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

IMPACT OF E-CIGARETTES ON THE ORAL HEALTH - LITERATURE REVIEW

E-cigarettes are electronic devices used to inhale aerosols generated from the vaporization of flavored liquids. Nowadays, the use of e-cigarettes has become one of the most popular alternatives to traditional smoking. The wide variety of devices and liquids makes it challenging to assess the health effects of using e-cigarettes. During the vaporization of e-liquids, toxins, carcinogens, and various other chemicals can be released and inhaled by the user. Limited data exist regarding the potential health impact of exposure to e-vapors, primarily derived from animal studies and in vitro research. The oral tissues are the first site of direct interaction with the components of the inhaled vapor. While e-cigarettes are commonly portrayed as safer alternatives to tobacco cigarettes, little is known about the short- or long-term health effects of their use. The aim of this review is to briefly present the available data regarding the impact of chemical ingredients and toxins present in e-cigarette vapors on oral cavity cells.

Human variation in gingival inflammation

Oral commensal bacteria actively participate with gingival tissue to maintain healthy neutrophil surveillance and normal tissue and bone turnover processes. Disruption of this homeostatic host-bacteria relationship occurs during experimental gingivitis studies where it has been clearly established that increases in the bacterial burden increase gingival inflammation. Here, we show that experimental gingivitis resulted in three unique clinical inflammatory phenotypes (high, low, and slow) and reveal that interleukin-1β, a reported major gingivitis-associated inflammatory mediator, was not associated with clinical gingival inflammation in the slow response group. In addition, significantly higher levels of Streptococcus spp. were also unique to this group. The low clinical response group was characterized by low concentrations of host mediators, despite similar bacterial accumulation and compositional characteristics as the high clinical response group. Neutrophil and bone activation modulators were down-regulated in all response groups, revealing novel tissue and bone protective responses during gingival inflammation. These alterations in chemokine and microbial composition responses during experimental gingivitis reveal a previously uncharacterized variation in the human host response to a disruption in gingival homeostasis. Understanding this human variation in gingival inflammation may facilitate the identification of periodontitis-susceptible individuals. Overall, this study underscores the variability in host responses in the human population arising from variations in host immune profiles (low responders) and microbial community maturation (slow responders) that may impact clinical outcomes in terms of destructive inflammation.

Probiotic therapy for periodontal and peri-implant health - silver bullet or sham?

Probiotics are thought to be beneficial microbes that influence health-related outcomes through host immunomodulation and modulation of the bacteriome. Its reported success in the treatment of gastrointestinal disorders has led to further research on its potential applicability within the dental field due to similarities such as a polymicrobial aetiology and disease associated microbial-shifts. Although the literature is replete with studies demonstrating its efficacy, the use of probiotics in dentistry continues to polarise opinion. Here, we explore the evidence for probiotics and its effect on periodontal and peri-implant health. MEDLINE, EMBASE, and CENTRAL were systemically searched from June 2010 to June 2020 based on a formulated search strategy. Of 1,956 potentially relevant articles, we selected 27 double-blinded randomised clinical trials in the areas of gingivitis, periodontitis, residual pockets during supportive periodontal therapy, and peri-implant diseases, and reviewed their efficacy in these clinical situations. We observed substantial variation in treatment results and protocols between studies. Overall, the evidence for probiotic therapy for periodontal and peri-implant health appears unconvincing. The scarcity of trials with adequate power and follow-up precludes any meaningful clinical recommendations. Thus, the routine use of probiotics for these purposes are currently unsubstantiated. Further multi-centre trials encompassing a standardised investigation on the most promising strains and administration methods, with longer observation times are required to confirm the benefits of probiotic therapy for these applications.

An Ayurvedic herbal extract inhibits oral epithelial cell IL-8 responses to host and bacterial agonists

BACKGROUND

Natural products constitute a promising class of therapeutics for the treatment of gingivitis and periodontitis as well as the maintenance of oral health. However, the limited understanding behind their potential mechanisms and modes of action have hampered their incorporation into popular western therapeutics. This in vitro study characterizes an Ayurvedic herbal extract mixture, which has been clinically shown to promote gingival health and homeostasis.

METHODS

Telomerase immortalized gingival keratinocytes (TIGK) were infected with either Fusobacterium nucleatum cell wall, live F. nucleatum, IL-1β or TNF-α for 4 hours with and without the herbal extract. The immunomodulatory effects of the extract on host IL-8 production was measured by ELISA.

RESULTS

It was found that the Ayurvedic herbal extract mixture inhibited gingival epithelial cell IL-8 expression in response to both bacterial and host cytokine agonists. The herbal extract inhibited IL-8 stimulated by F. nucleatum cell wall, live F. nucleatum, IL-1β, and TNF-α in a dose-dependent manner that was not a result of host cell death. Furthermore, the extract showed significantly different ID₅₀ doses demonstrating the differential ability to modulate both stimulated and basal IL-8 levels.

