Histopathological features of chronic and aggressive periodontitis

Peri-implantitis with a potential axis to brain inflammation: an inferential review

Peri-implantitis (PI) is a chronic, inflammatory, and infectious disease which affects dental implants and has certain similarities to periodontitis (PD). Evidence has shown that PD may be related to several types of systemic disorders, such as diabetes and insulin resistance, cardiovascular diseases, respiratory tract infections, adverse pregnancy outcomes, and neurological disorders. Furthermore, some types of bacteria in PD can also be found in PI, leading to certain similarities in the immunoinflammatory responses in the host. This review aims to discuss the possible connection between PI and neuroinflammation, using information based on studies about periodontal disorders, a topic whose connection with systemic alterations has been gaining the interest of the scientific community. Literature concerning PI, PD, and systemic disorders, such as neuroinflammation, brain inflammation, and neurological disorder, was searched in the PubMed database using different keyword combinations. All studies found were included in this narrative review. No filters were used. Eligible studies were analyzed and reviewed carefully. This study found similarities between PI and PD development, maintenance, and in the bacterial agents located around the teeth (periodontitis) or dental implants (peri-implantitis). Through the cardiovascular system, these pathologies may also affect blood-brain barrier permeability. Furthermore, scientific evidence has suggested that microorganisms from PI (as in PD) can be recognized by trigeminal fiber endings and start inflammatory responses into the trigeminal ganglion. In addition, bacteria can traverse from the mouth to the brain through the lymphatic system. Consequently, the immune system increases inflammatory mediators in the brain, affecting the homeostasis of the nervous tissue and vice-versa. Based on the interrelation of microbiological, inflammatory, and immunological findings between PD and PI, it is possible to infer that immunoinflammatory changes observed in PD can imply systemic changes in PI. This, as discussed, could lead to the development or intensification of neuroinflammatory changes, contributing to neurodegenerative diseases.

An injectable gel based on photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles for periodontitis treatment

Guided bone regeneration (GBR) is an effective strategy to promote periodontal tissue repair. The current study aimed to develop an injectable gel for GBR, composed of photo-cross-linkable hyaluronic acid and mesoporous bioactive glass nanoparticles (MBGNs) loaded with antibacterial minocycline hydrochloride (MNCl). Hyaluronic acid modified with methacrylic anhydride (MHA) that could be cross-linked under UV irradiation was first synthesized. Dynamic rheological evaluation of MHA under UV was carried out to determine its in-situ gelling feasibility and stability. Morphological and mechanical characterization was performed to determine the optimal concentration of MHA gels. Sol-gel derived MBGNs loaded with MNCl were further incorporated into MHA gels to obtain the injectable drug-loaded MBGN-MNCl/MHA gels. In vitro antibacterial, anti-inflammatory and osteogenic effects of this gel were evaluated. It was shown that the MHA gel obtained from 3 % MHA under UV treatment of 30s exhibited a suitable porous structure with a compressive strength of 100 kPa. MBGNs with particle size of ∼120 nm and mesopores were confirmed by TEM and SEM. MBGNs had a loading capacity of ∼120 mg/g for MNCl, exhibiting a sustained release behavior. The MBGN-MNCl/MHA gel was shown to effectively inhibit the proliferation of Streptococcus mutans and the expression of pro-inflammatory factors IL-6 and TNF-α by macrophages. It could on the other hand significantly promote the expression of osteogenic-related genes ALP, Runx2, OPN, and osterix of MC3T3-E1 cells. In conclusion, the current design using photo-crosslinkable MHA gel embedded with MNCl loaded MBGNs can serve as a promising injectable formulation for GBR treatment of irregular periodontal defects.

Sex effects on gingival transcriptomic patterns during initiation, progression, and resolution of periodontitis

BACKGROUND

The prevalence and severity of periodontitis demonstrates altered population distribution with age, sex, and race and ethnicity. While males exhibit greater frequency of disease, particularly with aging, the underlying basis for this observation remains obscure.

OBJECTIVE

This study used a nonhuman primate (Macaca mulatta) model of experimental ligature-induced periodontitis in adult animals to evaluate gingival transcriptomic differences stratified based upon sex of the animal.

METHODS

The 18 animals represented humans ages 40-80 years, with gingival tissue samples obtained at baseline, 0.5 months (initiation), 1 and 3 months (progression), and at 5 months that were 60 days after ligature removal for clinical disease resolution. Microarray analysis was used to quantify gene expression profiles in the gingival tissues.

RESULTS

The results demonstrated clear gene expression differences in healthy (baseline) tissues between the sexes, with elevations in females associated with immune responses and elevation in males related to tissue structural genes. With disease initiation, fewer genes differed between the sexes, while these differences were significantly increased in progressing disease and resolution, particularly in male animals. Overexpressed biological processes showed tissue structural/functional genes at initiation, with host response pathways altered during disease progression. Resolution samples generally demonstrated biological processes of cellular metabolism that differed from baseline healthy samples.

CONCLUSION

The transcriptomic findings support sex as a biological variable in periodontitis using a nonhuman primate model of experimental periodontitis.

Metaproteomics Characterizes the Human Gingival Crevicular Fluid Microbiome Function in Periodontitis

Periodontitis is the leading cause of tooth loss in adults worldwide. The human proteome and metaproteome characterization of periodontitis is not clearly understood. Gingival crevicular fluid samples were collected from eight periodontitis and eight healthy subjects. Both the human and microbial proteins were characterized by liquid chromatography coupled with high-resolution mass spectrometry. A total of 570 human proteins were found differentially expressed, which were primarily associated with inflammatory response, cell death, cellular junction, and fatty acid metabolism. For the metaproteome, 51 genera were identified, and 10 genera were found highly expressed in periodontitis, while 11 genera were downregulated. The analysis showed that microbial proteins related to butyrate metabolism were upregulated in periodontitis cases. In particular, correlation analysis showed that the expression of host proteins related to inflammatory response, cell death, cellular junction, and lipid metabolism correlates with the alteration of metaproteins, which reflect the changes of molecular function during the occurrence of periodontitis. This study showed that the gingival crevicular fluid human proteome and metaproteome could reflect the characteristics of periodontitis. This might benefit the understanding of the periodontitis mechanism.

