Black-pigmented Bacteroides spp. in the human oral cavity

The Impact of Prevotella on Neurobiology in Aging: Deciphering Dendritic Cell Activity and Inflammatory Dynamics

Prevotella species, notably Prevotella copri, significantly populate the human gut. In particular, P. copri is prevalent among non-Western populations with diets high in fiber. These species show complex relationships with diverse health aspects, associating with beneficial outcomes, including reduced visceral fat and improved glucose tolerance. Studies implicate various Prevotella species in specific diseases. Prevotella nigrescens and Porphyromonas gingivalis were linked to periodontal disease, promoting immune responses and influencing T helper type 17 (Th17) cells. Prevotella bivia was associated with bacterial vaginosis and a specific increase in activated cells in the vaginal mucosa. In contrast, they have shown substantial potential for inducing connective tissue degradation and alveolar bone resorption. Prevotella's role in neuroinflammatory disorders and autoinflammatory conditions such as Alzheimer's disease and Parkinson's disease has also been noted. The complex relationship between Prevotella and age-related conditions further extends to neurobiological changes in aging, with varying associations with Alzheimer's, Parkinson's, and other inflammatory conditions. Studies have also identified Prevotella to be implicated in cognitive decline in middle aged and the elderly. Future directions in this research area are anticipated to explore Prevotella-associated inflammatory mechanisms and therapeutic interventions. Investigating specific drug targets and immunomodulatory measures could lead to novel therapeutic strategies. Understanding how Prevotella-induced inflammation interacts with aging diseases would offer promising insights for treatments and interventions. This review urges ongoing research to discover therapeutic targets and mechanisms for moderating Prevotella-associated inflammation to further enhance our understanding and improve health outcomes.

Phages are unrecognized players in the ecology of the oral pathogen Porphyromonas gingivalis

BACKGROUND

Porphyromonas gingivalis (hereafter "Pg") is an oral pathogen that has been hypothesized to act as a keystone driver of inflammation and periodontal disease. Although Pg is most readily recovered from individuals with actively progressing periodontal disease, healthy individuals and those with stable non-progressing disease are also colonized by Pg. Insights into the factors shaping the striking strain-level variation in Pg, and its variable associations with disease, are needed to achieve a more mechanistic understanding of periodontal disease and its progression. One of the key forces often shaping strain-level diversity in microbial communities is infection of bacteria by their viral (phage) predators and symbionts. Surprisingly, although Pg has been the subject of study for over 40 years, essentially nothing is known of its phages, and the prevailing paradigm is that phages are not important in the ecology of Pg.

RESULTS

Here we systematically addressed the question of whether Pg are infected by phages-and we found that they are. We found that prophages are common in Pg, they are genomically diverse, and they encode genes that have the potential to alter Pg physiology and interactions. We found that phages represent unrecognized targets of the prevalent CRISPR-Cas defense systems in Pg, and that Pg strains encode numerous additional mechanistically diverse candidate anti-phage defense systems. We also found that phages and candidate anti-phage defense system elements together are major contributors to strain-level diversity and the species pangenome of this oral pathogen. Finally, we demonstrate that prophages harbored by a model Pg strain are active in culture, producing extracellular viral particles in broth cultures.

CONCLUSION

This work definitively establishes that phages are a major unrecognized force shaping the ecology and intra-species strain-level diversity of the well-studied oral pathogen Pg. The foundational phage sequence datasets and model systems that we establish here add to the rich context of all that is already known about Pg, and point to numerous avenues of future inquiry that promise to shed new light on fundamental features of phage impacts on human health and disease broadly. Video Abstract.

Pu-erh tea alleviated colitis-mediated brain dysfunction by promoting butyric acid production

Brain inflammation develops with increased colitis. Pu-erh tea is considered a potential dietary intervention to improve colitis. However, it's unclear whether Pu-erh tea helps alleviate colitis-mediated brain dysfunction. Here, we found that colitis triggered brain dysfunction and increased the risk of depression. Pu-erh tea improved gut-brain barrier function (increased ZO-1 and Occludin) and restored short-chain fatty acids (SCFAs) as well as neurotransmitter release (γ-GABA, 5-HT, and dopamine), which stemmed from the production of butyric acid (BA). Pu-erh tea and BA promoted the production of SCFAs by reshaping the gut microbes (increased Lactobacillus, Akkermansia, Faecalibaculum), thereby downregulating gut inflammatory protein expression (PI3K/AKT/NF-κB). SCFAs, especially BA, intervened directly in the blood-brain barrier via the gut-brain axis to restore neurotransmitter release. Collectively, our results highlighted that increasing BA through Pu-erh tea consumption may be a key mechanism for improving colitis-mediated brain dysfunction by lowering gut inflammation and balancing gut microbe-gut-brain axis homeostasis. These results provide a promising step that might encourage further investigations of Pu-erh tea as a protective agent for brain function in colitis patients.

Prevotella species as oral residents and infectious agents with potential impact on systemic conditions

Oral Prevotella are known as anaerobic commensals on oral mucosae and in dental plaques from early life onwards, including pigmented P. melaninogenica, P. nigrescens, and P. pallens and non-pigmented Prevotella species. Many Prevotella species contribute to oral inflammatory processes, being frequent findings in dysbiotic biofilms of periodontal diseases (P. intermedia, P. nigrescens), cariotic lesions (P. denticola, Alloprevotella (formerly Prevotella) tannerae), endodontic infections (P. baroniae, P. oris, P. multisaccharivorax), and other clinically relevant oral conditions. Over the years, several novel species have been recovered from the oral cavity without knowledge of their clinical relevance. Within this wide genus, virulence properties and other characteristics like biofilm formation seemingly vary in a species- and strain-dependent manner, as shown for the P. intermedia group organisms (P. aurantiaca, P. intermedia, P. nigrescens, and P. pallens). Oral Prevotella species are identified in various non-oral infections and chronic pathological conditions. Here, we have updated the knowledge of the genus Prevotella and the role of Prevotella species as residents and infectious agents of the oral cavity, as well as their detection in non-oral infections, but also gathered information on their potential link to cancers of the head and neck, and other systemic disorders.

Prevotella diversity, niches and interactions with the human host

The genus Prevotella includes more than 50 characterized species that occur in varied natural habitats, although most Prevotella spp. are associated with humans. In the human microbiome, Prevotella spp. are highly abundant in various body sites, where they are key players in the balance between health and disease. Host factors related to diet, lifestyle and geography are fundamental in affecting the diversity and prevalence of Prevotella species and strains in the human microbiome. These factors, along with the ecological relationship of Prevotella with other members of the microbiome, likely determine the extent of the contribution of Prevotella to human metabolism and health. Here we review the diversity, prevalence and potential connection of Prevotella spp. in the human host, highlighting how genomic methods and analysis have improved and should further help in framing their ecological role. We also provide suggestions for future research to improve understanding of the possible functions of Prevotella spp. and the effects of the Western lifestyle and diet on the host-Prevotella symbiotic relationship in the context of maintaining human health.

Microbiological and SEM assessment of atraumatic restorative treatment in adult dentition

OBJECTIVES

To investigate the practicability of atraumatic restorative treatment (ART) in adults in terms of marginal adaptation of restorations and microbiological changes in residual carious dentin.