CONCLUSIONS

In vitro investigation of this herbal extract mixture revealed that it has the ability to modulate gingival epithelial cell IL-8 expression in response to stimulation by bacterial components and host pro-inflammatory signals. This data demonstrates that the reduction in the gingival epithelial cell IL-8 response may in part be responsible for the previously reported ability of the Ayurvedic herbal extract mixture to reduce gingivitis in two separate human clinical studies.

Effect of non-surgical periodontal therapy on the degree of gingival inflammation and stress markers related to pregnancy

OBJECTIVES

The purpose of this study was to determine the impact of nonsurgical periodontal therapy considering the salivary stress-related hormone and cytokine levels in the gingival crevicular fluid (GCF) on pregnant and nonpregnant women.

MATERIAL AND METHODS

Thirty non-pregnant (control group) and 30 pregnant women (test group) that met the study inclusion criteria were chosen. Only participants with gingivitis were included. Clinical data and samples of GCF and saliva were collected at baseline and after periodontal therapy. The levels of interleukin-1 beta (Κ-1β) and IL-10, and concentration of salivary chromogranin A (CgA) hormone were analyzed by enzyme-linked immunosorbent assay (ELISA). The repeated measures analysis of variance was used for intragroup and intergroup analyses.

RESULTS

A major decrease in the gingival inflammation was observed in both groups after periodontal therapy (p<0.05). Periodontal treatment decreased the level of IL-1β in GCF (p<0.05) in control group, but no statistical difference was determined for GCF IL-1β in the test group. However, after periodontal therapy, the CgA hormone concentration was reduced in both groups (p<0.05). However, there was no difference in salivary CgA concentration, GCF IL-10 levels, and perceived stress scale (PSS)-10 between the groups (p>0.05).

CONCLUSIONS

Within the limitations of this study, periodontal therapy significantly improved the periodontal status and stress level. In addition, the severity of the gingival inflammation during pregnancy was related to stress. However, further studies will be needed to substantiate these early findings.

A pilot study of the gingival response when smokers switch from smoking to vaping

Introduction Tobacco smoking is one of the most important risk factors for periodontitis as it alters the host response to plaque. Although the prevalence of tobacco smoking has declined in recent years, the use of electronic-cigarettes (vaping) has increased. The effect of vaping on the gingiva is unknown and an evidence-base needs to be established before providing dental advice about the use of these products.Objective To compare the gingival health of a group of established smokers before and after substituting vaping for smoking tobacco.Design Pilot.Setting Guy's Dental Hospital (England) from April-December 2015.Materials and methods Twenty established smokers (all staff members at Guy's Hospital) with mild periodontal disease replaced their regular smoking habits with the use of e-cigarettes for two weeks.Main outcome measure The primary outcome measure of gingival inflammation was bleeding on probing. Levels of selected pro-inflammatory cytokines in GCF, saliva and serum samples were also determined.Results and conclusions There was a statistically significant increase in gingival inflammation when tobacco smokers switched from smoking to vaping for two weeks. However, this result must be interpreted with extreme caution since this is only a pilot study. Nonetheless, this study should provide a stepping stone to encourage further investigation of the effects of vaping on periodontal health.

Salivary cytokine levels in early gingival inflammation

Salivary protein levels have been studied in periodontitis. However, there is lack of information on salivary cytokine levels in early gingival inflammation. The aim of this study was to determine salivary levels of vascular endothelial growth factor (VEGF), interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1, IL-1β, and IL-1 receptor antagonist (IL-1Ra) in gingival inflammation. Twenty-eight systemically and orally healthy nonsmokers abstained from oral hygiene protocols for 10 days. After that, self-performed cleaning was resumed for 14 days. Plaque and gingival indexes were measured, and saliva samples were collected at days 1, 4, 7, 10, and 24. Salivary cytokines were detected with Luminex®-xMAP™. Salivary IL-1β, IL-1Ra, and VEGF levels decreased after 10 days' development of experimental gingivitis and reached baseline levels at the end of the 2-week resolution period. Salivary IL-8 levels decreased and remained low during development and resolution of experimental gingivitis. Initial inflammation in gingival tissues is associated with a decrease in inflammatory cytokines in saliva. Further studies are needed to evaluate if inflammatory cytokines bind to their functional receptors within the gingival tissue during early gingivitis, which may limits their spillover to the gingival crevice and ultimately saliva.

Regular consumption of Lactobacillus reuteri-containing lozenges reduces pregnancy gingivitis: an RCT

Aim

This randomized controlled trial assessed the impact of Lactobacillus reuteri on pregnancy gingivitis in healthy women.

