Europe's contribution to the evaluation of the use of systemic antimicrobials in the treatment of periodontitis.

This narrative review celebrates Europe's contribution to the current knowledge on systemically administered antimicrobials in periodontal treatment. Periodontitis is the most frequent chronic noncommunicable human disease. It is caused by dysbiotic bacterial biofilms and is commonly treated with subgingival instrumentation. However, some sites/patients do not respond adequately, and its limitations and shortcomings have been recognized. This has led to the development of alternative or adjunctive therapies. One is the use of antimicrobials to target bacteria in subgingival biofilms in the periodontal pocket, which can be targeted directly through the pocket entrance with a locally delivered antibiotic or systemically by oral, intravenous, or intramuscular methods. Since the early 20th century, several studies on systemic antibiotics have been undertaken and published, especially between 1990 and 2010. Europe's latest contribution to this topic is the first European Federation of Periodontology, S3-level Clinical Practice Guideline, which incorporates recommendations related to the use of adjuncts to treat stage I-III periodontitis. Understanding the etiopathogenesis of periodontal diseases, specifically periodontitis, has influenced the use of systemic periodontal antibiotic therapy. Randomized clinical trials and systematic reviews with meta-analyses have demonstrated the clinical advantages of adjunctive systemic antimicrobials. However, current recommendations are restrictive due to concerns about antibiotic misuse and the increase in microbial antibiotic resistance. European researchers have contributed to the use of systemic antimicrobials in the treatment of periodontitis through clinical trials and by providing rational guidelines. Nowadays, European researchers are exploring alternatives and directing clinical practice by providing evidence-based guidelines to limit the use of systemic antimicrobials.

Erythritol air polishing in the surgical treatment of peri-implantitis: A randomized controlled trial.

OBJECTIVES: To compare erythritol air polishing with implant surface cleansing using saline during the surgical treatment of peri-implantitis. MATERIAL AND METHODS: During a resective surgical intervention, implant surfaces were randomly treated with either air polishing (test group n = 26 patients/53 implants) or saline-soaked cotton gauzes (control group n = 31 patients/ 40 implants). Primary outcome was change in mean bleeding on probing (BoP) from baseline to 12 months follow-up. Secondary outcomes were changes in mean suppuration on probing (SoP), plaque score (Plq), probing pocket depth (PPD), marginal bone loss (MBL), periodontal full-mouth scores (PFMS), and levels of 8 classical periodontal pathogens. Clinical and radiographical parameters were analyzed using multilevel regression analyses. Microbiological outcomes were analyzed using the Mann-Whitney U test. RESULTS: No differences between the test and control group were found for BoP over 12 months of follow-up, nor for the secondary parameters Plq, PPD, and MBL. Between both groups, a significant difference was found for the levels of SoP (p = 0.035). No significant effect on microbiological levels was found. A total number of 6 implants were lost in the test group and 10 in the control group. At 1-year follow-up, a successful treatment outcome (PPD<5 mm, max 1 out of 6 sites BoP, no suppuration and no progressive bone loss >0.5 mm) was achieved for a total of 18 implants (19.2%). CONCLUSIONS: Erythritol air polishing as implant surface cleansing method was not more effective than saline during resective surgical treatment of peri-implantitis in terms of clinical, radiographical, and microbiological parameters. Both therapies resulted in low treatment success. TRIAL REGISTRY: https://www.trialregister.nl/ Identifier: NL8621.

Systemic antibiotic therapy as an adjunct to non-surgical peri-implantitis treatment: A single-blind RCT.

AIM: The aim of this single-blind RCT was to evaluate the adjunctive clinical and microbiological effect of systemic amoxicillin (AMX) plus metronidazole (MTZ) to non-surgical treatment of peri-implantitis. MATERIAL AND METHODS: Patients (N = 62) with peri-implantitis were randomly assigned to receive full-mouth mechanical debridement and decontamination and use of chlorhexidine (control group) or combined with antibiotic therapy of AMX/MTZ (test group). Primary outcome was change in bleeding score from baseline (T0 ) to 3-month follow-up (T3 ). Secondary parameters were plaque, suppuration, PPD, CAL, bone level, microbiology, adverse events and need for additional surgery. Data were analysed with linear multiple regression analysis. RESULTS: 57 patients with 122 implants completed 3-month follow-up. Both groups showed major clinical improvements at T3 in both peri-implant and periodontal parameters. However, no significant differences were observed between both groups for any of the primary or secondary parameters. CONCLUSIONS: Systemic antibiotic therapy of AMX/MTZ does not improve clinical and microbiological outcomes of non-surgical peri-implantitis treatment and should not be routinely recommended. Although complete disease resolution may be difficult to achieve, meticulously performed full-mouth non-surgical treatment, achieving a high level of daily oral hygiene and healthy periodontal tissues, can significantly improve the starting position of the subsequent (surgical) peri-implantitis treatment phase.

