Influence of gender on periodontal outcomes: A retrospective analysis of eight randomized clinical trials.

AIMS: To explore the influence of gender on periodontal treatment outcomes in a dataset of eight RCTs conducted in Brazil, United States, and Germany. METHODS: Clinical parameters were compared between men and women with stages III/IV grades B/C generalized periodontitis at baseline and 1-year post-therapy, including scaling and root planing with or without antibiotics. RESULTS: Data from 1042 patients were analyzed. Men presented a tendency towards higher probing depth (p = .07, effect size = 0.11) and clinical attachment level (CAL) than women at baseline (p = .01, effect size = 0.16). Males also presented statistically significantly lower CAL gain at sites with CAL of 4-6 mm at 1-year post-therapy (p = .001, effect size = 0.20). Among patients with Grade B periodontitis who took antibiotics, a higher frequency of women achieved the endpoint for treatment (i.e., ≤4 sites PD ≥5 mm) at 1 year than men (p < .05, effect size = 0.12). CONCLUSION: Men enrolled in RCTs showed a slightly inferior clinical response to periodontal therapy in a limited number of sub-analyses when compared to women. These small differences did not appear to be clinically relevant. Although gender did not dictate the clinical response to periodontal treatment in this population, our findings suggest that future research should continue to explore this topic.

Epigenome-wide association study using peripheral blood leukocytes identifies genomic regions associated with periodontal disease and edentulism in the Atherosclerosis Risk in Communities study.

AIM: To investigate individual susceptibility to periodontitis by conducting an epigenome-wide association study using peripheral blood. MATERIALS AND METHODS: We included 1077 African American and 457 European American participants of the Atherosclerosis Risk in Communities (ARIC) study who had completed a dental examination or reported being edentulous at Visit 4 and had available data on DNA methylation from Visit 2 or 3. DNA methylation levels were compared by periodontal disease severity and edentulism through discovery analyses and subsequent testing of individual CpGs. RESULTS: Our discovery analysis replicated findings from a previous study reporting a region in gene ZFP57 (6p22.1) that was significantly hypomethylated in severe periodontal disease compared with no/mild periodontal disease in European American participants. Higher methylation levels in a separate region in an unknown gene (located in Chr10: 743,992-744,958) was associated with significantly higher odds of edentulism compared with no/mild periodontal disease in African American participants. In subsequent CpG testing, four CpGs in a region previously associated with periodontitis located within HOXA4 were significantly hypermethylated in severe periodontal disease compared with no/mild periodontal disease in African American participants (odds ratio per 1 SD increase in methylation level: cg11015251: 1.28 (1.02, 1.61); cg14359292: 1.24 (1.01, 1.54); cg07317062: 1.30 (1.05, 1.61); cg08657492: 1.25 (1.01, 1.55)). CONCLUSIONS: Our study highlights epigenetic variations in ZPF57 and HOXA4 that are significantly and reproducibly associated with periodontitis. Future studies should evaluate gene regulatory mechanisms in the candidate regions of these loci.

Newly identified pathogens in periodontitis: evidence from an association and an elimination study.

We assessed the level of evidence for the presence of new periodontal pathogens by (i) comparing the occurrence of non-classical periodontal taxa between healthy vs. periodontitis patients (Association study); (ii) assessing the modifications in the prevalence and levels of these species after treatments (Elimination study). In the Association study, we compared the prevalence and levels of 39 novel bacterial species between periodontally healthy and periodontitis patients. In the Elimination study, we analyzed samples from periodontitis patients assigned to receive scaling and root planing alone or with metronidazole+ amoxicillin TID/ 14 days. Levels of 79 bacterial species (39 novel and 40 classic) were assessed at baseline, 3 and 12 months post-therapy. All samples were analyzed using Checkerboard DNA-DNA hybridization. Out of the 39 novel species evaluated, eight were categorized as having strong and four as having moderate association with periodontitis. Our findings suggest strong evidence supporting Lancefieldella rimae, Cronobacter sakazakii, Pluralibacter gergoviae, Enterococcus faecalis, Eubacterium limosum, Filifactor alocis, Haemophilus influenzae, and Staphylococcus warneri, and moderate evidence supporting Escherichia coli, Fusobacterium necrophorum, Spiroplasma ixodetis, and Staphylococcus aureus as periodontal pathogens. These findings contribute to a better understanding of the etiology of periodontitis and may guide future diagnostic and interventional studies.