Clinical, radiographic and histopathologic features of early-onset gingivitis and periodontitis in cats (1997-2022)

OBJECTIVES

This study aimed to characterize the clinical, radiographic and histopathologic features of early-onset gingivitis (EOG) and periodontitis in cats.

METHODS

The medical records database was searched for cats diagnosed with histologically confirmed EOG or periodontitis from 1997 to 2022. Information such as medical history, lifestyle factors, clinical presentation, radiographic and histopathologic features were included for 27 client-owned cats. Response to treatment and long-term follow-up was also recorded.

RESULTS

Moderate-to-severe periodontal disease was radiographically confirmed in 78% (21/27) of cats with moderate-to-severe EOG, compared with the evidence of periodontal disease noted in 30% (8/27) of cases during awake oral examination. Horizontal bone loss, along with missing teeth, were the predominant radiographic features noted in 89% (24/27) of cases. The predominant histopathologic feature was moderate-to-severe, erosive-to-ulcerative, neutrophilic and lymphoplasmacytic inflammation with varying degrees of epithelial and stromal hyperplasia. Two cats developed feline chronic gingivostomatitis (FCGS)-like lesions, and seven cats exhibited worsening of aggressive periodontitis (AP). Lack of improvement in the severity of gingivitis or clinical signs evident at the first follow-up appointment was significantly associated with progression of disease (P = 0.004).

CONCLUSIONS AND RELEVANCE

The results of this study demonstrate the importance of oral evaluations in cats as early as 6 months of age. For cats exhibiting substantial gingivitis, an anesthetized evaluation, periodontal treatment and long-term monitoring are recommended. Given the high frequency of moderate-to-severe periodontitis encountered in these cats, clients should be informed about the potential need for tooth extractions. EOG may progress to AP. Finally, this study suggests that there could be a link between EOG and FCGS; however, further studies are needed to better characterize this condition and establish any potential link between the two entities.

In Vitro Homeostasis of Rat Oral Epithelial Cell Cultures Following Withdrawal of Periodontal Pathogens

Inflammation of periodontal tissues is the consequence of interaction between periodontal pathogens and immune system. This is associated with increased expression of inflammatory cytokines, which may exert destructive effect to the periodontal tissues when released over long period. The aim of this study was to chronologically track the homeostasis of oral keratinocytes following removal of periodontal pathogens. This was done by investigating expression of selected inflammatory markers and integrity of epithelial monolayers in vitro. Rat oral keratinocytes were stimulated with heat-killed Fusobacterium nucleatum and Porphyromonas gingivalis over 7-days then bacteria were washed away and epithelial cells re-cultured for 3-days. Expression of IL-1β, IL-6, and IL-8 was measured by ELISA while transcription of tissue inhibitor of metalloproteinase-1 (TIMP-1) and matrix metalloproteinase -8 (MMP-8) was measured by polymerase chain reaction before and after removal of bacteria. Integrity of epithelial sheet was investigated by using transepithelial electrical resistance. Data showed general downregulation of IL-1b, IL-6, and IL-8 associated with restoring transcription of TIMP-1 and MMP-8 to normal level following removal of bacteria from epithelial cultures. However, expression of IL-8 and MMP-8 remained significantly higher than unstimulated epithelial cells despite withdrawal of F. nucleatum and P. gingivalis respectively from oral keratinocytes cultures. In addition, integrity of epithelial barrier function remained compromised even after removal of P. gingivalis. Results suggest that even after three days following removal of periodontal pathogens, oral keratinocytes sustained persistent upregulation of certain inflammatory markers that could compromise integrity of epithelial barrier function.

Do patients with aggressive and chronic periodontitis exhibit specific differences in the subgingival microbial composition? A systematic review

BACKGROUND

The 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions grouped the diseases previously recognized as chronic (CP) or aggressive (AgP) periodontitis under a single category named periodontitis. The rationale for this decision was the lack of specific patterns of immune-inflammatory response or microbial profiles associated with CP or AgP. However, no previous studies have compiled the results of all studies comparing subgingival microbial data between these clinical conditions. Thus, this systematic review aimed to answer the following focused question: "Do patients with AgP periodontitis present differences in the subgingival microbiota when compared with patients with CP?"

METHODS

A systematic review was conducted according to the PRISMA statement. The MEDLINE, EMBASE, and Cochrane databases were searched up to June 2019 for studies of any design (except case reports, case series, and reviews) comparing subgingival microbial data from patients with CP and AgP.

RESULTS

A total of 488 articles were identified and 56 were included. Thirteen studies found Aggregatibacter actinomycetemcomitans elevated in AgP in comparison with CP, while Fusobacterium nucleatum, Parvimonas micra, and Campylobacter rectus were elevated in AgP in a few studies. None of these species were elevated in CP. However, the number of studies not showing statistically significant differences between CP and AgP was always higher than that of studies showing differences.

CONCLUSION

These results suggested an association of A. actinomycetemcomitans with AgP, but neither this species nor the other species studied to date were unique to or could differentiate between CP and AgP (PROSPERO #CRD42016039385).

Butyrate rather than LPS subverts gingival epithelial homeostasis by downregulation of intercellular junctions and triggering pyroptosis

AIM

To investigate the effects of sodium butyrate (NaB) and lipopolysaccharide (LPS) on gingival epithelial barrier.

MATERIAL AND METHODS

We cultured human primary gingival epithelial cells and investigated the effects of NaB and LPS on gingival epithelial barrier and involved mechanisms at in vitro and in vivo levels by immunostaining, confocal microscopy, field emission scanning electron microscopy (FE-SEM), transmission electronic microscopy (TEM), transepithelial electrical resistance (TEER), FTIC-dextran flux, flow cytometry, real-time PCR and Western blot assays.

