Modulation of clinical expression of plaque-induced gingivitis. III. Response of "high responders" and "low responders" to therapy

Gingival crevicular fluid during experimental gingivitis: A review of immune and tissue regulation

BACKGROUND

This systematic review summarized the features of human experimental gingivitis (EG) in terms of immune responses and tissue remodeling in the gingival crevicular fluid (GCF).

METHODS

Systematic searches were conducted to screen the literature published from January 1960 to June 2024 from MEDLINE (PubMed), EMBASE, and Web of Science. The selected studies were prospective trials evaluating the immune responses and tissue remodeling mediators in GCF before and after EG via oral hygiene refrain. Evidence quality and risk of bias were assessed.

RESULTS

Thirty studies with 594 volunteers met the inclusion criteria, analyzing 74 clinical parameters and biomarkers in GCF samples. Consistent with EG induction, the EG sites showed an increase in plaque index (PI), gingival index (GI), and myeloperoxidase (MPO) (an indicator of neutrophil migration). In addition, the expression levels of interleukin (IL)-1α and IL-1β were increased, also consistent with the previous literature investigating active lesions of periodontal inflammation during gingivitis. However, the expression of macrophage inflammatory protein (MIP)-1 β, monocyte chemoattractant protein (MCP)-1, CCL2, and fractalkine/CX3CL1 decreased among EG in multiple studies demonstrating an EG effect on recruitment and cellular communication of mononuclear cells. In contrast, the levels of fibroblast growth factors (FGFs), vascular endothelial growth factor (VEGF), and anti-inflammatory cytokines showed insignificant changes during EG induction. Aging, stress level, and the diabetes status of the volunteer populations affected the outcomes.

CONCLUSIONS

The features of acute inflammatory lesions of EG with limited tissue destruction showcase that it is a valuable tool to investigate the initial immune responses on gingival tissue against bacterial challenges.

PLAIN LANGUAGE SUMMARY

This review examined how human experimental gingivitis (EG) affects immune responses and tissue changes in the fluid around the gums. Researchers analyzed studies published from 1960 to 2024, focusing on those that looked at immune responses and tissue changes in gum fluid before and after participants stopped brushing their teeth to induce EG. The review included 30 studies with 594 participants, exploring various health markers in gum fluid. When EG was induced, areas of the gums showed increased plaque and markers of inflammation, indicating an inflammatory response. Specifically, two inflammatory proteins (interleukin [IL]-1α and IL-1β) were found in greater expression, which aligns with what previous research has shown in gum disease. However, levels of certain proteins that help attract monocytes and macrophages decreased, suggesting changes in how these cells communicate during EG. Additionally, the levels of growth factors and anti-inflammatory substances did not change significantly. Factors such as age, stress, and diabetes also influenced the outcomes. These findings help us understand early immune responses in gum disease, which is crucial for developing prevention strategies and improving oral health overall.

The evaluation of salivary leucine-rich alpha-2 glycoprotein (LRG) and C-reactive protein (CRP) in humans with periodontal health or periodontal disease

OBJECTIVE

The purpose of the present research is to evaluate the salivary levels of leucine-rich alpha-2 glycoprotein (LRG) and C-reactive protein (CRP) in periodontal health and disease (gingivitis and stage III periodontitis) and also to compare the discriminative efficiencies of both biomarkers in periodontal disease.

BACKGROUND

LRG is a new acute-phase protein whose functions are still being investigated. LRG and CRP are both biomarkers that are increased by inflammation. No clinical study has yet investigated the comparison of the level of LRG and CRP in periodontal health, gingivitis and periodontitis in saliva samples.

METHODS

A total of 60 individuals, including 20 periodontally healthy (control group/group C), 20 with gingivitis (group G), and 20 with Stage III periodontitis (group P), who were systemically healthy and non-smokers, participated in this study. Periodontal charts were used for recording clinical periodontal parameters and saliva LRG and CRP levels were measured by ELISA. Analyzing the area under the curve (AUC) was performed by the receiver-operating characteristics curve.

RESULTS

Salivary levels of LRG and CRP were significantly higher in disease groups than in group C (p < .05). Positive statistically significant correlations were observed between both biomarkers and clinical parameters (p < .05). There was also a strong positive correlation between two biomarkers (p < .05). In distinguishing periodontal disease from periodontal health, LRG (AUC = 0.833) and CRP (AUC = 0.826) were found to have similar accuracy (p = .923).

CONCLUSION

LRG and CRP may be useful and similarly effective biomarkers in the diagnosis of periodontal diseases based on the findings of this study.