MATERIALS AND METHODS

The occlusal dentin caries of 25 permanent molar teeth were removed with hand instruments. The total counts of bacteria (TCB) and the facultative anaerobic bacteria (FAB), mutans streptococci (MS), and Lactobacillus spp. (LB) counts in the affected dentin were evaluated quantitatively. The weights of the samples were measured with an electronic balance (Shimadzu, Type AX200, Japan). The cavities were restored with glass ionomer cement (Ketac^TM Molar Easymix, ESPE Dental AG, Seefeld, Germany). Twenty replicas of randomly selected ART restorations were prepared and marginal adaptation was evaluated by scanning electron microscopy (SEM). After 6 months, the same protocols were repeated. Data were analyzed with paired sample t-tests, Wilcoxon t-tests, Pearson and Spearman correlations, and chi-square tests (p<0.05).

RESULTS

In the sixth month, restoration loss and pulpitis were not observed. The mean weight of samples removed from the cavity floor was less than the baseline (0.014±0.009 and 0.023±0.013 g, respectively) (p<0.01), and the counts of total bacteria, FAB, MS, and LB significantly decreased compared to baseline (p<0.01). The frequency of marginal gaps was increased (p< 0.01).

CONCLUSIONS

ART showed that the counts of microorganisms decreased after 6 months although the marginal gap rates of restorations increased.

CLINICAL RELEVANCE

ART can be a reliable treatment approach in adults for 6 months due to the decrease in microorganism counts, although gaps exist.

Maintaining a protective state for human periodontal tissue

Periodontitis, caused by infection with periodontal pathogens, is primarily characterized by inflammatory bone resorption and destruction of connective tissue. Simply describing periodontitis as a specific bacterial infection cannot completely explain the various periodontal tissue destruction patterns observed. Periodontal tissue damage is thought to be caused by various factors. In recent years, research goals for periodontal pathogens have shifted from searching for specific pathogens to investigating mechanisms that damage periodontal tissues. Bacteria interact directly with the host in several ways, influencing expression and activity of molecules that evade host defenses, and destroying local tissues and inhibiting their repair. The host's innate and acquired immune systems are important defense mechanisms that protect periodontal tissues from attack and invasion of periodontal pathogens, thus preventing infection. Innate and acquired immunity have evolved to confront the microbial challenge, forming a seamless defense network in periodontal tissues. In the innate immune response, host cells quickly detect, via specialized receptors, macromolecules and nucleic acids present on bacterial cell walls, and this triggers a protective, inflammatory response. The work of this subsystem of host immunity is performed mainly by phagocytes, beta-defensin, and the complement system. In addition, the first line of defense in oral innate immunity is the junctional epithelium, which acts as a physical barrier to the entry of oral bacteria and other nonself substances. In the presence of a normal flora, junctional epithelial cells differentiate actively and proliferate apically, with concomitant increase in chemotactic factor expression recruiting neutrophils. These immune cells play an important role in maintaining homeostasis and the protective state in periodontal tissue because they eliminate unwanted bacteria over time. Previous studies indicate a mechanism for attracting immune cells to periodontal tissue with the purpose of maintaining a protective state; although this mechanism can function without bacteria, it is enhanced by the normal flora. A better understanding of the relationship between the protective state and its disruption in periodontal disease could lead to the development of new treatment strategies for periodontal disease.

Identification of Potential Oral Microbial Biomarkers for the Diagnosis of Periodontitis

Periodontitis is a chronic and multifactorial inflammatory disease that can lead to tooth loss. At present, the diagnosis for periodontitis is primarily based on clinical examination and radiographic parameters. Detecting the periodontal pathogens at the subgingival plaque requires skilled professionals to collect samples. Periodontal pathogens are also detected on various mucous membranes in patients with periodontitis. In this study, we characterized the oral microbiome profiles from buccal mucosa and supragingival space in a total of 272 healthy subjects as a control group, and periodontitis patients as a disease group. We identified 13 phyla, 193 genera, and 527 species and determined periodontitis-associated taxa. Porphyromonas gingivalis, Tannerella forsythia, Treponema denticolar, Filifactor alocis, Porphyromonas endodontalis, Fretibacterium fastiosum and Peptostreptococcus species were significantly increased in both the buccal mucosa and the supragingival space in periodontitis patients. The identified eight periodontitis-associated bacterial species were clinically validated in an independent cohort. We generated the prediction model based on the oral microbiome profiles using five machine learning algorithms, and validated its capability in predicting the status of patients with periodontitis. The results showed that the oral microbiome profiles from buccal mucosa and supragingival space can represent the microbial composition of subgingival plaque and further be utilized to identify potential microbial biomarkers for the diagnosis of periodontitis. Besides, bacterial community interaction network analysis found distinct patterns associated with dysbiosis in periodontitis. In summary, we have identified oral bacterial species from buccal and supragingival sites which can predict subgingival bacterial composition and can be used for early diagnosis of periodontitis. Therefore, our study provides an important basis for developing easy and noninvasive methods to diagnose and monitor periodontitis.

Comparison of Subgingival and Buccal Mucosa Microbiome in Chronic and Aggressive Periodontitis: A Pilot Study

Periodontal microorganisms not only colonize subgingival pockets, but also are detected on various mucous membranes in patients with periodontitis. The object of this pilot study was, using the next-generation sequencing of 16S RNA gene, to characterize the microbiota in two oral habitats (buccal mucosas and subgingival pockets) in patients with different forms of periodontitis. Thirty-two buccal swab samples and 113 subgingival samples were obtained from eleven subjects with chronic periodontitis (ChP), twelve subjects with aggressive periodontitis (AgP), and nine periodontally healthy individuals (HP). Using Miseq Sequencing of 16S rRNA gene, we found that the subgingival and buccal mucosa microbiome of ChP and AgP patients both differed from HP. Meanwhile, Veillonella, Treponema, Filifactor, Fretibacterium, Peptostreptococcaceae_[XI][G-6], Peptostreptococcaceae_[XI][G-5], Bacteroidetes_[G-5], Bacteroidetes_[G-3], Peptostreptococcaceae_[XI][G-4], Peptostreptococcaceae_[XI][G-2] significantly increased both in buccal and subgingival plaque samples in periodontitis subjects (ChP and AgP) compared with HP. Moreover, the results based on the Unweighted UniFrac distance showed that buccal and subgingival plaque samples from the same individuals show higher community divergence than same habitats from different subject samples. This study demonstrated that the microbiome of buccal mucosa can be influenced by periodontitis. However, subgingival and buccal mucosa microbiome seem to be characterized by species-specific colonization patterns. This pilot study provides a glimpse at the changes of subgingival and buccal mucosa associated with periodontitis from a holistic view. Further studies should be taken to illuminate the interplay between these detected changes and periodontitis development.

Azithromycin and erythromycin susceptibility and macrolide resistance genes in Prevotella from patients with periodontal disease

OBJECTIVES

To study oral Prevotella spp. isolated from patients with chronic periodontitis, to determine their susceptibility to azithromycin and erythromycin and to screen the presence of macrolide resistance genes therein.

MATERIAL AND METHODS

Isolates with a Prevotella-like morphology were obtained from subgingival samples of 52 patients with chronic periodontitis. Each isolate was identified to the species level by sequencing of the 16S rRNA gene. In 100 Prevotella spp. isolates, azithromycin and erythromycin susceptibility was determined using the E test method, and the screening of erm(A), erm(B), erm(C), erm(F), erm(G), erm(Q) and mef(A) genes was done by PCR.