RESULTS

Our results showed that NaB, rather than LPS, destroyed the epithelial barrier by breaking down cell-cell junctions and triggering gingival epithelial cell pyroptosis with characteristic morphological changes, including swollen cells, large bubbles, pore formation in the plasma membrane and subcellular organelles changes. The upregulated expression of pyroptosis-related markers, caspase-3 and gasdermin-E (GSDME) contributed to this effect. Pyroptosis aroused by NaB is a pro-inflammatory cell death. Pyroptotic cell death provoked inflammatory responses by upregulation of IL-8 and MCP-1, and releasing intracellular contents into the extracellular microenvironment after pyroptotic rupture of the plasma membrane.

CONCLUSIONS

Our new findings indicate that butyrate is a potent destructive factor of gingival epithelial barrier and pro-inflammatory mediator, which shed a new light on our understanding of periodontitis initiation.

The subgingival microbial community of feline periodontitis and gingivostomatitis: characterization and comparison between diseased and healthy cats

Periodontitis is a common and important health problem in domestic cats. The subgingival microbiota of cats diagnosed with chronic periodontitis (CP), aggressive periodontitis (AP), and feline chronic gingivostomatitis (FCGS) are not well characterized. Thus, the aim of the present study was to characterize and compare the periodontal microbiota of periodontally healthy cats versus cats diagnosed with CP, AP, and FCGS by using next-generation sequencing. In total, 44 domestic cats were enrolled, and 139 subgingival samples were subjected to 16S rRNA gene sequencing to investigate the microbiota composition of each periodontal group evaluated. Our results identified several key genera previously described in periodontal disease (e.g. Treponema and Filifactor) and in the oral microbiota (e.g. Moraxella and Capnocytophaga) of healthy cats. Phylogenetic beta diversity analysis showed that the microbiota of periodontally healthy cats were distinguishable from diseased cats. Even though most of the genera known to be associated with periodontal disease were also identified in healthy cats, they were present at significantly lower relative abundance. Remarkably, alpha diversity was found to be higher in the disease groups compared to healthy animals. These results suggest a pathological mechanism involving opportunistic behavior. Our findings corroborate those in the current literature regarding the complexity of the subgingival microbiota of the domestic cat and reveal both differences and similarities among periodontally healthy and diseased cats.

Immunologische Ex-vivo-Untersuchung zur Wirkung potenzierter Substanzen bei parodontaler Entzündung unter Verwendung der Durchflusszytometrie

<b><i>Hintergrund:</i></b> Bei der Behandlung parodontaler Entzündungen werden in der Versorgungspraxis auch homöopathische Mittel eingesetzt. Noch ist weniger über deren grundlegende Wirkprinzipien bekannt. Ziel dieser Arbeit war es daher, die Auswirkungen potenzierter Substanzen bei parodonta­ler Entzündung mittels Durchflusszytometrie zu untersuchen. <b><i>Material und Methoden:</i></b> Lymphozyten aus Blutproben von drei Parodontitis-Patienten und drei gematchten gesunden Probanden wurden extrahiert und mit stark verdünnten wässrigen Extrakten (D12 und C200) aus Mercurius solubilis, Silicea, Sulphur, Tuberculinum oder Placebo inkubiert. Um die Lymphozytenexpression zu untersuchen, wurde die Durchflusszytometrie für CD45R0- und CD25-Antikörper angewandt. Die statistische Analyse wurde unter Verwendung von Histogramm- und bivariaten Dot-Plot-Analysen durchgeführt. <b><i>Ergebnisse:</i></b> Veränderungen der Expression von CD25 und CD45R0 wurden bei Mercurius C200, Mercurius D12, Silicea D12 und Sulphur D12 beobachtet. Mit 36,47% zeigte Sulphur D12 die höchsten Veränderungen in der CD45R0-Expression zwischen Verum und Placebo bei den Parodontitis-Patienten. Die CD25-Expression war in Mercurius D12 mit 18,68% am höchsten. Aufgrund der hohen Variabilität konnten die Ergebnisse jedoch nicht durch statistische Analysen untermauert werden. <b><i>Diskussion:</i></b> Diese Studie konnte zeigen, wie Effekte hoch verdünnter Substanzen mit modernen immunologischen Methoden analysiert werden können. Obwohl die Schlussfolgerungen aufgrund der hohen Variabilität der Lymphozytenexpression begrenzt sind, könnten die Ergebnisse dieser Pilotstu­die weitere Untersuchungen anregen.

Association between circulating levels of heat-shock protein 27 and aggressive periodontitis

Heat-shock protein (Hsp) 27 is a major intracellular molecular chaperone and controller of intracellular responses to inflammatory signals. In the extracellular space, recombinant Hsp27 has been described to exert anti-inflammatory activities. The aim of this study was to assess the association between circulating levels of Hsp27 and different types of periodontitis. Pro- and anti-inflammatory cytokines and the stress proteins Hsp27 and Hsp60 with proposed anti- and pro-inflammatory properties, respectively, were measured by two-site ELISA in the serum of patients with aggressive periodontitis (AgP, n = 30), chronic periodontitis (CP, n = 29) and periodontally healthy controls (H, n = 28). Furthermore, Hsp27 and Hsp60 levels were also measured longitudinally in 12 AgP patients at 6 time points up to 3 months after treatment. AgP patients had lower levels of Hsp27 compared to CP patients and healthy subjects (adjusted one-way ANOVA, p < 0.001, followed by post hoc Tukey HSD comparisons), while no differences in levels of Hsp60 or cytokines between the three groups were detected. In CP patients and H subjects, the systemic Hsp27 levels correlated with Hsp60 (r = 0.43, p < 0.001; r = 0.59, p < 0.001, respectively) and with pro-inflammatory cytokines TNF-α (r = 0.48, p < 0.001; r = 0.55, p < 0.001, respectively) and IL-6 (r = 0.44, p < 0.01). However, no such correlations were detected in AgP cases. No consistent temporal patterns of changes of Hsp27 concentration were detected across AgP patients following periodontal treatment. This study provides the first evidence that Hsp27 may be differentially expressed and regulated in AgP patients as compared with CP patients and healthy individuals.

