Aging and its Impact on Innate Immunity and Inflammation: Implications for Periodontitis

The Role of Senescence in Experimental Periodontitis at the Causal Level: An in Vivo Study

The occurrence and severity of periodontitis (PD) tend to increase with age, and yet the underlying mechanisms remain unclear. Immune senescence is known to be triggered in mice and humans as they age. Experimental PD in mice has been shown to induce senescence biomarkers p16 INK4a and p21, dysfunction of antigen-presenting cells (APCs), and activation of the senescence-associated secretory phenotype (SASP). However, the causal links of senescence to experimental PD are not yet established. This study aims to elucidate the role of senescence in experimental PD at a causal level. The P16-3MR mouse model harbors the p16INK4a (Cdkn2a) promoter, driving in vivo expression of synthetic Renilla luciferase, monomeric red fluorescent protein (mRFP), and herpes simplex virus-1 thymidine kinase (HSV-TK). This facilitates in vivo identification of p16 INK4a activation at the cellular level and the consequences of selective elimination of p16INK4a-positive cells by ganciclovir (GCV) treatment. Mice were treated with/without GCV for two weeks during ligature-induced PD. In vivo bioluminescence imaging quantified p16INK4a activation, while Western blot and immunofluorescence analyses assessed key senescence and inflammatory markers (p16, p21, p53, Cyclin D1, p-H2A.X, IL17, and IL1β). Alveolar bone volume was analyzed by micro-CT and histomorphometry. Our findings demonstrate that clearance of senescent cells in mice subjected to experimental PD alleviates inflammation and mitigates bone loss. These results suggest a causal role for senescence in PD pathology, raising the future prospect of senolytic agents for therapeutic intervention in PD.

The impact of aging on neutrophil functions and the contribution to periodontitis

The increasing aging population and aging-associated diseases have become a global issue for decades. People over 65 show an increased prevalence and greater severity of periodontitis, which poses threats to overall health. Studies have demonstrated a significant association between aging and the dysfunction of neutrophils, critical cells in the early stages of periodontitis, and their crosstalk with macrophages and T and B lymphocytes to establish the periodontal lesion. Neutrophils differentiate and mature in the bone marrow before entering the circulation; during an infection, they are recruited to infected tissues guided by the signal from chemokines and cytokines to eliminate invading pathogens. Neutrophils are crucial in maintaining a balanced response between host and microbes to prevent periodontal diseases in periodontal tissues. The impacts of aging on neutrophils' chemotaxis, anti-microbial function, cell activation, and lifespan result in impaired neutrophil functions and excessive neutrophil activation, which could influence periodontitis course. We summarize the roles of neutrophils in periodontal diseases and the aging-related impacts on neutrophil functional responses. We also explore the underlying mechanisms that can contribute to periodontitis manifestation in aging. This review could help us better understand the pathogenesis of periodontitis, which could offer novel therapeutic targets for periodontitis.

Serum Nutrients, Periodontitis and Biological Ageing

INTRODUCTION

Telomeres are nucleotide sequences found at the end of chromosomes, and their shortening is associated with chronological and biological ageing, oxidative stress and malnutrition. Shorter telomeres have been shown to be associated with periodontitis. Dietary nutrients are also influential factors in the aetiology and progression of periodontitis and other chronic inflammatory diseases. We tested the hypothesis that blood serum levels of folate, vitamin D, vitamin E, cis-β-carotene and/or β-cryptoxanthin are associated with telomere lengths and periodontitis and that these relationships are modified by factors that also affect periodontitis (e.g., age, sex, smoking, race/ethnicity).

METHODS

Laboratory and demographic data collected by the NHANES 1999-2002 survey of 10,793 study participants were analysed. The data included age (binned every 10 years starting at age 30), race/ethnicity (White, Black, Hispanic), sex (male, female), periodontitis (none/mild, moderate/severe), vitamin levels (low, medium, high), telomere lengths (base pairs) and smoking (yes, no). Statistical analyses were performed with ANOVA tests.

RESULTS

Periodontitis was significantly associated with vitamin D, vitamin E and cis-β-carotene. Telomere length was significantly associated with vitamin E and cis-β-carotene. There were statistically significant interactions between the following vitamins and covariates on telomere length: folate and sex, vitamin D and periodontitis, vitamin D and race/ethnicity and vitamin E and sex.

CONCLUSIONS

Certain blood nutrients may disrupt biological ageing, with periodontitis as a co-morbidity. Some of these relationships are modified by demographic variables such as sex and race/ethnicity.

Procyanidin B2 targeted CCR7 expression to inhibit the senescence-associated secretory phenotype through the NF-κB pathway to promote osteogenic differentiation of periodontal ligament stem cells in periodontitis

Periodontitis is recognized as a chronic inflammatory disease, with aging emerging as a significant risk factor. Cellular senescence plays a crucial role in the biological process of aging. The senescence-associated secretory phenotype (SASP) is characterized by a series of pro-inflammatory factors, chemokines, and proteases, which are hallmark characteristics of senescent cells. These factors collectively alter the local environment, impacting the function of periodontal ligament stem cells (PDLSCs). Procyanidin B2 (PB2), the main dimer of oligomeric procyanidins, possesses antioxidant, anti-inflammatory, and anti-cancer properties. The molecular mechanisms through which PB2 exerts its protective effects against periodontitis remain incompletely understood. Therefore, this research aimed to investigate the effects and underlying mechanisms of PB2 on the osteogenic differentiation of PDLSCs within an inflammatory environment. To simulate a chronic inflammatory condition, PDLSCs were stimulated with Porphyromonas gingivalis Lipopolysaccharide (Pg. LPS). The findings indicated that PB2 significantly alleviated the inflammatory responses, enhanced the activity of antioxidant enzymes, and upregulated the osteogenic differentiation of PDLSCs stimulated by Pg. LPS. RNA sequencing (RNA-Seq) revealed that Pg. LPS influenced the cell cycle, cellular senescence, and NF-κB signaling pathways. In contrast, PB2 treatment reduced the number of senescent cells and diminished the expression of senescence-associated proteins and genes. Western blot analysis verified that PB2 also decreased the levels of CCR7 and suppressed the NF-κB signaling pathways. In conclusion, PB2 targeted CCR7 expression to inhibit the SASP through NF-κB signaling pathway, demonstrating its anti-inflammatory and osteogenic properties, positioning PB2 as a promising therapeutic option for the adjuvant treatment of periodontitis.

The Role of Interleukin-8 in the Estimation of Responsiveness to Steps 1 and 2 of Periodontal Therapy

OBJECTIVE

To investigate the association between interleukin-8 (IL-8) levels in gingival crevicular fluid (GCF) and total oral fluid (TOF) and the responsiveness to steps 1 and 2 of periodontal therapy.

MATERIALS AND METHODS

One-hundred and fifty-nine patients affected by periodontitis received steps 1 and 2 of periodontal therapy. At baseline, TOF and GCF samples were collected and analysed for IL-8 (Il-8TOF/IL-8GCF) using flow cytometry. Therapy outcomes were relative proportions of residual periodontal pockets (PPD%), pocket closure (PC) rates and pocket probing depth (PPD) reductions; these were associated with IL-8TOF/IL-8GCF.

RESULTS

High IL-8TOF was significantly associated with higher residual PPD% (p = 0.044) and lower PPD reduction compared to low IL-8TOF (high 0.79 ± 1.20 mm vs. low 1.20 ± 1.20 mm, p < 0.001) in non-smokers, while in smokers high IL-8GCF was related to lower PPD reduction (high 0.62 ± 1.22 mm vs. low 0.84 ± 1.12 mm, p = 0.009). Furthermore, high baseline IL-8TOF was significantly associated with poorer PC rates compared to medium and low concentrations in both non-smokers (high 41% vs. medium 55% vs. low 58%, p < 0.001) and smokers (high 34% vs. medium 44% vs. low 46%, p < 0.001).

CONCLUSION

High IL-8 concentrations at baseline had a significant impact on residual PPD%, PC rates and PPD reduction. The findings suggest that, especially in non-smokers, baseline IL-8 levels collected from the TOF could serve as a component in the estimation of responsiveness to steps 1 and 2 of periodontal therapy.

Peptidyl arginine deiminase-4 inhibitor ameliorates pulmonary fibrosis through positive regulation of developmental endothelial locus-1

Recurring lung injury, chronic inflammation, aberrant tissue repair and impaired tissue remodelling contribute to the pathogenesis of pulmonary fibrosis (PF). Neutrophil extracellular traps (NETs) are released by activated neutrophils to trap, immobilise and kill invading pathogen and is facilitated by peptidyl arginine deiminase-4 (PAD-4). Dysregulated NETs release and abnormal PAD-4 activation plays a crucial role in activating pro-fibrotic events in PF. Developmental endothelial locus-1 (Del-1), expressed by the endothelial cells of lungs and brain acts as an endogenous inhibitor of inflammation and fibrosis. We have hypothesised that PAD-4 inhibitor exerts anti-inflammatory and anti-fibrotic effects in mice model of PF. We have also hypothesised by PAD-4 regulated the transcription of Del-1 through co-repression and its inhibition potentiates anti-fibrotic effects of Del-1. In our study, the PAD-4 inhibitor chloro-amidine (CLA) demonstrated anti-NETotic and anti-inflammatory effects in vitro in differentiated HL-60 cells. In a bleomycin-induced PF mice model, CLA administration in two doses (3 mg/kg, I.P and 10 mg/kg, I.P) improved lung function, normalized bronchoalveolar lavage fluid parameters, and attenuated fibrotic events, including markers of extracellular matrix and epithelial-mesenchymal transition. Histological analyses confirmed the restoration of lung architecture and collagen deposition with CLA treatment. ELISA, IHC, IF, RT-PCR, and immunoblot analysis supported the anti-NETotic effects of CLA. Furthermore, BLM-induced PF reduced Del-1 and p53 expression, which was normalized by CLA treatment. These findings suggest that inhibition of PAD-4 results in amelioration of PF in animal model and may involve modulation of Del-1 and p53 pathways, warranting further investigation.