RESULTS

Prevotella intermedia and Prevotella nigrescens were the most identified species (33% each). Minimum inhibitory concentrations (MICs) ranges for both antibiotics were 0.016/0.032 to >256 μg/ml. MIC₅₀ values for azithromycin and erythromycin were 1.5 and 1 μg/ml, respectively, and MIC₉₀ values were >256 μg/ml for both antibiotics. Nineteen per cent of the isolates carried erm(B), and 51% carried erm(F).

CONCLUSIONS

The MIC values found were high compared to previous studies. erm(F) was greatly prevalent, and we describe for the first time the erm(B) gene in Prevotella spp. The presence of either of the genes seems to be associated with a higher degree of resistance to azithromycin and erythromycin.

Risk factors for the presence of dental black plaque

In order to evaluate risk factors related to the presence of extrinsic dental black stain, a total of 94 orally healthy volunteers (47 individuals with dental black stain and 47 individuals without dental black stain) were recruited from ten different dental clinics in Valencia and Castellón (Spain). Data regarding their oral hygiene, dietary habits, and oral health status were gathered by questionnaire. Samples of dental plaque, saliva and drinking water were collected for chemical analysis. Three factors were found to be statistically significantly associated with dental black stain, (i) consuming water with high iron content, (ii) consuming water with high pH, and (iii) having a high salivary pH. Other factors such as smoking, taking iron supplements or consuming caffeinated drinks were not found to be risk factors for the presence of black stain. A multivariate logistic regression analysis showed that drinking tap or osmosis-purified water and lower levels of salivary iron increase the risk of having dental black stain. Overall, several risk factors for the presence of dental black stain have been identified. The main modifiable risk factor identified in this study was the consumption of tap or osmosis drinking water.

Actinomyces and Alimentary Tract Diseases: A Review of Its Biological Functions and Pathology

Actinomyces are nonmotile, filamentous, Gram-positive bacteria that cause actinomycosis in immunodeficiency patients. Although the prognosis of actinomycosis is good, the diagnosis of actinomycosis is quite difficult. Recent studies on actinomycosis have shown that Actinomyces play an important role in various biological and clinical processes, such as the formation of dental plaque and the degradation of organics in the gastrointestinal tract. Here, the distribution of Actinomyces in the digestive tract, and different biological effects of actinomycosis, and its clinical association with inflammatory diseases are discussed. Furthermore, an overview of the most commonly used treatment methods and drugs used to treat Actinomyces infected alimentary canal diseases is presented.

Microbial colonization of the periodontal pocket and its significance for periodontal therapy

The aim of this paper was to evaluate strategies for periodontal therapy from the perspective of periodontal disease being a consequence of microbial colonization of the periodontal pocket environment. In classic bacterial infections the diversity of the microbiota decreases as the disease develops. In most cases of periodontitis, however, the diversity of the flora increases. Most incriminating bacteria are thought to harm tissues significantly only if present in high numbers over prolonged periods of time. Clinical trials have repeatedly demonstrated that scaling and root planing, a procedure that aims to remove subgingival bacterial deposits by scraping on the tooth surface within the periodontal pocket, is effective. At present, for the therapy of any form of periodontal disease, there exists no protocol with proven superiority, in terms of efficiency or effectiveness, over scaling and root planing plus systemic amoxicillin and metronidazole. Some exponents advocate rationing these drugs for patients with a specific microbial profile. However, the evidence for any benefit of bacteriology-assisted clinical protocols is unsatisfactory. Treated sites are subject to recolonization with a microbiota similar to that present before therapy. The degree and speed of recolonization depends on the treatment protocol, the distribution patterns of periodontal microorganisms elsewhere in the oral cavity and the quality of the patient's oral hygiene. To limit the use of antibiotics and to avoid accumulation of harmful effects by repeated therapy, further efforts must be made to optimize procedures addressing the microbial colonization and recolonization of the periodontal pocket.

Population-Genomic Insights into Variation in Prevotella intermedia and Prevotella nigrescens Isolates and Its Association with Periodontal Disease

High-throughput sequencing has helped to reveal the close relationship between Prevotella and periodontal disease, but the roles of subspecies diversity and genomic variation within this genus in periodontal diseases still need to be investigated. We performed a comparative genome analysis of 48 Prevotella intermedia and Prevotella nigrescens isolates that from the same cohort of subjects to identify the main drivers of their pathogenicity and adaptation to different environments. The comparisons were done between two species and between disease and health based on pooled sequences. The results showed that both P. intermedia and P. nigrescens have highly dynamic genomes and can take up various exogenous factors through horizontal gene transfer. The major differences between disease-derived and health-derived samples of P. intermedia and P. nigrescens were factors related to genome modification and recombination, indicating that the Prevotella isolates from disease sites may be more capable of genomic reconstruction. We also identified genetic elements specific to each sample, and found that disease groups had more unique virulence factors related to capsule and lipopolysaccharide synthesis, secretion systems, proteinases, and toxins, suggesting that strains from disease sites may have more specific virulence, particularly for P. intermedia. The differentially represented pathways between samples from disease and health were related to energy metabolism, carbohydrate and lipid metabolism, and amino acid metabolism, consistent with data from the whole subgingival microbiome in periodontal disease and health. Disease-derived samples had gained or lost several metabolic genes compared to healthy-derived samples, which could be linked with the difference in virulence performance between diseased and healthy sample groups. Our findings suggest that P. intermedia and P. nigrescens may serve as “crucial substances” in subgingival plaque, which may reflect changes in microbial and environmental dynamics in subgingival microbial ecosystems. This provides insight into the potential of P. intermedia and P. nigrescens as new predictive biomarkers and targets for effective interventions in periodontal disease.

Restriction Fragment Length Polymorphism Analysis of the Fimbrillin Locus, fimA, of Porphyromonas gingivalis

With hybridization probes derived from the fimbrial locus of Porphyromonas gingivalis strain 381, fimA381' restriction fragment length polymorphisms (RFLPs) were examined at the fimbrillin locus in 39 human and animal strains of this species. The 39 strains were subdivided into nine RFLP groups (I-IX) after genomic digests were probed with the internal coding sequence of the fimA381 gene. Thirty-three strains showed one or more AluI fragments of moderate-to-high homology (≥77%) with the internal coding sequence of fimA381. These strains were distributed into the first seven RFLP groups, based solely on the size of the major hybridizing AluI fragment. Five human strains (RFLP Group VIII) had only one Alu I fragment that hybridized very poorly with this probe. One animal strain did not have homology at all (RFLP Group IX). When all AluI fragments that hybridized with fimA381 were analyzed, RFLP groups I-VIII were further differentiated into 25 distinct RFLP patterns. Hybridizations were also performed with the internal coding sequence of fimA381 to probe PstI genomic digests of selected strains that appeared to have lesser homology with fimA381. These hybridizations were performed to determine the level and location of the region of poor homology within the fimA genes of these strains. The results suggested that fimbrial coding sequences are more commonly conserved between these strains in the 5'-region of the fimA locus (≥92% sequence homology). However, the five human strains of RFLP Group VIII had only one PstI fragment that hybridized very poorly with a probe derived from fimA381 coding sequence, and this sequence homology (only > 66%) was located in the central or 3'-end of the fimA gene. The 5'-region of the fimA allele in Group VIII strains did not have any detectable sequence homology. In contrast, the Group VIII strains were highly homologous with the sequences flanking the fimA381 gene. This indicates that these strains do possess a fimA allele at the same chromosomal location as fimA381.

