Effects of folate mouthwash on experimental gingivitis in man

Although the experimental gingivitis model has been used extensively since 1965, some doubts exist concerning the nature of the tissue response in this model. Accordingly, the present study was designed to determine whether or not experimental gingivitis responded to 0.1% folate mouthwash (MW) in a similar manner to that already reported for established gingivitis. 20 male dental students took part in a double blind cross-over study which involved two 3-week experimental periods with random allocation to folate or placebo MW. The experimental site was the lower anterior area and 24 points of gingival examination were made at baseline and weeks 1, 2 and 3. Inflammation was assessed by presence or absence of colour change, and bleeding being slight, profuse or absent when gingivae were stroked with a blunt probe. A plaque sample was evaluated using dark field microscopy, and dry weight of accumulated plaque was measured at the end of each experimental period. Folate MW did not appear to have any statistically significant effects on accumulated plaque, or clinical signs of experimental gingivitis in this study. The different response of experimental gingivitis to folate MW, compared with the response of established gingivitis already reported, further suggests that experimental gingivitis may not represent an authentic replica of the cellular and immunological responses occurring in established gingivitis.     

Microbiota of gingivitis in man

ABSTRACT – A Study on the predominant cultivable microorganisms inhabiting gingival crevices affected with a chronic gingivitis was carried out using the roll tube culture technique. Samples were obtained from nine individuals 25–42 years of age. Gram-positive rods made up 26.1% of the isolates and included mainly Actinomyces naeslundii, Actinomyces israelii , and Actinomyces viscosus. Streptococcus mitis and Streptococcus sanguis together made up 26.8% of the cultivable organisms. Feptostreptococcus averaged 3.0% of the organisms recovered. Gram-negative anaerobic rods constituted 25.0% of the total isolates with Fusobacterium nucleatum, Bacteroides melaninogenicus ss. intermedius, Bacteroides ochraceus , other Bacteroides species, Selenomonas sputigena , and Campylobacter sputorum as the most predominant isolates. Haemophilus parainfiuenzae averaged about 14% and Veillonella species 4.3% of the cultivable microflora. The data presented indicate that the subgingival microflora of a chronic gingivitis differs from those of healthy periodontium and advanced adult and juvenile periodontitis. This might suggest that different infectious processes may be operative in various clinical entities of periodontal disease.     

Chemotactic activity in experimental gingivitis

abstract — Forty-eight dental students were screened regarding the rate of plaque formation. The four most rapid (RPF-group) and the four slowest (SPF-group) plaque formers were selected and compared as to: (1) the development of gingivitis during a 14-day period without oral hygiene, (2) the chemotactic activity elaborated by (a) gingival crevicular material (GCM) sampled 24 h after withdrawal of oral hygiene measures and (b) 4- and 8-day-old plaques, and (3) permeability-inducing factors in 4- and 8-day-old plaques. The Gingival Index, Plaque Index and flow of gingival fluid were used for assessing plaque formation and gingivitis development. The chemotactic activity was estimated with the use of Boyden's in vitro model, and subcutaneously implanted wound chambers were used for demonstrating change in vascular permeability. It was found that: (1) individuals vary considerably with regard to the rate of formation of dental plaque, (2) gingivitis developed faster in the RPF group than in the SPF group, (3) GCM sampled already 24 h after cessation of oral hygiene yielded higher chemotactic activity in the RPF group than in the SPF group, and (4) the RPF and SPF groups did not differ from one another regarding chemotactic activity or permeability-inducing activity of equal amounts (wet weight) of plaque.     

Variability of gingival bleeding in experimental gingivitis trials

Gingival bleeding is a difficult parameter to assess in experimental trials. The Confirmed Bleeding Day was recently developed as a measurement for this purpose. It was observed that considerable variations existed between the measurements made in a pilot study and an experimental trial, and these variations were subjected to a statistical analysis. The reasons for the variations are discussed, and recommendations made for the design of experimental trials involving gingival bleeding.     