Localized microbially induced inflammation influences distant healthy tissues in the human oral cavity

Variation in human immune response to the same bacterial or viral pathogen is well established in the literature. Variation in immune response to microbial challenge has also been observed within the human oral cavity. Our recent study focused on characterizing observed variations in microbially induced gingival inflammation-resulting in three distinct clinical Inflammatory Responder Types (IRTs): High-IRT, Low-IRT, and Slow-IRT. Here, we applied a high-resolution temporal multiomic analysis during microbially induced inflammation in order to characterize the effects of localized oral inflammation on distant healthy tissues in young healthy adults. Our results highlight a nonlocalized subclinical effect with alterations in proinflammatory host mediators and an ecological shift toward dysbiosis within the subgingival microbiome in an IRT-dependent manner-despite maintained oral hygiene. Our results provide mechanistic insight into how healthy tissues within humans are influenced by distant localized inflammation and may ultimately become susceptible to disease.

Salivary Biomarkers for Dental Caries Detection and Personalized Monitoring

This study investigated the potential of salivary bacterial and protein markers for evaluating the disease status in healthy individuals or patients with gingivitis or caries. Saliva samples from caries- and gingivitis-free individuals (n = 18), patients with gingivitis (n = 17), or patients with deep caries lesions (n = 38) were collected and analyzed for 44 candidate biomarkers (cytokines, chemokines, growth factors, matrix metalloproteinases, a metallopeptidase inhibitor, proteolytic enzymes, and selected oral bacteria). The resulting data were subjected to principal component analysis and used as a training set for random forest (RF) modeling. This computational analysis revealed four biomarkers (IL-4, IL-13, IL-2-RA, and eotaxin/CCL11) to be of high importance for the correct depiction of caries in 37 of 38 patients. The RF model was then used to classify 10 subjects (five caries-/gingivitis-free and five with caries), who were followed over a period of six months. The results were compared to the clinical assessments of dental specialists, revealing a high correlation between the RF prediction and the clinical classification. Due to the superior sensitivity of the RF model, there was a divergence in the prediction of two caries and four caries-/gingivitis-free subjects. These findings suggest IL-4, IL-13, IL-2-RA, and eotaxin/CCL11 as potential salivary biomarkers for identifying noninvasive caries. Furthermore, we suggest a potential association between JAK/STAT signaling and dental caries onset and progression.

Resilience of the oral microbiome

The human mouth harbors a complex microbiota, the composition of which is potentially influenced by a wide range of factors, including the intake of food and drink, the availability of endogenous nutrients, the host immune system, drug treatments, and systemic diseases. Despite these possible influences, the oral microbiota is remarkably resilient, particularly in comparison with the microbiota of the large intestine. Diet, with the exception of excessive and/or frequent consumption of fermentable carbohydrate or supplementation with nitrate, has minimal impact on the composition of the oral bacterial community. The common oral diseases dental caries and the periodontal diseases is associated with modification of the oral microbiota primarily as a result of the ecological changes induced by excessive acid production and inflammation, respectively. Systemically-administered antimicrobials have only a small effect on the composition of the oral bacterial community, and while locally delivered antimicrobials can have some clinical benefits, the biofilm lifestyle of oral bacteria lends them substantial resistance to the agents used. Saliva plays an important role in oral microbial ecology, by supplying nutrients and providing protection against colonization by nonoral organisms. Dry mouth is one condition that has a major effect on the microbiota, resulting in increased colonization by opportunistic pathogens. Some systemic diseases do affect the oral microbiome, notably diabetes, in which raised levels of glucose in saliva and tissue impact on bacterial nutrition.

Toothpastes with Enzymes Support Gum Health and Reduce Plaque Formation

Enzymes in toothpastes can support host immune responses, and thus maintain oral health. This study aimed to investigate gingival health and the plaque-reducing effects of enzyme-containing toothpastes. A laboratory study tested the antimicrobial potential of different enzyme-containing toothpaste formulations. Two promising formulations (enzyme-containing toothpastes with glucose oxidase and D-glucose with (C+) and without Citrox (C-) Citrox) were investigated in a clinical crossover trial (two slurries: sodium lauryl sulfate-containing (SLS), a toothpaste without SLS (reference), and water). Subjects (n = 20) abstained from toothbrushing for four days and rinsed with a toothpaste slurry. Bleeding on probing (BOP) and plaque indices (PI) were measured. A mixed linear model was used to statistically compare the slurries with respect to BOP and PI change. The in vitro bacterial growth-inhibiting evaluation showed the best results for SLS, followed by C+ and C-. The change in BOP and PI exhibited statistically significant differences to water rinsing (BOP; PI changes in % points (difference of the baseline and post-rinse values: water = 8.8%; 90.0%; C+ = -1.4%; 80.4%; SLS = 1.5%; 72.1%; reference = 0.8%; 77.5%; C- = -1.8%; 75.1%). All slurries exhibited anti-gingivitis and anti-plaque effects, resulting in a prophylactic benefit for limited-access regions during brushing.