Purinergic signaling during Porphyromonas gingivalis infection

Despite recent advances unraveling mechanisms of host-pathogen interactions in innate immunity, the participation of purinergic signaling in infection-driven inflammation remains an emerging research field with many unanswered questions. As one of the most-studied oral pathogens, Porphyromonas gingivalis is considered as a keystone pathogen with a central role in development of periodontal disease. This pathogen needs to evade immune-mediated defense mechanisms and tolerate inflammation in order to survive in the host. In this review, we summarize evidence showing that purinergic signaling modulates P. gingivalis survival and cellular immune responses, and discuss the role played by inflammasome activation and cell death during P. gingivalis infection.

Association between Polycystic Ovary Syndrome and Gut Microbiota

Polycystic ovary syndrome (PCOS) is the most frequent endocrinopathy in women of reproductive age. It is difficult to treat PCOS because of its complex etiology and pathogenesis. Here, we characterized the roles of gut microbiota on the pathogenesis and treatments in letrozole (a nonsteroidal aromatase inhibitor) induced PCOS rat model. Changes in estrous cycles, hormonal levels, ovarian morphology and gut microbiota by PCR-DGGE and real-time PCR were determined. The results showed that PCOS rats displayed abnormal estrous cycles with increasing androgen biosynthesis and exhibited multiple large cysts with diminished granulosa layers in ovarian tissues. Meanwhile, the composition of gut microbiota in letrozole-treated rats was different from that in the controls. Lactobacillus, Ruminococcus and Clostridium were lower while Prevotella was higher in PCOS rats when compared with control rats. After treating PCOS rats with Lactobacillus and fecal microbiota transplantation (FMT) from healthy rats, it was found that the estrous cycles were improved in all 8 rats in FMT group, and in 6 of the 8 rats in Lactobacillus transplantation group with decreasing androgen biosynthesis. Their ovarian morphologies normalized. The composition of gut microbiota restored in both FMT and Lactobacillus treated groups with increasing of Lactobacillus and Clostridium, and decreasing of Prevotella. These results indicated that dysbiosis of gut microbiota was associated with the pathogenesis of PCOS. Microbiota interventions through FMT and Lactobacillus transplantation were beneficial for the treatments of PCOS rats.

Efficacy of Photodynamic Therapy and Lasers as an Adjunct to Scaling and Root Planing in the Treatment of Aggressive Periodontitis - A Clinical and Microbiologic Short Term Study

INTRODUCTION

Aggressive periodontitis comprises a group of rare, severe, rapidly progressive form of periodontitis. Conventional treatment includes mechanical debridement augmented with adjunctive antimicrobial therapy. Development of antibiotic resistance has led to use of lasers. Photodynamic therapy (PDT) is a novel non-invasive therapeutic approach with increased site and pathogen specificity. This study compares PDT and Lasers as an adjunct to conventional Scaling in the treatment of patients with aggressive periodontitis.

MATERIALS AND METHODS

Fifteen untreated aggressive periodo-ntitis patients were randomly assigned in a split mouth design for one of the following treatment modalities: 1) SRP alone; (2) SRP + Diode Laser irradiation with 810 nm at 1W, continuous mode for 30 sec per tooth; (3) SRP + PDT on "0" day; (4) SRP + PDT on "0", 7(th) and 21(st) day. The clinical parameters included PI, BOP, PPD, CAL recorded at the baseline & 3(rd) month. The site with greatest probing pocket depth (PPD) was selected from each quadrant for bacterial sampling and cultured for Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis & Prevotella intermedia.

RESULTS

Statistically significant reduction in clinical & microbial parameters was seen. Sites 4 showed a greater reduction compared to other groups.

CONCLUSION

Photodynamic therapy is a valuable treatment modality adjunctive to conventional scaling and root planing.

Comparative evaluation of the efficacy of curcumin gel with and without photo activation as an adjunct to scaling and root planing in the treatment of chronic periodontitis: A split mouth clinical and microbiological study

Aims and Objectives:

Harnessing Mother Nature's bountiful remedies for rejuvenation has been in vogue since time immemorial. Turmeric contains the polyphenol Curcumin in its rhizome. It produces reactive oxygen species (ROS) with visible light irradiation as photodynamic therapy (PDT) - which validates its use in the treatment of periodontitis. This study compares Curcumin and Curcumin PDT as an adjunct to conventional Scaling and Root Planing (SRP) with SRP alone in the treatment of patients with chronic periodontitis.

Materials and Methods:

Sixty sites in fifteen untreated chronic periodontitis patients were randomly assigned in a split mouth design for one of the treatment modalities; 1) Scaling and root planing (SRP) alone, (2) SRP + Curcumin application for 5 min, (3) SRP + Curcumin application for 5 min + irradiation with blue light emitting diode of wavelength 470 nm for 5 min. (Curcumin PDT) on 0 day.(4) SRP + Curcumin PDT on “0”, 7^th and 21^st day. The clinical parameters included plaque index (PI), bleeding on probing (BOP) measured by sulcus bleeding index (SBI), probing pocket depth (PPD), clinical attachment level (CAL) recorded at the baseline & 3^rd month. The site with greatest probing pocket depth (PPD) was selected from each quadrant for bacterial sampling and culturing for Aggregatibacter actinomycetemcomitans (Aa) and other black pigment producing microorganisms (BPB) like Porphyromonas gingivalis & Prevotella intermedia.

Conclusion:

The present study showed that Curcumin photodynamic therapy is a valuable treatment modality adjunctive to conventional scaling and root planing over Curcumin application. Moreover, multiple adjunctive applications of photodynamic therapy are more beneficial than single application in reducing clinical & microbiological parameters.

Anaerobic culture to detect periodontal and caries pathogens

BACKGROUND

Anaerobic culture has been critical in our understanding of the oral microbiotas.

HIGHLIGHT

Studies in advanced periodontitis in the 1970's revealed microbial complexes that associated with different clinical presentations. Taxonomy studies identified species newly-observed in periodontitis as Aggregatibacter (Actinobacillus) actinomycetemcomitans, Campylobacter (Wolinella) rectus and other Campylobacter species, and Tannerella (Bacteroides) forsythia. Anaerobic culture of initial periodontitis showed overlap in the microbiota with gingivitis, and added Selenomonas noxia and Filifactor alocis as putative periodontal pathogens. Porphyromonas gingivalis and T. forsythia were found to be associated with initial periodontitis in adults. The dominant microbiota of dental caries differs from that of periodontitis. The major cariogenic species are acidogenic and acid tolerant species particularly Streptococcus mutans, and Lactobacillus and Bifidobacterium species. Anaerobic culture of severe early childhood caries revealed a widely diverse microbiota, comparable to that observed using cloning and sequencing. The PCR-based cloning approach, however, underestimated Actinobacteria compared with culture. Only a subset of the caries-associated microbiota was acid tolerant, with different segments of the microbiota cultured on blood agar compared to a low pH acid agar. While the major caries-associated species was S. mutans, a new species, Scardovia wiggsiae, was significantly associated with early childhood caries. Higher counts of S. wiggsiae were also observed in initial white spot carious lesions in adolescents.

