Influence of the Menstrual Cycle on the Oral Microbial Flora in Women: A Case-Control Study Including Men as Control Subjects

Subgingival microbial profiles in pre- and postmenopausal women: Associations with serum estradiol levels

BACKGROUND

Subgingival dental plaque is an ecosystem playing a key role in supporting both oral health and systemic health. Menopause-related changes have the potential to disrupt its balance, which is crucial to postmenopausal well-being. Our study explored how circulating estradiol levels correlate with subgingival microbial composition using checkerboard DNA-DNA hybridization in premenopausal and postmenopausal women. We also demonstrated that combining this method with 16S ribosomal RNA (rRNA) sequencing insights remains valuable for examining subgingival ecology.

METHODS

We assessed 40 bacterial species in 77 premenopausal and 81 postmenopausal women using checkerboard DNA-DNA hybridization and measured serum estradiol with enzyme-linked immunosorbent assay (ELISA). Women were categorized by subgingival dysbiosis severity using a modified Subgingival Microbial Dysbiosis Index (mSMDI). Six women from each normobiotic and dysbiotic subgroup across premenopausal and postmenopausal women underwent 16S rRNA sequencing analysis.

RESULTS

DNA checkerboard analysis revealed that most observed variability in individual bacterial proportions is associated with periodontitis. Two species, Leptotrichia buccalis and Streptococcus constellatus, exhibited differences related to estradiol levels within the premenopausal group (p = 0.055 and p = 0.009, respectively). 16S rRNA sequencing confirmed the mSMDI's validity in categorizing normobiotic and dysbiotic states. Menopausal status was not associated with a dysbiotic shift in the subgingival microbiome despite significantly more attachment loss in postmenopausal compared to premenopausal women.

CONCLUSIONS

Our results indicate that decreased estradiol levels or increased attachment loss during menopause are not associated with changes in species abundance or dysbiotic shifts in women. The mSMDI may be a useful tool for classifying subgingival ecology based on its normobiotic or dysbiotic inclination.

Oral microbiome changes associated with the menstrual cycle in healthy young adult females

The relationship between the menstrual cycle and the oral microbiome has not been clarified. The purpose of this study was to assess potential changes in the oral microbiome of healthy young adults using 16S rRNA-based sequencing. Eleven females (aged 23–36 years) with stable menstrual cycles and without any oral problems were recruited. Saliva samples were collected before brushing every morning during the menstrual period. Based on basal body temperatures, menstrual cycles were divided into four phases, namely the menstrual, follicular, early luteal, and late luteal phases. Our results showed that the follicular phase had a significantly higher abundance ratio of the Streptococcus genus than the early and late luteal phases, whereas the abundance ratios of the Prevotella 7 and Prevotella 6 genera were significantly lower in the follicular phase than those in the early and late luteal phases and that in the early luteal phase, respectively. Alpha diversity by the Simpson index was significantly lower in the follicular phase than that in the early luteal phase, and beta diversity showed significant differences among the four phases. Using the relative abundance data and copy numbers of the 16S rRNA genes in the samples, the bacterial amounts in the four phases were compared, and we observed that the follicular phase had significantly lower amounts of the Prevotella 7 and Prevotella 6 genera than the menstrual and early luteal phase, respectively. These results indicate reciprocal changes with the Streptococcus genus and Prevotella genera, particularly in the follicular phase. In the present study, we showed that the oral microbiome profiles are affected by the menstrual cycles of healthy young adult females.

Association of general health and lifestyle factors with the salivary microbiota - Lessons learned from the ADDITION-PRO cohort

INTRODUCTION

Previous research indicates that the salivary microbiota may be a biomarker of oral as well as systemic disease. However, clarifying the potential bias from general health status and lifestyle-associated factors is a prerequisite of using the salivary microbiota for screening.