Addition of cariogenic pathogens to complex oral microflora drives significant changes in biofilm compositions and functionalities.

BACKGROUND: Dental caries is a microbe and sugar-mediated biofilm-dependent oral disease. Of particular significance, a virulent type of dental caries, known as severe early childhood caries (S-ECC), is characterized by the synergistic polymicrobial interaction between the cariogenic bacterium, Streptococcus mutans, and an opportunistic fungal pathogen, Candida albicans. Although cross-sectional studies reveal their important roles in caries development, these exhibit limitations in determining the significance of these microbial interactions in the pathogenesis of the disease. Thus, it remains unclear the mechanism(s) through which the cross-kingdom interaction modulates the composition of the plaque microbiome. Here, we employed a novel ex vivo saliva-derived microcosm biofilm model to assess how exogenous pathogens could impact the structural and functional characteristics of the indigenous native oral microbiota. RESULTS: Through shotgun whole metagenome sequencing, we observed that saliva-derived biofilm has decreased richness and diversity but increased sugar-related metabolism relative to the planktonic phase. Addition of S. mutans and/or C. albicans to the native microbiome drove significant changes in its bacterial composition. In addition, the effect of the exogenous pathogens on microbiome diversity and taxonomic abundances varied depending on the sugar type. While the addition of S. mutans induced a broader effect on Kyoto Encyclopedia of Genes and Genomes (KEGG) ortholog abundances with glucose/fructose, S. mutans-C. albicans combination under sucrose conditions triggered unique and specific changes in microbiota composition/diversity as well as specific effects on KEGG pathways. Finally, we observed the presence of human epithelial cells within the biofilms via confocal microscopy imaging. CONCLUSIONS: Our data revealed that the presence of S. mutans and C. albicans, alone or in combination, as well as the addition of different sugars, induced unique alterations in both the composition and functional attributes of the biofilms. In particular, the combination of S. mutans and C. albicans seemed to drive the development (and perhaps the severity) of a dysbiotic/cariogenic oral microbiome. Our work provides a unique and pragmatic biofilm model for investigating the functional microbiome in health and disease as well as developing strategies to modulate the microbiome. Video Abstract.

Pursuing new periodontal pathogens with an improved RNA-oligonucleotide quantification technique (ROQT).

OBJECTIVE: The aim of this study was to optimize the sensitivity, specificity and cost-effectiveness of the RNA-Oligonucleotide Quantification Technique (ROQT) in order to identify periodontal pathogens that remain unrecognized or uncultured in the oral microbiome. DESIGN: Total nucleic acids (TNA) were extracted from subgingival biofilm samples using an automated process. RNA, DNA and Locked Nucleic Acid (LNA) digoxigenin-labeled oligonucleotide probes targeting 5 cultivated/named species and 16 uncultivated or unnamed bacterial taxa were synthesized. Probe specificity was determined by targeting 96 oral bacterial species; sensitivity was assessed using serial dilutions of reference bacterial strains. Different stringency temperatures were compared and new standards were tested. The tested conditions were evaluated analyzing samples from periodontally healthy individuals, and patients with moderate or severe periodontitis. RESULTS: The automated extraction method at 63°C along with LNA-oligunucleotides probes, and use of reverse RNA sequences for standards yielded stronger signals without cross-reactions. In the pilot clinical study, the most commonly detected uncultivated/unrecognized species were Selenomonas sp. HMT 134, Prevotella sp. HMT 306, Desulfobulbus sp. HMT 041, Synergistetes sp. HMT 360 and Bacteroidetes HMT 274. In the cultivated segment of the microbiota, the most abundant taxa were T. forsythia HMT 613 and Fretibacterium fastidiosum (formerly Synergistetes) HMT 363. CONCLUSIONS: In general, samples from severe patients had the greatest levels of organisms. Classic (T. forsythia, P. gingivalis) and newly proposed (F. alocis and Desulfobulbus sp. HMT 041) pathogens were present in greater amounts in samples from severe periodontitis sites, followed by moderate periodontitis sites.

Circulating IgG antibodies to periodontal bacteria and lung cancer risk in the CLUE cohorts.