Gingival inflammation influences oral health-related quality of life in individuals living in a rural area of southern Brazil

AIM

The aim of the present cross-sectional study was to evaluate whether the extent levels of gingival inflammation (GI) in whole mouth or restricted to the anterior region are independently associated with oral health-related quality of life (OHRQoL) in individuals living in a rural area of southern Brazil.

MATERIALS AND METHODS

A probability sample of 688 individuals was submitted to a full-mouth periodontal examination at six sites on each tooth. Extent levels of GI in whole mouth and restricted to anterior region were dichotomously considered when bleeding on probing (BoP) occurred at 20% or more of whole-mouth sites and at 10% or more of anterior region sites, respectively, in individuals with probing depths ≤3 mm, totalling 121 individuals analysed, aged 15-82 years. OHRQoL was assessed using the simplified version of the Oral Health Impact Profile (OHIP₁₄ ) questionnaire. Adjusted multilevel Poisson regression analysis was used with a conceptual hierarchical approach to calculate the rate ratio (RR) of OHIP₁₄ scores.

RESULTS

In the adjusted model, higher extent levels of full-mouth GI (RR = 1.23; 95% confidence interval [CI]: 1.06-1.44; p = .004) and GI restricted to the anterior region (RR = 1.29; 95% CI: 1.11-1.51; p ≤ .001) were significantly associated with poorer OHRQoL.

CONCLUSIONS

The extent of GI in whole mouth (≥20% of sites with BoP) and in the anterior region (≥10% of sites with BoP) was independently associated with OHRQoL in individuals living in a rural area.

Sex differences in the association between obesity and gingivitis among 12-year-old South Brazilian schoolchildren

OBJECTIVE

To assess the association between weight status and gingivitis in a representative sample of 12-year-old schoolchildren from South Brazil.

BACKGROUND

An association between obesity and gingivitis in children and adolescents has been observed; however, the present evidence has major limitations.

METHODS

A cross-sectional study was conducted in Porto Alegre, South Brazil, from September 2009 to December 2010 and included a representative sample of 1528 12-year-old schoolchildren attending public and private schools. Data collection included the application of a questionnaire, recording of anthropometric measures (weight and height), and clinical examination (gingival bleeding index, recorded in four sites per tooth). The outcome of the study was the prevalence of gingivitis, defined as the proportion of schoolchildren presenting ≥52% of bleeding sites (based on the median). Weight status was categorized according to body mass index into normal, overweight, or obese. The association between predictor variables and gingivitis prevalence was assessed using Poisson regression models. Unadjusted and adjusted prevalence ratios (PR) and their 95% confidence intervals (95% CI) were estimated.

RESULTS

Gingivitis prevalence was 48.7% (95% IC = 33.8-63.6) and, on average, schoolchildren presented 51.8% (95% IC = 46.2-57.5) of bleeding sites. Obese individuals had 13% higher prevalence for presenting gingivitis than did normal-weight ones (PR = 1.13, 95% CI = 1.09-1.18, P < .001). The stratified analysis showed that this association was sex-specific: Obese girls presented a greater chance of having gingivitis (adjusted PR = 1.21, 95% CI = 1.09-1.34, P < .001), but such association was not observed among boys (PR = 1.07, 95% CI = 0.95-1.20, P = .29).

CONCLUSION

This study showed sex differences in the association between obesity and gingivitis among 12-year-old South Brazilian schoolchildren.

Dental plaque-induced gingival conditions

OBJECTIVE

This review proposes revisions to the current classification system for gingival diseases and provides a rationale for how it differs from the 1999 classification system.

IMPORTANCE

Gingival inflammation in response to bacterial plaque accumulation (microbial biofilms) is considered the key risk factor for the onset of periodontitis. Thus, control of gingival inflammation is essential for the primary prevention of periodontitis.

FINDINGS

The clinical characteristics common to dental plaque-induced inflammatory gingival conditions include: a) clinical signs and symptoms of inflammation that are confined to the gingiva: b) reversibility of the inflammation by removing or disrupting the biofilm; c) the presence of a high bacterial plaque burden to initiate the inflammation; d) systemic modifying factors (e.g., hormones, systemic disorders, drugs) which can alter the severity of the plaque-induced inflammation and; e) stable (i.e., non-changing) attachment levels on a periodontium which may or may not have experienced a loss of attachment or alveolar bone. The simplified taxonomy of gingival conditions includes: 1) introduction of the term "incipient gingivitis;" 2) a description of the extent and severity of gingival inflammation; 3) a description of the extent and severity of gingival enlargement and; 4) a reduction of categories in the dental plaque-induced gingival disease taxonomy.