MATERIALS & METHODS

ADDDITION-PRO is a nationwide Danish cohort, nested within the Danish arm of the Anglo-Danish-Dutch Study of Intensive treatment in People with Screen-Detected Diabetes in Primary Care. Saliva samples from n=746 individuals from the ADDITION-PRO cohort were characterized using 16s rRNA sequencing. Alpha- and beta diversity as well as relative abundance of genera was examined in relation to general health and lifestyle-associated variables. Permutational multivariate analysis of variance (PERMANOVA) was performed on individual variables and all variables together. Classification models were created using sparse partial-least squares discriminant analysis (sPLSDA) for variables that showed statistically significant differences based on PERMANOVA analysis (p < 0.05).

RESULTS

Glycemic status, hemoglobin-A_1c (HbA_1c) level, sex, smoking and weekly alcohol intake were found to be significantly associated with salivary microbial composition (individual variables PERMANOVA, p < 0.05). Collectively, these variables were associated with approximately 5.8% of the observed differences in the composition of the salivary microbiota. Smoking status was associated with 3.3% of observed difference, and smoking could be detected with good accuracy based on salivary microbial composition (AUC 0.95, correct classification rate 79.6%).

CONCLUSIONS

Glycemic status, HbA_1c level, sex, smoking and weekly alcohol intake were significantly associated with the composition of the salivary microbiota. Despite smoking only being associated with 3.3% of the difference in overall salivary microbial composition, it was possible to create a model for detection of smoking status with a high correct classification rate. However, the lack of information on the oral health status of participants serves as a limitation in the present study. Further studies in other cohorts are needed to validate the external validity of these findings.

Sex Steroid Hormones as a Balancing Factor in Oral Host Microbiome Interactions

Sex steroid hormones (SSH) are cholesterol-derived molecules. They are secreted into saliva and enter the oral cavity, triggering physiological responses from oral tissues, with possible clinical implications, such as gingival inflammation and bleeding. SSH and hormonal changes affect not only oral host cells but also oral microorganisms.

Historically, most research has focused on the effect of hormonal changes on specific bacteria and yeasts. Recently a broader effect of SSH on oral microorganisms was suggested. In order to assess the role of SSH in host-microbe interactions in the oral cavity, this review focuses on how and up to what extent SSH can influence the composition and behavior of the oral microbiome. The available literature was reviewed and a comprehensive hypothesis about the role of SSH in host-microbiome interactions is presented. The limited research available indicates that SSH may influence the balance between the host and its microbes in the oral cavity.

Dysbiosis of the Human Oral Microbiome During the Menstrual Cycle and Vulnerability to the External Exposures of Smoking and Dietary Sugar

Physiological hormonal fluctuations exert endogenous pressures on the structure and function of the human microbiome. As such, the menstrual cycle may selectively disrupt the homeostasis of the resident oral microbiome, thus compromising oral health. Hence, the aim of the present study was to structurally and functionally profile the salivary microbiome of 103 women in reproductive age with regular menstrual cycle, while evaluating the modifying influences of hormonal contraceptives, sex hormones, diet, and smoking. Whole saliva was sampled during the menstrual, follicular, and luteal phases (n = 309) of the cycle, and the participants reported questionnaire-based data concerning their life habits and oral or systemic health. No significant differences in alpha-diversity or phase-specific clustering of the overall microbiome were observed. Nevertheless, the salivary abundances of genera Campylobacter, Haemophilus, Prevotella, and Oribacterium varied throughout the cycle, and a higher species-richness was observed during the luteal phase. While the overall community structure maintained relatively intact, its functional properties were drastically affected. In particular, 11 functional modules were differentially abundant throughout the menstrual cycle, including pentose phosphate metabolism, and biosynthesis of cobalamin and neurotransmitter gamma-aminobutyric acid. The menstrual cycle phase, but not oral contraceptive usage, was accountable for greater variations in the metabolic pathways of the salivary microbiome. Further co-risk factor analysis demonstrated that Prevotella and Veillonella were increased in current smokers, whereas high dietary sugar consumption modified the richness and diversity of the microbiome during the cycle. This is the first large study to systematically address dysbiotic variations of the oral microbiome during the course of menstrual cycle, and document the additive effect of smoking and sugar consumption as environmental risk factors. It reveals the structural resilience and functional adaptability of the oral microbiome to the endogenous hormonal pressures of the menstrual cycle, while revealing its vulnerability to the exogenous exposures of diet and smoking.