Materials and Methods

Forty‐five healthy women (24 test/21 placebo) with pregnancy gingivitis in the third trimester of pregnancy were enrolled. At baseline Gingival Index (GI) and Plaque Index (PlI) were assessed at the Ramfjord teeth and venous blood taken for TNF‐α analysis. Subsequently participants were randomly provided with lozenges to be consumed 2 × daily until birth (approx. 7 weeks) containing ≥10⁸CFU L. reuteri ATCC PTA 5289 and ≥10⁸CFU L. reuteri DSM 17938 (test) or being devoid of L. reuteri (placebo). Within 2 days after birth recording of GI, PlI and blood sampling were repeated.

Results

At baseline, mean GI and mean PlI did not differ significantly between both groups. In the test group mean TNF‐α serum level was significantly (p < 0.02) lower than in the placebo group. At reevaluation, mean GI and mean PlI of the test group were both significantly (p < 0.0001) lower than in the placebo group. Mean TNF‐α serum level did no longer differ significantly between the groups.

Conclusions

The consumption of L. reuteri lozenges may be a useful adjunct in the control of pregnancy gingivitis.

Stimulation of the nitrate-nitrite-NO-metabolism by repeated lettuce juice consumption decreases gingival inflammation in periodontal recall patients: a randomized, double-blinded, placebo-controlled clinical trial

AIM

This prospective, parallel group, two-armed, double-blind, placebo-controlled randomized trial evaluated the impact of dietary nitrate consumption on gingival inflammation in periodontal recall patients.

MATERIAL AND METHODS

Forty-four (23 test/21 placebo) periodontal recall patients with chronic gingivitis were enrolled. At baseline, gingival index (GI), plaque control record (PCR) and salivary nitrate level (SNL) were recorded, followed by sub- and supragingival debridement. Subsequently, participants were randomly provided with 100 ml bottles of a lettuce juice beverage to be consumed 3× daily over 14 days, containing either a standardized amount of nitrate resulting in an intake of approximately 200 mg nitrate per day (test) or being devoid of nitrate (placebo).

RESULTS

At baseline, mean GI, PCR and SNL did not differ significantly between the groups. At day 14, mean GI of the test group was significantly reduced compared to baseline and significantly lower (p = 0.002) than in the placebo group (GI 0.3 versus 0.5). Also, mean SNL in the test group was significantly higher than in the placebo group (54.0 μg/ml versus 27.8 μg/ml; p < 0.035). Mean PCR did not change significantly in both groups.

CONCLUSIONS

Dietary nitrate consumption may be a useful adjunct in the control of chronic gingivitis.

Experimental mucositis and experimental gingivitis in persons aged 70 or over. Clinical and biological responses

Objectives

To compare in persons aged 70 years or older the clinical and inflammatory changes occurring around implants and natural teeth during and after a phase of undisturbed plaque accumulation.

Material and methods

Twenty partially edentulous participants with titanium implants refrained from oral hygiene practices while being clinically monitored in weekly intervals for 21 days. Teeth and implants were then cleaned, oral hygiene resumed, and the participants were further monitored for 3 weeks. Twelve biomarkers were assessed in gingival and peri‐implant crevicular fluid (GCF, PCF).

Results

During 3 weeks of oral hygiene abstention, the gingival index (GI) continuously increased. On day 21, there were significantly more sites with GI >1 at implants than at teeth. After restarting oral hygiene, the GI decreased markedly in both groups. Throughout the experiment, the plaque index was significantly higher on teeth than on implants.

The different biomarkers reacted variably. IL‐1β increased significantly with plaque accumulation. IL‐1β, GM‐CSF, TNF‐α, and IFN‐γ were significantly higher in GCF compared to PCF at day 21. IL‐8 decreased significantly in GCF up to day 14. MIP‐1β decreased significantly in GCF, but not in PCF. At the 3‐week follow‐up, the levels of all biomarkers assessed in GCF and PCF had returned to baseline values.

Conclusions

In an elderly cohort, plaque accumulation induced an inflammatory reaction around both teeth and implants. Although there was less plaque accumulation on implants, the peri‐implant mucosa showed a stronger clinical response than gingiva.

Effects of triclosan on host response and microbial biomarkers during experimental gingivitis

AIM

This exploratory randomized, controlled clinical trial sought to evaluate anti-inflammatory and -microbial effects of triclosan during experimental gingivitis as assessed by host response biomarkers and biofilm microbial pathogens.

MATERIALS AND METHODS

Thirty participants were randomized to triclosan or control dentifrice groups who ceased homecare for 21 days in an experimental gingivitis (EG) protocol. Plaque and gingival indices and saliva, plaque, and gingival crevicular fluid (GCF) were assessed/collected at days 0, 14, 21 and 35. Levels and proportions of 40 bacterial species from plaque samples were determined using checkerboard DNA-DNA hybridization. Ten biomarkers associated with inflammation, matrix degradation, and host protection were measured from GCF and saliva and analysed using a multiplex array. Participants were stratified as "high" or "low" responders based on gingival index and GCF biomarkers and bacterial biofilm were combined to generate receiver operating characteristic curves and predict gingivitis susceptibility.