CONCLUSIONS

Dental plaque-induced gingival inflammation is modified by various systemic and oral factors. The appropriate intervention is crucial for the prevention of periodontitis.

Plaque-induced gingivitis: Case definition and diagnostic considerations

OBJECTIVE

Clinical gingival inflammation is a well-defined site-specific condition for which several measurement systems have been proposed and validated, and epidemiological studies consistently indicate its high prevalence globally. However, it is clear that defining and grading a gingival inflammatory condition at a site level (i.e. a "gingivitis site") is completely different from defining and grading a "gingivitis case" (GC) (i.e. a patient affected by gingivitis), and that a "gingivitis site" does not necessarily mean a "GC". The purpose of the present review is to summarize the evidence on clinical, biochemical, microbiologic, genetic markers as well as symptoms associated with plaque-induced gingivitis and to propose a set of criteria to define GC.

IMPORTANCE

A universally accepted case definition for gingivitis would provide the necessary information to enable oral health professionals to assess the effectiveness of their prevention strategies and treatment regimens; help set priorities for therapeutic actions/programs by health care providers; and undertake surveillance.

FINDINGS

Based on available methods to assess gingival inflammation, GC could be simply, objectively and accurately identified and graded using bleeding on probing score (BOP%) CONCLUSIONS: A patient with intact periodontium would be diagnosed as a GC according to a BOP score ≥ 10%, further classified as localized (BOP score ≥ 10% and ≤30%) or generalized (BOP score > 30%). The proposed classification may also apply to patients with a reduced periodontium, where a GC would characterize a patient with attachment loss and BOP score ≥ 10%, but without BOP in any site probing ≥4 mm in depth.

Hypoxia and collagen crosslinking in the healthy and affected sites of periodontitis patients

Present study suggests that diseased sites of periodontitis with stage 3 grade B and C had decreased fibroblast cell density, hypoxia-inducible factor (HIF) and vascular endothelial growth factor (VEGF) expressions while increased inflammatory cell counts compared to both healthy sites of the periodontitis patients and healthy controls. Collagen maturation enzymes also decreased in the diseased sites. Objective: The present study aimed at determining markers of hypoxia and collagen crosslinking in healthy and diseased gingiva from healthy individuals and periodontitis patients. Methods: Group-1; healthy individuals, Group-2; healthy sites of periodontitis patients-stage 3 grade B, (H-GradeB) Group-3; diseased sites of periodontitis patients-stage 3 grade B, (D-GradeB). Group-4; healthy sites of periodontitis patients-stage 3 grade C, (H-GradeC). Group-5; diseased sites of periodontitis patients-stage 3 grade C, (D-GradeC). Plaque index (PI), gingival index (GI) and clinical attachment levels (CALs) were recorded. Gingival biopsies were obtained. Fibroblast and inflammatory cells were counted. HIF-1α, prolyl hydroxylase (PH), VEGF, lysyl oxidase (LOX) and lysyl hydroxylase (LH) levels were determined via immunohistochemistry. Results: Fibroblast cell counts were lower in D-GradeC and D-GradeB than other groups. C group had highest fibroblast cell counts. Inflammatory cell counts were highest in the D-GradeC and lowest in C group. HIF-1α levels were highest in C group and decreased in diseased sites. Lowest value was observed in D-GradeC group. VEGF, PH, and LH levels were higher in the control group compared to other groups. LOX levels were similar in the groups except for D-GradeC. LOX levels were similar in the groups except for D-GradeC which is significantly lower than those of the control group and healthy sites. Conclusions: The results revealed that diseased sites of periodontitis patients had decreased fibroblast cells, HIF and VEGF expressions while increased inflammatory cells. Collagen crosslinking tend to decrease with disease regardless of stage and grade of disease.

Effect of a structured plaque control on MMP-1 and MMP-9 crevicular levels in patients with desquamative gingivitis associated with oral lichen planus

OBJECTIVES

No data are available in the literature on the extent to which the immune host-response and bacterial-elicited inflammation separately contributes to the increase in gingival crevicular fluid (GCF) levels of inflammatory biomarkers in patients affected by desquamative gingivitis (DG) secondary to oral lichen planus (OLP). The aim of this study was to investigate the effect of a structured plaque control intervention on GCF levels of MMP-1 and MMP-9 in OLP patients with DG and to compare them with those of non-OLP patients.

MATERIALS AND METHODS

The study population consisted of 18 unrelated Caucasian patients with DG, while 18 periodontally healthy subjects were recruited for the control group. Periodontal parameters and GCF biomarker amounts were evaluated at baseline and 2 months after a structured plaque control intervention, comprising professional oral hygiene sessions, manual toothbrushing, and interdental cleaning advice, only for DG patients. Determination of MMP-1 and MMP-9 levels was carried out by means of an enzyme-linked immunosorbent assay.