CONCLUSION

In periodontitis and dental caries, anaerobic culture studies of advanced disease provided a comprehensive analysis of the microbiota of these infections. Anaerobic culture highlighted the limitation of PCR with standard primers that underestimate detection of Actinobacteria.

Learned and unlearned concepts in periodontal diagnostics: a 50-year perspective

In the past 50 years, conceptual changes in the field of periodontal diagnostics have paralleled those associated with a better scientific understanding of the full spectrum of processes that affect periodontal health and disease. Fifty years ago, concepts regarding the diagnosis of periodontal diseases followed the classical pathology paradigm. It was believed that the two basic forms of destructive periodontal disease were chronic inflammatory periodontitis and 'periodontosis'- a degenerative condition. In the subsequent 25 years it was shown that periodontosis was an infection. By 1987, major new concepts regarding the diagnosis and pathogenesis of periodontitis included: (i) all cases of untreated gingivitis do not inevitably progress to periodontitis; (ii) progression of untreated periodontitis is often episodic; (iii) some sites with untreated periodontitis do not progress; (iv) a rather small population of specific bacteria ('periodontal pathogens') appear to be the main etiologic agents of chronic inflammatory periodontitis; and (v) tissue damage in periodontitis is primarily caused by inflammatory and immunologic host responses to infecting agents. The concepts that were in place by 1987 are still largely intact in 2012. However, in the decades to come, it is likely that new information on the human microbiome will change our current concepts concerning the prevention, diagnosis and treatment of periodontal diseases.

Evaluation of the effect of one stage versus two stage full mouth disinfection on C-reactive protein and leucocyte count in patients with chronic periodontitis

Background:

Conventional non-surgical periodontal therapy is carried out in quadrant basis with 1-2 week interval. This time lag may result in re-infection of instrumented pocket and may impair healing. Therefore, a new approach to full-mouth non-surgical therapy to be completed within two consecutive days with full-mouth disinfection has been suggested. In periodontitis, leukocyte counts and levels of C-reactive protein (CRP) are likely to be slightly elevated, indicating the presence of infection or inflammation. The aim of this study is to compare the efficacy of one stage and two stage non-surgical therapy on clinical parameters along with CRP levels and total white blood cell (TWBC) count.

Materials and Methods:

A total of 20 patients were selected and were divided into two groups. Group 1 received one stage full mouth dis-infection and Group 2 received two stages FMD. Plaque index, sulcus bleeding index, probing depth, clinical attachment loss, serum CRP and TWBC count were evaluated for both the groups at baseline and at 1 month post-treatment.

Results:

The results were analyzed using the Student t-test. Both treatment modalities lead to a significant improvement of the clinical and hematological parameters; however comparison between the two groups showed no significant difference after 1 month.

Conclusion:

The therapeutic intervention may have a systemic effect on blood count in periodontitis patients. Though one stage FMD had limited benefits over two stages FMD, the therapy can be accomplished in a shorter duration.

Metagenomic sequencing reveals microbiota and its functional potential associated with periodontal disease

Although attempts have been made to reveal the relationships between bacteria and human health, little is known about the species and function of the microbial community associated with oral diseases. In this study, we report the sequencing of 16 metagenomic samples collected from dental swabs and plaques representing four periodontal states. Insights into the microbial community structure and the metabolic variation associated with periodontal health and disease were obtained. We observed a strong correlation between community structure and disease status, and described a core disease-associated community. A number of functional genes and metabolic pathways including bacterial chemotaxis and glycan biosynthesis were over-represented in the microbiomes of periodontal disease. A significant amount of novel species and genes were identified in the metagenomic assemblies. Our study enriches the understanding of the oral microbiome and sheds light on the contribution of microorganisms to the formation and succession of dental plaques and oral diseases.

Purification and characterization of a novel secondary fimbrial protein from Porphyromonas gulae

Background

Porphyromonas gulae are black-pigmented anaerobic bacteria isolated from the gingival sulcus of various animal hosts and are distinct from Porphyromonas gingivalis originating in humans. We previously reported the antigenic similarities of 41-kDa fimbriae between P. gulae ATCC 51700 and P. gingivalis ATCC 33277. In this study, to clarify the presence of another type of fimbriae of P. gulae, we have purified and characterized the secondary fimbrial protein from P. gulae ATCC 51700.

Methods

The secondary fimbrial protein was purified from P. gulae ATCC 51700 using an immunoaffinity column coupling with antibodies against the 41-kDa fimbrial protein. The expression of fimbriae on the cell surface of P. gulae ATCC 51700 was investigated by transmission electron microscopy. The N-terminal amino acid sequence was determined by an amino acid sequencer system.

Results

The molecular mass of this protein was approximately 53-kDa, as estimated by SDS-PAGE. The polyclonal antibodies against the 53-kDa protein did not react with the 41-kDa fimbrial protein of P. gulae ATCC 51700. Immunogold electron microscopy revealed that anti-53-kDa fimbrial serum bound to fimbria on the cell surface of P. gulae ATCC 51700. The amino acid sequence of the N-terminal 15 residues of the 53-kDa fimbrial protein showed only 1 of 15 residues identical to the 41-kDa fimbrial protein.

Conclusion

The 53-kDa fimbriae are different in molecular weight and antigenicity from the 41-kDa fimbrial protein of P. gulae ATCC 51700. These results clearly suggest that the 41-kDa and the 53-kDa fimbriae are distinct types of fimbriae expressed simultaneously by this organism.

Porphyromonas gingivalis fimbriae carbohydrate specificity assessment by glycomics

Porphyromonas gingivalis is a major pathogen in adult periodontitis. Fimbriae play an important role in the initial interaction between the bacteria and the host. Our earlier studies suggested that the oligosaccharide moiety of lactoferrin is involved in the interaction with fimbriae. Porphyromonas gingivalis fimbriae bound strongly to albumin-fucosylamide (albumin-1-amido-1-deoxy-L-fucose) and to a lesser extent to albumin-N-acetyl-D-galactosamine (albumin-p-aminophenyl-N-acetyl-β-D-galactosaminide, but failed to bind bovine serum albumin. In this study we explored the glycan array to determine the carbohydrate-binding specificity of P. gingivalis fimbriae. Purified fimbriae bind to glycans which have a Lewis(x), Galβ1-4(Fucα1-3) GlcNAcβ structure in common. Interestingly, all glycans have a terminal fucose moiety and if fucose is removed, the fimbriae fail to bind. This is the first study that suggests that fucose is important for P. gingivalis fimbriae binding.