RESULTS

No differences in mean PI and GI values were observed between groups and non-significant trends of reduction of host response biomarkers with triclosan treatment. Triclosan significantly reduced levels of A. actinomycetemcomitans and P. gingivalis during induction of gingivitis.

CONCLUSIONS

Triclosan reduced microbial levels during gingivitis development (ClinicalTrials.gov NCT01799226).

Effects of curcumin on crevicular levels of IL-1β and CCL28 in experimental gingivitis

BACKGROUND

Curcumin has anti-inflammatory properties. The aim of this study was to compare interleukin-1β (IL-1β) and chemokine (C-C motif) ligand 28 (CCL28) levels following a topical application of curcumin (CRM), chlorhexidine (CHX) and chlorhexidine-metronidazole (CHX-MTZ) in an experimental gingivitis human model.

METHODS

Sixty systemically healthy selected subjects were randomly assigned to one of three topical antigingivitis gels. Each gel was applied twice daily for 10 minutes as the sole method of oral hygiene for 29 days on the test quadrant only. Modified gingival index (MGI), plaque index (PI), bleeding on probing (BOP) and probing depth (PD) were assessed at baseline, 29 days and 60 days. Estimation of IL-1β and CCL28 levels in gingival crevicular fluid was done at baseline and at 29 days.

RESULTS

The increase of IL-1β in the CRM (14.52 ± 16.6 pg/ml) and CHX-MTZ (31.63 ± 15.96) groups was significantly less than that of the CHX group (70.55 ± 38.81). Similar results were also observed for CCL28 (CRM: 8.12 ± 8.78 pg/ml; CHX-MTZ: 12.81 ± 18.68; CHX: 41.15 ± 22.82). All groups had a significant increase in MGI, PI and BOP at 29 days.

CONCLUSIONS

The anti-inflammatory potential of topical curcumin was similar to CHX-MTZ but superior to CHX in affecting IL-1β and CCL28 levels.

Salivary and crevicular fluid interleukins in gingivitis

INTRODUCTION

Gingivitis is a frequent inflammatory process of the gum tissue that is mainly caused by the accumulation of plaque. The immune response against inflammatory processes is regulated in part by cytokines.

AIMS

Given that a continuous inflammation exists in gingivitis, it would be logical to assume that the interleukins will be altered locally in those patients. Therefore, the aim of this review was to check whether there is evidence that the interleukins can be used as diagnostic markers of inflammation levels in patients with gingivitis.

MATERIALS AND METHODS

A bibliographical search was undertaken using the key words interleukin and gingivitis in Pubmed, Cochrane, Scopus and Embase. Only those articles published over the last 10 years that were systematic reviews, case-controls or cohort studies in which interleukins in saliva and/or crevicular fluid was investigated in patients with gingivitis were selected.

RESULTS

Finally 15 articles were selected, all of them being case-control studies. The interleukins analyzed in the reviewed articles were: IL-1β, IL-8, IL-18, IL-11, IL-12, TNFα, IL-4, IL-17, IL-1α and IL-6. The most commonly studied interleukin is IL-1β and most authors agree that it is higher in the saliva and/or crevicular fluid of patients with gingivitis. Therefore, it could be used as a diagnostic marker of the degree of inflammation in gingivitis. Moreover, as far as the other interleukins studied are concerned, there is no clear consensus among the authors.

CONCLUSION

There is sufficient evidence to suggest that IL-1β in saliva and/or crevicular fluid can be used as a marker of the degree of inflammation in gingivitis. Key words:Interleukins, gingivitis, saliva, crevicular fluid.

Salivary biomarkers associated with gingivitis and response to therapy

BACKGROUND

Salivary biomarkers are potentially important for determining the presence, risk, and progression of periodontal disease. However, clinical translation of biomarker technology from lab to chairside requires studies that identify biomarkers associated with the transitional phase between health and periodontal disease (i.e., gingivitis).

METHODS

Eighty participants (40 with gingivitis, 40 healthy) provided saliva at baseline and 7 to 30 days later. An additional sample was collected from gingivitis participants 10 to 30 days after dental prophylaxis. Clinical parameters of gingival disease were recorded at baseline and the final visit. Salivary concentrations of interleukin (IL)-1β, IL-6, matrix metalloproteinase (MMP)-8, macrophage inflammatory protein (MIP)-1α, and prostaglandin E2 (PGE2) were measured.