BACKGROUND: Oral health is a key indicator of overall health, well-being, and quality of life. Several studies have provided new evidence about the role of oral diseases, specifically periodontitis, in generating risk for various forms of cancers, including lung, colorectal, and pancreatic cancers. METHODS: Incident lung cancer cases (n = 192) and matched controls (n = 192) were selected from participants of the CLUE I and CLUE II cohorts. Archived serum samples collected from participants in 1974 (in CLUE I) were analyzed using immunoblotting for immunoglobulin G (IgG) antibody levels to 13 bacteria of the periodontium. Associations between antibody levels and lung cancer were estimated using conditional logistic regression. RESULTS: Most of the periodontal bacterial antibodies measured were inversely associated with lung cancer risk; of these, 3 were statistically significant (Prevotellaintermedia, Actinomyces naeslundii, and Veillonella parvula). A statistically significant positive association was observed for one of the Porphyromonas gingivalis strains after adjusting for P. intermedia. The sum of the logarithm of antibodies against the 13 measured bacteria was inversely associated with risk of lung cancer when the analysis was restricted to a longer follow-up (31-44 years after blood collection, highest vs lowest quartile: odds ratio = 0.26, 95% confidence interval = 0.08 to 0.84). CONCLUSIONS: Findings from this study highlight the complexity of using serum IgG antibodies to periodontal bacteria to identify associations between oral pathogens and risk of lung cancer. The inverse associations observed for antibodies to periodontal bacteria suggest that these may represent markers of immunity that provide some advantage in reducing the development of lung cancer.

Antibodies to oral pathobionts and colon cancer risk in the CLUE I cohort study.

Periodontitis has been associated with an increased risk for gastrointestinal cancers. The objective of our study was to investigate the association of antibodies to oral bacteria and the risk of colon cancer in a cohort setting. Using the CLUE I cohort, a prospective cohort initiated in 1974 in Washington County, Maryland, we conducted a nested case-control study to examine the association of levels of IgG antibodies to 11 oral bacterial species (13 total strains) with risk of colon cancer diagnosed a median of 16 years later (range: 1-26 years). Antibody response was measured using checkerboard immunoblotting assays. We included 200 colon cancer cases and 200 controls matched on age, sex, cigarette smoking status, time of blood draw and pipe or cigar smoking status. Controls were selected using incidence density sampling. Conditional logistic regression models were used to assess the association between antibody levels and colon cancer risk. In the overall analysis, we observed significant inverse associations for 6 of the 13 antibodies measured (P-trends <.05) and one positive association for antibody levels to Aggregatibacter actinomycetemcomitans (ATCC 29523; P-trend = .04). While we cannot rule out a role for periodontal disease in colon cancer risk, findings from our study suggest that a strong adaptive immune response may be associated with a lower risk of colon cancer. More studies will need to examine whether the positive associations we observed with antibodies to A. actinomycetemcomitans reflect a true causal association for this bacterium.

Subgingival host-microbiome metatranscriptomic changes following scaling and root planing in grade II/III periodontitis.

AIM: To assess the effects of scaling and root planing (SRP) on the dynamics of gene expression by the host and the microbiome in subgingival plaque samples. MATERIALS AND METHODS: Fourteen periodontitis patients were closely monitored in the absence of periodontal treatment for 12 months. During this period, comprehensive periodontal examination and subgingival biofilm sample collection were performed bi-monthly. After 12 months, clinical attachment level (CAL) data were compiled and analysed using linear mixed models (LMM) fitted to longitudinal CAL measurements for each tooth site. LMM classified the sites as stable (S), progressing (P), or fluctuating (F). After the 12-month visit, subjects received SRP, and at 15 months they received comprehensive examination and supportive periodontal therapy. Those procedures were repeated at the 18-month visit, when patients were also sampled. Each patient contributed with one S, one P, and one F site collected at the 12- and 18-month visits. Samples were analysed using Dual RNA-Sequencing to capture host and bacterial transcriptomes simultaneously. RESULTS: Microbiome and host response behaviour were specific to the site's progression classification (i.e., S, P, or F). Microbial profiles of pre- and post-treatment samples exhibited specific microbiome changes, with progressing sites showing the most significant changes. Among them, Porphyromonas gingivalis was reduced after treatment, while Fusobacterium nucleatum showed an increase in proportion. Transcriptome analysis of the host response showed that interleukin (IL)-17, TNF signalling pathways, and neutrophil extracellular trap formation were the primary immune response activities impacted by periodontal treatment. CONCLUSIONS: SRP resulted in a significant "rewiring" of host and microbial activities in the progressing sites, while restructuring of the microbiome was minor in stable and fluctuating sites.