Age-dependent prevalence of malocclusions requiring treatment according to the KIG classification : A multipart cross-sectional study over a 10-year period from the district of Viersen/North Rhine

BACKGROUND AND AIM

Patients with statutory health insurance (SHI) in Germany must undergo an assessment of orthodontic treatment need using the "Kieferorthopädische Indikationsgruppen" (KIG; orthodontic indication groups) classification system since 2002. A treatment need only exists if anomalies of a certain degree of severity are present. The aim of this study was to evaluate the age-dependent prevalence and percentage distribution of KIG grades requiring treatment in patients with SHI before the age of 18 over a 10-year period.

PATIENTS AND METHODS

Between 2012 and 2021, treatment indication existed for 1951 (1025 female, 926 male) out of 2288 patients with SHI in the cohort of this study before the age of 18 according to current SHI guidelines. The KIG classification was based on the highest existing KIG grade. There were no multiple classifications. The patient cohort was divided into three patient groups (PG) according to chronological age for analysis: PG 1 < 10 years of age (early treatment), PG 2 10 to < 13 years of age (main treatment) and PG 3 13 to < 18 years of age (late treatment).

RESULTS

In PG 1 (454 patients), the KIG classifications D (26.5%), K (25.5%), M (19.4%), and P (18.0%) dominated. In PG 2 (998 patients), classifications D (33.2%), predominated, whereas K (7.5%) and M (5.9%) rarely occurred. The classifications E (12.6%) and P (13.3%) appeared quite frequently. Transverse deviations occurred only about half as often in PG 2 as in PG 1 and PG 3. In PG 3 (499 patients), the classification E (17.6%) was particularly common, while P (2.6%) was rare. The proportion of KIG grades 5 decreased depending on age: 19% in PG 1, 13.5% in PG 2, 10.4% in PG 3. The prevalence of sagittal classifications was highest in all age groups (45.9% in PG 1, 39.1% in PG 2, 31.5% in PG 3).

CONCLUSIONS

The distribution of KIG classifications requiring treatment was not homogeneous, but age dependent. The differences were particularly evident in the early treatment group and may be due to the limited applicability of the KIG classification system in patients before late mixed dentition. With increasing age at initial examination, the prevalence of sagittal classifications decreased, while that of vertical classifications increased. Still, the sagittal classifications D and M occurred most frequently in all age groups. The KIG classification D was always the most common in all patients until the age of 18.

Periodontal disease: A systemic condition

For decades, periodontitis has been considered to be a local inflammatory disease of the periodontal tissues in the oral cavity. Initially, associations of periodontitis with a multitude of noncommunicable diseases were each studied separately, and relationships were shown. The associations of periodontitis with morbidities, such as cardiovascular diseases, rheumatoid arthritis, diabetes mellitus, respiratory diseases, have been demonstrated. As most such studies were cross-sectional in nature, questions about causality cannot be univocally answered. And periodontitis as an independent risk factor for one systemic disease, becomes even more difficult to assess since recently periodontitis has also been associated with multimorbidity. Periodontitis and many systemic diseases share environmental, lifestyle and genetic risk factors, and share immunopathology. Moreover, suffering from one common noncommunicable disease may increase the susceptibility for another such chronic disease; the systemic effects of one condition may be one of various risk factors for another such disease. The overarching effect of any systemic disease is it causing a pro-inflammatory state in the individual; this has also been shown for periodontitis. Moreover, in periodontitis a prothrombotic state and elevated immunological activity have been shown. As such, when we consider periodontal disease as another systemic disease, it can affect the susceptibility and progression of other systemic diseases, and importantly, vice versa. And with this, it is not surprising that periodontitis is associated with a variety of other noncommunicable diseases. The medical definition of a systemic disease includes diseases that affect different organs and systems. Thus, the aim of this opinion paper is to propose that periodontitis should be considered a systemic disease in its own right and that it affects the individual's systemic condition and wellbeing. The dental and medical profession and researchers alike, should adapt this paradigm shift, advancing periodontal disease out of its isolated anatomical location into the total of chronic noncommunicable diseases, being for some conditions a comorbid disease and, vice versa, comorbidities can affect initiation and progression of periodontal disease.

Healing sequelae following tooth extraction and dental implant placement in an aged, ovariectomy model

At present, a lack of consensus exists regarding the clinical impact of osteoporosis on alveolar bone metabolism during implant osseointegration. While limited preclinical and clinical evidence demonstrates a negative influence of osteoporosis on dental extraction socket healing, no preclinical studies offer data on the results of implant placement in 6-mo-old, ovariectomized (OVX) Sprague-Dawley rats. This study aimed to investigate the outcomes of dental tooth extraction socket healing and implant placement in a rodent model of osteoporosis following daily vehicle (VEH) or abaloparatide (ABL) administration. Micro-CT and histologic analysis demonstrated signs of delayed wound healing, consistent with alveolar osteitis in extraction sockets following 42 d of healing in both the VEH and ABL groups. In a semiquantitative histological analysis, the OVX-ABL group demonstrated a tendency for improved socket regeneration with a 3-fold greater rate for moderate socket healing when compared to the OVX-VEH group (43% vs 14%), however, this finding was not statistically significant (p=.11). No significant differences were observed between vehicle and test groups in terms of implant outcomes (BMD and bone volume/total volume) at 14- and 21-d post-implant placement. Abaloparatide (ABL) significantly increased BMD of the femoral shaft and intact maxillary alveolar bone sites in OVX animals, demonstrating the therapeutic potential for oral hard tissue regeneration. The present model involving estrogen-deficiency-induced bone loss demonstrated an impaired healing response to dental extraction and implant installation.

In silico analysis of DEL-1 and inflammation-related genes in lung squamous cell carcinoma

AIM

Twenty to thirty percent of non-small cell lung cancers (NSCLC) are caused by lung squamous cell carcinoma (LUSC), especially in smokers and there has been limited study previously evaluating the situation in terms of the genome and gene expression profile, which demonstrates the relationship among DEL-1, leucocyte recruitment, and pro-inflammatory cytokines in LUSC.

MATERIAL AND METHODS

In the current study, the m-RNA expression patterns and mutation profiles of our target genes, such as, pro-inflammatory cytokines, chemoattractant molecules, and DEL-1 genes, in 511 LUSC patients. To find the harmful mutations, the PolyPhen-2 and SNAP programs were employed. Not only gene expression was detected, but also survival analysis and correlation between DEL-1 and other target genes' expression levels were explored too.

RESULTS

Target genes such as, DEL-1, TNF, IL-18, IL-1, CXCL8, CXCL13, and IL-6 were found to have a total genetic anomaly carrying rate of 16.4%. Seven mutations were found, and two of those mutations have a pathogenic aspect. Deep deletion and gene amplification of the genetic anomalies were also observed. According to gene expression analysis results in the LUSC patient group; DEL-1 and IL-6 levels were significantly lower than those of the control group, whereas the CXCL13 level was found to be higher.

CONCLUSION

Findings of the current study revealed that, there is a significant role of DEL-1 in LUSC pathogenesis. Since present study is an in silico-centered study, this approach can give more insight on experimental studies. These events may support that one of the cancer improvement mechanisms depending on DEL-1 gene at the molecular level.

Periodontal disease as a model to study chronic inflammation in aging

Periodontal disease is a chronic inflammatory condition that results in the destruction of the teeth supporting tissues, eventually leading to the loss of teeth and reduced quality of life. In severe cases, periodontal disease can limit proper nutritional intake, cause acute pain and infection, and cause a withdrawal from social situations due to esthetic and phonetic concerns. Similar to other chronic inflammatory conditions, periodontal disease increases in prevalence with age. Research into what drives periodontal disease pathogenesis in older adults is contributing to our general understanding of age-related chronic inflammation. This review will present periodontal disease as an age-related chronic inflammatory disease and as an effective geroscience model to study mechanisms of age-related inflammatory dysregulation. The current understanding of the cellular and molecular mechanisms that drive inflammatory dysregulation as a function of age will be discussed with a focus on the major pathogenic immune cells in periodontal disease, which include neutrophils, macrophages, and T cells. Research in the aging biology field has shown that the age-related changes in these immune cells result in the cells becoming less effective in the clearance of microbial pathogens, expansion of pathogenic subpopulations, or an increase in pro-inflammatory cytokine secretions. Such changes can be pathogenic and contribute to inflammatory dysregulation that is associated with a myriad of age-related disease including periodontal disease. An improved understanding is needed to develop better interventions that target the molecules or pathways that are perturbed with age in order to improve treatment of chronic inflammatory conditions, including periodontal disease, in older adult populations.

CXCR4-mediated neutrophil dynamics in periodontitis

BACKGROUND AND OBJECTIVE

Periodontitis is a common oral disease closely related to immune response and this study is aimed to identify the key immune-related pathogenic genes and analyze the infiltration and function of immune cells in the disease using bioinformatics methods.