RESULTS

Clinical features of health and gingivitis were stable at both baseline visits. Participants with gingivitis demonstrated significantly higher bleeding on probing (BOP), plaque index (PI), and gingival index (GI) (P ≤0.002) and a significant drop in BOP, PI, and GI post-treatment (P ≤0.001). Concentrations of MIP-1α and PGE2 were significantly higher (2.8 times) in the gingivitis group than the healthy group (P ≤0.02). After dental prophylaxis, mean biomarker concentrations did not decrease significantly from baseline in the gingivitis group, although concentrations of IL-1β, IL-6, and MMP-8 approached healthy levels, whereas MIP-1α and PGE2 concentrations remained significantly higher than in the healthy group (P ≤0.04). Odds ratio analyses showed that PGE2 concentrations, alone and in combination with MIP-1α, readily discriminated gingivitis from health.

CONCLUSIONS

Salivary PGE2 and MIP-1α discriminate gingivitis from health, and patients with gingivitis who return to clinical health continue to produce inflammatory mediators for weeks after dental prophylaxis.

Local and systemic inflammatory responses to experimentally induced gingivitis

This study profiled the local and systemic inflammatory responses to experimentally induced gingivitis. Eight females participated in a 21-day experimental gingivitis model followed by a 14-day resolution phase. Bleeding on probing and plaque index scores were assessed before, during, and after resolution of gingival inflammation, and samples of saliva, GCF, and plasma were collected. Samples were assessed for biomarkers of inflammation using the BioPlex platform and ELISA. There were no significant changes in GCF levels of cytokines during the experimental phase; however, individual variability in cytokine profiles was noted. During resolution, mean GCF levels of IL-2, IL-6, and TNF-α decreased and were significantly lower than baseline levels (P = 0.003, P = 0.025, and P = 0.007, resp.). Furthermore, changes in GCF levels of IL-2, IL-6, and TNF-α during resolution correlated with changes in plaque index scores (r = 0.88, P = 0.004; r = 0.72, P = 0.042; r = 0.79, P = 0.019, resp.). Plasma levels of sICAM-1 increased significantly during the experimental phase (P = 0.002) and remained elevated and significantly higher than baseline levels during resolution (P < 0.001). These results support the concept that gingivitis adds to the systemic inflammatory burden of an individual.

Association of interleukin-1 polymorphisms with periodontitis in Down syndrome

This study examined the association of IL1 genetic polymorphisms (IL-1A +4845, IL-1B +3954 & IL-1RN +2018) with periodontal disease status of Down syndrome (DS) individuals. Fifty-four DS patients (18-56 yr, 48.15% male, 77.78% Caucasians) were recruited from the Georgia Regional Hospital (GRH) health care system. Two comparable groups (71 mentally retarded patients and 87 control subjects) were also recruited. All subjects were nonsmokers. Periodontal evaluations (plaque index, gingival index, bleeding-on probing and clinical attachment levels (AL)), personal and professional dental care habits were recorded. Blood was collected by a venipuncture. The IL-1A +4845, IL-1B +3954 & IL-1RN +2018 loci were genotyped by the TaqMan assay. No statistically significant differences were noted in the distribution of IL-1 gene polymorphisms between the three groups. The IL-1 variant genotypes varied by race; for both IL-1A and IL-1RN, the variant gene was significantly more prevalent among whites than non-whites (ps > 0.1). ANCOVA, which also adjusted for age, showed a 3-way interaction among dental visits, gene variation and Down status [(F(1, 179) = 3.96, P = 0.048 in White subjects and F(1, 241) = 2.96, P = 0.087 in all subjects). Post-hoc t-tests confirmed lower levels of AL in IL-1RN-variant Down subjects receiving more frequent dental visits (P < 0.05). ANCOVA, which also adjusted for age, showed an interaction between IL-1A/B gene variation and Down status (F(1, 174) = 3.04, P = 0.083 in White subjects and F(1, 235) = 3.72, P = 0.055 in all subjects). Post-hoc t-tests confirmed lower levels of AL in IL-1A/B-variant Down subjects (P < 0.05). The distribution of variant IL-1 genes in DS subjects was not different from the general population. However the association between the carriage of the IL-1 rare alleles and periodontitis differed between the Down and non-Down subjects. The carriage of the IL-1 rare alleles in the Down subjects tended to confer a protective effect against loss of periodontal attachment.

Gingival tissue transcriptomes in experimental gingivitis

AIMS

We investigated the sequential gene expression in the gingiva during the induction and resolution of experimental gingivitis.

MATERIAL AND METHODS

Twenty periodontally and systemically healthy non-smoking volunteers participated in a 3-week experimental gingivitis protocol, followed by debridement and 2-week regular plaque control. We recorded clinical indices and harvested gingival tissue samples from four interproximal palatal sites in half of the participants at baseline, Day 7, Day 14 and Day 21 (the "induction phase"), and at Day 21, Day 25, Day 30 and Day 35 in the other half (the "resolution phase"). RNA was extracted, amplified, reversed transcribed, amplified, labelled and hybridized using Affymetrix Human Genome U133Plus2.0 microarrays. Paired t-tests compared gene expression changes between consecutive time points. Gene ontology analyses summarized the expression patterns into biologically relevant categories.