The effect of a topical non-steroidal anti-inflammatory drug on the development of experimental gingivitis in man

24 healthy volunteers abstained from tooth-cleaning for 17 days. Parameters of gingival health were recorded on days 1 and 17. On days 4, 6, 8, 11, 13 and 15, each volunteer randomly received, on a double-blind basis, 100 ml of 10 mM flurbiprofen solution in buffered preservative to one upper quadrant of the mouth. The contralateral quadrant received preservative only. Applications were made using a pulsed jet irrigating system. Gingivitis developed in all patients and there were no significant differences between the treatments for gingival index or pocket probing depths. When gingival health was re-established, 4 volunteers had a further 3 irrigations of flurbiprofen at intervals of 2 days. Plasma levels of flurbiprofen were determined after the 1st and 3rd irrigations. Assays showed that the drug was present in the plasma of all 4 subjects (range 0.2-0.7 micrograms/ml). Gingival health was re-established in 6 further volunteers from the original study. They then abstained from toothbrushing for 17 days, during which one maxillary quadrant was irrigated with the buffered preservative solution. The irrigations were made on the same basis as in the original study. Gingivitis again developed in these quadrants, although when the results were compared to the equivalent data from the first investigation, significantly greater median values for probing pocket depths and gingival indices were found in the latter study. Therefore, it appears that systemic absorption of flurbiprofen may have reduced the severity of the developing inflammatory lesions.     

The reversal of localized experimental gingivitis

Twenty dental students randomly divided into four groups of five participated in this trial. Three weeks of supervised oral hygiene preceded the study in order to ensure a optimum state of gingival health. The gingival condition was assessed by means of the Gingival Index and measurements of gingival exudate. Plaque accumulation was assessed by means of the Plaque Index. Using plaque-guards, two 21-day periods were alllowed for the induction of localized experimental gingivitis around a lateral incisor and adjacent canine in each jaw. The contralateral areas served as controls. Habitual oral hygiene procedures were maintained in all other areas of the mouth throughout the experimental periods. Following 21 days of localized plaque accumulation in the mandibular experimental areas, mechanical toothcleaning procedures were introduced at intervals of once a day (Group A), once every second day (Group B), once every third day (Group C) and once every fourth day (Group D). Groups A and B regained gingival health in 10 days. The experiment was then repeated in the maxillary experimental areas. Group A, rinsing once daily with chlorhexidine solution regained gingival health in 4 days. The results obtained in the localized experimental gingivitis model were similar to those reported when totally withdrawing oral hygiene.     

Effect of experimental neutropenia on initial gingivitis in dogs

Abstract – The role of neutrophilic granulocytes in the loss of gingival collagen has been studied by inducing experimental neutropenia during initial gingivitis in beagle dogs. Neutropenia was induced for 4 d in three animals with normal gingiva by repeated injections of rabbit anti-neutrophil serum. During neutropenia microbial plaque was allowed to form on the teeth. Samples of junctional (crevicular) leukocytes and gingival fluid were taken on days 0 and 4. Block biopsies of buccal gingiva were obtained on day 4. Stained semi- and ultrathin sections were used for histometric and serologic tissue analysis. Gingival fluid flow increased from day 0 to day 4 in all dogs while junctional leukocytes increased in one dog only. Subgingival plaque had formed in most biopsies, and in the junctional epithelium very few neutrophilic granulocytes were present. In the coronal connective tissue subjacent to the junctional epithelium lymphoid cells, structurally abnormal neutrophilic granulocytes and monocytes/macrophages were diffusely scattered. The gingival collagen appeared mainly displaced by the inflammatory cells rather than dissolved. The data suggest that neutrophilic granulocytes may contribute to the loss of gingival collagen during initial gingivitis in dogs. The neutrophils also seem to be of importance for the limitation of subgingival plaque growth along the tooth surface.     

Influence of cigarette smoking on vascular reaction during experimental gingivitis

Abstract — The influence of cigarette smoking on the vascular reaction during plaque induced gingivitis was studied in humans for 28 days. Sixteen healthy dental students, 8 smokers and 8 non-smokers, aged 19–42 yr, volunteered for the experiment. A numerical method was used for the evaluation of the vascular reaction. With the aid of stereophotographs changes in the number of gingival vessels were followed during the experiment. It was found that the number of vessels identified increased over time during the experiment in both smokers and non-smokers. However, in spite of the fact that the plaque accumulation rate was equal, the vascular reaction was less pronounced in smokers. At the end of the experiment after 28 days the intensity of the vascular reaction in smokers was only 50% of that observed in non-smokers. The difference was statistically significant at the P -level of 0.05. One week after termination of the experiment and reinstitution of oral hygiene the number of gingival vessels equaled the pre-experimental values in both groups. The results indicate that the vascular reaction associated with plaque induced gingivitis is suppressed in smokers.     