METHODS

Transcriptome datasets and single-cell RNA sequencing (scRNA-seq) datasets were downloaded from the GEO database. We utilized weighted correlation network analysis and least absolute selection and shrinkage operator, protein-protein interaction network construction to screen out key pathogenic genes as well as conducted the cell-type identification by estimating relative subsets of RNA transcripts algorithm to analyze and characterize immune cell types in periodontal tissues. In addition to bioinformatics validations, clinical and cell samples were collected and mouse periodontitis models were constructed to validate the important role of key genes in periodontitis.

RESULTS

Bioinformatics analysis pointed out the positive correlation between CXCR4 expression and periodontitis, and revealed the increased infiltration of neutrophils in periodontal inflammatory. Similar results were obtained from clinical samples and animal models. In addition, the clustering and functional enrichment results based on CXCR4 expression levels included activation of immune response and cell migration, implying the possible function of CXCR4 on regulating neutrophil dynamics, which might contribute to periodontitis. Subsequent validation experiments confirmed that the increased expression of CXCR4 in neutrophils under periodontitis, where cell migration-related pathways also were activated.

CONCLUSION

CXCR4 could be the key pathogenic gene of periodontitis and CXCR4/CXCL12 signal axial might contribute to the development of periodontitis by mediating neutrophil dynamics, suggesting that CXCR4 could be a potential target to help identify novel strategies for the clinical diagnosis and treatment of periodontitis.

Clonal hematopoiesis driven by mutated DNMT3A promotes inflammatory bone loss

Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.

Interplay between diabetes mellitus and periodontal/pulpal-periapical diseases

This longevity of life expectancy has indirectly led to an increase in the number of chronic diseases such as periodontitis, apical periodontitis (AP), and diabetes mellitus (DM) in the aging society, thus affecting people's quality of life. There is an interaction between periodontitis/AP and DM with a two-way relationship. Although type 1 and 2 diabetes (T1DM, T2DM) have different etiologies, glycemic control may affect the infection, inflammation and tissue healing of periodontitis and AP. Non-surgical periodontal treatment may influence the glycemic control as shown by decrease of HbA1c level in T2DM patient. However, the effect of periodontal treatment on glycemic control in T1DM and root canal treatment/apical surgery on T1DM and T2DM patients awaits investigation. DM may affect the periodontal and periapical tissues possibly via altered oral microbiota, impairment of neutrophils' activity and host immune responses and cytokine production, induction of oxidative stress etc. While periodontitis associated systemic inflammation and hyperlipidemia is suggested to contribute to the control of T2DM, more intricate studies are necessary to clarify the detailed mechanisms. The interactions between DM (T1DM and T2DM) and periodontitis and AP are therefore reviewed to provide a basis for the treatment of subsequent patients with pulpal/periodontal disease and diabetes. A two-pronged approach of medical and dental treatment is needed for the management of these patients, with emphasis on blood glucose control and improving oral hygiene and periodontal maintenance care, to ensure the best treatment outcome.

Association between weight-adjusted-waist index and periodontitis risk: A cross-sectional study

BACKGROUND

There may be an association between obesity and periodontitis, yet no studies have investigated the correlation between the new obesity indicator, the weight-adjusted-waist Index (WWI), and periodontitis.

OBJECTIVE

This study aims to investigate the association between the novel obesity index, weight-adjusted-waist index, and periodontitis.

SUBJECTS AND METHODS

WWI was utilized to assess obesity, through measuring waist circumference (WC) and body weight. We analyzed cross-sectional NHANES data from 2009 to 2014 (1) using multivariate logistic regression to explore WWI's association with moderate/severe periodontitis; (2) conducting subgroup analyses and interaction tests; and (3) fitting smoothed curves to the age-stratified logistic regression model.

RESULTS

The study involved 11,256 individuals, with 48.55% having moderate/severe periodontitis. Upon adjusting for all relevant variables, a significant correlation between WWI and moderate/severe periodontitis was observed (OR = 1.08, 95% CI: 1.01-1.17). Compared to the lowest quartile of WWI, there was a significant increase in the likelihood of moderate/severe periodontitis in Quartile 2 (OR = 1.21, 95% CI: 1.06-1.39) and Quartile 3 (OR = 1.23, 95% CI: 1.07-1.42). Subgroup analyses for gender, age, education, smoking, and diabetes highlighted a positive association between WWI and moderate/severe periodontitis in all subgroups, except for the diabetic population and individuals aged 65 years and older.

CONCLUSION

The analysis revealed a positive correlation between WWI, a novel obesity index, and moderate/severe periodontitis prevalence through diverse modeling approaches.

Global trends in research on aging associated with periodontitis from 2002 to 2023: a bibliometric analysis

Background

Aging has been implicated in many chronic inflammatory diseases, including periodontitis. Periodontitis is an inflammatory disease caused by long-term irritation of the periodontal tissues by the plaque biofilm on the surface of the teeth. However, only a few bibliometric analyses have systematically studied this field to date. This work sought to visualize research hot spots and trends in aging associated with periodontitis from 2002 to 2023 through bibliometric approaches.

Methods

Graphpad prism v8.0.2 was used to analyse and plot annual papers, national publication trends and national publication heat maps. In addition, CtieSpace (6.1.6R (64-bit) Advanced Edition) and VOSviewer (version 1.6.18) were used to analyse these data and visualize the scientific knowledge graph.

Results

The number of documents related to aging associated with periodontitis has steadily increased over 21 years. With six of the top ten institutions in terms of publications coming from the US, the US is a major driver of research in this area. journal of periodontology is the most published journal in the field. Tonetti MS is the most prolific authors and co-cited authors in the field. Journal of Periodontology and Journal of Clinical Periodontology are the most popular journals in the field with the largest literature. Periodontitis, Alzheimer's disease, and peri-implantitis are current hot topics and trends in the field. Inflammation, biomarkers, oxidative stress cytokines are current research hotspots in this field.

Conclusion

Our research found that global publications regarding research on aging associated with periodontitis increased dramatically and were expected to continue increasing. Inflammation and aging, and the relationship between periodontitis and systemic diseases, are topics worthy of attention.

A retrospective analysis of the role of age and sex in outcomes of non-surgical periodontal therapy at a single academic dental center

The present study examined the role of age and sex in the outcomes of non-surgical periodontal therapy (NSPT). De-identified demographic and periodontal characteristics of patients who presented for baseline periodontal evaluation, NSPT, and periodontal re-evaluation were abstracted from electronic health records. Independent associations of age and sex with severe periodontitis defined as ≥ 5 mm clinical attachment loss (CAL) and ≥ 6 mm probing depth (PD) were determined using multinomial logistic regression. The null hypothesis was rejected at α < 0.05. A total of 2866 eligible subjects were included in the analysis. Significantly lower odds of CAL ≤ 4 mm than CAL ≥ 5 mm (reference) were observed in adults aged 35-64 (odds ratio, OR, 0.19; 95% confidence interval, CI 0.13, 0.29) and ≥ 65 years (OR 0.13; 95% CI 0.07, 0.25) compared to those aged 18-34 years. Odds of PD < 4 mm versus PD ≥ 6 mm (reference) were lower in adults aged 35-64 years than those aged 18-34 years (OR 0.71; 95% CI 0.55, 0.90) and higher in females compared to males (OR 1.67; 95% CI 1.14, 2.44). These results suggest more compromised post-NSPT outcomes in older adults and males compared to the respective populations and highlight the need for personalized therapeutic strategies in these populations.

Prevalence of malocclusions requiring treatment according to the KIG classification : A multipart cross-sectional study over a 20-year period in the district of Viersen/North Rhine

BACKGROUND AND AIM

In Germany, the reimbursement of orthodontic treatment costs within the framework of the statutory health insurance (GKV) was restricted on 01 January 2002 by the introduction of the orthodontic indication groups (KIG). The aim of this study was to evaluate the prevalence of findings requiring treatment in a specialist practice over a 20-year period. The results were then compared with data from existing older studies.

PATIENTS AND METHODS

The distribution of treatment-eligible KIG (KIG classifications grades 3-5) among patients with statutory health insurance in an orthodontic practice in North Rhine was determined over a 20-year period (2002-2021) after the introduction of the KIG system. This period was additionally scrutinized in four 5‑year periods according to the operating cycles of the practice. Findings were classified into the highest of 19 possible KIG treatment needs levels. Multiple classifications were not made.

RESULTS

Orthodontic treatment was indicated in a total of 4537 (2393 female, 2144 male) patients according to current statutory health insurance guidelines. The KIG classification "D" (increased overjet) was the most frequent within the observed 20 years with 24.3%. Among 11 KIG classifications, 86.1% of the 6 most frequent and 13.9% of the 5 rarest findings were observed constantly over all periods. Of 19 possible indications, "D4" was the most frequent with 19.6%. Of 4537 patients, 20.7% had KIG grade 3, 63.6% KIG grade 4 and 15.7% KIG grade 5. The prevalence of sagittal deviations "D" and "M" was 35.0%, transverse "B" and "K" 17.9% and vertical "O" and "T" 3.7%. Tooth position anomalies "E" and "P" had a share of 24.6%.

CONCLUSIONS

The present study confirms existing findings as well as the nationwide data of the National Association of Statutory Health Insurance Dentists (KZBV) from 2020: The sagittal deviations "D" (increased overjet) and "M" (negative overjet) represented the most frequent findings with KIG D4 as the most common classification. The prevalence and age distribution of KIG grades 3-5 requiring treatment corresponded to nationwide comparative data.