RESULTS

The median gingival index was 0 at baseline, 2 at Day 21 and 1 at Day 35. Differential gene regulation peaked during the third week of induction and the first 4 days of resolution. Leucocyte transmigration, cell adhesion and antigen processing/presentation were the top differentially regulated pathways.

CONCLUSIONS

Transcriptomic studies enhance our understanding of the pathobiology of the reversible inflammatory gingival lesion and provide a detailed account of the dynamic tissue responses during the induction and resolution of experimental gingivitis.

Endotoxemia and the host systemic response during experimental gingivitis

AIM

To assess endotoxemia episodes and subsequent changes in serum inflammatory biomarkers using the experimental gingivitis model.

MATERIALS AND METHODS

Data from 50 healthy black and white adult males and females were compared for serum concentrations of endotoxin, and serum biomarkers [neutrophil oxidative activity, interleukin (IL)-1β, IL-6, IL-8, C-reactive protein (CRP), and fibrinogen] at baseline, at 3 weeks of experimental gingivitis, and after 2 weeks of recovery. Means were compared using repeated measures analysis of variance.

RESULTS

Endotoxemia was reported in 56% of the serum samples at 3 weeks of induced gingivitis. At 2 weeks of recovery, endotoxin levels decreased to levels similar to those reported at baseline. Neutrophil oxidative activity increased significantly following 3 weeks of gingivitis versus baseline (p<0.05). In the endotoxin-negative group this increase was associated with the black subjects whereas in the endotoxin-positive group change in neutrophil activity was driven by the female subpopulation. Serum cytokines, CRP, and fibrinogen levels did not change during the study.

CONCLUSIONS

Experimental gingivitis was associated with endotoxemia and hyperactivity of circulating neutrophils, but not with changes in systemic levels of cytokines and acute-phase proteins. This may be attributed to the mild nature and the short duration of the induced gingivitis.

Interleukin-1 beta levels in gingival crevicular fluid and serum under naturally occurring and experimentally induced gingivitis

AIMS

To evaluate the interleukin-1 beta (IL-1 beta) levels in gingival crevicular fluid (GCF) and serum in either naturally occurring (N-O) or experimentally induced (E-I) plaque-associated gingivitis.

MATERIAL AND METHODS

Thirty-seven periodontally healthy subjects were evaluated in real life conditions (N-O gingivitis) as well as after 21 days of experimental gingivitis trial (E-I gingivitis). During the experimental gingivitis trial, in one maxillary quadrant (test quadrant), gingival inflammation was induced by oral hygiene abstention, while in the contralateral (control) quadrant, oral hygiene was routinely continued. IL-1 beta concentrations in N-O and E-I gingivitis were investigated for IL-1B(+3954) and IL-1B(-511) gene polymorphisms.

RESULTS

(i) GCF IL-1 beta concentrations in E-I gingivitis were significantly higher compared with N-O gingivitis; (ii) an intra-individual correlation between GCF concentrations of IL-1 beta detected in N-O and E-I gingivitis was observed in control quadrants, but not in test quadrants; (iii) IL-1 beta concentration in GCF was associated with IL-1B(+3954) genotype only at test quadrants; (iv) IL-1 beta was detectable in serum only at low levels in a limited number of subjects, without difference between gingivitis conditions.

CONCLUSIONS

Aspects of the bacterial challenge to the gingival tissues, such as the amount of plaque deposits and plaque accumulation rate, appear to affect the IL-1 beta levels in GCF in subjects with a specific IL-1B genotype.

Gingival transcriptome patterns during induction and resolution of experimental gingivitis in humans

BACKGROUND

To our knowledge, changes in the patterns of whole-transcriptome gene expression that occur during the induction and resolution of experimental gingivitis in humans were not previously explored using bioinformatic tools.

METHODS

Gingival biopsy samples collected from 14 subjects during a 28-day stent-induced experimental gingivitis model, followed by treatment, and resolution at days 28 through 35 were analyzed using gene-expression arrays. Biopsy samples were collected at different sites within each subject at baseline (day 0), at the peak of gingivitis (day 28), and at resolution (day 35) and processed using whole-transcriptome gene-expression arrays. Gene-expression data were analyzed to identify biologic themes and pathways associated with changes in gene-expression profiles that occur during the induction and resolution of experimental gingivitis using bioinformatic tools.

RESULTS

During disease induction and resolution, the dominant expression pathway was the immune response, with 131 immune response genes significantly up- or downregulated during induction, during resolution, or during both at P <0.05. During induction, there was significant transient increase in the expression of inflammatory and oxidative stress mediators, including interleukin (IL)-1 alpha (IL1A), IL-1 beta (IL1B), IL8, RANTES, colony stimulating factor 3 (CSF3), and superoxide dismutase 2 (SOD2), and a decreased expression of IP10, interferon inducible T-cell alpha chemoattractant (ITAC), matrix metalloproteinase 10 (MMP10), and beta 4 defensin (DEFB4). These genes reversed expression patterns upon resolution in parallel with the reversal of gingival inflammation.