Effect of adhesive antibiotic TA on plaque and gingivitis in man

The adhesive antibiotic TA was applied to the dento-gingival junction of 8 human volunteers, suffering from moderate to severe gingivitis. 2 diametrically opposed quadrants of the mouth received 4 applications of 0.1 mg TA, while the other 2 quadrants were treated with a placebo and served as controls. The plaque index, gingival index and bleeding index were scored periodically for 2 weeks and in 4 patients for up to 30 days. The TA-treated quadrants showed a rapid decrease in all 3 indices following 2 treatments. A further improvement was observed with the 3rd and 4th treatments. 30 days after the onset of the experiment and 23 days after the last application, the indices were still considerably lower than the initial values.     

Reversibility of experimental peri-implant mucositis compared with experimental gingivitis in humans

Objective: To monitor clinical, microbiological and host‐derived alterations occurring around teeth and titanium implants during the development of experimental gingivitis/mucositis and their respective healing sequence in humans. Material and methods: Fifteen subjects with healthy or treated periodontal conditions and restored with dental implants underwent an experimental 3‐week period of undisturbed plaque accumulation in the mandible. Subsequently, a 3‐week period with optimal plaque control was instituted. At Days 0, 7, 14, 21, 28, 35 and 42, the presence/absence of plaque deposits around teeth and implants was assessed, (plaque index [PlI]) and the gingival/mucosal conditions were evaluated (gingival index[GI]). Subgingival/submucosal plaque samples and gingival/mucosal crevicular fluid (CF) samples were collected from two pre‐determined sites around each experimental unit. CF samples were analyzed for matrix‐metalloproteinase‐8 (MMP‐8) and interleukin‐1beta (IL‐1β). Microbial samples were analyzed using DNA–DNA hybridization for 40 species. Results: During 3 weeks of plaque accumulation, the median PlI and GI increased significantly at implants and teeth. Implant sites yielded a greater increase in the median GI compared with tooth sites. Over the 6‐week experimental period, the CF levels of MMP‐8 were statistically significantly higher at implants compared with teeth (P<0.05). The CF IL‐1β levels did not differ statistically significantly between teeth and implants (P>0.05). No differences in the total DNA counts between implant and tooth sites were found at any time points. No differences in the detection frequency were found for putative periodontal pathogens between implant and tooth sites. Conclusion: Peri‐implant soft tissues developed a stronger inflammatory response to experimental plaque accumulation when compared with that of their gingival counterparts. Experimental gingivitis and peri‐implant mucositis were reversible at the biomarker level. Clinically, however, 3 weeks of resumed plaque control did not yield pre‐experimental levels of gingival and peri‐implant mucosal health indicating that longer healing periods are needed. To cite this article:
Salvi GE, Aglietta M, Eick S, Sculean A, Lang NP & Ramseier CA. Reversibility of experimental peri‐implant mucositis compared with experimental gingivitis in humans.
Clin. Oral Impl. Res. 23 , 2012; 182–190.
doi: 10.1111/j.1600‐0501.2011.02220.x     

The influence of experimental gingivitis on plaque formation

The rate of plaque growth was assessed using daily Plaque Index measurements over a 7-day period in eleven dental students with an initial mean Gingival Indes of 1.21 (+/- 0.05). The mean Gingival Index was then reduced to 0.27 (+/- 0.04) and the rate of plaque growth assessed in the same way. Bacterial smears were taken from the teeth at intervals during both experimental periods and percentage counts of various morphological types of bacteria made. The rate of plaque growth was found to be significantly greater when the Gingival Index was high compared with when the Gingival Index was low (P less than 0.001). There was also an earlier development of a complex bacterial flora when the Gingival Index was high. The hypothesis is presented that gingival exudate has no inhibitory action on the formation of dental plaque, but contains substances which enhance bacterial aggregation and the colonization of the tooth surfaces by these aggregates.     

Effect of hydrogen peroxide on developing plaque and gingivitis in man

The present experiment was undertaken to assess the effect of hydrogen peroxide release during mouth rinsings on the composition of the microbiota of developing plaque in humans and the amount and pathogenecity of the plaque formed. The trial was designed as a double-blind crossover study of the effect of a mouthwash (Amosan) had a placebo rinse on the development of plaque and gingivitis in young adults. The active compound was available as a powder; the rinse consisted of 1.7 g powder dissolved in 30 ml hot tap water. Fourteen dental students participated in the trial. The students were examined during two consecutive periods, each consisting of one preparatory (during which active tooth cleaning measures were carefully practiced) and one main test period (during which mouth rinsings were the only plaque control measure). Each of the two test periods was initiated by a baseline examination following which the participants rinsed either with the active or the placebo mouthwash. The rinsings were performed immediately after breakfast, after lunch and after dinner. Measurements of Plaque and Gingival Index scores were performed 4, 7 and 14 days after the start of the no-toothbrushing period. Bacteria were sampled and examined after 7 and 14 days of trial. The results demonstrated that a mouthwash which released hydrogen peroxide effectively prevented the colonization of filaments, fusiforms, motile and curved rods as well as spirochetes in developing plaque. The mouthwash which was used as the only oral hygiene measure during a 2-week period furthermore markedly reduced the amount of plaque formed and significantly retarded gingivitis development. It is suggested that H202 released by mouthwashes during rinsing may prevent or retard the colonization and multiplication of anaerobic bacteria.     