A novel macrolide-Del-1 axis to regenerate bone in old age

Aging is associated with increased susceptibility to chronic inflammatory bone loss disorders, such as periodontitis, in large part due to the impaired regenerative potential of aging tissues. DEL-1 exerts osteogenic activity and promotes bone regeneration. However, DEL-1 expression declines with age. Here we show that systemically administered macrolide antibiotics and a non-antibiotic erythromycin derivative, EM-523, restore DEL-1 expression in 18-month-old ("aged") mice while promoting regeneration of bone lost due to naturally occurring age-related periodontitis. These compounds failed to induce bone regeneration in age-matched DEL-1-deficient mice. Consequently, these drugs promoted DEL-1-dependent functions, including alkaline phosphatase activity and osteogenic gene expression in the periodontal tissue while inhibiting osteoclastogenesis, leading to net bone growth. Macrolide-treated aged mice exhibited increased skeletal bone mass, suggesting that this treatment may be pertinent to systemic bone loss disorders. In conclusion, we identified a macrolide-DEL-1 axis that can regenerate bone lost due to aging-related disease.

Bioinformatics reveals the pathophysiological relationship between diabetic nephropathy and periodontitis in the context of aging

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes mellitus. Periodontitis (PD) is a microbially-induced chronic inflammatory disease that is thought to have a bidirectional relationship with diabetes mellitus. DN and PD are recognized as models associated with accelerated aging. This study is divided into two parts, the first of which explores the bidirectional causal relationship through Mendelian randomization (MR). The second part aims to investigate the relationship between PD and DN in terms of potential crosstalk genes, aging-related genes, biological pathways, and processes using bioinformatic methods. MR analysis showed no evidence to support a causal relationship between DN and PD (P = 0.34) or PD and DN (P = 0.77). Using the GEO database, we screened 83 crosstalk genes overlapping in two diseases. Twelve paired genes identified by Pearson correlation and the four hub genes in the key cluster were jointly evaluated as key crosstalk-aging genes. Using support vector machine recursive feature elimination (SVM-RFE) and maximal clique centrality (MCC) algorithms, feature selection established five genes as the key crosstalk-aging genes. Based on five key genes, an ANN diagnostic model with reliable diagnosis of two diseases was developed. Gene enrichment analysis indicates that AGE-RAGE pathway signaling, the complement system, and multiple immune inflammatory pathways may be involved in common features of both diseases. Immune infiltration analysis reveals that most immune cells are differentially expressed in PD and DN, with dendritic cells and T cells assuming vital roles in both diseases. Overall, although there is no causal link, CSF1R, CXCL6, VCAM1, JUN and IL1B may be potential crosstalk-aging genes linking PD and DN. The common pathways and markers explored in this study could contribute to a deeper understanding of the common pathogenesis of both diseases in the context of aging and provide a theoretical basis for future research.

Ageing and Inflammation: What Happens in Periodontium?

Periodontitis is a chronic inflammatory disease with a high incidence and severity in the elderly population, making it a significant public health concern. Ageing is a primary risk factor for the development of periodontitis, exacerbating alveolar bone loss and leading to tooth loss in the geriatric population. Despite extensive research, the precise molecular mechanisms underlying the relationship between ageing and periodontitis remain elusive. Understanding the intricate mechanisms that connect ageing and inflammation may help reveal new therapeutic targets and provide valuable options to tackle the challenges encountered by the rapidly expanding global ageing population. In this review, we highlight the latest scientific breakthroughs in the pathways by which inflammaging mediates the decline in periodontal function and triggers the onset of periodontitis. We also provide a comprehensive overview of the latest findings and discuss potential avenues for future research in this critical area of investigation.

Immune-related signature of periodontitis and Alzheimer's disease linkage

Background: Periodontits (PD) and Alzheimer's disease (AD) are both associated with ageing and clinical studies increasingly evidence their association. However, specific mechanisms underlying this association remain undeciphered, and immune-related processes are purported to play a signifcant role. The accrual of publicly available transcriptomic datasets permits secondary analysis and the application of data-mining and bioinformatic tools for biological discovery. Aim: The present study aimed to leverage publicly available transcriptomic datasets and databases, and apply a series of bioinformatic analysis to identify a robust signature of immune-related signature of PD and AD linkage. Methods: We downloaded gene-expresssion data pertaining PD and AD and identified crosstalk genes. We constructed a protein-protein network analysis, applied immune cell enrichment analysis, and predicted crosstalk immune-related genes and infiltrating immune cells. Next, we applied consisent cluster analysis and performed immune cell bias analysis, followed by LASSO regression to select biomarker immune-related genes. Results: The results showed a 3 gene set comprising of DUSP14, F13A1 and SELE as a robust immune-related signature. Macrophages M2 and NKT, B-cells, CD4+ memory T-cells and CD8+ naive T-cells emerged as key immune cells linking PD with AD. Conclusion: Candidate immune-related biomarker genes and immune cells central to the assocation of PD with AD were identified, and merit investigation in experimental and clinical research.

Association between the severity of periodontitis, COVID-19, C-reactive protein and interleukin-6 levels in hospitalized patients: a case‒control study

BACKGROUND

The COVID-19 pandemic is perhaps one of the most important events of the 21st century. Periodontitis is one of the most prevalent diseases of the oral cavity. Due to possible pathways of interaction between these two diseases, we investigated their association.

METHODS

The study population consisted of hospitalized patients with established COVID-19 diagnoses. Patients with mild to moderate COVID-19 were considered controls, while cases had severe to critical COVID-19. Periodontal examination and serum and saliva sampling were performed for each patient. Relevant medical data were extracted from patients' hospital files.

RESULTS

Of the enrolled patients, 122 were included in the statistical analyses. The severity of periodontitis was directly and significantly correlated with the severity of COVID-19 (P < 0.001). Patients with generalized stage III or IV periodontitis displayed an adjusted odds ratio of 4.24 for severe to critical COVID-19. Salivary and serum interleukin-6 levels were significantly associated with COVID-19 severity (P values: 0.002 and 0.004, respectively). Hospitalization length was significantly associated with the severity of periodontitis (P = 0.004). Clinical attachment level and gingival index were associated with increased odds for adverse events (P values: 0.004 and 0.035, respectively), while number of remaining teeth was associated with decreased odds for adverse events (P = 0.023).

CONCLUSIONS

This study showed that the severity of periodontitis is associated with the severity of COVID-19. This association might manifest as increased odds of adverse events. COVID-19 severity was associated with higher levels of salivary and serum interleukin-6 levels.

Relationship between circulating senescence-associated secretory phenotype levels and severity of type 2 diabetes-associated periodontitis: A cross-sectional study

BACKGROUND

Senescence-associated secretory phenotype (SASP) has recently been found to drive comorbid diabetes and periodontitis by inducing a chronic, low-degree inflammatory state. Here, we sought to explore the relationship between circulating SASP and the severity of type 2 diabetes-associated periodontitis (DP).

METHODS

Eighty patients (middle-aged periodontitis, M-P group; aged periodontitis, A-P group; M-DP group; and A-DP group; n = 20) provided gingival epithelium, serum, and periodontal clinical parameters. Circulating levels of 12 DP-related SASP factors were analyzed by immunoassay. Correlation between periodontal clinical parameters and circulating SASP levels was analyzed by Spearman's rank correlation coefficient and back propagation artificial neural network (BPNN). Senescence markers (p16, p21, and HMGB1) in gingiva were determined by immunofluorescence assay.

RESULTS

M-DP group had increased serum levels of twelve SASP factors compared with the M-P group (p < 0.5). Serum levels of IL-6, IL-4, and RAGE were higher in the A-DP group than the A-P group (p < 0.5). The circulating concentrations of certain SASP proteins, including IL-1β, IL-4, MMP-8, OPG, RANKL, and RAGE were correlated with the clinical parameters of DP. BPNN showed that serum SASP levels had considerable predictive value for CAL of DP. Additionally, the DP group had higher expressions of p16, p21, and cytoplasmic-HMGB1 in the gingiva than the P group (p < 0.5).

CONCLUSIONS

Significantly enhanced circulating SASP levels and aggravated periodontal destruction were observed in patients with DP. Importantly, a non-negligible association between serum SASP levels and the severity of DP was found.

Rejuvenation of Mesenchymal Stem Cells to Ameliorate Skeletal Aging

Advanced age is a shared risk factor for many chronic and debilitating skeletal diseases including osteoporosis and periodontitis. Mesenchymal stem cells develop various aging phenotypes including the onset of senescence, intrinsic loss of regenerative potential and exacerbation of inflammatory microenvironment via secretory factors. This review elaborates on the emerging concepts on the molecular and epigenetic mechanisms of MSC senescence, such as the accumulation of oxidative stress, DNA damage and mitochondrial dysfunction. Senescent MSCs aggravate local inflammation, disrupt bone remodeling and bone-fat balance, thereby contributing to the progression of age-related bone diseases. Various rejuvenation strategies to target senescent MSCs could present a promising paradigm to restore skeletal aging.

