque is continuously present on the surface of the lesion.     

Experimental contact hypersensitivity in the gingiva of dogs

Application of l-dinitro-2.4-chlorbenzene (DNCB, 0.05 % in Orabase^®) onto the gingiva in one side of the jaws was performed daily for six days in a group of sensitized dogs. Contralaterally only the vehicle was applied. Anti-thymocyte serum (ATS) was injected into the dogs after three days of application. The effects on the gingiva were studied by inflammatory cell counts in sections of gingival biopsies and by measurements of crevicular leukocytes, gingival fluid and acid phosphatase activity in crevicular samples.
The numbers of inflammatory cells in the gingival biopsies as well as the figures of the gingival crevice parameters were higher in the DNCB side as compared to the control side on day 3. Immuno-suppression with ATS affected all parameters as observed from the data of day 6 of the experiment. The results of the study indicate that gingival contact hypersensitivity to DNCB can be elicited in beagle dogs and that this reaction is reflected in crevicular parameters of gingival inflammation.     

The effect of locally released oxygen on the development of plaque and gingivitis in man

Abstract An experimental gingivitis study was designed to test the effect of a 5-min twice daily oxygen application on the development of plaque and onset of gingivitis A method for the local application of medical grade oxygen to the upper anterior teeth was developed, with the lower anterior teeth used as controls. Fourteen periodontally healthy dental students of average age 21.9 years participated in the study. There was no significant effect of oxygen on plaque formation, crevicular fluid flow, or the number of gingival bleeding sites. Experimental and control gingival segments exhibited bleeding on probing at an average of 6.6 days after cessation of mechanical plaque control, much earlier than reported in other experimental gingivitis studies.     

Oral leukocytes and gingivitis in the primary dentition

A survey was performed to evaluate the relationships among orogranulocytic migratory rale, gingival index and plaque index in a group of systematically healthy preschool children.
The fifty children selected for study had only primary teeth, no pharyngeal or extragingival inflammation and were taking no medication. Each child was subjectively scored for the amount of bacterial plaque and gingival inflammation present. The rate of migration of leukocytes into the oral cavity per 30 second period was determined from the last three of ten 30 second consecutive oral saliva rinses as an objective measure of gingival inflammation.
A minimal amount of localized mild marginal gingivitis was observed in the presence of a rather large plaque accumulation. No significant correlation was observed between rates of oral leukocyte migration and the degree of gingival inflammation. However, the leukocyte migratory rates in this group were quite low as compared to those found in adults by other investigators.     

Influence of horinonal contraceptives on the gingiva of women

Gestagen hormones commonly used as contraceptive in women, induce a hormonal situation which to some extent simulates pregnancy. The aim of the present investigation was to study the gingival conditions of women before and during 12 months of regular ose of contraceptive preparations. Two kinds of contraceptives were used: Delpregnin® and Gestadydral®. The mesial aspects of the gingiva of 5 maxillary incisors and canines were studied before beginning the experiment and after 2, 6, and 12 montks of hormone therapy. Jntracrevicolar sampling of gingival exudate was performed a.m. Brill (1959).
Both the Delpregnin-group and the Gestadydral-groiip showed an increase in amount of exudate during the 12 months. At the use of Delpregnin there was a gradual increase in exudation during tke first six months of hormone therapy. In the group using Gestadydral, no increase in amount of exudate could be noted during the first six months, whereas a significant increase of the gingival exudate occurred between the last two examinations.
The findings are discussed in view of current knowledge of gestagene hormone action on vascular permeability.     