Genetic Factors and the Risk of Periodontitis Development: Findings from a Systematic Review Composed of 13 Studies of Meta-Analysis with 71,531 Participants

Purpose. This work aimed to synthesize the results of recent meta-analysis focusing on polymorphism in inflammatory mediators and its relation with the risk of periodontitis development. Materials and Methods. A systematic search was conducted using databases for publications prior to October 2016. Three examiners extracted data from articles with a clear association between polymorphisms in the inflammatory mediator gene and the development of periodontitis through meta-analysis using the fixed or randomized statistical models to calculate the Odds Ratio with values of P < 0.05 considered significant. Results. A total of 13 meta-analysis articles with 25 polymorphisms in seven interleukins (IL-1A, IL-1B, IL-4, IL-6, IL-8, IL-10, and IL-18), three cellular receptors (Fcγ receptors: FCGR2A, FCGR3A, and FCGR3B), and five inflammatory mediators (COX-2, MMP-2, MMP-3, MMP-8, and MMP-9), with a total of 71,531 participants, approaching different classifications of the disease. Conclusion. The study demonstrated that polymorphisms in the IL-1A, IL-1B, IL-6, IL-10, MMP-3 (chronic form), and MMP-9 (chronic form) polymorphisms were significantly associated with the risk of developing periodontitis, whereas other polymorphisms in the IL-4, IL-8, IL-18, Fcγ, COX-2, MMP-2, MMP-3 (aggressive), MMP-8, and MMP-9 (aggressive) polymorphisms had no significant association with risk of developing periodontitis.

Differentiation of Chronic and Aggressive Periodontitis by FTIR Spectroscopy

Without longitudinal clinical data, it is difficult to differentiate some cases of chronic periodontitis (CP) and aggressive periodontitis (AgP). Furthermore, both forms of disease are exacerbated by tobacco use. Therefore, this cross-sectional study was planned, primarily, to determine the ability of Fourier-transform infrared (FTIR) spectroscopy to distinguish CP and AgP patients by analysis of human saliva samples and, secondarily, to assess the potential confounding influence of smoking on discriminating disease-specific spectral signatures. FTIR spectra were collected from patients with a clinical diagnosis of CP (n = 18; 7 smokers) or AgP (n = 23; 9 smokers). Self-reported smoking status, which may be unreliable, was confirmed by salivary cotinine analysis. Spectral band area analysis and hierarchical cluster analyses were performed to clarify if the 2 periodontitis groups as well as smoker and nonsmoker patients could be differentiated from each other. Significant variations in lipid, amino acid, lactic acid, and nucleic acid content were found between nonsmoker CP and AgP groups. Although significantly lower lipid, phospholipid, protein, amino acid, lactic acid, and nucleic acid content was noted in the smoker AgP group compared with the nonsmoker AgP group, in the CP group, phospholipid, protein, amino acid, and lactic acid content was significantly lower for smokers compared with the nonsmokers. Based on these variations, nonsmoker CP and AgP patients were discriminated from each other with high sensitivity and specificity. Successful differentiation was also obtained for the smoker CP and AgP groups. Thiocyanate levels successfully differentiated smokers from nonsmokers, irrespective of periodontal status, with 100% accuracy. Differentiation of AgP and CP forms, concomitant with determination of smoking status, may allow the dental health professional to tailor treatment accordingly.

Immature, but Not Mature, Dendritic Cells Are More Often Present in Aggressive Periodontitis Than Chronic Periodontitis: An Immunohistochemical Study

BACKGROUND

Dendritic cells (DCs) form a key link between innate and adaptive immune responses. The aim of this study is to analyze presence and distribution of immature (im) and mature (m) DCs in gingival tissue samples obtained from patients diagnosed with aggressive periodontitis (AgP), chronic periodontitis (CP), and clinically healthy periodontium (control group).

METHODS

Gingival tissue samples obtained from patients with: 1) AgP (aged <35 years); 2) CP (aged ≥35 years); and 3) control group (aged >18 years) (n = 10 per group) were collected. Two-way analysis of variance and posterior Fisher least significant difference test were used to observe differences between the means of cells positively marked for imDC (S100, CD1a, and CD207) and mDC (CD208) immunomarkers.

RESULTS

imDCs were more numerous in AgP than CP and control groups, being statistically significant only for S100+ cells. Conversely, mDCs were visualized in higher numbers in CP than AgP and control groups (both P <0.05). Considering frequency of immunostained cells, the number of S100+ cells was greater than CD207+ and CD1a+ cells, followed by a lesser number of CD208+ cells, in all groups.

CONCLUSIONS

Considering that the ability of DCs to regulate immunity is dependent on DC maturation, results suggest that predominance of imDCs appears to be involved in AgP pathogenesis, probably due to lack of ability to induce immune cell activation. Further studies are necessary to elucidate the role of DC maturation in regulating immune responses in periodontal disease.

Parameters of oxidative stress in saliva from patients with aggressive and chronic periodontitis

OBJECTIVES

Free radicals play an important role in the onset and progression of many diseases. The aim of this study was to investigate the contribution of oxidative stress in the pathology of aggressive (AgP) and chronic (CP) periodontitis and its relation with the clinical periodontal status.

METHODS

Eighty subjects were divided into two groups: 20 patients with AgP and 20 patients with CP with their 20 corresponding matched controls, based on clinical attachment loss (CAL), probing pocket depth (PPD), and bleeding on probing (BOP). Saliva reactive oxygen species (ROS), lipid peroxidation, and non-enzymatic antioxidant defences were measured by luminol-dependent chemiluminescence assay, as thiobarbituric acid-reactive substances (TBARs) and total radical-trapping antioxidant potential (TRAP), respectively. Pearson's correlation and multivariate analysis were used to determine the relationship between ROS and TBARs and the clinical parameters.

RESULTS

ROS and TBARs were increased in AgP while TRAP was decreased, comparing with CP. In AgP, a strong and positive correlation was observed between ROS and TBARs and they were closely associated with CAL and PPD.

DISCUSSION

In AgP, but not in CP, oxidative stress is a high contributor to periodontal pathology and it is closely associated with the clinical periodontal status.