CONCLUSIONS

A relatively small subset (11.9%) of the immune response genes analyzed by array was transiently activated in response to biofilm overgrowth, suggesting a degree of specificity in the transcriptome-expression response. The fact that this same subset demonstrates a reversal in expression patterns during clinical resolution implicates these genes as being critical for maintaining tissue homeostasis at the biofilm-gingival interface. In addition to the immune response pathway as the dominant response theme, new candidate genes and pathways were identified as being selectively modulated in experimental gingivitis, including neural processes, epithelial defenses, angiogenesis, and wound healing.

The effect of age on the gingival crevicular fluid composition during experimental gingivitis. A pilot study

Background:

Cytokines have been proposed as potentially useful diagnostic or prognostic markers of periodontal inflammation related alterations during the experimental gingivitis model. The role of ageing in periodontal disease needs further elucidation; therefore investigations of its influence on host response are needed.

Objective:

To study the effect of age on interleukins IL -6, IL-8 and TNF-a levels in gingival crevicular fluid (GCF) and their correlations to clinical parameters during experimental gingivitis.

Materials and Methods: Five young subjects (20-22 years old) and five old subjects (61-65 years old), all periodontal healthy, participated in this clinical trial. A professional plaque control programme was undertaken to establish healthy gingival conditions at baseline. Plaque index (PI), gingival index (GI) were recorded at 60 sites at baseline, after 21 days of no oral hygiene and one week later after professional cleaning and reestablishment of oral hygiene procedures. A total of 180 samples were analyzed with ELISA for levels of IL -6, IL-8 and TNF-a in gingival crevicular fluid. The examination included the mesiobuccal sites of the Ramfjord teeth. Comparisons between and within groups were performed by non-parametric tests (Mann- Withney) and correlations were sought for with Wilcoxon test. Significance was set at p=0.05.

Results:

Results showed significant diferences between the two groups with regard to the plaque and bleeding scores and GCF volume, all of which proved to be more pronounced in old group. With respect to laboratory data, mean cytokine concentrations were in general lower in young group. TNF-a had a steady increase for the adults, which was found to be statistically significant between Days 0 and 21, IL-8 showed a statistically significant decrease at Day 28 in the young group and finally IL-6 showed a fluctuation, which was totally adverse for the two groups at each time point.

Conclusion:

Within the limitations of the present study, age cannot be identified as a factor that strongly affects the cytokine expression and fluctuations even in a well-controlled environment of inflammation, such as experimental gingivitis.

Pro-inflammatory biomarkers during experimental gingivitis in patients with type 1 diabetes mellitus: a proof-of-concept study

AIM

To compare gingival crevicular fluid (GCF) biomarker levels and microbial distribution in plaque biofilm (SP) samples for subjects with type 1 diabetes (T1DM) versus healthy subjects without diabetes during experimental gingivitis (EG).

MATERIALS AND METHODS

A total of nine T1DM patients and nine healthy controls of age and gender similar to the T1DM patients were monitored for 35 days during EG. Hygiene practices were stopped for 3 weeks, and GCF, SP, plaque index (PI) and gingival index were determined. IL-1beta, IL-8, MMP-8 and MMP-9 were quantified by enzyme-linked immunosorbent assay, and SP samples were assessed by DNA-DNA hybridization for a panel of 40 subgingival microbial species.

RESULTS

IL-1beta levels in T1DM patients were elevated compared with healthy individuals, and showed differences between groups at 7-21 days while healthy patients showed IL-1beta increases from baseline to 14-21 days (p<0.05). Differences were observed in MMP-9 levels between patients with and without T1DM at 7-14 days (p<0.05). Orange complex species and PI measurements displayed a superior correlation with biomarker levels when compared with other complexes or clinical measurements during EG.

CONCLUSIONS

The mean GCF biomarker levels for IL-1beta and MMP-8 were most significantly elevated in T1DM subjects compared with healthy individuals during EG, not resulting from differences in the mean PI or microbial composition.

Neutrophil response to dental plaque by gender and race

The inflammatory response, which has both genetic and environmental components, is a central mechanism linking oral and systemic diseases. We hypothesized that dental plaque accumulation over 21 days in the experimental gingivitis model would elicit systemic inflammatory responses [change in white blood cell (WBC) count and neutrophil activity], and that these responses would differ by gender/race. We recruited 156 healthy young adults, including black and white males and females. Plaque Index (PI), Gingival Index (GI), systemic WBC counts, and peripheral neutrophil oxidative activity were recorded. Overall, 128 participants completed the study. During the experimental phase, the correlation between PI and GI was 0.79. Total WBC and neutrophil counts did not change. Neutrophil activity increased in blacks but not whites, suggesting that there may be racial differences in the inflammatory response to dental plaque accumulation.