Microcirculatory dynamics in experimental human gingivitis

Abstract The purpose of this study was to determine the changes that occur in the gingival microcirculation during the development of experimental gingivitis in humans. There have been no studies published to date combining videomicroscopy and laser Doppler flowmetry to study vascular dynamics in experimental gingivitis. Alterations occurring in the microcirculation of the marginal gingiva in 10 (18–30-year-old), healthy male humans when they suspended oral hygiene procedures in a proscribed area for 12–16 days were monitored. A partial mouth, experimental gingivitis model was employed. Gingival health was evaluated before and after the experimental period by assessing gingival and plaque indices and gingival crevicular fluid volume. Gingival vascular monitoring included measurement of red blood cell velocity in individual gingival microvessels via video-microscopy and measurement of regional gingival blood flow using laser doppler flowmetry. The number of vessels visible in a given microscopic field in a given subject and the number of vessels exhibiting flow were also determined from the videotapes. Systemic cardiovascular and respiratory parameters were monitored to ensure that gingival vascular changes were not secondary to systemic changes. Gingivitis developed in all subjects; significant increases (Student t-test, P < 0.05) were seen in plaque index, gingival index, bleeding on probing and crevicular fluid volume. No change in superficial capillary blood velocity and a significant decrease in gingival regional blood flow were seen with gingivitis. A significant increase in the number of vessels visible in microscopic fields and a decrease in the % of vessels exhibiting flow were observed. Gingival microcirculation exhibited a dramatic, dynamic change in response to the development and progression of gingivitis.     

Experimental gingivitis in man

During a 5 day period without oral hygiene, 4 groups each consisting of 3 subjects with healthy gingivae, rinsed their mouths with solutions of tetracycline, vancomycin, polymyxin B or distilled water. Gingival plaque accumulated rapidly in the group rinsing with water, while tetracycline, and to a lesser degree vancomycin and polymyxin B inhibited plaque formation. Clinical gingivitis was not observed in any of the participants, but gingival exudate and leukocyte emigration were noted and seen to increase during the experimental period, especially in the water group. Rinsing with antibiotics inhibited these signs of subclinical inflammation to varying degrees. The bacterial composition of the gingival plaque changed in the water group during the experimental period towards a higher percentage of gram-negative bacteria, following the pattern observed in previous investigations. Tetracycline markedly reduced the numbers of gingival plaque organisms, while polymyxin B favored a proliferation of gram-positive cocci and short rods and depressed gram-negative bacteria. Rinsing with vancomycin resulted in a pronounced shift towards an almost pure gram-negative plaque flora. It is concluded that local administration of antibiotics with a limited spectrum may be useful for the study of the pathogenicity of the different components of the gingival microbial flora.     

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.     

Effect of decomplementation by carragheenan on the emigration of neutrophils and monocytes into dog gingival crevices

The role of complement in the emigration of blood neutrophils and monocytes into gingival crevices has been studied in dogs by experimental decomplementation.
Blood neutrophils and monocytes were labelled by intravenously injected colloidal carbon. At various time intervals after labelling and decomplementation by carragheenan cellular samples were taken from the gingival crevices. Labelled neutrophils and monocytes were found in both healthy and inflamed gingival crevices indicating a continuous migration of these cells in spite of decomplementation.
For comparison the migration of leukocytes into skin window lesions was studied. Early leukocyte emigration was found to be inhibited in the decomplemented animals, but could be initiated by the application of dental plaque to the lesions.
The results suggest that complement activation by immune complexes is not necessary for the continuous migration of leukocytes into gingival crevices. Other factors such as chemotactic substances present in dental plaque may be responsible for the continuous migration of leukocytes into gingival crevices.     

The effect of glass ionomer cement and composite resin fillings on marginal gingiva

Abstract Glass ionomer cement and composite resin are the most popular restorative materials in operative dentistry today. Earlier studies have shown more crevicular exudate around different types of composite resins than around intact enamel surfaces. The aim of this study was (1) to investigate plaque, retention on and the condition of the gingiva around, 1-year-old, subgingivally located, glass ionomer cement and composite resin fillings, and (2) to compare the initiation of gingival inflammation around these materials with that around enamel during a 14-day period of experimental gingivitis. Plaque index, gingival index, bleeding on probing and crevicular fluid were recorded and compared intra-individually. The amount of plaque and the degree of gingivitis adjacent to the composite fillings were not significantly higher than those for the glass ionomer cement and enamel surfaces in both the cross sectional and the experimental gingivitis study. Composite resin surfaces showed significantly higher crevicular fluid levels than did enamel at all days in the experimental gingivitis study. Glass ionomer cement showed significantly higher values at day-0 and day-7.     