Aggressive Periodontitis: microbes and host response, who to blame?

A paradigm shift several decades ago elucidated that aggressive periodontitis (AgP) was not a degenerative disorder but a rapid progressive form of plaque-induced inflammatory periodontal disease. Ensuing years of research have led to linkage analysis identification of specific genetic defects responsible for AgP in some families and to the finding that subgingival detection of A. actinomycet-emcomitans JP2 clone is a predictive factor for disease onset and progression. However, rather disappointingly, these ‘proven’ risk factors are only detected in a small subset of AgP cases. Recent advances are leading to a new paradigm shift, with the realization that genetically-driven dysbiotic changes in the subgingival microbiota may predispose to a cascade of events leading to the rapid periodontal tissue destruction seen in AgP. This review tries to dissect the existing literature on the host response-microbial axis of AgP and to propose possible pathogenic pathways in line with current theories.

Predictors of tooth loss due to periodontal disease in patients following long-term periodontal maintenance

AIM

To analyse patient-related factors (PRFs) and tooth-related factors (TRFs) associated with tooth loss due to periodontal disease (TLPD) in patients undergoing periodontal maintenance (PM).

MATERIAL AND METHODS

The sample consisted of 500 patients (mean follow-up of 20 years). The impact of PRFs on TLPD was analysed with Poisson regression and multivariate logistic regression. The simultaneous impact of PRFs and TRFs was analysed with multilevel logistic regression and Cox regression.

RESULTS

Tooth loss due to periodontal disease was 515 (mean 0.05 patient/year). The significant PRFs were severe periodontitis (p < 0.001), aggressive periodontitis (p < 0.001), smoking (p = 0.018), bruxism (p = 0.022) and baseline number of teeth (p = 0.001). These PRFs allowed characterizing patients losing more teeth. The whole TRFs analysed were significant, depending on the type of tooth and the category of each factor (e.g. mobility 0, 1, 2, and 3). The significant PRFs increased the risk of TLPD by 2 to 3 times while TRFs increased the risk to a higher extent. Mobility was the main TRF.

CONCLUSIONS

Severe periodontitis, aggressive periodontitis, smoking, bruxism and baseline number of teeth, as well as the whole TRFs analysed, were associated with TLPD.

Mini but mighty: microRNAs in the pathobiology of periodontal disease

MicroRNAs (miRNAs) are a family of small, noncoding RNA molecules that negatively regulate protein expression either by inhibiting initiation of the translation of mRNA or by inducing the degradation of mRNA molecules. Accumulating evidence suggests that miRNA-mediated repression of protein expression is of paramount importance in a broad range of physiologic and pathologic conditions. In particular, miRNA-induced dysregulation of molecular processes involved in inflammatory pathways has been shown to contribute to the development of chronic inflammatory diseases. In this review, first of all we provide an overview of miRNA biogenesis, the main mechanisms of action and the miRNA profiling tools currently available. Then, we summarize the available evidence supporting a specific role for miRNAs in the pathobiology of periodontitis. Based on a review of available data on the differential expression of miRNAs in gingival tissues in states of periodontal health and disease, we address specific roles for miRNAs in molecular and cellular pathways causally linked to periodontitis. Our review points to several lines of evidence suggesting the involvement of miRNAs in periodontal tissue homeostasis and pathology. Although the intricate regulatory networks affected by miRNA function are still incompletely mapped, further utilization of systems biology tools is expected to enhance our understanding of the pathobiology of periodontitis.

Differential Gene Expression Profiles Reflecting Macrophage Polarization in Aging and Periodontitis Gingival Tissues

Recent evidence has determined a phenotypic and functional heterogeneity for macrophage populations. This plasticity of macrophage function has been related to specific properties of subsets (M1 and M2) of these cells in inflammation, adaptive immune responses and resolution of tissue destructive processes. This investigation hypothesized that targeted alterations in the distribution of macrophage phenotypes in aged individuals, and with periodontitis would be skewed towards M1 inflammatory macrophages in gingival tissues. The study used a non-human primate model to evaluate gene expression profiles as footprints of macrophage variation in healthy and periodontitis gingival tissues from animals 3-23 years of age and in periodontitis tissues in adult and aged animals. Significant increases in multiple genes reflecting overall increases in macrophage activities were observed in healthy aged tissues, and were significantly increased in periodontitis tissues from both adults and aged animals. Generally, gene expression patterns for M2 macrophages were similar in healthy young, adolescent and adult tissues. However, modest increases were noted in healthy aged tissues, similar to those seen in periodontitis tissues from both age groups. M1 macrophage gene transcription patterns increased significantly over the age range in healthy tissues, with multiple genes (e.g. CCL13, CCL19, CCR7 and TLR4) significantly increased in aged animals. Additionally, gene expression patterns for M1 macrophages were significantly increased in adult health versus periodontitis and aged healthy versus periodontitis. The findings supported a significant increase in macrophages with aging and in periodontitis. The primary increases in both healthy aged tissues and, particularly periodontitis tissues appeared in the M1 phenotype.

Serum and salivary matrix metalloproteinases, neutrophil elastase, myeloperoxidase in patients with chronic or aggressive periodontitis

Salivary, serum matrix metalloproteinase-8 (MMP-8), tissue inhibitor of matrix metalloproteinases-1 (TIMP-1), neutrophil elastase (NE), and myeloperoxidase (MPO) levels were investigated in generalized chronic periodontitis (GCP), generalized aggressive periodontitis (GAgP), and healthy groups. Whole-mouth clinical periodontal measurements were recorded. Salivary, serum concentrations of MMP-8, MPO, TIMP-1, and NE were determined by immunofluorometric assay or ELISA in 18 patients with GCP, 23 patients with GAgP, 18 individuals with healthy periodontium. Patients in the GAgP group were younger than the other groups (p<0.05). The study groups were similar in gender, smoking status. Plaque index was higher in GCP than GAgP group (p<0.05). Biochemical data were similar in periodontitis groups. Salivary, serum MPO, and salivary NE concentrations were higher; TIMP-1 concentrations were lower in the periodontitis groups than the controls (p<0.05). The present data support a close relationship between salivary, serum protease content and clinical periodontal parameters in patients with generalized periodontitis.