The burden of diabetes on the soft tissue seal surrounding the dental implants

Soft tissue seal around implant prostheses is considered the primary barrier against adverse external stimuli and is a critical factor in maintaining dental implants' stability. Soft tissue seal is formed mainly by the adhesion of epithelial tissue and fibrous connective tissue to the transmembrane portion of the implant. Type 2 diabetes mellitus (T2DM) is one of the risk factors for peri-implant inflammation, and peri-implant disease may be triggered by dysfunction of the soft tissue barrier around dental implants. This is increasingly considered a promising target for disease treatment and management. However, many studies have demonstrated that pathogenic bacterial infestation, gingival immune inflammation, overactive matrix metalloproteinases (MMPs), impaired wound healing processes and excessive oxidative stress may trigger poor peri-implant soft tissue sealing, which may be more severe in the T2DM state. This article reviews the structure of peri-implant soft tissue seal, peri-implant disease and treatment, and moderating mechanisms of impaired soft tissue seal around implants due to T2DM to inform the development of treatment strategies for dental implants in patients with dental defects.

Identification and validation of a classifier based on hub aging-related genes and aging subtypes correlation with immune microenvironment for periodontitis

BACKGROUND

Periodontitis (PD), an age-related disease, is characterized by inflammatory periodontal tissue loss, and with the general aging of the global population, the burden of PD is becoming a major health concern. Nevertheless, the mechanism underlying this phenomenon remains indistinct. We aimed to develop a classification model for PD and explore the relationship between aging subtypes and the immune microenvironment for PD based on bioinformatics analysis.

MATERIALS AND METHODS

The PD-related datasets were acquired from the Gene Expression Omnibus (GEO) database, and aging-related genes (ARGs) were obtained from the Human Aging Genomic Resources (HAGR). Four machine learning algorithms were applied to screen out the hub ARGs. Then, an artificial neural network (ANN) model was constructed and the accuracy of the model was validated by receiver operating characteristic (ROC) curve analysis. The clinical effect of the model was evaluated by decision curve analysis (DCA). Consensus clustering was employed to determine the aging expression subtypes. A series of bioinformatics analyses were performed to explore the PD immune microenvironment and its subtypes. The hub aging-related modules were defined using weighted correlation network analysis (WGCNA).

RESULTS

Twenty-seven differentially expressed ARGs were dysregulated and a classifier based on four hub ARGs (BLM, FOS, IGFBP3, and PDGFRB) was constructed to diagnose PD with excellent accuracy. Subsequently, the mRNA levels of the hub ARGs were validated by quantitative real-time PCR (qRT-PCR). Based on differentially expressed ARGs, two aging-related subtypes were identified. Distinct biological functions and immune characteristics including infiltrating immunocytes, immunological reaction gene sets, the human leukocyte antigen (HLA) gene, and immune checkpoints were revealed between the subtypes. Additionally, the black module correlated with subtype-1 was manifested as the hub aging-related module and its latent functions were identified.

CONCLUSION

Our findings highlight the critical implications of aging-related genes in modulating the immune microenvironment. Four hub ARGs (BLM, FOS, IGFBP3, and PDGFRB) formed a classification model, and accompanied findings revealed the essential role of aging in the immune microenvironment for PD, providing fresh inspiration for PD etiopathogenesis and potential immunotherapy.

Microbiome landscape of lesions and adjacent normal mucosal areas in oral lichen planus patient

The pathogenesis of oral lichen planus (OLP) remains unclear, and microbial dysbiosis has been proposed to play a role in the pathogenesis of OLP. Oral mucosal swabs from 77 OLP patients and 76 healthy subjects were collected. The bacterial community among the OLP lesion, the adjacent normal mucosal, and the oral mucosal surface in healthy people were analyzed by 16S sequencing. The factor of gender and age that may affect the flora distribution of OLP patients were explored. Results indicate no significant difference in microbiota between OLP and the adjacent group. Compared with the healthy group, Neisseria, Haemophilus, Fusobacterium, Porphyromonas, Rothia, Actinomyces, and Capnocytophaga significantly increased in the OLP group. Actinomyces increased in male OLP patients, and the other six bacteria increased in female OLP patients. In female OLP patients, Lautropia and Dialister were positively correlated with age. While in male OLP patients, Moraxella, Porphyromonas, and Fusobacterium were positively correlated with age. Functional enrichment analysis suggested that abnormal energy metabolism related to ATP synthases, abnormal transport and metabolism of glycans, amino acids, and vitamins, and disorders of the local immune microenvironment might exist in OLP lesion.

Cellular Senescence and Periodontitis: Mechanisms and Therapeutics

Periodontitis is a chronic inflammatory disease which increases in prevalence and severity in the older population. Aging is a leading risk factor for periodontitis, which exacerbates alveolar bone loss and results in tooth loss in the elderly. However, the mechanism by which aging affects periodontitis is not well understood. There is considerable evidence to suggest that targeting cellular senescence could slow down the fundamental aging process, and thus alleviate a series of age-related pathological conditions, likely including alveolar bone loss. Recently, it has been discovered that the senescent cells accumulate in the alveolar bone and promote a senescence-associated secretory phenotype (SASP). Senescent cells interacting with bacteria, together with secreted SASP components altering the local microenvironment and inducing paracrine effects in neighboring cells, exacerbate the chronic inflammation in periodontal tissue and lead to more alveolar bone loss. This review will probe into mechanisms underlying excessive alveolar bone loss in periodontitis with aging and discuss potential therapeutics for the treatment of alveolar bone loss targeting cellular senescence and the SASP. Inspecting the relationship between cellular senescence and periodontitis will lead to new avenues of research in this field and contribute to developing potential translatable clinical interventions to mitigate or even reverse the harmful effects of aging on oral health.

Human gingival mesenchymal stem cells retain their growth and immunomodulatory characteristics independent of donor age

Aging has been reported to deteriorate the quantity and quality of mesenchymal stem cells (MSCs), which affect their therapeutic use in regenerative medicine. A dearth of age-related stem cell research further restricts their clinical applications. The present study explores the possibility of using MSCs derived from human gingival tissues (GMSCs) for studying their ex vivo growth characteristics and differentiation potential with respect to donor age. GMSCs displayed decreased in vitro adipogenesis and in vitro and in vivo osteogenesis with age, but in vitro neurogenesis remained unaffected. An increased expression of p53 and SIRT1 with donor age was correlated to their ability of eliminating tumorigenic events through apoptosis or autophagy, respectively. Irrespective of donor age, GMSCs displayed effective immunoregulation and regenerative potential in a mouse model of LPS-induced acute lung injury. Thus, we suggest the potential of GMSCs for designing cell-based immunomodulatory therapeutic approaches and their further extrapolation for acute inflammatory conditions such as acute respiratory distress syndrome and COVID-19.

The niche-specialist and age-related oral microbial ecosystem: crosstalk with host immune cells in homeostasis

Although characterization of the baseline oral microbiota has been discussed, the current literature seems insufficient to draw a definitive conclusion on the interactions between the microbes themselves or with the host. This study focuses on the spatial and temporal characteristics of the oral microbial ecosystem in a mouse model and its crosstalk with host immune cells in homeostasis. The V3V4 regions of the 16S rRNA gene of 20 samples from four niches (tongue, buccal mucosa, keratinized gingiva and hard palate) and 10 samples from two life stages (adult and old) were analysed. Flow cytometry (FCM) was used to investigate the resident immune cells. The niche-specialist and age-related communities, characterized based on the microbiota structure, interspecies communications, microbial functions and interactions with immune cells, were addressed. The phylum Firmicutes was the major component in the oral community. The microbial community profiles at the genus level showed that the relative abundances of the genera Bacteroides, Lactobacillus and Porphyromonas were enriched in the gingiva. The abundance of the genera Streptococcus, Faecalibaculum and Veillonella was increased in palatal samples, while the abundance of Neisseria and Bradyrhizobium was enriched in buccal samples. The genera Corynebacterium, Stenotrophomonas, Streptococcus and Fusobacterium were proportionally enriched in old samples, while Prevotella and Lacobacillus were enriched in adult samples. Network analysis showed that the genus Lactobacillus performed as a central node in the buccal module, while in the gingiva module, the central nodes were Nesterenkonia and Hydrogenophilus. FCM showed that the proportion of Th1 cells in the tongue samples (38.18 % [27.03–49.34 %]) (mean [range]) was the highest. The proportion of γδT cells in the buccal mucosa (25.82 % [22.1–29.54 %]) and gingiva (20.42 % [18.31–22.53 %]) samples was higher (P<0.01) than those in the palate (14.18 % [11.69–16.67 %]) and tongue (9.38 % [5.38–13.37 %] samples. The proportion of Th2 (31.3 % [16.16–46.44 %]), Th17 (27.06 % [15.76–38.36 %]) and Treg (29.74 % [15.71–43.77 %]) cells in the old samples was higher than that in the adult samples (P<0.01). Further analysis of the interplays between the microbiomes and immune cells indicated that Th1 cells in the adult group, nd Th2, Th17 and Treg cells in the old group were the main immune factors strongly associated with the oral microbiota. For example, Th2, Th17 and Treg cells showed a significantly positive correlation with age-related microorganisms such as Sphingomonas, Streptococcus and Acinetobacter, while Th1 cells showed a negative correlation. Another positive correlation occurred between Th1 cells and several commensal microbiomes such as Lactobacillus, Jeotgalicoccus and Sporosarcina. Th2, Th17 and Treg cells showed the opposite trend. Together, our findings identify the niche-specialist and age-related characteristics of the oral microbial ecosystem and the potential associations between the microbiomes and the mucosal immune cells, providing critical insights into mucosal microbiology.