RESULTS

Plaque control program led to improvement in all examined clinical parameters and resulted in significant decrease in GCF total amount and concentration of MMP-1 and MMP-9 in comparison to baseline (p < 0.001). However, MMP-1 and MMP-9 levels in DG patients were still significantly higher than those in the healthy control group (p < 0.01).

CONCLUSIONS

These findings would seem to support an intrinsic upregulated expression of MMPs in DG patients that is exacerbated by bacterial plaque.

CLINICAL RELEVANCE

The present outcomes provide further scientific grounds for the importance of strict professional oral hygiene sessions in DG patients.

The subgingival periodontal microbiota of the aging mouth

Different mechanisms have been hypothesized to explain the increase in prevalence and severity of periodontitis in older adults, including shifts in the periodontal microbiota. However, the actual impact of aging on the composition of subgingival biofilms remains unclear. In the present article, we provide an overview of the composition of the subgingival biofilm in older adults and the potential effects of age on the oral microbiome. In particular, this review covers the following topics: (i) the oral microbiota of an aging mouth; (ii) the effects of age and time on the human oral microbiome; (iii) the potential impact of inflammaging and immunosenescence in the host-oral microbiota interactions; and (iv) the relationship of the aging oral microbiota and Alzheimer's disease. Finally, we present analyses of data compiled from large clinical studies that evaluated the subgingival microbiota of periodontally healthy subjects and patients with periodontitis from a wide age spectrum (20-83 years of age).

The Porphyromonas gingivalis/Host Interactome Shows Enrichment in GWASdb Genes Related to Alzheimer's Disease, Diabetes and Cardiovascular Diseases

Periodontal disease is of established etiology in which polymicrobial synergistic ecology has become dysbiotic under the influence of Porphyromonas gingivalis. Following breakdown of the host's protective oral tissue barriers, P. gingivalis migrates to developing inflammatory pathologies that associate with Alzheimer's disease (AD). Periodontal disease is a risk factor for cardiovascular disorders (CVD), type II diabetes mellitus (T2DM), AD and other chronic diseases, whilst T2DM exacerbates periodontitis. This study analyzed the relationship between the P. gingivalis/host interactome and the genes identified in genome-wide association studies (GWAS) for the aforementioned conditions using data from GWASdb (P < 1E-03) and, in some cases, from the NCBI/EBI GWAS database (P < 1E-05). Gene expression data from periodontitis or P. gingivalis microarray was compared to microarray datasets from the AD hippocampus and/or from carotid artery plaques. The results demonstrated that the host genes of the P. gingivalis interactome were significantly enriched in genes deposited in GWASdb genes related to cognitive disorders, AD and dementia, and its co-morbid conditions T2DM, obesity, and CVD. The P. gingivalis/host interactome was also enriched in GWAS genes from the more stringent NCBI-EBI database for AD, atherosclerosis and T2DM. The misregulated genes in periodontitis tissue or P. gingivalis infected macrophages also matched those in the AD hippocampus or atherosclerotic plaques. Together, these data suggest important gene/environment interactions between P. gingivalis and susceptibility genes or gene expression changes in conditions where periodontal disease is a contributory factor.

Resilience of the Oral Microbiota in Health: Mechanisms That Prevent Dysbiosis

Dental diseases are now viewed as a consequence of a deleterious shift in the balance of the normally stable resident oral microbiome. It is known that frequent carbohydrate consumption or reduced saliva flow can lead to caries, and excessive plaque accumulation increases the risk of periodontal diseases. However, when these "disease drivers" are present, while some individuals appear to be susceptible, others are more tolerant or resilient to suffering from undesirable changes in their oral microbiome. Health-maintaining mechanisms that limit the effect of disease drivers include the complex set of metabolic and functional interrelationships that develop within dental biofilms and between biofilms and the host. In contrast, "positive feedback loops" can develop within these microbial communities that disrupt resilience and provoke a large and abrupt change in function and structure of the ecosystem (a microbial "regime shift"), which promotes dysbiosis and oral disease. For instance, acidification due to carbohydrate fermentation or inflammation in response to accumulated plaque select for a cariogenic or periopathogenic microbiota, respectively, in a chain of self-reinforcing events. Conversely, in tolerant individuals, health-maintaining mechanisms, including negative feedback to the drivers, can maintain resilience and promote resistance to and recovery from disease drivers. Recently studied health-maintaining mechanisms include ammonia production, limiting a drop in pH that can lead to caries, and denitrification, which could inhibit several stages of disease-associated positive feedback loops. Omics studies comparing the microbiome of, and its interaction with, susceptible and tolerant hosts can detect markers of resilience. The neutralization or inhibition of disease drivers, together with the identification and promotion of health-promoting species and functions, for example, by pre- and probiotics, could enhance microbiome resilience and lead to new strategies to prevent disease.