Optimizing the quality of clinical studies on oral microbiome: A practical guide for planning, performing, and reporting

With this review, we aim to increase the quality standards for clinical studies with microbiome as an output parameter. We critically address the existing body of evidence for good quality practices in oral microbiome studies based on 16S rRNA gene amplicon sequencing. First, we discuss the usefulness of microbiome profile analyses. Is a microbiome study actually the best approach for answering the research question? This is followed by addressing the criteria for the most appropriate study design, sample size, and the necessary data (study metadata) that should be collected. Next, we evaluate the available evidence for best practices in sample collection, transport, storage, and DNA isolation. Finally, an overview of possible sequencing options (eg, 16S rRNA gene hypervariable regions, sequencing platforms), processing and data interpretation approaches, as well as requirements for meaningful data storage, sharing, and reporting are provided.

Effect of cigarette smoking on subgingival bacteria in healthy subjects and patients with chronic periodontitis

Background

Cigarette smoking is known to increase the risk of periodontal destruction and developing chronic periodontitis (CP). It is also reported to affect the subgingival bacterial profile among CP patients. However, studies on the effect of smoking on the bacterial profile among healthy subjects are still limited. Therefore, the aim of this study was to investigate the impact of smoking on the subgingival bacterial profile in both healthy adults and CP patients.

Methods

Subgingival plaque samples were collected from CP patients (30 nonsmokers and 9 smokers) and healthy subjects (37 non-smokers and 18 smokers). Genomic DNA was extracted and 25 bacterial species were detected using PCR of 16S rRNA. Comparing smokers to non-smokers from each group was conducted using chi2 and binary logistic regression analysis.

Results

After correcting for confounding factors, the odds of having Slackia exigua, Selenomonas sputigena and Campylobacter rectus was higher among healthy smokers (ORadj = 10.1, 6.62 and 5.62 respectively). While for CP group, the highest odds were observed for Treponema amylovorum, Treponema medium, Slackia exigua and Treponema vincentii (ORadj = 20.7, 7.97, 6.37 and 5.37 respectively) and the increase in Treponema amylovorum was statistically significant (p = 0.05).

Conclusion

Smoking affects the subgingival bacterial profile in healthy individuals and is responsible for the depletion of beneficial bacteria and the increase in periodontopathogenic bacteria. In the CP patient group, our study suggests that subgingival bacteria (particularly Treponema species) make a more substantial contribution in the etiology of CP among non-smokers. Further studies using a larger sample set and more sensitive and quantitative techniques (such as real -time PCR) are needed to enhance our understanding of the exact effect of smoking on subgingival biofilm.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-017-0359-4) contains supplementary material, which is available to authorized users.

Effects of Scaling and Root Planing on Gingival Status during Menstrual Cycle- A Cross-Sectional Analytical Study

INTRODUCTION

Variations in sex steroid hormones, noticeable through the menstrual cycle of women, may impact periodontal health. A relationship between female sex hormone levels and periodontal changes during puberty, pregnancy, and menopause has been reported. Little research on gingival status at different periods of menstrual cycle, but very less work has been done to observe the effect of scaling on gingival status during different periods of menstrual cycle.