The impact of the stone age diet on gingival conditions in the absence of oral hygiene

BACKGROUND

The objective of this study was to assess the oral microbiota and clinical data in subjects without access to traditional oral hygiene methods and who ate a diet available in the Stone Age.

METHODS

Ten subjects living in an environment replicating the Stone Age for 4 weeks were enrolled in this study. Bleeding on probing (BOP), gingival and plaque indices, and probing depth (PD) were assessed at baseline and at 4 weeks. Microbiologic samples were collected at the mesio-buccal subgingival aspects of all teeth and from the dorsum of the tongue and were processed by checkerboard DNA-DNA hybridization methods.

RESULTS

No subject had periodontitis. Mean BOP decreased from 34.8% to 12.6% (P <0.001). Mean gingival index scores changed from 0.38 to 0.43 (not statistically significant) and mean plaque scores increased from 0.68 to 1.47 (P <0.001). PD at sites of subgingival sampling decreased (mean difference: 0.2 mm; P <0.001). At week 4, the total bacterial count was higher (P <0.001) for 24 of 74 species, including Bacteroides ureolyticus, Eikenella corrodens, Lactobacillus acidophilus, Capnocytophaga ochracea, Escherichia coli, Fusobacterium nucleatum naviforme, Haemophilus influenzae, Helicobacter pylori, Porphyromonas endodontalis, Staphylococcus aureus (two strains), Streptococcus agalactiae, Streptococcus anginosis, and Streptococcus mitis. Bacterial counts from tongue samples were higher at baseline (P <0.001) for 20 species, including Tannerella forsythia (previously T. forsythensis), Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans; serotype a), and Streptococcus spp.

CONCLUSIONS

The experimental gingivitis protocol is not applicable if the diet (e.g., Stone Age) does not include refined sugars. Although plaque levels increased, BOP and PD decreased. Subgingival bacterial counts increased for several species not linked to periodontitis, whereas tongue bacterial samples decreased during the study period.

Acute stress induces proinflammatory signaling at chronic inflammation sites

OBJECTIVES

To analyze in a randomized controlled study whether acute psychological stress alters local proinflammatory signals in a human model of chronic inflammation, i.e., gingivitis. Chronic inflammation represents a crucial factor in a variety of diseases and factors that contribute to the onset and progression of disease. Psychological stress is assumed to represent such a factor. However, experimental human research in this area is rare.

METHODS

A total of 25 students (n = 11 females, 14 males) suffering from gingivitis were subjected to a stress (public-speaking task) and to a control condition in randomized order. Local concentrations of interleukin (IL)-8 were quantified as an indicator of proinflammatory activity at sites of inflammation. IL-8 is a strong proinflammatory mediator and involved in a variety of disease processes. Samples were taken at sites of inflammation before stress versus control condition and 0, 45, and 90 minutes afterward.

RESULTS

A significant main effect (p = .03) of acute stress on local IL-8 was found. Stress induced an increase of IL-8-concentrations; univariate effect sizes varied between d = 0.23 and d = 0.36.

CONCLUSION

This is the first human experimental in vivo study demonstrating that psychological stress alters the local concentrations of IL-8 under conditions of chronic inflammation. It provides direct evidence acute stress is involved in the regulation of local proinflammatory responses in chronic inflammation. Future studies should now explore the effects of more enduring stress conditions and the factors mediating stress effects on inflammatory signals.

A combination of alleles 2 of interleukin (IL)-1A(-889) and IL-1B(+3954) is associated with lower gingival bleeding tendency in plaque-induced gingivitis in young adults of Arabic heritage

The aim of this study was to investigate the possible association of a distinct combination of polymorphisms in the interleukin (IL)-1 gene cluster on gingival bleeding tendency in young adult Arabs with plaque-induced gingivitis. Fifty otherwise healthy, nonsmoking volunteers, 19-28 years of age, participated. Clinical examinations included periodontal probing depth, bleeding on probing, and plaque index. Probing was done with a pressure-controlled probe at about 1.27 MPa. Examinations were repeated after 2 and 4 weeks. Polymorphisms in the IL-1 gene cluster were assessed using a reverse hybridization assay. A subject carrying alleles 2 at IL-1A ( -889 ) and IL-1B ( +3954 ) was designated genotype-positive. Twenty-six subjects were genotype-positive (52%). A repeated measures two-level (occasion, subject) model of the proportion of sites bleeding on probing, which was adjusted for gender, average plaque index, probing depth, and calculus, revealed a significantly lower proportion of bleeding sites in genotype-positive subjects (estimate -0.050, standard error 0.025, p < 0.05). Biserial correlations of bleeding proportions were high (0.71-0.78), confirming the steady-state plaque environment. It was concluded that inflammatory responses to dental plaque were considerably dampened in genotype-positive, nonsmoking young adults of Arabic heritage.