Porphyromonas gingivalis induces RANKL in bone marrow stromal cells: involvement of the p38 MAPK

Periodontitis is a bacterially-induced oral inflammatory disease that is characterised by tissue degradation and bone loss. Porphyromonas gingivalis is a gram negative bacterial species highly associated with the pathogenesis of chronic periodontitis. Receptor activator of nuclear factor-kB ligand (RANKL) induces bone resorption whilst osteoprotegerin (OPG) is a decoy receptor that blocks this process. Cyclooxygenase-2 (COX-2) is an enzyme responsible for the production of prostaglandin (PGE)(2,) which is a major inflammatory mediator of bone resorption. Mitogen-activated protein kinases (MAPK) are intracellular signalling molecules involved in various cell processes, including inflammation. This study aimed to investigate the effect of P. gingivalis on MAPKs and their involvement in the regulation of RANKL, OPG and COX-2 expression in bone marrow stromal cells. P. gingivalis challenge resulted in the phosphorylation of primarily the p38 MAPK. RANKL and COX-2 mRNA expressions were up-regulated, whereas OPG was down-regulated by P. gingivalis. The p38 synthetic inhibitor SB203580 abolished the P. gingivalis-induced RANKL and COX-2 expression, but did not affect OPG. Collectively, these results suggest that the p38 MAPK pathway is involved in the induction of RANKL and COX-2 by P. gingivalis, providing further insights into the pathogenic mechanisms of periodontitis.

Effect of smoking on subgingival microflora of patients with periodontitis in Japan

Background

Smoking is a risk factor for periodontitis. To clarify the contribution of smoking to periodontitis, it is essential to assess the relationship between smoking and the subgingival microflora. The aim of this study was to gain an insight into the influence of smoking on the microflora of Japanese patients with periodontitis.

Methods

Sixty-seven Japanese patients with chronic periodontitis (19 to 83 years old, 23 women and 44 men) were enrolled in the present study. They consisted of 30 smokers and 37 non-smokers. Periodontal parameters including probing pocket depth (PPD) and bleeding on probing (BOP) and oral hygiene status were recorded. Detection of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum/periodonticum, Treponema denticola and Campylobacter rectus in subgingival plaque samples was performed by polymerase chain reaction. Association between the detection of periodontopathic bacteria and smoking status was analyzed by multiple logistic regression analysis and chi-square test.

Results

A statistically significant association was found between having a PPD ≥ 4 mm and detection of T. denticola, P. intermedia, T. forsythia, or C. rectus, with odds ratios ranging from 2.17 to 3.54. A significant association was noted between BOP and the detection of C. rectus or P. intermedia, and smoking, with odds ratios ranging from 1.99 to 5.62. Prevalence of C. rectus was higher in smokers than non-smokers, whereas that of A. actinomycetemcomitans was lower in smokers.

Conclusions

Within limits, the analysis of the subgingival microbial flora in smokers and non-smokers with chronic periodontitis suggests a relevant association between smoking and colonization by the specific periodontal pathogens including C. rectus.

In vitro studies of the ablation mechanism of periodontopathic bacteria and decontamination effect on periodontally diseased root surfaces by erbium:yttrium-aluminum-garnet laser

The erbium:yttrium-aluminum-garnet (Er:YAG) laser is now increasingly used in periodontal therapy. The purpose of this study was to investigate the effect of Er:YAG laser irradiation on the morphology of periodontopathic bacteria and to compare the bacterial elimination effect of the laser and the ultrasonic scaler on diseased root surfaces in vitro. Colonies of Porphyromonas gingivalis were exposed to a single-pulse Er:YAG laser at 40 mJ and were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, 20 pairs of periodontally diseased root surfaces with subgingival calculi of freshly extracted teeth were treated by Er:YAG laser scaling at 40 mJ/pulse (14.2 J/cm(2) per pulse) and 10 Hz with water spray or ultrasonic scaling, or were not treated. The efficiency of each treatment was determined as the area treated per second, and the treated surfaces were examined by SEM. The material scraped from the treated root surfaces was cultured in aerobic and anaerobic conditions, and the numbers of colony forming units (CFUs) were compared. SEM and TEM showed that the Er:YAG laser had easily ablated the bacterial colony, leaving an ablation spot with a crater and the surrounding affected area showing melted branch-like structures. The laser irradiation was as equally effective and efficient as the ultrasonic scaler in performing root surface debridement. The CFUs after laser treatment were significantly fewer than those after ultrasonic scaling in aerobic and anaerobic culture conditions. Er:YAG laser ablates periodontopathic bacteria with thermal vaporization, and its bacterial elimination effect on the diseased root surfaces appears to be superior to that of the ultrasonic scaler.

Proteome analysis of Porphyromonas gingivalis cells placed in a subcutaneous chamber of mice

INTRODUCTION

Porphyromonas gingivalis, an oral anaerobic bacterium, is considered a major pathogen for chronic periodontitis. Pathogenic bacteria usually upregulate or downregulate gene expression to combat the protective responses of their hosts.

METHODS

To determine what protein is regulated when P. gingivalis cells invade host tissues, we analyzed the proteome of P. gingivalis cells that were placed in a mouse subcutaneous chamber by two-dimensional gel electrophoresis and mass spectrometry.

RESULTS

Fourteen proteins were upregulated, while four proteins were downregulated. We focused on three upregulated proteins, PG1089 (DNA-binding response regulator RprY), PG1385 (TPR domain protein), and PG2102 (immunoreactive 61-kDa antigen), and constructed mutant strains that were defective in these proteins. Mouse abscess model experiments revealed that the mutant strain defective in PG1385 was clearly less virulent than the wild-type parent strain.

CONCLUSION

These results indicate that the PG1385 protein is involved in P. gingivalis virulence and that the method used here is useful when investigating the P. gingivalis proteins responsible for virulence.

Porphyromonas gingivalis regulates the RANKL-OPG system in bone marrow stromal cells

Porphyromonas gingivalis is a Gram-negative anaerobe implicated in chronic periodontitis, a bacterial-induced inflammatory condition that causes destruction of the periodontal connective tissues and underlying alveolar bone. The receptor activator of nuclear factor-kappaB ligand (RANKL) is a cytokine that directly stimulates osteoclastogenesis and bone resorption, whereas its decoy receptor osteoprotegerin (OPG) blocks this action. This study aimed to investigate the effects of P. gingivalis culture supernatants on RANKL and OPG expression in W20-17 bone marrow stromal cells, and evaluate the involvement of its virulence factors, particularly gingipains and lipopolysaccharide. P. gingivalis up-regulated RANKL and down-regulated OPG mRNA expression and protein production. These effects were blocked by indomethacin, suggesting mediation by prostaglandins. Furthermore, P gingivalis induced the production of prostaglandin E(2). Heat-inactivation, or chemical inhibition of P. gingivalis gingipains did not affect RANKL and OPG regulation. However, lipopolysaccharide depletion by polymyxin B abolished RANKL induction, and partly rescued the suppression of OPG. In conclusion, P. gingivalis regulates the RANKL-OPG system via prostaglandin E(2) in bone marrow stromal cells, in a manner that favours osteoclastogenesis. A non-proteolytic and non-proteinaceous P. gingivalis component is involved in these events, most probably its lipopolysaccharide. This activity may contribute to the bone loss characteristic of periodontitis.

Full-mouth treatment concepts for chronic periodontitis: a systematic review

OBJECTIVES

To systematically review the effectiveness of full-mouth treatment concepts for chronic periodontitis.

MATERIAL AND METHODS

A search was conducted for randomized, controlled clinical trials including full-mouth scaling with (FMD) or without (FMS) the use of antiseptics and quadrant scaling (control). Data sources included COHG, CENTRAL, MEDLINE and EMBASE. Reviewers independently conducted data abstraction and quality assessment. The primary outcome was tooth loss; secondary outcomes were the reductions of PPD and BOP and a gain of CAL.