Comparison of experimental gingivitis with persistent gingivitis: differences in clinical parameters and cytokine concentrations

BACKGROUND AND OBJECTIVE: Experimental gingivitis has been studied extensively as a well-controlled laboratory model of gingivitis. It is unclear, however, how experimental gingivitis compares with persistent plaque and gingivitis in more naturalistic settings. The present study compares both conditions in a randomized controlled design. MATERIAL AND METHODS: Twenty-six students suffering from plaque and gingivitis were randomly assigned to either a persistent gingivitis or an experimental gingivitis condition. Subjects with persistent gingivitis continued their habitual (i.e. insufficient) oral hygiene behaviour, resulting in persistence of plaque and gingivitis. Experimental gingivitis consisted of initial prophylaxis and subsequent total neglect of oral hygiene. Crevicular interleukin-1beta and interleukin-8 and clinical data were assessed weekly. RESULTS: After 4 wk, subjects with experimental gingivitis showed significantly more plaque accumulation (p = 0.005), higher interleukin-1beta (p = 0.037), and lower interleukin-8 (p = 0.043) concentrations than subjects with persistent gingivitis. Whereas in experimental gingivitis we observed considerable fluctuations in clinical and immunological parameters over the 4-wk period, persistent gingivitis was characterized by little fluctuation, indicating that we were monitoring an inflammatory steady state. CONCLUSION: The data indicate that conditions observed after 4 wk of experimental gingivitis are not comparable with persistent gingival inflammation in a naturalistic setting. Results are discussed with respect to current studies, indicating that chronic inflammation may reflect a stage of down-regulated pro-inflammatory response.     

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.     

Mouthrinses in "experimental gingivitis" studies

The experimental gingivitis study design is a frequently used clinical model for the evaluation of the effects of antimicrobial agents on developing plaque and gingivitis. In individuals who at the start of the experiment have clean teeth and healthy gingivae and who use a mouthrinse containing the test agent as the only tooth cleaning measure during a period of 14-21 days, the anti-plaque and anti-gingivitis potential of the agent can be properly evaluated. The present paper describes different designs of experimental gingivitis studies for the evaluation of chemotherapeutic agents used to control supragingival plaque formation. Findings reported in the literature with respect to the effects obtained by various antimicrobial compounds are also reported.     

Effect of pre-experimental maintenance care duration on the development of gingivitis in a partial mouth experimental gingivitis model

The present study was designed to evaluate if different periods of supervised oral hygiene prior to the experimental gingivitis trial have an effect on the amount of inflammation which develops in the 'toothshield' model. Two groups were compared. One group (Group A) was supervised over a 5-month period before experimental gingivitis. Six months later Group A participated in a second trial, this time receiving only a 1-month pretrial. A second group (Group B) which served as a control was supervised over a pre-trial period of 1-month prior to the start of the experimental gingivitis phase. During the pre-trial period all subjects undertook a regime of vigorous oral hygiene which included polishing of the test quadrant in the upper jaw and supervised subgingival brushing, interdental taping or the use of toothpicks. The presence of plaque and bleeding were assessed. Following the pre-trial period all plaque control measures in the experimental area were prevented during oral hygiene periods by the temporary placement of soft, loosely fitting vinyl toothshield guard. During this period they accumulated plaque rapidly and developed a generalized gingivitis. The results of this study indicate that, irrespective of the length of the pre-trial period, subjects by group develop a comparable mean level of plaque and gingival bleeding. However, the extent to which gingivitis develops differs among individuals and was for a number of subjects not consistent. Therefore, in designing an experimental gingivitis trial care should be taken to include a sufficient number of subjects to account for individual variation.     