Oral biofilm dysbiosis during experimental periodontitis.

OBJECTIVES: We have previously characterized the main osteoimmunological events that occur during ligature periodontitis. This study aims to determine the polymicrobial community shifts that occur during disease development. METHODS: Periodontitis was induced in C57BL/6 mice using the ligature-induced periodontitis model. Healthy oral mucosa swabs and ligatures were collected every 3 days from 0 to 18 days post-ligature placement. Biofilm samples were evaluated by 16SrRNA gene sequencing (Illumina MiSeq) and QIIME. Time-course changes were determined by relative abundance, diversity, and rank analyses (PERMANOVA, Bonferroni-adjusted). RESULTS: Microbial differences between health and periodontal inflammation were observed at all phylogenic levels. An evident microbial community shift occurred in 25 genera during the advancement of "gingivitis" (3-6 days) to periodontitis (9-18 days). From day 0 to 18, dramatic changes were identified in Streptococcus levels, with an overall decrease (54.04%-0.02%) as well an overall increase of Enterococcus and Lactobacillus (23.7%-73.1% and 10.1%-70.2%, respectively). Alpha-diversity decreased to its lowest at 3 days, followed by an increase in diversity as disease advancement. Beta-diversity increased after ligature placement, indicating that bone loss develops in response to a greater microbial variability (p = 0.001). Levels of facultative and strict anaerobic bacteria augmented over the course of disease progression, with a total of eight species significantly different during the 18-day period. CONCLUSION: The data supports that murine gingival inflammation and alveolar bone loss develop in response to microbiome shifts. Bacterial diversity increased during progression to bone loss. These findings further support the utilization of the periodontitis ligature model for microbial shift analysis under different experimental conditions.

Viruses, periodontitis, and comorbidities.

Seminal studies published in the 1990s and 2000s explored connections between periodontal diseases and systemic conditions, revealing potential contributions of periodontal diseases in the initiation or worsening of systemic conditions. The resulting field of periodontal medicine led to the publication of studies indicating that periodontal diseases can influence the risk of systemic conditions, including adverse pregnancy outcomes, cardiovascular and respiratory diseases, as well as Alzheimer disease and cancers. In general, these studies hypothesized that the periodontal bacterial insult and/or the associated proinflammatory cascade could contribute to the pathogenesis of these systemic diseases. While investigations of the biological basis of the connections between periodontal diseases and systemic conditions generally emphasized the bacteriome, it is also biologically plausible, under an analogous hypothesis, that other types of organisms may have a similar role. Human viruses would be logical "suspects" in this role, given their ubiquity in the oral cavity, association with periodontal diseases, and ability to elicit strong inflammatory response, compromise immune responses, and synergize with bacteria in favor of a more pathogenic microbial consortium. In this review, the current knowledge of the role of viruses in connecting periodontal diseases and systemic conditions is examined. We will also delve into the mechanistic basis for such connections and highlight the importance of those relationships in the management and treatment of patients.

Effect of micro-osteoperforations on the gene expression profile of the periodontal ligament of orthodontically moved human teeth.

OBJECTIVES: This study aimed to evaluate the effect of micro-osteoperforations (MOPs) on the gene expression profile of the periodontal ligament (PDL) of orthodontically moved teeth. MATERIALS AND METHODS: Fifteen participants were randomly assigned into two groups: tooth movement only (Tr1, n = 7) and tooth movement supplemented with MOPs (Tr2, n = 8). In each subject, orthodontic tooth movement (OTM) was performed on premolar in one side, while no force was applied on contralateral premolar (Unt, n = 15). Seven days after loading, premolars were extracted for orthodontic reasons. RNA extraction from PDL and subsequent RNA-sequencing were performed. False discovery rates (Padj < 0.05) and log2 fold change (+ / - 1.5) thresholds were used to identify sets of differentially expressed genes (DEGs) among the groups. DEGs were analyzed with gene ontology enrichment, KEGG, and network analysis. RESULTS: Three hundred thirty-one DEGs were found between Tr1 and Unt, and 356 between Tr2 and Unt. Although, there were no significantly DEGs between Tr2 and Tr1, DEGs identified exclusively in Tr1 vs. Unt were different from those identified exclusively in Tr2 vs. Unt. In Tr1, genes were related to bone metabolism processes, such as osteoclast and osteoblast differentiation. In Tr2, genes were associated to inflammation processes, like inflammatory and immune responses, and cellular response to tumor necrosis factor. CONCLUSIONS: MOPs do not significantly alter the PDL gene expression profile of orthodontically moved human teeth. This study provides for the first time evidence on the whole PDL gene expression profiles associated to OTM in humans. Novel biomarkers for OTM are suggested for additional research. Clinical relevance The identified biomarkers provide new insights into the molecular mechanisms that would occur when OTM is supplemented with MOPs. These markers are expected to be useful in the near future for the application of personalized strategies related to the OTM.