Studies of host responses during experimental gingivitis in humans

The aim of the study was to find out whether autologous supragingival plaques collected at various times during the development of experimental gingivitis in men differ in their potential to induce PMN responses in vitro. Ten subjects refrained from all oral hygiene for a period of 21 days. At day 0, Day 3 and Day 21 after cressation of oral hygiene clinical indices (plaque index, gingival index, gingival crevicular fluid flow) were assessed plaque was collected at day 3 and Day 21 after cessation of Oral hygiene clinical indices (plaque index, gingival index, gingival crevicular fluid flow) were assessed plaque was collected at Day 3 and Day 21. PMNs, isolated from peripheral blood 1–2 months after the non-brushing period were incubated with the various autologous plaques in the presence or the absence of autologous serum. Supernatants of cell cultures were monitored for extracellular release of lysosomal constituents, viz. lysozyme, myeloperoxidase and lactoferrin. There was no difference in the amounts of lysozyme, myeloperox dase and lactoferrin. There was no difference in the amounts of lysozyme or myeloperoxidase released by PMNs. The inclusion of fresh serum enhanced PMN release reactions but there was no significant differences in the relative capacity of Day 0, Day3 and Day 21 sera to modulate PMN responses. A statistically significant positive correlation was established betwen the magnitude of lactoferrin release from PMNs exposed to Day 3 plaque and the gingival fluid flow recorded on Day3. Lactoferrin is segregated in the specific granules of the PMNs which also contain other cationic proteins, collagenases and neutral proteinases. These data suggest that a possible causal relationship may exit between the release of PMN constituents and the development of inflammation during the early phases of gingivitis.     

Experimental periodontitis in the Beagle dog

The purpose of the present investigation was to study the sequential stages in the development of a periodontal lesion starting from a healthy periodontium. Twenty inbred Beagle dogs 10 months of age and weighing 10–12 kilos were used. The animals were equally divided into one experimental and one control group. Throughout the experiment all dogs were given a diet containing 400 gm pellets and 25 gm soya flower. From day zero the teeth (in the left jaws) of the control dogs were twice dally subjected to a careful but gentle brushing with tooth brush and dentifrice. The teeth of the experimental group animals were not cleaned. The dogs were examined at regular intervals during an 18 month period.
The results show that it is possible in young dogs to induce gingivitis which gradually develops into periodontitis simply by allowing plaque to accumulate on teeth. The cleaned teeth did not show signs of gingivitis or periodontitis during the entire experiment. It is proposed that in the Beagle dog the progression of the lesion during an 18 month period may occur in three stages: I) subclinical gingivitis, II) clinical gingivitis and III) periodontal breakdown. Subclinical gingivitis was characterized by a rapidly increasing gingival exudation and migration of crevicular leukocytes, i. e. signs off acute inflammation. Clinical gingivitis was characterized by changes in gingival colour, texture and bleeding tendency but only minor alterations of the number of crevicular leukocytes. Periodontal breakdown, characterized by loss of subgingival fiber attachment, occurred only in areas of clinical gingivitis.     

Differences in the inflammatory response in young and old human subjects during the course of experimental gingivitis

The aim of the present experiment was to study changes in (i) the composition of the inflammatory cell infiltrates and (ii) levels of alpha 2-macroglobulin, lactoferrin and IgG subclasses in gingival crevicular fluid in young and old individuals during 3 weeks of plaque formation. To establish healthy gingival conditions, all subjects received professional tooth cleaning during a 4 week pre-experimental period. The experimental sites included the mesio-palatal, palatal, and disto-palatal surfaces of all teeth present in the 15...25 tooth region. At baseline (day 0) assessments of plaque and gingivitis, microbial sampling and gingival fluid assessment were performed and one gingival biopsy harvested from each subject. Following the baseline examination, the participants abolished mechanical tooth cleaning measures in the palatal and approximal surfaces of 15...25. The clinical examination and the gingival fluid measurement were repeated on days 7, 14 and 21 of no oral hygiene. The microbiological sampling and the biopsy procedure were repeated on days 7 and 21. The gingival crevicular fluid samples harvested from the old individuals had higher levels of alpha 2-macroglobulin and IgG3 compared to young subjects. The immunohistochemical analyses of the biopsies demonstrated that the gingival lesion representing the old individuals harbored a higher proportion of B-cells and a lower density of PMN cells compared to the infiltrate in the young group of subjects. It is suggested that differences exist in the inflammatory response to de novo plaque formation in young and old individuals.     