MATERIALS AND METHODS

Thirty female subjects, aged 18-25 years were selected for a three month study. In Stage 1, clinical parameters {Plaque Index (PI), Gingival Index (GI), Modified Sulcular Bleeding Index (mSBI) and Probing depth (PD)} were recorded at three different time intervals {OV (Ovulation), PM (Premenstruation), M (Menstruation)} of their menstrual cycle, without scaling and polishing. In Stage 2, all clinical parameters were recorded at their subsequent menstrual cycle after scaling and polishing.

RESULTS

In interstage analysis, OV 1 > OV 2, PM 1 > PM 2 and M 1> M 2. In intrastage analysis, for PI, mean difference between all values was not statistically significant. For mSBI, PM 1 > OV 1 > M 1, also PM 2 > OV 2 > M 2. For GI, PM 1 > OV 1 > M 1, also PM 2 > OV 2 > M 2. For PD, mean difference was not statistically significant.

CONCLUSION

Ovarian hormones influence gingival status of females, with an increase observed primarily during PM and OV phases of menstrual cycle. Scaling leads to a subsequent decrease in gingival inflammation.

Association between Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in subgingival plaque and clinical parameters, in Argentine patients with aggressive periodontitis

BACKGROUND

Aggregatibacter actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) have been associated with aggressive (AgP) and chronic periodontitis.

OBJECTIVE

The aim of this study was to evaluate the levels of Aa and Pg in gingival crevicular fluid (GCF) of patients with AgP and its relation with clinical parameters.

DESIGN

Sixteen females and fourteen males with clinical diagnosis of AgP aged 17-23 years and their match's controls, were included in this study. Clinical recording concerning probing pocket depth, clinical attachment level, plaque index and gingival bleeding index were performed at baseline, 30 and 60 days after baseline. After clinical examination GCF samples were analyzed for Aa and Pg with a real-time polymerase chain reaction technique. Patients group was treated with a combined of mechanical and oral antibiotic therapy (doxycycline 100 mg/day, during 21 days). A multivariate analysis was used to determine the relationship between Aa and Pg counts with clinical parameters.

RESULTS

GCF from all subjects was positive for Aa and PG. In controls Pg concentration was higher than Aa (Pg: 42,420 ± 3,034 copies/ml; Aa: 66.6 ± 5.4 copies/ml p < 0.001) while in patients both microbes showed the same concentration (Aa: 559,878 ± 39,698 Pg: 572,321 ± 58,752). A significant and positive correlation was observed between counts of Aa and Pg (R square: 0.7965, p < 0.0001). Female showed more counts/ml. Aa might be closely associated with clinical parameters while Pg did not. At 30 and 60 days Aa counts in patients were similar to controls while Pg counts were equal to baseline. However, in spite of Pg presence a clinical improvement was observed in all patients.

CONCLUSIONS

In our population the presence of Aa may be associated with AgP while Pg may be in GCF as an opportunistic pathogen which might caused disease when the ecological balance was favorable.

Effect of menopause on women's periodontium

Steroid sex hormones have a significant effect on different organ systems. As far as gingiva is concerned, they can influence the cellular proliferation, differentiation and growth of keratinocytes and fibroblasts. Estrogen is mainly responsible for alterations in blood vessels and progesterone stimulates the production of inflammatory mediators. In addition, some micro-organisms found in the human mouth synthesize enzymes needed for steroid synthesis and catabolism. In women, during puberty, ovulation, pregnancy, and menopause, there is an increase in the production of sex steroid hormones which results in increased gingival inflammation, characterized by gingival enlargement, increased gingival bleeding, and cervicular fluid flow and microbial changes.

A molecular survey of S. mutans and P. gingivalis oral microbial burden in human saliva using relative endpoint polymerase chain reaction (RE-PCR) within the population of a Nevada dental school revealed disparities among minorities

Background

The University of Nevada, Las Vegas School of Dental Medicine recently opened an orthodontic treatment clinic to address the needs of the racially and ethnically diverse population of Southern Nevada, primarily focusing on the treatment and care of low-income and minority patients. Although orthodontic treatment and therapy has been shown to induce changes in the oral cavity, much of this evidence was collected from traditional White, teenage orthodontic clinic populations. The primary goal of this study was to describe the microbial burden of the cariogenic and periodontal pathogens, Streptococcus mutans and Porphyromonas gingivalis within the UNLV-SDM patient population.