Citizen-science reveals changes in the oral microbiome in Spain through age and lifestyle factors

The relevance of the human oral microbiome to our understanding of human health has grown in recent years as microbiome studies continue to develop. Given the links of the oral cavity with the digestive, respiratory and circulatory systems, the composition of the oral microbiome is relevant beyond just oral health, impacting systemic processes across the body. However, we still have a very limited understanding about intrinsic and extrinsic factors that shape the composition of the healthy oral microbiome. Here, we followed a citizen-science approach to assess the relative impact on the oral microbiome of selected biological, social, and lifestyle factors in 1648 Spanish individuals. We found that the oral microbiome changes across age, with middle ages showing a more homogeneous composition, and older ages showing more diverse microbiomes with increased representation of typically low abundance taxa. By measuring differences within and between groups of individuals sharing a given parameter, we were able to assess the relative impact of different factors in driving specific microbial compositions. Chronic health disorders present in the analyzed population were the most impactful factors, followed by smoking and the presence of yeasts in the oral cavity. Finally, we corroborate findings in the literature that relatives tend to have more similar oral microbiomes, and show for the first time a similar effect for classmates. Multiple intrinsic and extrinsic factors jointly shape the oral microbiome. Comparative analysis of metabarcoding data from a large sample set allows us to disentangle the individual effects.

mTOR Signaling in the Regulation of CD4+ T Cell Subsets in Periodontal Diseases

Periodontal disease results from the inflammatory infiltration by the microbial community which is marked through tooth mobility and alveolar bone resorption. The inflammation in periodontal disease is mediated by CD4⁺ T cells through cytokine secretion and osteoclastogenetic activity. Historically, the inflammatory model in periodontal disease is described through disruption of the balance between two subsets of T helper cells which are T-helper type 1 (Th1) and T-helper type 2 (Th2). However, more and more studies have found that apart from subsets of helper T cells, regulatory T-cells and Th17 cells are also involved in the pathogenesis of periodontal diseases. Growing evidence proves that helper T cells differentiation, activation, and subset determination are under the strong impact of mTOR signaling. mTOR signaling could promote Th1 and Th17 cell differentiation and inhibit Treg commitment through different mTOR complexes, therefore we anticipate a regulation effect of mTOR signaling on periodontal diseases by regulating CD4⁺ T cell subsets. This review aims to integrate the topical researches about the role of different types of Th cells in the pathogenesis of periodontal diseases, as well as the regulation of mTOR signaling in the specification and selection of Th cell commitment.

Osteoporosis and periodontal diseases - An update on their association and mechanistic links

Periodontitis and osteoporosis are prevalent inflammation-associated skeletal disorders that pose significant public health challenges to our aging population. Both periodontitis and osteoporosis are bone disorders closely associated with inflammation and aging. There has been consistent intrigue on whether a systemic skeletal disease such as osteoporosis will amplify the alveolar bone loss in periodontitis. A survey of the literature published in the past 25 years indicates that systemic low bone mineral density (BMD) is associated with alveolar bone loss, while recent evidence also suggests a correlation between clinical attachment loss and other parameters of periodontitis. Inflammation and its influence on bone remodeling play critical roles in the pathogenesis of both osteoporosis and periodontitis and could serve as the central mechanistic link between these disorders. Enhanced cytokine production and elevated inflammatory response exacerbate osteoclastic bone resorption while inhibiting osteoblastic bone formation, resulting in a net bone loss. With aging, accumulation of oxidative stress and cellular senescence drive the progression of osteoporosis and exacerbation of periodontitis. Vitamin D deficiency and smoking are shared risk factors and may mediate the connection between osteoporosis and periodontitis, through increasing oxidative stress and impairing host response to inflammation. With the connection between systemic and localized bone loss in mind, routine dental exams and intraoral radiographs may serve as a low-cost screening tool for low systemic BMD and increased fracture risk. Conversely, patients with fracture risk beyond the intervention threshold are at greater risk for developing severe periodontitis and undergo tooth loss. Various Food and Drug Administration-approved therapies for osteoporosis have shown promising results for treating periodontitis. Understanding the molecular mechanisms underlying their connection sheds light on potential therapeutic strategies that may facilitate co-management of systemic and localized bone loss.

Maladaptive trained immunity and clonal hematopoiesis as potential mechanistic links between periodontitis and inflammatory comorbidities

Periodontitis is bidirectionally associated with systemic inflammatory disorders. The prevalence and severity of this oral disease and linked comorbidities increases with aging. Here, we review two newly emerged concepts, trained innate immunity (TII) and clonal hematopoiesis of indeterminate potential (CHIP), which together support a potential hypothesis on how periodontitis affects and is affected by comorbidities and why the susceptibility to periodontitis and comorbidities increases with aging. Given that chronic diseases are largely triggered by the action of inflammatory immune cells, modulation of their bone marrow precursors, the hematopoietic stem and progenitor cells (HSPCs), may affect multiple disorders that emerge as comorbidities. Such alterations in HSPCs can be mediated by TII and/or CHIP, two non-mutually exclusive processes sharing a bias for enhanced myelopoiesis and production of innate immune cells with heightened proinflammatory potential. TII is a state of elevated immune responsiveness based on innate immune (epigenetic) memory. Systemic inflammation can initiate TII in the bone marrow via sustained rewiring of HSPCs, which thereby display a skewing toward the myeloid lineage, resulting in generation of hyper-reactive or "trained" myeloid cells. CHIP arises from aging-related somatic mutations in HSPCs, which confer a survival and proliferation advantage to the mutant HSPCs and give rise to an outsized fraction of hyper-inflammatory mutant myeloid cells in the circulation and tissues. This review discusses emerging evidence that supports the notion that TII and CHIP may underlie a causal and age-related association between periodontitis and comorbidities. A holistic mechanistic understanding of the periodontitis-systemic disease connection may offer novel diagnostic and therapeutic targets for treating inflammatory comorbidities.

Mucosal circadian rhythm pathway genes altered by aging and periodontitis

As circadian processes can impact the immune system and are affected by infections and inflammation, this study examined the expression of circadian rhythm genes in periodontitis.

METHODS

Macaca mulatta were used with naturally-occurring and ligature-induced periodontitis. Gingival tissue samples were obtained from healthy, diseased, and resolved sites in four groups: young (≤3 years), adolescent (3-7 years), adult (12-26) and aged (18-23 years). Microarrays targeted circadian rhythm (n = 42), inflammation/tissue destruction (n = 11), bone biology (n = 8) and hypoxia pathway (n = 7) genes.

RESULTS

The expression of many circadian rhythm genes, across functional components of the pathway, was decreased in healthy tissues from younger and aged animals, as well as showing significant decreases with periodontitis. Negative correlations of the circadian rhythm gene levels with inflammatory mediators and tissue destructive/remodeling genes were particularly accentuated in disease. A dominance of positive correlations with hypoxia genes was observed, except HIF1A, that was uniformly negatively correlated in health, disease and resolution.

CONCLUSIONS

The chronic inflammation of periodontitis exhibits an alteration of the circadian rhythm pathway, predominantly via decreased gene expression. Thus, variation in disease expression and the underlying molecular mechanisms of disease may be altered due to changes in regulation of the circadian rhythm pathway functions.

Serum Alkaline Phosphatase and Calcium in Relation to Periodontal Status among Perimenopausal and Postmenopausal Women

Background:

Menopause is a physiological phenomenon that occurs in aging women. Periodontal disease is associated with menopausal status. Alkaline phosphatase (ALP) plays a role in general and periodontal bone turnover. Calcium is essential for the maintenance of bone and teeth, and serum ALP and calcium are specific bone markers related to the acceleration of bone mass loss in elderly women and periodontitis.

Objectives:

The aim of this study was to correlate the levels of serum ALP and calcium with periodontal status in perimenopausal and postmenopausal women with periodontitis.

Methods:

A total of 22 perimenopausal and 49 postmenopausal women underwent a full periodontal examination assessing the pocket depth, number of teeth lost, clinical attachment loss, plaque index, calculus index, and papillary bleeding index. Using these measurements, the subjects were divided according to periodontal severity. Serum ALP and calcium were measured using the Enzyme-Linked Immunosorbent Assay (ELISA) method. A correlation between serum ALP and calcium to periodontal status was investigated.

Results:

Serum ALP was significantly correlated with the severity of periodontitis, clinical attachment loss, and the number of teeth lost among perimenopausal and postmenopausal women (p < 0.05). Serum calcium levels were not correlated with periodontal status.

Conclusion:

Postmenopausal women tended to have more periodontal breakdown, and the level of serum ALP was increased in severe periodontitis.

Oral disease burden of dentate older adults living in long-term care facilities: FINORAL study

BACKGROUND

A growing number of older adults have natural teeth and are at high risk of oral diseases, which are induced by oral bacterial accumulation and proceed unnoticed and quietly. Our aim was (1) to examine the association of oral disease burden (ODB) with health and functioning among dentate long-term care residents, and (2) to find easily detectable signs for nurses to identify residents' poor oral health.

METHODS

In this cross-sectional observational study dentists examined 209 residents' oral status, and nurses assessed residents for their functioning and nutrition in long-term care facilities in Helsinki, Finland. ODB was defined by asymptotic dental score (ADS). Six clinical signs of residents' poor oral health were considered as potentially easy for nurses to detect: lesions on lips, teeth with increased mobility, lesions on oral mucosa, eating soft or pureed food, unclear speech, and needing assistance in eating. The association of these was tested with high ODB as outcome.