Generalized Aggressive Periodontitis Associated With a Plasma Cell Gingivitis Lesion: A Case Report and Non-Surgical Treatment

INTRODUCTION

Plasma cell gingivitis (PCG) is an unusual inflammatory condition characterized by dense, band-like polyclonal plasmacytic infiltration of the lamina propria. Clinically, it appears as gingival enlargement with erythema and swelling of the attached and free gingiva and is not associated with any loss of attachment. The aim of this report is to present a rare case of severe generalized aggressive periodontitis (GAgP) associated with a PCG lesion that was successfully treated and maintained non-surgically.

CASE PRESENTATION

A 32-year-old white male with a non-contributory medical history presented with gingival enlargement with diffuse erythema and edematous swelling, predominantly around teeth #5 through #8. Clinical and radiographic examination revealed generalized severe periodontal breakdown. A complete blood count and biochemical tests were within normal limits. Histologic and immunohistochemical examination were consistent with PCG. A diagnosis of severe GAgP associated with a PCG lesion was assigned. Treatment included elimination of possible allergens and non-surgical periodontal treatment in combination with azithromycin. Clinical examination at reevaluation revealed complete resolution of gingival enlargement, erythema, and edema and localized residual probing depths of 5 mm. One year after treatment, the clinical condition was stable. Radiographs indicated improved bone levels and formation of crestal lamina dura.

CONCLUSION

This case report highlights the unusual coexistence of GAgP and PCG, in which non-surgical treatment with elimination of all possible causes in combination with antimicrobials resulted in elimination of the gingival enlargement and significant improvement of periodontal parameters.

The role of activated cytotoxic T cells in etiopathogenesis of periodontal disease: does it harm or does it heal?

The objective of this study was to determine the phenotypic profile of blood mononuclear cells, specifically CD8⁺/CD28⁺ cells, in patients with generalized aggressive periodontitis (GAgP) and chronic periodontitis (CP) in peripheral blood and in blood obtained from periodontal defect site which might contribute to tissue damage. 13 GAgP, 11 chronic periodontitis (CP) and 5 healthy controls (H) were included in the study. Plaque index (PI), bleeding on probing (BoP), periodontal probing depth (PPD) and clinical attachment level (CAL) were recorded. Blood from the base of periodontal defect site and peripheral blood from the antecubital vein were obtained. Relative counts of CD45⁺, CD3⁺, CD4⁺, CD8⁺/CD28⁺, CD8⁺/CD28⁻, CD19⁺, CD16⁺/CD56⁺/CD3, CD3⁺/CD16⁺/CD56⁺ receptors were determined with two color flow cytometry using monoclonal antibodies. BoP, PPD and CAL were significantly higher in both periodontitis groups than healthy controls (p <0.05). Activated cytotoxic T cells, CD8⁺/CD28⁺ cells, were significantly elevated in GAgP and CP groups compared to HC both in blood obtained from defect site and blood obtained from systemic circulation (p <0.05). GAgP and CP patients have an increased levels of activated cytotoxic T cells as a result of inflammation which may cause severe tissue damage that lead to severe and rapid loss of periodontal tissues.

Periodontal progression based on radiographic records: An observational study in chronic and aggressive periodontitis

OBJECTIVES

The current classification assumes that aggressive periodontitis (AgP) has a faster rate of progression than chronic periodontitis (CP). However, this has not been clearly proven and difficulties exist in establishing progression. This study aimed to assess the feasibility of retrospectively utilising previous records for clinical diagnosis of periodontal diseases and to assess if two different patterns of disease progression exist between AgP and CP.

MATERIALS AND METHODS

Previous radiographic records of a cohort of 235 patients clinically diagnosed with AgP or CP were requested from the referring general dental practitioners (GDPs). Comparable radiographic records were analysed in order to assess progression patterns and associate these with clinical diagnosis, by multilevel analysis.

RESULTS

43 patients out of the initial 235 had comparable radiographs retrieved from the GDPs. 858 sites were followed for an average 6.6 years. Radiographically, AgP showed a faster linear pattern of progression than CP (0.31mm/year vs. 0.20mm/year, p<0.001).

CONCLUSION

This study provides evidence for a faster disease progression in untreated AgP compared to CP as assessed by radiographic bone levels. Furthermore, it shows that retrievability of previous radiographs from GDPs is unpredictable and GDPs should be encouraged to send them along with their referral.

CLINICAL SIGNIFICANCE

The importance of differentially diagnosing AgP and CP might be useful in establishing a clinically relevant definition for periodontal disease progression and may have an impact on the clinical management of aggressive periodontitis, since our findings show that there is continuous destruction in patients with aggressive periodontitis if left untreated.

General immune status and oral microbiology in patients with different forms of periodontitis and healthy control subjects

Objective

Immunological processes in the etiopathogenesis of periodontitis, especially the aggressive form, are not well understood. This study examined clinical as well as systemic immunological and local microbiological features in healthy controls and patients with different forms of periodontitis.

Materials and Methods

14 healthy subjects, 15 patients diagnosed with aggressive periodontitis, and 11 patients with chronic periodontitis were recruited. Periodontal examination was performed and peripheral blood was collected from each patient. Lymphocyte populations as well as the release of cytokines by T-helper cells were determined by flow cytometry and enzyme linked immunosorbent spot assay. Subgingival plaque samples were taken from each individual and immediately cultivated for microbiological examination.

Results

When stimulating peripheral blood mononuclear cells (PBMCs) with lipopolysaccharide, a higher IL-1β release was found in patients with moderate chronic periodontitis compared to the other groups (p<0.01). Numbers of B-cells, naïve and transitional B-cells, memory B-cells, and switched memory B-cells were within the reference range for all groups, but patients with chronic periodontitis showed the highest percentage of memory B-cells without class switch (p = 0.01). The subgingival plaque differed quantitatively as well as qualitatively with a higher number of Gram-negative anaerobic species in periodontitis patients. Prevotella denticola was found more often in patients with aggressive periodontitis (p<0.001) but did not show an association to any of the systemic immunological findings. Porphyromonas gingivalis, which was only found in patients with moderate chronic periodontitis, seems to be associated with an activation of the systemic immune response.