Long-term dynamics of the human oral microbiome during clinical disease progression.

BACKGROUND: Oral microbiome dysbiosis is linked to overt inflammation of tooth-supporting tissues, leading to periodontitis, an oral condition that can cause tooth and bone loss. Microbiome dysbiosis has been described as a disruption in the symbiotic microbiota composition's stability that could adversely affect the host's health status. However, the precise microbiome dynamics that lead to dysbiosis and the progression of the disease are largely unknown. The objective of our study was to investigate the long-term dynamics of periodontitis progression and its connection to dysbiosis. RESULTS: We studied three different teeth groups: sites that showed disease progression, sites that remained stable during the study, and sites that exhibited a cyclic deepening followed by spontaneous recovery. Time-series analysis revealed that communities followed a characteristic succession of bacteria clusters. Stable and fluctuating sites showed high asynchrony in the communities (i.e., different species responding dissimilarly through time) and a reordering of the communities where directional changes dominated (i.e., sample distance increases over time) in the stable sites but not in the fluctuating sites. Progressing sites exhibited low asynchrony and convergence (i.e., samples distance decreases over time). Moreover, new species were more likely to be recruited in stable samples if a close relative was not recruited previously. In contrast, progressing and fluctuating sites followed a neutral recruitment model, indicating that competition between closely related species is a significant component of species-species interactions in stable samples. Finally, periodontal treatment did not select similar communities but stabilized α-diversity, centered the abundance of different clusters to the mean, and increased community rearrangement. CONCLUSIONS: Here, we show that ecological principles can define dysbiosis and explain the evolution and outcomes of specific microbial communities of the oral microbiome in periodontitis progression. All sites showed an ecological succession in community composition. Stable sites were characterized by high asynchrony, a reordering of the communities where directional changes dominated, and new species were more likely to be recruited if a close relative was not recruited previously. Progressing sites were characterized by low asynchrony, community convergence, and a neutral model of recruitment. Finally, fluctuating sites were characterized by high asynchrony, community convergence, and a neutral recruitment model.

Bacterial resistance to minocycline after adjunctive minocycline microspheres during periodontal maintenance: A randomized clinical trial.

BACKGROUND: Despite widespread use, the impact of minocycline hydrochloride microspheres on the shifts of oral bacterial species resistant to minocycline remains unknown. This study aimed at examining the percentage and taxonomy of minocycline-resistant isolates in saliva and subgingival plaque samples before and after minocycline microspheres application in periodontitis patients during maintenance. METHODS: Patients received supra- and sub-gingival debridement with (test) or without (control) minocycline microspheres application to sites with probing depth >4 mm and were clinically monitored at baseline, 1, 3, and 6 months. Samples were collected at baseline, 1 and 6 months and analyzed via cultivation with or without 4 µg/mL minocycline. Percentage of resistant strains was determined by colony counting and taxonomy by checkerboard DNA-DNA hybridization. Significant clinical changes were sought with the Mann-Whitney test and differences in percentage of resistant isolates with the Friedman and Mann-Whitney tests. RESULTS: Groups showed similar clinical improvements. Mean percentage of resistant isolates rose at 1 month and decreased at 6 months in saliva and plaque samples in test group (P <0.05) but remained unchanged in control group. Percentage of resistant isolates of Gemella morbillorum and Eubacterium saburreum increased significantly at 6 months in both groups. Antibiotic resistance by Aggregatibacter actinomycetemcomitans, Tannerella forsythia, and Porphyromonas gingivalis was either absent or infrequent. CONCLUSION: Minocycline microspheres result in transient selection of minocycline resistant species in saliva and subgingival plaque samples.

Microbiome changes in young periodontitis patients treated with adjunctive metronidazole and amoxicillin.