RESULTS

Of 216 identified abstracts, seven trials were included. Meta-analysis revealed a weighted mean difference (WMD) for the reduction of PPD between FMD and control of 0.53 mm [95% confidence interval (CI) (0.28, 0.77), p<0.0001] in moderately deep pockets of single-rooted teeth. The WMD for gain in CAL was 0.33 mm [95% CI (0.04, 0.63), p=0.03] in moderately deep pockets of single- and multi-rooted teeth. Comparing FMD and FMS, the WMD for the reduction of CAL amounted to 0.74 mm [95% CI (0.17, 1.31), p=0.01] in deep pockets of multi-rooted teeth in favour of FMS. For BOP a WMD -18.0% [95% CI (-34.30, -1.70), p=0.03] was calculated in deep pockets of single-rooted teeth in favour of FMD.

CONCLUSIONS

In adults with chronic periodontitis only minor differences in treatment effects were observed between the treatment strategies.

Determination of active site of lysine-specific cysteine proteinase (Lys-gingipain) by use of a Porphyromonas gingivalis plasmid system

Porphyromonas gingivalis, a major etiological bacterium of periodontal diseases, produces a unique lysine-specific cysteine proteinase (Lys-gingipain, Kgp) implicated in the virulence of this organism. Our observations show the expression of a catalytically active recombinant Kgp in a P. gingivalis Kgp-null mutant and the restoration of its functions by the use of a shuttle plasmid vector stable in P. gingivalis. The Kgp-expressing mutant exhibited a similar catalytic activity to that of the wild-type strain. This mutant also restored the ability to form black-pigmented colonies on blood agar plates and to generate a 19-kDa haemoglobin receptor protein responsible for haemoglobin binding. In order to establish the importance of the active-site Cys residue and elucidate its role in bacterial black pigmentation we constructed three Kgp mutants with changed potential active-site Cys residues. The cells expressing a single mutation (C476A) showed the high Kgp activity and the black pigmentation. In contrast, the cells expressing the single mutant (C477A) and the double mutant (C476A/C477A) exhibited neither Kgp activity nor black pigmentation. These results indicate that the 477th Cys residue is essential for both the Kgp activity and the black pigmentation of P. gingivalis.

Induction of immune responses and prevention of alveolar bone loss by intranasal administration of mice with Porphyromonas gingivalis fimbriae and recombinant cholera toxin B subunit

INTRODUCTION

Adult periodontitis is initiated by specific periodontal pathogens represented by Porphyromonas gingivalis; however, an effective measure for preventing the disease has not yet been established. In this study, the effectiveness of a vaccine composed of fimbriae of P. gingivalis and recombinant cholera toxin B subunit (rCTB) was evaluated using BALB/c mice.

METHODS

Fimbriae and rCTB were co-administered intranasally to BALB/c mice on days 0, 14, 21, and 28. On day 35, mice were sacrificed to determine immunoglobulin levels in serum, saliva, and nasal and lung extracts by enzyme-linked immunosorbent assay. The prevention effect of the vaccine on P. gingivalis-induced periodontitis in mice was evaluated by measuring alveolar bone loss.

RESULTS

The rCTB significantly increased serum immunoglobulin (Ig)A levels when mice were administered with a minimal amount (0.5 microg) of the fimbrial antigen. The adjuvant effect on serum IgG production was indistinct because the minimal amount of the antigen still induced a large amount of IgG. In contrast to systemic responses, a fimbria-specific secretory IgA response was strongly induced by co-administration of rCTB and 0.5 microg fimbriae; the same amount of the antigen alone scarcely induced a response. Histopathological examination revealed IgA-positive plasma cells in the nasal mucosal tissue but no observable mast cells in the area. In addition, nasal administration of the fimbrial vaccine significantly protected the mice from P. gingivalis-mediated alveolar bone loss.

CONCLUSION

Nasal vaccination with a combination of fimbriae and rCTB can be an effective means of preventing P. gingivalis-mediated periodontitis.

Characterizing the specific coaggregation between Actinobacillus actinomycetemcomitans serotype c strains and Porphyromonas gingivalis ATCC 33277

A visual coaggregation study showed specific interspecies coaggregation between an Actinobacillus actinomycetemcomitans serotype c strain and Porphyromonas gingivalis strains ATCC 33277 and 381. We mutagenized A. actinomycetemcomitans SUNYaB 67 (serotype c) with transposon IS903phikan and isolated three transposon insertion mutants that had a reduced ability to aggregate with P. gingivalis ATCC 33277. The three transposon insertions in the mutant strains mapped to the genes at ORF12, ORF13 and ORF16 of the gene cluster responsible for producing serotype c-specific polysaccharide antigen (SPA). Western blot analysis with serotype c-specific antibody showed that these strains did not produce the high-molecular-mass smear of SPA. Furthermore, two SPA-deficient mutants and an SPA-producing mutant were constructed. The two SPA-deficient mutants were deficient for ORF12 and ORF14, which are necessary for the synthesis of serotype c-SPA, and the SPA-producing mutant was deficient for ORF17, which is not related to SPA synthesis. The ORF12- and ORF14-deficient mutants showed reduced ability to aggregate with P. gingivalis ATCC 33277, while the ORF17-deficient mutant aggregated with ATCC 33277 to the same extent as wild-type SUNYaB 67. Our findings suggest that serotype c-SPA of A. actinomycetemcomitans mediates coaggregation with P. gingivalis ATCC 33277.

Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis subgingival presence, species-specific serum immunoglobulin G antibody levels, and periodontitis disease recurrence

BACKGROUND AND OBJECTIVE

The biological and clinical effects of antibody against periodontal pathogenic bacteria are incompletely understood. This study evaluated the inter-relationships among periodontal levels of cultivable Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, species-specific serum immunoglobulin G (IgG) antibody levels, and periodontitis disease activity.

MATERIAL AND METHODS

Forty-three adults who had previously been treated for periodontitis and who also harbored cultivable A. actinomycetemcomitans or P. gingivalis were evaluated semiannually for clinical disease recurrence over a 36-month period. Each patient provided subgingival microbial samples, for the recovery of A. actinomycetemcomitans and P. gingivalis, from the two deepest pockets in each dentition sextant. A. actinomycetemcomitans and P. gingivalis serum IgG antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA), together with whole-cell sonicate extracts from A. actinomycetemcomitans serotypes a-c and P. gingivalis ATCC 33277. Data were analyzed using the Mantel-Haenszel chi-square and Fisher exact two-tailed tests.

RESULTS

Eighteen (60.0%) of 30 A. actinomycetemcomitans-positive subjects, and 10 (76.9%) of 13 P. gingivalis-positive subjects, exhibited recurrent periodontal breakdown within 36 months of periodontal therapy. Nineteen (67.9%) of the 28 patients with active periodontitis had A. actinomycetemcomitans or P. gingivalis serum antibody levels below designated threshold values. In comparison, 10 (66.7%) of 15 culture-positive clinically stable subjects showed A. actinomycetemcomitans or P. gingivalis serum antibody levels above threshold values. The difference between specific antibody levels in periodontitis-active and periodontitis-stable patients was statistically significant (p = 0.032).