Conclusion

Differences between aggressive periodontitis and moderate chronic periodontitis are evident, which raises the question of an inadequate balance between systemic immune response and bacterial infection in aggressive periodontitis.

Treatment of aggressive periodontitis

Despite etiological differences between aggressive and chronic periodontitis, the treatment concept for aggressive periodontitis is largely similar to that for chronic periodontitis. The goal of treatment is to create a clinical condition that is conducive to retaining as many teeth as possible for as long as possible. When a diagnosis has been made and risk factors have been identified, active treatment is commenced. The initial phase of active treatment consists of mechanical debridement, either alone or supplemented with antimicrobial drugs. Scaling and root planing has been shown to be effective in improving clinical indices, but does not always guarantee long-term stability. Antimicrobials can play a significant role in controlling aggressive periodontitis. Few studies have been published on this subject for localized aggressive periodontitis, but generalized aggressive periodontitis has been subject to more scrutiny. Studies have demonstrated that systemic antibiotics as an adjuvant to scaling and root planing are more effective in controlling disease compared with scaling and root planing alone or with supplemental application of local antibiotics or antiseptics. It has also become apparent that antibiotics ought to be administered with, or just after, mechanical debridement. Several studies have shown that regimens of amoxicillin combined with metronidazole or regimens of clindamycin are the most effective and are preferable to regimens containing doxycycline. Azithromycin has been shown to be a valid alternative to the regimen of amoxicillin plus metronidazole. A limited number of studies have been published on surgical treatment in patients with aggressive periodontitis, but the studies available show that the effect can be comparable with the effect on patients with chronic periodontitis, provided that proper oral hygiene is maintained, a strict maintenance program is followed and modifiable risk factors are controlled. Both access surgery and regenerative techniques have shown good results in patients with aggressive periodontitis. Once good periodontal health has been obtained, patients must be enrolled in a strict maintenance program that is directed toward controlling risk factors for disease recurrence and tooth loss. The most significant risk factors are noncompliance with regular maintenance care, smoking, high gingival bleeding index and poor plaque control. There is no evidence to suggest that daily use of antiseptic agents should be part of the supportive periodontal therapy for aggressive periodontitis.

Gingival tissue transcriptomes identify distinct periodontitis phenotypes

The currently recognized principal forms of periodontitis-chronic and aggressive-lack an unequivocal, pathobiology-based foundation. We explored whether gingival tissue transcriptomes can serve as the basis for an alternative classification of periodontitis. We used cross-sectional whole-genome gene expression data from 241 gingival tissue biopsies obtained from sites with periodontal pathology in 120 systemically healthy nonsmokers with periodontitis, with available data on clinical periodontal status, subgingival microbial profiles, and serum IgG antibodies to periodontal microbiota. Adjusted model-based clustering of transcriptomic data using finite mixtures generated two distinct clusters of patients that did not align with the current classification of chronic and aggressive periodontitis. Differential expression profiles primarily related to cell proliferation in cluster 1 and to lymphocyte activation and unfolded protein responses in cluster 2. Patients in the two clusters did not differ with respect to age but presented with distinct phenotypes (statistically significantly different whole-mouth clinical measures of extent/severity, subgingival microbial burden by several species, and selected serum antibody responses). Patients in cluster 2 showed more extensive/severe disease and were more often male. The findings suggest that distinct gene expression signatures in pathologic gingival tissues translate into phenotypic differences and can provide a basis for a novel classification.

Proteomics for the discovery of biomarkers and diagnosis of periodontitis: a critical review

Periodontitis is a common chronic and destructive disease whose pathogenetic mechanisms remain unclear. Due to their sensitivity and global scale, proteomics studies offer the opportunity to uncover critical host and pathogen activity indicators and can elucidate clinically applicable biomarkers for improved diagnosis and treatment of the disease. This review summarizes the literature of proteomics studies on periodontitis and comprehensively discusses commonly found candidate biomarkers. Key considerations in the design of an experimental proteomics platform are also outlined. The applicability of protein biomarkers across the progression of periodontitis and unexplored areas of research are highlighted.

Molecular differences between chronic and aggressive periodontitis

The 2 major forms of periodontitis, chronic (CP) and aggressive (AgP), do not display sufficiently distinct histopathological characteristics or microbiological/immunological features. We used molecular profiling to explore biological differences between CP and AgP and subsequently carried out supervised classification using machine-learning algorithms including an internal validation. We used whole-genome gene expression profiles from 310 'healthy' or 'diseased' gingival tissue biopsies from 120 systemically healthy non-smokers, 65 with CP and 55 with AgP, each contributing with ≥ 2 'diseased' gingival papillae (n = 241; with bleeding-on-probing, probing depth ≥ 4 mm, and clinical attachment loss ≥ 3 mm), and, when available, a 'healthy' papilla (n = 69; no bleeding-on-probing, probing depth ≤ 4 mm, and clinical attachment loss ≤ 4 mm). Our analyses revealed limited differences between the gingival tissue transcriptional profiles of AgP and CP, with genes related to immune responses, apoptosis, and signal transduction overexpressed in AgP, and genes related to epithelial integrity and metabolism overexpressed in CP. Different classifying algorithms discriminated CP from AgP with an area under the curve ranging from 0.63 to 0.99. The small differences in gene expression and the highly variable classifier performance suggest limited dissimilarities between established AgP and CP lesions. Future analyses may facilitate the development of a novel, 'intrinsic' classification of periodontitis based on molecular profiling.