RESULTS

Participants were grouped according to their ADS scores: low (n = 39), moderate (n = 96) and high ODB (n = 74). ODB was linearly associated with coronary artery disease and poor cognitive and physical functioning: needing assistance in eating, poor ability to make contact, and unclear speech but not with other diseases including dementia or demographic characteristics. Furthermore, ODB was linearly associated with eating soft or pureed food. Of the six selected, easily detectable signs, having at least two positive signs gave 89% sensitivity to detecting high ODB.

CONCLUSION

Poor oral health was common and ODB accumulated among residents with poor functioning. Nurses may use a few easily detectable signs to screen residents' oral health when considering a resident's need for consultation with an oral health professional.

Developmental endothelial locus-1 as a potential biomarker for the incidence of acute exacerbation in patients with chronic obstructive pulmonary disease

BACKGROUND

Despite the high disease burden of chronic obstructive pulmonary disease (COPD) and risk of acute COPD exacerbation, few COPD biomarkers are available. As developmental endothelial locus-1 (DEL-1) has been proposed to possess beneficial effects, including anti-inflammatory effects, we hypothesized that DEL-1 could be a blood biomarker for COPD.

OBJECTIVE

To elucidate the role of plasma DEL-1 as a biomarker of COPD in terms of pathogenesis and for predicting acute exacerbation.

METHODS

Cigarette smoke extract (CSE) or saline was intratracheally administered to wild-type (WT) and DEL-1 knockout (KO) C57BL/6 mice. Subsequently, lung sections were obtained to quantify the degree of emphysema using the mean linear intercept (MLI). Additionally, plasma DEL-1 levels were compared between COPD and non-COPD participants recruited in ongoing prospective cohorts. Using negative binomial regression analysis, the association between the plasma DEL-1 level and subsequent acute exacerbation risk was evaluated in patients with COPD.

RESULTS

In the in vivo study, DEL-1 KO induced emphysema (KO saline vs. WT saline; P = 0.003) and augmented CSE-induced emphysema (KO CSE vs. WT CSE; P < 0.001) in 29 mice. Among 537 participants, patients with COPD presented plasma log (DEL-1) levels lower than non-COPD participants (P = 0.04), especially non-COPD never smokers (P = 0.019). During 1.2 ± 0.3 years, patients with COPD in the lowest quartile of Log(DEL-1) demonstrated an increased risk of subsequent acute exacerbation, compared with those in the highest quartile of Log(DEL-1) (adjusted incidence rate ratio, 3.64; 95% confidence interval, 1.03-12.9).

CONCLUSION

Low DEL-1 levels are associated with COPD development and increased risk of subsequent COPD acute exacerbation. DEL-1 can be a useful biomarker in patients with COPD.

Nitrate-rich diet alters the composition of the oral microbiota in periodontal recall patients

BACKGROUND

This follow-up study evaluated microbiome changes in periodontal recall patients after consuming a nitrate-rich diet that led to a marked decrease of gingival inflammation.

METHODS

Subgingival microbial samples of 37 patients suffering from gingival inflammation with reduced periodontium were taken before professional mechanical plaque removal (baseline) and subsequently after 2 weeks of regularly consuming a lettuce juice beverage (day 14) containing a daily dosage of 200 mg of nitrate (test group, n = 18) or being void of nitrate (placebo group, n = 19). Three hundred base pairs paired-end sequencing of the V3-V4 hypervariable region of the 16S rDNA was performed.

RESULTS

At baseline, there were no significant differences about the bacterial diversity parameters between the groups (Mann-Whitney U test). After intervention in the test group, Rothia and Neisseria, including species reducing nitrate, increased significantly (negative binomial regression model). Alpha diversity decreased significantly from 115.69 ± 24.30 to 96.42 ± 24.82 aRSVs/sample (P = 0.04, Wilcoxon signed-rank test), accompanied by a significant change in beta diversity (P < 0.001, PERMANOVA). In the control group, however, no genus changed significantly, and alpha-, as well as beta-diversity did not change significantly.

CONCLUSIONS

The decrease of gingival inflammation in periodontal recall patients induced by a nitrate-rich diet is accompanied by significant compositional changes within the subgingival microbiome.

Polymicrobial communities in periodontal disease: Their quasi-organismal nature and dialogue with the host

In health, indigenous polymicrobial communities at mucosal surfaces maintain an ecological balance via both inter-microbial and host-microbial interactions that promote their own and the host's fitness, while preventing invasion by exogenous pathogens. However, genetic and acquired destabilizing factors (including immune deficiencies, immunoregulatory defects, smoking, diet, obesity, diabetes and other systemic diseases, and aging) may disrupt this homeostatic balance, leading to selective outgrowth of species with the potential for destructive inflammation. This process, known as dysbiosis, underlies the development of periodontitis in susceptible hosts. The pathogenic process is not linear but involves a positive-feedback loop between dysbiosis and the host inflammatory response. The dysbiotic community is essentially a quasi-organismal entity, where constituent organisms communicate via sophisticated physical and chemical signals and display functional specialization (eg, accessory pathogens, keystone pathogens, pathobionts), which enables polymicrobial synergy and dictates the community's pathogenic potential or nososymbiocity. In this review, we discuss early and recent studies in support of the polymicrobial synergy and dysbiosis model of periodontal disease pathogenesis. According to this concept, disease is not caused by individual "causative pathogens" but rather by reciprocally reinforced interactions between physically and metabolically integrated polymicrobial communities and a dysregulated host inflammatory response.

Biological Aging and Periodontal Disease: Analysis of NHANES (2001-2002)

INTRODUCTION

Periodontitis is a chronic inflammatory disease caused by multiple potential contributing factors such as bacterial biofilm infection of the tissues surrounding the teeth and environmental determinants and a dysregulated host response for modifying and resolving the inflammation. Because periodontal disease is a major public health concern with substantial increases in the prevalence and severity in aging populations, previous studies of periodontitis tended to approach the disease as an age-associated outcome across the life span. However, few investigations have considered that, as a chronic noncommunicable disease, periodontitis may not simply be a disease that increases with age but may contribute to more rapid biologic aging.

OBJECTIVES

Increasing population data supports the potential disconnect between chronological aging and biologic aging, which would contribute to the heterogeneity of aging phenotypes within chronologic ages across populations. Thus, our aim was to test whether periodontal disease affects biological aging across the life span.

METHODS

The prevalence of periodontitis in the adult US population is a portion of the assessment of the National Health and Nutrition Examination Survey (NHANES), which has been ongoing since 1971 through 2-y cycles sampling populations across the country. We used NHANES 2001-2002 to test the hypothesis that the presence/severity of periodontal disease as an exposure variable would negatively affect telomere length, a measure of biological aging, and that this relationship is modified by factors that also affect the progression of periodontitis, such as sex, race/ethnicity, and smoking.

RESULTS

The data demonstrated a significant impact of periodontitis on decreasing telomere lengths across the life span. These differences were modulated by age, sex, race/ethnicity, and smoking within the population.

CONCLUSION

The findings lay the groundwork for future studies documenting broader effects on biological aging parameters as well as potential intervention strategies for periodontitis in driving unhealthy aging processes.

KNOWLEDGE TRANSFER STATEMENT

Periodontitis is a chronic inflammatory disease and dysregulated host response. Shortening of telomeres is a reflection of biologic aging. Decreased telomere lengths with periodontitis are seemingly related to chronic infection and persistent local and systemic inflammation. These findings suggest that periodontitis is not simply a disease of aging but may also transmit chronic systemic signals that could affect more rapid biological aging. Clinicians can use this outcome to recognize the role of periodontitis in driving unhealthy aging processes in patients.

Current understanding of periodontal disease pathogenesis and targets for host-modulation therapy

Recent advances indicate that periodontitis is driven by reciprocally reinforced interactions between a dysbiotic microbiome and dysregulated inflammation. Inflammation is not only a consequence of dysbiosis but, via mediating tissue dysfunction and damage, fuels further growth of selectively dysbiotic communities of bacteria (inflammophiles), thereby generating a self-sustained feed-forward loop that perpetuates the disease. These considerations provide a strong rationale for developing adjunctive host-modulation therapies for the treatment of periodontitis. Such host-modulation approaches aim to inhibit harmful inflammation and promote its resolution or to interfere directly with downstream effectors of connective tissue and bone destruction. This paper reviews diverse strategies targeted to modulate the host periodontal response and discusses their mechanisms of action, perceived safety, and potential for clinical application.

The association of periodontal diseases with metabolic syndrome and obesity

Periodontitis is a multifactorial chronic inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth-supporting apparatus. Globally, it is estimated that 740 million people are affected by its severe form. Periodontitis has been suggested to be linked to obesity and metabolic syndrome. Obesity, defined as excessive fat accumulation, is a complex multifactorial chronic inflammatory disease, with a high and increasing prevalence. Metabolic syndrome is defined as a cluster of obesity, dyslipidemia, hypertension, and dysglycemia. Obesity, metabolic syndrome and periodontitis are among the most common non-communicable diseases and a large body of evidence from epidemiologic studies supports the association between these conditions. Extensive research has established plausible mechanisms to explain how these conditions can negatively impact each other, pointing to a bidirectional adverse relationship. At present there is only limited evidence available from a few intervention studies. Nevertheless, the global burden of periodontitis combined with the obesity epidemic has important clinical and public health implications for the dental team. In accordance with the common risk factor approach for tackling non-communicable diseases, it has been proposed that oral healthcare professionals have an important role in the promotion of periodontal health and general well-being through facilitation of healthy lifestyle behaviours.