CONCLUSIONS

Serum levels of IgG antibodies against A. actinomycetemcomitans or P. gingivalis in periodontitis-stable patients were higher than those in patients with active periodontitis. The results suggest that elevated levels of IgG antibody against A. actinomycetemcomitans and P. gingivalis have a detectable protective effect against periodontal infections with these microorganisms.

Periodontal pathogens: a quantitative comparison of anaerobic culture and real-time PCR

Periodontitis is a multi-factorial chronic inflammatory and destructive disease of the tooth-supporting tissues. Quantitative anaerobic culture techniques have been used for microbial diagnosis of the different forms of the disease. The aim of this study was to compare real-time PCR with quantitative anaerobic culture for detection and quantification of 5 prominent periodontal pathogens. Real-time PCR assays with the 16s rRNA genes of Actinobacillus actinomycetemcomitans, Prevotella intermedia, Tannerella forsythensis, Peptostreptococcus micros and Fusobacterium spp. were developed. The PCR was validated on pure cultures of various bacterial strains. Subsequently, subgingival plaque samples from 259 adult patients with periodontitis were analyzed with quantitative anaerobic culture and real-time PCR. A standard curve for DNA quantification was created for each primer-probe set based on colony-forming units equivalents. All bacterial species were correctly identified. The lower limits of detection by PCR varied between 1-50 colony-forming units equivalents depending on the species. No cross-reactivities with heterologous DNA of other bacterial species were observed. Real-time PCR results showed a high degree of agreement with anaerobic culture results. Real-time PCR is a reliable alternative for diagnostic quantitative anaerobic culture of subgingival plaque samples.

Quantitative analysis of multi-species oral biofilms by TaqMan Real-Time PCR

Oral infectious diseases, including dental caries, various forms of periodontitis and oral malodor, are not caused by a single pathogen. The etiology of these diseases is known to be associated with bacterial accumulation and plaque composition on the hard and soft tissues of the oral cavity. Therefore, the quantitative, as well as qualitative, analysis of the microorganisms present in oral biofilms, namely dental plaque, subgingival plaque and tongue debris, is important for diagnosis and rational treatment decisions. The quantitative microbial analysis of oral multi-species biofilms also provides useful information for establishing the etiology of oral infectious diseases. Recently, a 5' fluorogenic, nuclease-based, real-time polymerase chain reaction (PCR) technique has been increasingly employed for the quantitative microbial assessment of the human oral cavity. We review the development and use of TaqMan real-time PCR for quantifying oral bacteria, its role in the diagnosis of oral infectious diseases and their microbial etiology.

Loop-mediated isothermal amplification method for rapid detection of the periodontopathic bacteria Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola

Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method, was developed for the rapid detection of the major periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. The LAMP method amplifies DNA with high specificity, efficiency, and rapidity under isothermal conditions using a set of four specially designed primers and a DNA polymerase with strand displacement activity. In this study, we initially designed the primers for LAMP assays to detect these bacteria and evaluated the specificity and sensitivity of these assays. The specificities of the primers for these bacteria were examined using various oral bacteria and various reaction times. The lower detection limits of the 60-min LAMP reaction without loop primers were 1 microg/tube for P. gingivalis, 10 fg/tube for T. forsythia, and 1 ng/tube for T. denticola. Addition of the loop primers for each bacterium improved the detection specificities and sensitivities by several magnitudes. Furthermore, LAMP assays were applied to the rapid detection of these periodontal pathogens in clinical specimens, and the results were compared with those of conventional PCR detection. The results of the LAMP assays corresponded to those of conventional PCR assays. These results indicate that the LAMP assay is an extremely rapid, highly sensitive, specific method. This method is very useful for the rapid detection of periodontopathic bacteria and the diagnosis of periodontal disease.

Effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise ultrasonic debridement

BACKGROUND

The aim of this randomized controlled clinical trial was to determine the effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise therapy.

MATERIAL AND METHODS

Thirty-six subjects with chronic periodontitis, were randomly allocated to three groups--quadrant-wise ultrasonic debridement, single-visit full-mouth ultrasonic debridement with povidone iodine and single-visit full-mouth ultrasonic debridement with water. Whole-mouth plaque, bleeding on probing (BOP), pocket depth and attachment level were recorded before treatment and 1, 3 and 6 months post-treatment. Plaque and saliva samples were collected for microbiological analysis.

RESULTS

After treatment, all groups showed significant improvement in clinical parameters. Full-mouth treatments resulted in similar improvements in full-mouth mean plaque percentage, probing pocket depth and probing attachment level as conventional therapy. When data were analysed based on pocket depth and tooth type, there was no difference between groups in probing depth reduction or attachment gains. The full-mouth groups demonstrated greater reduction in BOP% and number of pockets > or =5 mm and the total treatment time was significantly shorter. The detection frequencies of periodontal pathogens in plaque and saliva showed slight changes with no difference between groups.

CONCLUSION

Single-visit full-mouth mechanical debridement may have limited additional benefits over quadrant-wise therapy in the treatment of periodontitis, but can be completed in a shorter time.

A novel exopolysaccharide from a clinical isolate of Prevotella nigrescens: purification, chemical characterization and possible role in modifying human leukocyte phagocytosis

Prevotella nigrescens, a gram-negative black-pigmented anaerobic rod, has frequently been isolated from periodontitis and periapical periodontitis lesions. We have isolated an exopolysaccharide-producing P. nigrescens, strain 22, from a chronic periodontitis lesion. The purpose of this study was to determine the chemical composition and function of the exopolysaccharide associated with this clinical isolate. The chemical composition and structure of the purified exopolysaccharide from strain 22 were determined by high performance liquid chromatography and methylation analysis. To define the biological function of this exopolysaccharide, a chemically induced exopolysaccharide nonproducing mutant, strain 328, which was derived from strain 22, was established. The biological effects of exopolysaccharide were determined by comparing the ability of strain 22, strain 328 or heat-killed strain 22 to form abscesses in mice and to interfere with the phagocytic activity of peripheral blood polymorphonuclear leukocytes. Chemical analysis showed that isolated exopolysaccharide consisted of mannose (521.6 microg/mg), glucose (25.6 microg/mg), fructose (65.8 microg/mg), galactose (12.5 microg/mg), arabinose (6.2 microg/mg), xylose (3.2 microg/mg), rhamnose (6.1 microg/mg), and ribose (0.6 microg/mg). Methylation analysis of exopolysaccharide indicated that the linkages of mannose were primarily (1-->2, 1-->6) (1-->2) (1-->6), and (1-->3). Strain 22 and, to a lesser extent, its heat-killed counterpart induced greater abscess formation in mice than strain 328, even though the enzymatic profile of strain 22 was similar to that of strain 328. The ability of strain 328 to induce abscess formation was restored by adding the purified exopolysaccharide isolated from strain 22 to the cell suspension of strain 328. Exopolysaccharide alone failed to induce abscess formation in mice. Further, strain 328 but not the untreated or heat-killed strain 22, was phagocytosed by polymorphonuclear leukocytes both in the presence and in the absence of opsonic factors. The results suggest that these polysaccharides isolated from strain 22, which primarily consisted of mannose, may play a key role in the development of the chronic inflammatory lesion from which this strain was isolated.