Activation of invariant NK T cells in periodontitis lesions

Periodontitis is one of the most prevalent human inflammatory diseases. The major clinical phenotypes of this polymicrobial, biofilm-mediated disease are chronic and aggressive periodontitis, the latter being characterized by a rapid course of destruction that is generally attributed to an altered immune-inflammatory response against periodontal pathogens. Still, the biological basis for the pathophysiological distinction of the two disease categories has not been well documented yet. Type I NKT cells are a lymphocyte subset with important roles in regulating immune responses to either tolerance or immunity, including immune responses against bacterial pathogens. In this study, we delineate the mechanisms of NKT cell activation in periodontal infections. We show an infiltration of type I NKT cells in aggressive, but not chronic, periodontitis lesions in vivo. Murine dendritic cells infected with aggressive periodontitis-associated Aggregatibacter actinomycetemcomitans triggered a type I IFN response followed by type I NKT cell activation. In contrast, infection with Porphyromonas gingivalis, a principal pathogen in chronic periodontitis, did not induce NKT cell activation. This difference could be explained by the absence of a type I IFN response to P. gingivalis infection. We found these IFNs to be critical for NKT cell activation. Our study provides a conceivable biological distinction between the two periodontitis subforms and identifies factors required for the activation of the immune system in response to periodontal bacteria.

New attempts to modify periodontal risk assessment for generalized aggressive periodontitis: a retrospective study

BACKGROUND

Periodontal risk assessment (PRA) model was designed for risk evaluation of treated patients with periodontal disease. However, its use on generalized aggressive periodontitis (GAgP) had been scarcely reported. This study aims to investigate the association of original PRA/modified PRA (MPRA) and compliance of periodontal maintenance with long-term treatment outcomes of Chinese patients with GAgP.

METHODS

Eighty-eight patients from a GAgP cohort, who completed active periodontal treatment (APT) and accepted reevaluation 3 to 11 years (mean of 5.5 years) afterward, were enrolled. PRA was modified (three strategies involving replacement of bleeding on probing with bleeding index >2, counting sites with probing depth ≥6 mm and changing method of bone loss [BL] calculation) to classify patients into different risk groups based on data at the first recall after APT. PRA and three MPRA models were investigated regarding long-term association with tooth loss (TL) and alteration of bone level (∆BL).

RESULTS

Based on original PRA, 87 patients (98.8%) had a high-risk profile. According to three MPRA models, annual TL per patient values were greater in high-risk groups than in low-to-moderate risk groups (MPRA-1, 0.20 ± 0.33 versus 0.04 ± 0.14; MPRA-2, 0.18 ± 0.32 versus 0.05 ± 0.14; MPRA-3, 0.17 ± 0.32 versus 0.05 ± 0.15; P <0.05). By MPRA-1, irregular compliers with low-to-moderate risk profile had greater ∆BL (0.027 ± 0.031, indicating bone increment) than those with high risk (-0.012 ± 0.064, tendency for BL). For regular compliers, no significant differences of annual TL or ∆BL were found between risk groups.

CONCLUSIONS

MPRA models could be used for evaluating the long-term outcomes of Chinese patients with severe GAgP, especially irregular compliers. High-risk patients of MPRAs exhibited more TL and less bone fill than low-to-moderate risk ones.

Role of the NK cell-activating receptor CRACC in periodontitis

Periodontitis is a highly prevalent, biofilm-mediated chronic inflammatory disease that results in the loss of the tooth-supporting tissues. It features two major clinical entities: chronic periodontitis, which is more common, and aggressive periodontitis, which usually has an early onset and a rapid progression. Natural killer (NK) cells are a distinct subgroup of lymphocytes that play a major role in the ability of the innate immune system to steer immune responses. NK cells are abundant in periodontitis lesions, and NK cell activation has been causally linked to periodontal tissue destruction. However, the exact mechanisms of their activation and their role in the pathophysiology of periodontitis are elusive. Here, we show that the predominant NK cell-activating molecule in periodontitis is CD2-like receptor activating cytotoxic cells (CRACC). We show that CRACC induction was significantly more pronounced in aggressive than chronic periodontitis and correlated positively with periodontal disease severity, subgingival levels of specific periodontal pathogens, and NK cell activation in vivo. We delineate how Aggregatibacter actinomycetemcomitans, an oral pathogen that is causally associated with aggressive periodontitis, indirectly induces CRACC on NK cells via activation of dendritic cells and subsequent interleukin 12 (IL-12) signaling. In contrast, we demonstrate that fimbriae from Porphyromonas gingivalis, a principal pathogen in chronic periodontitis, actively attenuate CRACC induction on NK cells. Our data suggest an involvement of CRACC-mediated NK cell activation in periodontal tissue destruction and point to a plausible distinction in the pathobiology of aggressive and chronic periodontitis that may help explain the accelerated tissue destruction in aggressive periodontitis.

Oral hygiene, periodontal health and chronic obstructive pulmonary disease exacerbations

AIM

To assess the associations of oral hygiene and periodontal health with chronic obstructive pulmonary disease (COPD) exacerbations.

MATERIAL AND METHODS

In total, 392 COPD patients were divided into frequent and infrequent exacerbation (≥2 times and <2 times in last 12 months) groups. Their lung function and periodontal status were examined. Information on oral hygiene behaviours was obtained by interview.

RESULTS

In the univariate analysis, fewer remaining teeth, high plaque index (PLI) scores, low tooth brushing times, and low regular supra-gingival scaling were significantly associated with COPD exacerbations (all p-values <0.05). After adjustment for age, gender, body mass index, COPD severity and dyspnoea severity, the associations with fewer remaining teeth (p = 0.02), high PLI scores (p = 0.02) and low tooth brushing times (p = 0.008) remained statistically significant. When stratified by smoking, fewer remaining teeth (OR = 2.05, 95% CI: 1.04-4.02) and low tooth brushing times (OR = 4.90, 95% CI: 1.26-19.1) among past smokers and high PLI scores (OR = 3.43, 95% CI: 1.19-9.94) among never smokers were significantly associated with COPD exacerbations.

CONCLUSIONS

Fewer remaining teeth, high PLI scores, and low tooth brushing times are significant correlates of COPD exacerbations, indicating that improving periodontal health and oral hygiene may be a potentially preventive strategy against COPD exacerbations.