Gingival condition in areas of minimal and appreciable width of keratinized gingival

Sixteen dental, dental hygiene, and dental assisting students and dental faculty members who had contralateral or unilateral areas of minimal (less than or equal to 1.0 mm) and appreciable (greater than or equal to 2.0 mm) widths of keratinized gingiva on mid-buccal plaque-free surfaces of mandibular bicuspids were examined. Gingival exudate amounts and clinical inflammation based on color change and/or swelling and bleeding on probing were evaluated. The results showed that gingiva with "appreciable" width as well as gingiva with "minimal" width of keratinized tissue exhibited only minute amounts of gingival exudate. Also, there were generally no clinical signs of inflammation for both types of tissue. From the groups of 16, six subjects were selected who had contralateral pairs of minimal and appreciable keratinized gingiva. They were instructed to cease oral hygiene in the lower bicuspid area for 25 days. At day 0, 4, 7, 11, 14, 18, 21, and 25, plaque, gingival exudate, and clinical gingival inflammation were evaluated. Results revealed increases in plaque, gingival exudate scores and clinical gingival inflammation over the 25-day period with no apparent difference between the areas with minimal and appreciable width of keratinized gingiva.     

Resistin in gingival crevicular fluid and induction of resistin release by Porphyromonas gingivalis lipopolysaccharide in human neutrophils

Hiroshima Y, Bando M, Inagaki Y, Mihara C, Kataoka M, Murata H, Shinohara Y, Nagata T, Kido J. Resistin in gingival crevicular fluid and induction of resistin release by Porphyromonas gingivalis lipopolysaccharide in human neutrophils. J Periodont Res 2012; 47: 554–562. © 2012 John Wiley & Sons A/S Background and Objective: Resistin is an adipocytokine that induces insulin resistance and is predominantly expressed in adipocytes and peripheral blood mononuclear cells. Resistin expression increases in inflammatory diseases as well as diabetes mellitus, and is upregulated by bacterial pathogens and proinflammatory cytokines. The aim of this study was to identify resistin in human gingival crevicular fluid, to compare the resistin levels in gingival crevicular fluid between subjects with and without periodontitis and diabetes mellitus and to investigate the regulation of resistin release from human neutrophils by Porphyromonas gingivalis lipopolysaccharide (P‐LPS). Material and Methods: Gingival crevicular fluid samples were collected from patients with chronic periodontitis (n = 24), patients with diabetes mellitus‐related periodontitis (n = 18) and healthy subjects (n = 21). Resistin in gingival crevicular fluid was determined using western blot analysis and an ELISA kit. The glycated hemoglobin (HbA_1c) value was obtained from patients with diabetes mellitus‐related periodontitis by a medical interview. Human neutrophils were cultured with P‐LPS (0–1000 ng/mL), or incubated with inhibitors of actin or microtubule polymerization in the absence or presence of P‐LPS. The medium and cellular fractions were used for determination of resistin by ELISA. Results: The resistin level in gingival crevicular fluid from patients with periodontitis or diabetes mellitus‐related periodontitis was significantly higher than that of healthy subjects. The resistin level in gingival crevicular fluid was correlated with gingival index score, but not blood HbA_1c value. The P‐LPS increased resistin release from human neutrophils, and its induction was decreased by actin polymerization inhibitors. Conclusion: We show, for the first time, the presence of resistin in gingival crevicular fluid. A high resistin level in gingival crevicular fluid samples from periodontitis patients may to some extent be related to P‐LPS‐induced resistin release from neutrophils.