Erythritol airpolishing in the non-surgical treatment of peri-implantitis: A randomized controlled trial.

OBJECTIVES: To compare erythritol air polishing with piezoelectric ultrasonic scaling in the non-surgical treatment of peri-implantitis. MATERIAL AND METHODS: Eighty patients (n = 139 implants) with peri-implantitis (probing pocket depth (PPD) ≥5 mm, marginal bone loss (MBL) ≥2 mm as compared to bone level at implant placement, bleeding, and/or suppuration on probing (BoP/SoP)) were randomly allocated to air polishing or ultrasonic treatment. The primary outcome was mean BoP (%) at 3 months after therapy (T3). Secondary outcomes were mean SoP (%), plaque score (Plq) (%), PPD (mm), MBL (mm), full mouth periodontal scores (FMPS) (%), levels of 8 classical periodontal pathogens, and treatment pain/discomfort (Visual Analog Scale, VAS). Patients who were considered successful at T3 were additionally assessed at 6, 9, and 12 months. Differences between both groups were analyzed using multilevel statistics. RESULTS: Three months after therapy, no significant difference in mean BoP (%) between the air polishing and ultrasonic therapy was found (crude analysis ß (95% CI) -0.037 (-0.147; 0.073), p = .380). Neither secondary outcomes SoP (%), Plq (%), PPD (mm), MBL (mm), FMPS (%), and periodontal pathogens showed significant differences. Treatment pain/discomfort was low in both groups (VAS score airpolishing group 2.1 (±1.9), ultrasonic 2.6 (±1.9); p = .222). All successfully treated patients at T3 (18.4%) were still considered successful at 12-month follow-up. CONCLUSIONS: Erythritol air polishing seems as effective as piezoelectric ultrasonic scaling in the non-surgical treatment of peri-implantitis, in terms of clinical, radiographical, and microbiological parameters. However, neither of the proposed therapies effectively resolved peri-implantitis. Hence, the majority of patients required further surgical treatment.

Effect of Anti-Rheumatic Treatment on the Periodontal Condition of Rheumatoid Arthritis Patients.

Periodontitis, a bacterial-induced infection of the supporting soft and hard tissues of the teeth (the periodontium), is common in patients with rheumatoid arthritis (RA). As RA and periodontitis underlie common inflammatory pathways, targeting the progression of RA might mediate both periodontitis and RA. On the other hand, patients with RA on immunosuppressive medication have an increased risk of infection. Therefore, the objective of this longitudinal observation study was to assess the effect of methotrexate (MTX) and anti-tumor necrosis factor-α (anti-TNF, etanercept) treatment on the periodontal condition of RA patients. Overall, 14 dentate treatment-naive RA patients starting with MTX and 12 dentate RA patients starting with anti-TNF therapy in addition to MTX were included. Follow-up was scheduled matching the routine protocol for the respective treatments. Prior to the anti-rheumatic treatment with MTX or the anti-TNF therapy in addition to MTX, and during follow-up, i.e., 2 months for MTX, and 3 and 6 months for the anti-TNF therapy in addition to MTX, the periodontal inflamed surface area (PISA) was measured. The efficacy of the anti-rheumatic treatment was assessed by determining the change in RA disease activity (DAS28-ESR). Furthermore, the erythrocyte sedimentation rates were determined and the levels of C-reactive protein, IgM-rheumatoid factor, anti-cyclic citrullinated protein antibodies, and antibodies to the periodontal pathogen Porphyromonas gingivalis, were measured. Subgingival sampling and microbiological characterization of the subgingival microflora was done at baseline. MTX or anti-TNF treatment did not result in an improvement of the periodontal condition, while both treatments significantly improved DAS28 scores (both p < 0.01), and reduced C-reactive protein levels and erythrocyte sedimentation rates (both p < 0.05). It is concluded that anti-rheumatic treatment (MTX and anti-TNF) has negligible influence on the periodontal condition of RA patients.

Biomarker levels in peri-implant crevicular fluid of healthy implants, untreated and non-surgically treated implants with peri-implantitis.

AIM: To compare biomarker levels in peri-implant crevicular fluid (PICF) of healthy implants with levels in PICF of implants with peri-implantitis (before and after non-surgical treatment). MATERIALS AND METHODS: Samples were taken from 20 healthy implants (n = 17 patients) and from 20 implants with peri-implantitis (n = 19 patients) before and 3 months after non-surgical treatment using the Airflow Master Piezon® (EMS). A Luminex™ assay was used to evaluate pro-inflammatory and anti-inflammatory cytokines IL-1ß, TNF-α, IL-6 and G-CSF, collagen degradation enzyme MMP-8, chemokines MCP-1 & MIP-1α/CCL3, bone markers OPG and sRANKL and interferon-γ. Clinical and radiographical characteristics were assessed. A Mann-Whitney U and Wilcoxon signed-rank test analysed between- and within-group differences. RESULTS: IL-1ß and MMP-8 levels were found significantly elevated in implants with peri-implantitis (p = .007; p = <.001, respectively). No difference in levels of TNF-α, IL-6, MCP-1 and MIP-1α/CCL3, OPG and G-CSF between healthy and diseased implants was found. Levels of sRANKL and INF-γ were under the level of detection. None of the biomarker levels improved after non-surgical therapy, and levels of IL-1ß and MMP-8 remained high. CONCLUSION: Implants diagnosed with peri-implantitis have higher levels of IL-1ß and MMP-8 in PICF compared to healthy implants. Non-surgical therapy did not influence the inflammatory immune response.