BACKGROUND: To our knowledge, to date, no studies have comprehensively assessed the changes occurring in the subgingival microbiome of young patients with periodontitis treated by means of mechanical and antibiotic therapy. Thus, this study aimed to use next-generation sequencing to evaluate the subgingival microbial composition of young patients with severe periodontitis treated with scaling and root planing and systemic metronidazole and amoxicillin. METHODS: Subgingival samples from healthy individuals and shallow and deep sites from periodontitis patients were individually collected at baseline and 90 days post-treatment. The samples were analyzed using 16S rRNA-gene sequencing (MiSeq-Illumina) and QIIME pipeline. Differences between groups for the microbiological data were determined using principal coordinate analysis (PCoA), linear mixed models, and the PERMANOVA test. RESULTS: One hundred samples were collected from 10 periodontitis patients and seven healthy individuals. PCoA analysis revealed significant partitioning between pre-and post-treatment samples. No major differences in the composition of the subgingival microbiota were observed between shallow and deep sites, at baseline or at 90-days post-treatment, and the microbiome of both site categories after treatment moved closer in similarity to that observed in periodontal health. Treatment significantly improved all clinical parameters and reduced the relative abundance of classical periodontal pathogens and of Fretibacterium fastidiosum, Eubacterium saphenum, Porphyromonas endodontalis, Treponema medium, Synergistetes, TM7, and Treponema spp, and increased that of Actinomyces, Rothia, Haemophilus, Corynebacterium, and Streptococci spp. CONCLUSION: Mechanical treatment associated with metronidazole and amoxicillin promoted a beneficial change in the microbiome of young individuals with severe periodontitis.

Impact of systemic factors in shaping the periodontal microbiome.

Since 2010, next-generation sequencing platforms have laid the foundation to an exciting phase of discovery in oral microbiology as it relates to oral and systemic health and disease. Next-generation sequencing has allowed large-scale oral microbial surveys, based on informative marker genes, such as 16S ribosomal RNA, community gene inventories (metagenomics), and functional analyses (metatranscriptomics), to be undertaken. More specifically, the availability of next-generation sequencing has also paved the way for studying, in greater depth and breadth, the effect of systemic factors on the periodontal microbiome. It was natural to investigate systemic diseases, such as diabetes, in such studies, along with systemic conditions or states, , pregnancy, menopause, stress, rheumatoid arthritis, and systemic lupus erythematosus. In addition, in recent years, the relevance of systemic "variables" (ie, factors that are not necessarily diseases or conditions, but may modulate the periodontal microbiome) has been explored in detail. These include ethnicity and genetics. In the present manuscript, we describe and elaborate on the new and confirmatory findings unveiled by next-generation sequencing as it pertains to systemic factors that may shape the periodontal microbiome. We also explore the systemic and mechanistic basis for such modulation and highlight the importance of those relationships in the management and treatment of patients.

Did Omics change periodontal therapy?

The starting point for defining effective treatment protocols is a clear understanding of the etiology and pathogenesis of a condition. In periodontal diseases, this understanding has been hindered by a number of factors, such as the difficulty in differentiating primary pathogens from nonpathogens in complex biofilm structures. The introduction of DNA sequencing technologies, including taxonomic and functional analyses, has allowed the oral microbiome to be investigated in much greater breadth and depth. This article aims to compile the results of studies, using next-generation sequencing techniques to evaluate the periodontal microbiome, in an attempt to determine how far the knowledge provided by these studies has brought us in terms of influencing the way we treat periodontitis. The taxonomic data provided, to date, by published association and elimination studies using next-generation sequencing confirm previous knowledge on the role of classic periodontal pathogens in the pathobiology of disease and include new species/genera. Conversely, species and genera already considered as host-compatible and others less explored were associated with periodontal health as their levels were elevated in healthy individuals and increased after therapy. Functional and transcriptomic analyses also demonstrated that periodontal biofilms are taxonomically diverse, functionally congruent, and highly cooperative. Very few interventional studies to date have examined the effects of treatment on the periodontal microbiome, and such studies are heterogeneous in terms of design, sample size, sampling method, treatment provided, and duration of follow-up. Hence, it is still difficult to draw meaningful conclusions from them. Thus, although OMICS knowledge has not yet changed the way we treat patients in daily practice, the information provided by these studies opens new avenues for future research in this field. As new pathogens and beneficial species become identified, future randomized clinical trials could monitor these species/genera more comprehensively. In addition, the metatranscriptomic data, although still embryonic, suggest that the interplay between the host and the oral microbiome may be our best opportunity to implement personalized periodontal treatments. Therapeutic schemes targeting particular bacterial protein products in subjects with specific genetic profiles, for example, may be the futuristic view of enhanced periodontal therapy.