Modulation of Clinical Expression of Plaque-induced Gingivitis: Effect of Incisor Crown Form

Evidence indicates that incisor crown form correlates with clinical periodontal features. It was hypothesized that incisor crown form may explain subject differences in gingivitis expression. The present experimental gingivitis study aimed to assess the effect of incisor crown form on plaque accumulation and gingival inflammation, and on individual susceptibility to plaque-induced gingivitis. Eighty-five periodontally healthy subjects were evaluated. A negative correlation was found between incisor crown width/crown length ratio and bleeding score (p = 0.045). From the 85 subjects, two groups of subjects with either ‘long-narrow’ or ‘short-wide’ incisor form were identified. The ‘long-narrow’ group had a significantly higher bleeding score than the ‘short-wide’ group (p = 0.014). No significant differences were found in the incisor crown width/crown length ratio between previously identified ‘high responder’ and ‘low responder’ subjects ( Trombelli et al., 2004a ). In conclusion, incisor crown form appears to affect the bleeding response of inflamed gingival tissues, while it exerts no influence on explaining differences in individuals’ susceptibility to plaque-induced gingivitis.

A combination of cis-2-decenoic acid and chlorhexidine removes dental plaque

OBJECTIVES

To investigate the ability of cis-2-decenoic acid (C2DA) to induce dispersion in single-species biofilms formed by Streptococcus mutans and Candida albicans, as well as to remove their bacterial-fungal dual-species biofilms when combined with low concentrations of chlorhexidine (CHX).

METHODS

For biofilm dispersal bioassays, single-species biofilms of S. mutans and C. albicans were grown on the inside surface of petri dishes, using a semi-batch culture method in which the medium was replaced every 24h for 5 days. Biofilms were then treated with very low concentrations of C2DA (100 and 310 nM) for 1h to release cells into the bulk liquid and to evaluate dispersed cell number by measuring the optical density (OD). To assess the ability of C2DA combined CHX treatments to remove tested microorganisms' dual-species biofilms, they were grown on saliva-coated hydroxyapatite (sHA) discs for 48 h and then were treated with three different concentrations of CHX (0.08%, 0.06% and 0.04%) alone or in combination with indicated concentrations of C2DA for 1 min twice daily for 3 subsequent days. Biofilms were then either subjected to the field emission scanning electron microscopy (FESEM) analysis or harvested and colony forming units (CFUs) were counted after plating on agar.

RESULTS

Treatment of pre-established biofilms with 310 nM C2DA caused an approximately two-fold increase in the number of planktonic cells in both cultures. A combination of 310 nM C2DA and 0.04% CHX resulted in significant removal (p-value <0.05) of dual-species biofilms from sHA discs surface.

CONCLUSIONS

Anti-biofilm characteristic of C2DA boosts the action of CHX even at low concentrations.

Porphyromonas gingivalis Periodontal Infection and Its Putative Links with Alzheimer's Disease

Periodontal disease (PD) and Alzheimer's disease (AD) are inflammatory conditions affecting the global adult population. In the pathogenesis of PD, subgingival complex bacterial biofilm induces inflammation that leads to connective tissue degradation and alveolar bone resorption around the teeth. In health, junctional epithelium seals the gingiva to the tooth enamel, thus preventing bacteria from entering the gingivae. Chronic PD involves major pathogens (Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia) which have an immune armoury that can circumvent host's immune surveillance to create and maintain an inflammatory mediator rich and toxic environment to grow and survive. The neurodegenerative condition, AD, is characterised by poor memory and specific hallmark proteins; periodontal pathogens are increasingly being linked with this dementing condition. It is therefore becoming important to understand associations of periodontitis with relevance to late-onset AD. The aim of this review is to discuss the relevance of finding the keystone periodontal pathogen P. gingivalis in AD brains and its plausible contribution to the aetiological hypothesis of this dementing condition.

Effect of probiotic lozenges on inflammatory reactions and oral biofilm during experimental gingivitis

AIM

Probiotic bacteria have been introduced for prevention and treatment of periodontal diseases. The aim was to assess if daily oral administration of probiotic bacteria could influence the inflammatory response and the composition of supragingival plaque in an experimental gingivitis model.