Aging affects responsiveness of peripheral blood mononuclear cells to immunosuppression of periodontal ligament stem cells

Objectives

The effect of age on the response of peripheral blood mononuclear cells (PBMCs) to immunosuppression induced by human periodontal ligament stem cells (hPDLSCs) is unclear. The identity of the cytokines most effective in inducing the PBMC immune response remains unknown. This study investigated the effects of age on immunophenotype, proliferation, activation, and cytokine secretion capacities of PBMCs following co-culture with hPDLSCs.

Methods

PBMCs were collected from younger (16–19 years) and older (45–55 years) donors, then co-cultured with confirmed hPDLSCs for various lengths of time. T lymphocyte proliferation and cell surface marker expression were analyzed by flow cytometry. Cytokine expression levels were measured by quantitative polymerase chain reaction assays and enzyme-linked immunosorbent assays.

Results

CD28 expression by T lymphocytes decreased with age, indicating reduced proliferation; CD95 expression increased with age, indicating enhanced apoptosis. Moreover, hPDLSCs inhibited T lymphocyte proliferation in both age groups; this inhibition was stronger in cells from older donors than in cells from younger donors. Age reduced the secretion of interleukin-2 and interferon-γ, whereas it increased the secretion of tumor necrosis factor-β by PBMCs cultured with hPDLSCs.

Conclusions

Aging may have a robust effect on the response of PBMCs towards hPDLSC-induced immunosuppression.

Global Prevalence of Periodontal Disease and Lack of Its Surveillance

BACKGROUND

Periodontal disease is a public health problem and is strongly associated with systemic diseases; however, its worldwide distribution is not fully understood.

OBJECTIVE

To evaluate global data of periodontal disease: (1) among adolescents, adults, and older population and (2) in low-, middle-, and high-income countries.

METHODS

This ecological study included data of periodontal disease from the World Health Organization's data bank which are based on the Community Periodontal Index of Treatment Needs (CPITN code: 0 = no disease; 1 = bleeding on probing; 2 = calculus; 3 = periodontal pocket (PD) 4-5 mm; 4 = PD (6+ mm). Age- and income-related periodontal disease inequalities were evaluated across the globe.

RESULTS

Compared with 9.3% of adults and 9.7% of older persons, 21.2% of adolescents had no periodontal disease (P = 0.005). Nearly 18.8% of adolescents compared with 8.9% of adults and 5% of older persons had bleeding on probing (P ≤ 0.001). Similarly, 50.3% of adolescents, 44.6% of adults, and 31.9% older persons demonstrated the occurrence of calculus (P = 0.01). On the other hand, older persons had the highest prevalence of PD 4-5 mm and PD 6+ mm than adults and adolescents (P ≤ 0.001). The distribution of periodontitis (CPITN code 3 + 4) in adults differed significantly in low- (28.7%), lower-middle- (10%), upper-middle- (42.5%), and high-income countries (43.7%) (P = 0.04). However, no significant differences in periodontitis (CPITN code 3 + 4) were observed in adolescents and older persons in low- to high-income countries.

CONCLUSIONS

Within the limitations of data, this study found that the distribution of periodontal disease increases with age. Periodontitis was the most common in older persons and in population from high-income countries.

The impact of diabetes on periodontal diseases

The susceptibility and severity of periodontal diseases is made more severe by diabetes, with the impact on the disease process inversely proportional to the level of glycemic control. Although type 1 diabetes mellitus and type 2 diabetes mellitus have different etiologies, and their impact on bone is not identical, they share many of the same complications. Studies in animals and humans agree that both forms of diabetes increase inflammatory events in periodontal tissue, impair new bone formation, and increase expression of RANKL in response to bacterial challenge. High levels of glucose, reactive oxygen species, and advanced glycation end-products are found in the periodontium of diabetic individuals and lead to increased activation of nuclear factor-kappa B and expression of inflammatory cytokines such as tumor necrosis factor and interleukin-1. Studies in animals, moreover, suggest that there are multiple cell types in periodontal tissues that are affected by diabetes, including leukocytes, vascular cells, mesenchymal stem cells, periodontal ligament fibroblasts, osteoblasts, and osteocytes. The etiology of periodontal disease involves the host response to bacterial challenge that is affected by diabetes, which increases the expression of RANKL and reduces coupled bone formation. In addition, the inflammatory response also modifies the oral microbiota to render it more pathogenic, as demonstrated by increased inflammation and bone loss in animals where bacteria are transferred from diabetic donors to germ-free hosts compared with transfer from normoglycemic donors. This approach has the advantage of not relying upon limited knowledge of the specific bacterial taxa to determine pathogenicity, and examines the overall impact of the microbiota rather than the presumed pathogenicity of a few bacterial groups. Thus, animal studies have provided new insights into pathogenic mechanisms that identify cause-and-effect relationships that are difficult to perform in human studies.

Heterogeneity of human serum antibody responses to P. gingivalis in periodontitis: Effects of age, race/ethnicity, and sex

Aging humans display an increased prevalence and severity of periodontitis, although the mechanisms underlying these findings remain poorly understood. This report examined antigenic diversity of P. gingivalis related to disease presence and patient demographics. Serum IgG antibody to P. gingivalis strains ATCC33277, FDC381, W50 (ATCC53978), W83, A7A1-28 (ATCC53977) and A7436 was measured in 426 participants [periodontally healthy (n = 61), gingivitis (N = 66) or various levels of periodontitis (N = 299)]. We hypothesized that antigenic diversity in P. gingivalis could contribute to a lack of "immunity" in the chronic infections of periodontal disease. Across the strains, the antibody levels in the oldest age group were lower than in the youngest groups, and severe periodontitis patients did not show higher antibody with aging. While 80 % of the periodontitis patients in any age group showed an elevated response to at least one of the P. gingivalis strains, the patterns of individual responses in the older group were also substantially different than the other age groups. Significantly greater numbers of older patients showed strain-specific antibody profiles to only 1 strain. The findings support that P. gingivalis may demonstrate antigenic diversity/drift within patients and could be one factor to help explain the inefficiency/ineffectiveness of the adaptive immune response in managing the infection.

Periodontitis is associated with disease severity and anti-double stranded DNA antibody and interferon-gamma levels in patients with systemic lupus erythematosus

OBJECTIVES

To analyse the correlation between periodontitis severity and disease activity, anti-double stranded DNA (anti-dsDNA) antibody, and interferon-gamma (IFN-γ) levels in patients with systemic lupus erythematous (SLE).

METHODS

We selected 61 patients with SLE (age 18-55 years) selected from a hospital in Malang, Indonesia. Clinical examination and laboratory tests were performed to assess disease activity. The severity of SLE was measured using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), while periodontitis severity was measured according to the Periodontal Index (PI) criteria. Levels of anti-dsDNA and IFN-γ were determined using an enzyme-linked immunosorbent assay. Optical density at 450 nm was measured using an automated plate reader.

RESULTS

The mean age of the subjects with SLE was 29 years, and mean disease duration was 2.8 years. Fifty-four of 61 (88.53%) subjects with SLE had periodontitis according to the PI. SLE subjects exhibited other clinical manifestations such as lupus nephritis, vasculitis, arthritis, mucocutaneous manifestation, fatigue, fever, and/or leukopenia. SLE severity was assessed according to the average SLEDAI score (17.70 ± 12.70), and average anti-dsDNA (122.6 ± 81.01 U/mL), and IFN-γ (14.64 ± 11.17 pg/mL) levels. There was a significantly positive correlation between periodontitis score and SLEDAI score (r = 0.927; p ≤ 0.0001), anti-dsDNA antibody (r = 0.948; p ≤ 0.0001), and IFN-γ (r = 0.951; p ≤ 0.0001) levels.

CONCLUSION

Results of the present study demonstrated that periodontitis was associated with SLE disease activity, and was a biomarker of immune aging. Furthermore, this biomarker could be a reliable predictor of periodontal condition and prognosis of periodontitis and can also help in selecting the most appropriate treatment strategy for periodontitis in patients with SLE.

Experimental mucositis/gingivitis in persons aged 70 or over: microbiological findings and prediction of clinical outcome

OBJECTIVES

To assess in persons aged 70 years or older the microbiological alterations occurring around implants and natural teeth during and after 3 weeks of undisturbed plaque accumulation. Furthermore, to test the predictive value of several markers at baseline for the extent of inflammation around implants and teeth after this period.

MATERIALS 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. Levels of six subgingival plaque microorganisms, the plaque index (PI), and the gingival index (GI) were assessed before (baseline), during (days 0, 7, 14, 21), and after plaque accumulation (days 28, 42). Six microorganisms; demographic and clinical variables at day 0 were further evaluated as potential predictors for presence of GI > 1 at days 21 and 28.

RESULTS

The detection frequency of the selected bacteria did not differ between implants and teeth at any time point. Bacteria counts decreased in the preparatory phase and increased in the plaque accumulation phase. Patterns observed at implants and teeth were similar. Only Parvimonas micra at day 21 reached significantly higher counts at implants than teeth. For the prediction of clinical outcome at day 21, in the multivariable model, only implant vs. tooth was significant indicator for the primary outcome (p = 0.01).

CONCLUSIONS

Overall, the analysis of subgingival/submucosal samples revealed only minor differences between implants and teeth during the development and resolution of inflammation.

CLINICAL RELEVANCE

Within the limitations of our study, with plaque accumulation, elders develop more inflammation around implants than around teeth, in spite of similar bacterial profiles.