The apical root canal system microbial communities determined by next-generation sequencing.

The aim of this study was to explore the microbial communities of endodontic infections at their apical portion by 16S rRNA Illumina sequencing and delineate the core microbiome of root canal infections and that of their associated clinical symptomatology. Samples were collected from fifteen subjects presenting one tooth with a root canal infection, and their associated symptoms were recorded. Samples were collected from the apical third of roots using a #10 K file and then amplified using multiple displacement amplification and PCR-amplified with universal primers. Amplicons were sequenced (V3-V4 hypervariable region of the 16S rRNA gene) using MiSeq (Illumina, CA). The microbial composition of the samples was determined using QIIME and HOMINGS. Data were analyzed using t tests and ANOVA. A total of 1,038,656 good quality sequences were obtained, and OTUs were assigned to 10 bacterial phyla, led by Bacteroidetes (51.2%) and Firmicutes (27.1%), and 94 genera were represented primarily by Prevotella (17.9%) and Bacteroidaceae G-1 (14.3%). Symptomatic teeth were associated with higher levels of Porphyromonas (p < 0.05) and Prevotella. P. endodontalis and P. oris were present in both cores. The present study demonstrated the complexity of the root canal microbiome and the "common denominators" of root canal infections and identified taxa whose virulence properties should be further explored. The polymicrobial etiology of endodontic infections has long been established. However, few studies have focused on expanding the breadth and depth of coverage of microbiome-infected root canals at their apical portion.

Antibacterial action of nitric oxide-releasing hyperbranched polymers against ex vivo dental biofilms.

OBJECTIVES: This study investigates the antibiofilm action of nitric oxide (NO)-releasing hyperbranched polymers against ex vivo multispecies periodontal biofilms. METHODS: The antibiofilm efficacy of NO-releasing hyperbranched polymers was evaluated as a function of NO-release properties, polymer concentrations, and oxygen levels in the exposure media. 16s rRNA sequencing technique was employed to evaluate the impact of NO-releasing hyperbranched polymers on the microbial composition of the biofilms. RESULTS: The addition of NO release significantly improved the antibiofilm action of the hyperbranched polymers, with NO-releasing hyperbranched polyamidoamines of largest NO payloads being more effective than hyperbranched polykanamycins. Furthermore, the NO-releasing hyperbranched polymers reduced the biofilm metabolic activity in a dose-dependent manner, killing biofilm-detached bacteria under both aerobic and anaerobic conditions, with greater antimicrobial efficacy observed under aerobic conditions. SIGNIFICANCE: These results demonstrate for the first time the potential therapeutic utility of NO-releasing hyperbranched polymers for treating multispecies dental biofilms.

Proposal of a Clinical Endpoint for Periodontal Trials: The Treat-to-Target Approach.

OBJECTIVE: The selection of proper outcome measures is a critical step in clinical research. Most randomized clinical trials (RCTs) assessing the effects of initial anti-infective periodontal therapies use surrogate outcomes as primary outcome variables, such as mean changes in probing depth (PD) or in clinical attachment. However, these parameters do not reflect disease remission/control at patient level, which has led to subjective interpretations of the data from RCTs and Systematic Reviews. Based on a comprehensive analysis of 724 patients from USA, Germany and Brazil treated for periodontitis, this paper suggests that the clinical endpoint of "≤4 sites with PD≥5mm" is effective in determining disease remission/control after active periodontal treatment and therefore, may represent a pertinent endpoint for applying the treat-to-target concept in RCTs. Furthermore, regression models showed that the presence of >10% and >20% sites with bleeding on probing in the mouth post-treatment increases the risk of a patient leaving the endpoint from 1-2 years (OR=3.5 and 8.7, respectively). Researchers are encouraged to present results on this outcome when reporting their trials, as this will allow for an objective comparison across studies and facilitate systematic reviews, and consequently, the extrapolation of data from research to clinical practice.

The Microbiome of Peri-implantitis: Is It Unique?

A better characterization of the peri-implant microbiome can improve the understanding of the etiology of peri-implant diseases. Ultimately, more detailed information about the peri-implantitis microbiome will lead to better strategies for prevention, supportive therapy, and risk assessment, as well as early diagnosis of peri-implantitis and timely intervention, all of which are critical for the long-term retention of implants.