MATERIALS AND METHODS

Eighteen healthy female adults volunteered after informed consent. A double-blind randomized placebo-controlled cross-over design was used. The buccal surface of first molars was used as experimental sites. A mouth-guard covering the first premolar to second molar was used when brushing, preventing accidental cleaning during 3 weeks of plaque accumulation. Lozenges containing L. reuteri (ATCC55730 and ATCC PTA5289) or placebo were taken twice a day. During the run-in and washout periods, professional tooth cleaning was performed 5 days/week. At baseline and follow-up, plaque index, gingival index and bleeding on probing were recorded. Samples of gingival crevicular fluid (GCF) were analysed for concentration of seven inflammatory mediators. Bacterial samples were processed with checkerboard DNA/DNA-hybridization.

RESULTS

All subjects presented a local plaque accumulation and developed manifest gingivitis at the test sites during the intervention periods. The volume of GCF increased in both groups but was statistically significant only in the placebo group (p < 0.05). The concentrations of IL1-β and IL-18 increased significantly (p < 0.05), while IL-8 and MIP1-β decreased (p < 0.05). No differences were displayed between test and placebo. Likewise, the microbial composition did not differ between the groups.

CONCLUSION

Daily intake of probiotic lozenges did not seem to significantly affect the plaque accumulation, inflammatory reaction or the composition of the biofilm during experimental 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.

Time as a factor in the identification of subjects with different susceptibility to plaque-induced gingivitis

OBJECTIVES

The purpose of this study was to assess whether identification of subjects with different susceptibility to plaque-induced gingival inflammation is dependent on the length of time of de novo plaque accumulation.

METHODS

Retrospective analysis of data obtained from a recently reported randomized split-mouth localized experimental gingivitis trial involving 96 healthy non-smokers. Gingival and plaque index, gingival crevicular fluid volume (GCF), angulated bleeding score, and the derived parameter cumulative plaque exposure (CPE) were recorded at days 0, 7, 14, and 21. The primary outcome variable to express severity of inflammation was GCF and each subject was a statistical unit. Based on subject distribution of GCF-day 21 residuals after standardization for CPE-day 21, two sub-populations (upper and lower distribution quartiles) were selected. They were, respectively, defined as "high responders" (HR) (n=24) and "low responders" (LR) (n=24) and characterized by significantly different severity of gingivitis to similar amounts of plaque deposits. The same analysis was repeated at days 7 and 14. Prevalence of HR and LR was compared between days using the chi(2) [ML] test.

RESULTS

For both day 7 and day 14, the quartile distribution of LR and HR was statistically significant (p=0.02). Fifty percent of LR and 71% of HR presented a consistent level of susceptibility to plaque-induced gingival inflammation even after only 7 and/or 14 days of plaque accumulation.

CONCLUSIONS

These findings support the concept that the subject-based susceptibility to plaque-induced gingival inflammation is an individual trait, only partly related to the length of time of exposure to plaque.

Modulation of clinical expression of plaque-induced gingivitis: effects of personality traits, social support and stress

BACKGROUND

Studies have shown an association between an acute stressful event and gingivitis. However, the possible effects of personality traits associated with stress resistance/susceptibility and current level of stress on the clinical expression of plaque-induced inflammation remain to be examined. The aim of this study was to characterize the subject-based clinical behaviour of the gingiva during experimental gingivitis in relation to personality profile, psychological stress and coping behaviour.

METHODS

Ninety-six systemically and periodontally healthy subjects (mean age: 23.6+/-1.7 years), 46 males and 50 females, non-smokers, participated in a randomized, split-mouth, localized experimental gingivitis trial. Prior to the trial, subjects were asked to complete self-administered questionnaires evaluating personality traits (Hardiness scale and Courtauld Emotional Control Scale), subjective stress (Visual Analogue Scale-Total Distress), social support (Multidimensional Scale of Perceived Social Support, MSPSS) and life events (Life Experiences Survey (LES)). The influence of psychosocial factors was investigated in the overall population as well as in two sub-populations with different inflammatory response to plaque accumulation.

RESULTS

No significant relationships were found between gingival inflammation variables and psychological measures. No significant differences were detected between subjects with different susceptibilties to plaque-associated gingivitis for any considered psychological variable. A significant association between plaque variables and LES (negative) or MSPSS (positive) was found; however, the variance explained by the model was low.

CONCLUSIONS

Differences in the current level of stress and psychosocial variables indicative of stress susceptibility do not account for variability in plaque accumulation and gingival inflammation during experimental gingivitis in young adults.

Association between serum concentrations of 25-hydroxyvitamin D and gingival inflammation

BACKGROUND

Vitamin D has been shown to have immunomodulatory effects in in vitro and in animal studies. However, data from clinical studies of inflammatory diseases are scarce.

OBJECTIVE

The purpose of this study was to evaluate the association between serum concentrations of 25-hydroxyvitamin D [25(OH)D] and gingival inflammation.