Effect of localized experimental gingivitis on early supragingival plaque accumulation

Abstract Previous investigations have reported increased plaque formation in the presence of gingival inflammation as compared with gingival health. In these investigations, experimental gingivitis has been induced by total abolition of oral hygiene such that increased levels of salivary bacteria could contribute to the increased plaque formation. In the present study, experimental gingivitis was localized to 2 selected teeth whilst maintaining normal oral hygiene measures in the rest of the mouth. The aim of this study was to investigate whether the mass of plaque accumulating in a 3-day period is influenced by the inflammatory status of the adjacent gingival margins. Following scaling, prophylaxis and a period of optimal hygiene to establish gingival health, “plaque-guards” were worn during routine oral hygiene performance to prevent any cleaning on the buccal surfaces of teeth 14 and 15 from days 0 to 3. On day 3, accumulated plaque was removed from a 1.5 mm zone on the buccal surfaces of 14 and 15 adjacent to the gingival margins and weighed immediately. Subjects continued to wear their plaque-guards during oral hygiene until day 14 to induce experimental gingivitis around the experimental teeth. At day 14, all plaque was cleaned from the buccal surfaces of the experimental teeth and the mass of plaque accumulating over the next 3 days weighed on day 17. Comparison of plaque weights showed that the wet-weight of 3 day-old plaque was higher in the presence of experimental gingivitis than in the presence of gingival health (p= 0.02). This observation suggests that the inflammatory status of the marginal gingival has an important effect on early, supragingival plaque accumulation.     

Interleukin-1 gene polymorphisms and experimental gingivitis

BACKGROUND: Recently, an association between the severity of periodontitis and specific variations in the interleukin-1 (IL1) alpha and beta genes has been demonstrated. AIM: : The purpose of this study was to evaluate the relationship of the IL1 genotype to the development of experimental gingivitis. MATERIALS AND METHODS: Twenty young adult subjects presenting with healthy gingival conditions participated after giving their informed consent. The group included 10 risk genotype positive (P+) and 10 risk genotype negative (P-) individuals. The IL1 genotypes were determined on DNA samples from peripheral blood using PCR-RFLP analyses for the IL1alpha and IL1beta polymorphisms. Experimental gingivitis was allowed to develop in two posterior sextants per subject. Bleeding on probing (BOP%) and gingival crevicular fluid volume (GCF) were assessed at baseline and days 2, 7, 9, 14, 16 and 21. The day 21 results for BOP and GCF as well as the rate of increase of these parameters - mean area under the curve (AUC) and mean increase per day (slope) - were evaluated using risk analyses for IL1 genotype, smoking status and gender. RESULTS: Experimental gingivitis developed with a gradual increase in BOP scores and GCF values (expressed as Periotron units=PU) from baseline to day 21 (BOP, P+: 0.5 to 26.0%; P-: 1.0 to 28.1%; GCF, P+: 36.8 to 138.5 PU, P-: 43.1 to 143.4 PU). No significant risk was associated with P+ and P- for day 21 results, AUC or slope. CONCLUSION: The results of this study failed to provide evidence that the IL1 risk genotype was associated with higher GCF volume and percentage BOP during the development of experimental gingivitis.     

A randomized, single-blind, parallel-group clinical study to evaluate the effect of soluble beta-1,3/1,6-glucan on experimental gingivitis in man

Background: Gingivitis is an inflammatory disorder of the periodontium induced by dental plaque bacteria. Soluble β‐1,3/1,6‐glucan (SBG) is known to enhance infection defense by preventing excessive inflammatory responses caused by bacterial endotoxins. Aim: The aim of the present study was to investigate the effect of SBG on experimental gingivitis in man. Material and Methods: Experimental gingivitis was induced over a period of 24 days in 30 healthy volunteers who were simultaneously treated with SBG. Two groups (n=10/group) rinsed twice daily with an SBG mouthwash that was either swallowed or expectorated. A third group (n=10) received a water rinse as a control. Plaque index (Pl.I), gingival index (GI), and amount of gingival crevicular fluid (GCF) were assessed at baseline and at six times during the study. Results: The results showed that in the SBG groups, GCF decreased significantly during the study. The swallow group experienced a significant increase in GCF during the first week. The control group followed the expected pattern of experimental gingivitis, with a significant increase in the gingival fluid secretion during the test period. There was a significant increase in GI and Pl.I during the study for all groups, with no significant differences between them. No adverse effects of SBG were recorded. Conclusions: In this 24‐day experimental gingivitis study of subjects who used either a SBG or a control mouthrinse: (1) all subjects had increased plaque and gingivitis, (2) GCF increased in control‐rinse subjects and GCF decreased in SBG‐rinse subjects. The only statistically significant difference between the SBG‐rinse and control‐rinse subjects was an increase in GCF at day 7 for subjects who rinsed and swallowed SBG.