Methods

Representative saliva samples were collected from healthy adult patients for DNA isolation. Relative endpoint polymerase chain reaction (RE-PCR) was performed to ascertain the presence and relative microbial burden of these oral pathogens.

Results

Nearly one quarter (13/56) or 23.3% of these patients had elevated levels of S. mutans, while (10/56) and 17.8% of these samples were found to have elevated levels of P. gingivalis, - with (90%) of P. gingivalis-positive samples from minority patients (X² = 17.921, d.f. = 1; p < 0.0001).

Conclusions

These findings of elevated P. gingivalis levels, primarily among minority patients, may suggest underlying oral health practices contributing to adverse oral health conditions within this population. Oral health knowledge and practices among minority patients may be strongly influenced by other factors, including education and socioeconomic status, suggesting additional research may be needed to accurately determine the most appropriate standards for care and oral health education within this patient population.

The influence of sex hormones on proinflammatory cytokines in gingiva of periodontally healthy premenopausal women

BACKGROUND AND OBJECTIVE

The aim of this work was to investigate any correlation between the fluctuation of levels of specific proinflammatory cytokines in gingival crevicular fluid and the fluctuation of sex hormones in peripheral blood at ovulation and progesterone peak.

MATERIAL AND METHODS

Eighteen premenopausal women with normal and consistent menstrual cycles and healthy periodontium were included in this study. The exclusion criteria were as follows: (i) pregnancy; (ii) use of oral contraceptives; (iii) metabolic or systemic disease that might affect the periodontium; (iv) use of antimicrobial or nonsteroidal anti-inflammatory drugs during the past 6 mo; and (v) smoking. The measurements were performed at two specific time points for each participant [(i) on the day of ovulation; and (ii) on the day of the progesterone peak) and included the following: (i) plaque index; (ii) bleeding on probing; and (iii) the gingival crevicular fluid levels of interleukin (IL)-1β, IL-6, IL-8 and tumor necrosis factor-α (TNF-α).

RESULTS

During the menstrual cycle, plaque index values remained unchanged (0.71 ± 0.07 at ovulation; 0.73 ± 0.08 at progesterone peak; p > 0.05), as did bleeding on probing (0.35 ± 0.07 at ovulation; 0.41 ± 0.07 at progesterone peak; p > 0.05). At ovulation, mean gingival crevicular fluid levels were as follows: IL-1β, 13.3 pg/sample; IL-6, 5.9 pg/sample; IL-8, 18.7 pg/sample; and TNF-α, 25.9 pg/sample. The corresponding values at progesterone peak were as follows: 14.1, 10.1, 19.5 and 26.3 pg/sample. Only IL-6 gingival crevicular fluid levels were significantly different between ovulation and progesterone peak (p < 0.05). This could reflect sensitivity to subclinical amounts of plaque and biofilm constituents.

CONCLUSION

The subclinical increase of IL-6 at progesterone peak is not accompanied by clinical changes in the periodontium.

The influence of sex steroid hormones on gingiva of women

Steroid sex hormones have a significant effect on different organ systems. As far as gingiva are concerned, they can influence the cellular proliferation, differentiation and growth of keratinocytes and fibroblasts. Estrogen is mainly responsible for alterations in blood vessels and progesterone stimulates the production of inflammatory mediators. In addition, some micro-organisms found in the human mouth synthesize enzymes needed for steroid synthesis and catabolism. In women, during puberty, ovulation and pregnancy, there is an increase in the production of sex steroid hormones which results in increased gingival inflammation, characterized by gingival enlargement, increased gingival bleeding and crevicular fluid flow and microbial changes.