DESIGN

We analyzed data from 77,503 gingival units (teeth) in 6700 never smokers aged 13 to >90 y from the third National Health and Nutrition Examination Survey. Multiple logistic regression models adjusted for subject- and site-specific covariates included age, sex, race-ethnicity, income, body mass index, diabetes, use of oral contraceptives and hormone replacement therapy among women, intake of vitamin C, missing teeth, full crown coverage, presence of calculus, frequency of dental visits, and dental examiner and survey phase. Generalized estimating equations were used to account for correlated observations within subjects.

RESULTS

Compared with sites in subjects in the lowest 25(OH)D quintile, sites in subjects in the highest 25(OH)D quintile were 20% (95% CI: 8%, 31%) less likely to bleed on gingival probing (P for trend < 0.001). The association appeared to be linear over the entire 25(OH)D range, was consistent across racial or ethnic groups, and was similar among men and women as well as among users and nonusers of vitamin and mineral supplements.

CONCLUSIONS

Vitamin D may reduce susceptibility to gingival inflammation through its antiinflammatory effects. Gingivitis may be a useful clinical model to evaluate the antiinflammatory effects of vitamin D.

Modulation of Clinical Expression of Plaque-Induced Gingivitis: Interleukin-1 Gene Cluster Polymorphisms

BACKGROUND

The purpose of the present study was to determine the association of interleukin-1 (IL-1) gene polymorphisms with clinical parameters of gingivitis in a large experimental gingivitis trial and with each of two subgroups, high responders (HR) and low responders (LR), with distinct susceptibility to gingivitis.

METHODS

Ninety-six systemically and periodontally healthy non-smokers, 46 males (mean age: 23.9+/-1.7) and 50 females (mean age: 23.3+/-1.6) were included in a randomized, split-mouth, localized 21-day experimental gingivitis trial. Plaque index (PI), gingival index (GI), gingival crevicular fluid volume (GCF), and angulated bleeding score (AngBS) were recorded. Two subgroups were defined from the total study population (HR, LR) characterized by substantially different severity of gingival inflammation despite similar plaque accumulation rate. The study population was typed for interleukin-1 alpha (IL-1A+4845), interleukin-1 beta (IL-1B+3953, IL-1B-511), and IL-1 receptor antagonist (IL-1RN, intron 2 variable number tandem repeats) gene polymorphisms. Gene variants were analyzed by amplifying the polymorphic region using polymerase chain reaction, followed by restriction-enzyme digestion and agarose gel electrophoresis.

RESULTS

Neither IL-1A+4845, IL-1B+3953, or the combined (IL-1A+4845 x 2 - IL-1B+3953 x 2) genotype was associated with clinical parameters in the overall population. IL-1RN was significantly associated with test quadrant PI (P= 0.046), GCF (P= 0.05), and GI (P= 0.018). The genotype distribution in HR and LR subjects was significantly different for IL-1RN (P= 0.045) and for IL-1B-511 (P= 0.023).

CONCLUSION

The results of the present study suggest an association between IL-1RN polymorphism and subject-based clinical behavior of the gingiva in response to de novo plaque accumulation, as well as a possible association between IL-1B-511 polymorphism and gingivitis susceptibility.

Evaluation of additional amine fluoride/stannous fluoride-containing mouthrinse during supportive therapy in patients with generalized aggressive periodontitis. A randomized, crossover, double-blind, controlled trial

OBJECTIVES

The objective of the present randomized controlled trial was to evaluate the efficacy of a mouthrinse containing a combination of AmF/SnF2 in controlling supragingival plaque accumulation and gingival inflammation during a 12-week period in patients affected by generalized aggressive periodontitis (GAP).

METHODS

Eighteen subjects, six males and 12 females, mean age: 32.2 years, were evaluated. One-half of the patients was either prescribed an AmF/SnF2-containing mouthrinse (test mouthrinse) or a control mouthrinse in addition to mechanical plaque control for 12 weeks. After a 2-week wash-out period, the patients received the alternative mouthrinse. Before and after treatment plaque index (PlI), gingival index (GI), angulated bleeding index (AngBI), tooth stain (GMSI), and tongue stain were recorded.

RESULTS

Test mouthrinse resulted in a statistically significant decrease in PlI (p = 0.029) and GI (p = 0.017). After treatment, PlI was significantly lower in test compared to control mouthrinse (p = 0.027). GMSI significantly increased post-treatment for both mouthrinse regimens (p < 0.001), a significantly higher score being observed for the test compared to control mouthrinse (p = 0.002).

CONCLUSIONS

The 12-week use of a AmF/SnF2-containing mouthrinse as an adjunct to conventional mechanical oral hygiene procedures in GAP patients was effective in controlling the amount of supragingival plaque deposits.