Non-surgical peri-implantitis treatment using a pocket irrigator device; clinical, microbiological, radiographical and patient-centred outcomes-A pilot study.

AIM: The aim of this prospective cohort study was to assess the effect of a pocket irrigator/evacuator device (IED) in the non-surgical treatment of peri-implantitis. MATERIAL AND METHODS: In total 24 patients having 38 implants diagnosed with peri-implantitis were included in this study. Peri-implant pockets were irrigated six times in three consecutive weeks. The primary outcome was bleeding on probing (BoP). Secondary outcome parameters included plaque index (Pl), suppuration on probing (SoP), probing pocket depth (PPD), marginal bone loss (MBL), presence and numbers of periodontal pathogens. Parameters were assessed at baseline and 3 months after the last treatment. Treatment pain perception was scored using the visual analog scale (VAS) after the first and last treatment. RESULTS: At 3 months, IED treatment revealed significant reduction of peri-implant BoP (71% [±20] vs 57% [±28] [P = .014]) and peri-implant plaque scores (10 [±14] to 5 [±9] [P = .039] [T0 vs T3 respectively]). Significant reduction in mean peri-implant PPD from 4.92 mm (SD ± 1.28) to 4.66 mm (SD ± 1.35) (P = .041) was observed. In addition, a reduction in VAS pain score between the first and the last (6th) treatment was found (P = .039). No reduction in SoP (P = .088) was found. No changes in mean periodontal full mouth plaque, BOP, SOP and PPD levels, MBL and microbiological outcomes were found. CONCLUSION: Beneficial clinical effects in terms of BoP, PPD and PI were found at 3 months after IED treatment. However, the IED does not seem to effectively treat peri-implantitis in terms of disease resolution.

Influence of Cervical Crown Contour on Marginal Bone Loss Around Platform-Switched Bone-Level Implants: A 5-Year Cross-Sectional Study.

PURPOSE: To evaluate the influence of the cervical crown contour on marginal bone loss and soft tissue health around platform-switched, posteriorly placed, two-piece implants. MATERIALS AND METHODS: A dataset from two previously conducted studies was used. Patients with single two-piece, platform-switched implants in between two natural teeth or adjacent to one natural tooth were included. Clinical parameters and standardized periapical radiographs from 1 month and 5 years after final crown placement were assessed. A new measurement method was developed to analyze geometric values of the cervical crown contour. Inter- and intraexaminer reliability were assessed. Emergence angles were measured at 1, 2, and 3 mm above the implant shoulder. Linear correlations between variables were determined by calculating Pearson correlation coefficients. RESULTS: A total of 64 patients with 67 posterior implants met the inclusion criteria. At 1, 2, and 3 mm above the implant shoulder, mean emergence angles at the mesial implant sites were 0.5 ± 2.8, 12.8 ± 12.8, and 18.0 ± 11.3 degrees, respectively. At the distal sites, the corresponding values were 2.8 ± 8.3, 16.2 ±16.6, and 18.7 ± 13.8 degrees, respectively. Mean marginal bone loss between 1 month and the 5-year evaluations was 0.14 ± 0.34 mm at the mesial aspect and 0.26 ± 0.47 at the distal aspect of implants. No correlation with peri-implant bone loss or soft tissue health could be found. No implants showed signs of peri-implantitis. CONCLUSION: The cervical crown contour at platform-switched, posteriorly placed, two-piece implants showed no correlation with peri-implant marginal bone loss or soft tissue health up to 5 years after implant placement.

Gingimaps: Protein Localization in the Oral Pathogen Porphyromonas gingivalis.

Porphyromonas gingivalis is an oral pathogen involved in the widespread disease periodontitis. In recent years, however, this bacterium has been implicated in the etiology of another common disorder, the autoimmune disease rheumatoid arthritis. Periodontitis and rheumatoid arthritis were known to correlate for decades, but only recently a possible molecular connection underlying this association has been unveiled. P. gingivalis possesses an enzyme that citrullinates certain host proteins and, potentially, elicits autoimmune antibodies against such citrullinated proteins. These autoantibodies are highly specific for rheumatoid arthritis and have been purported both as a symptom and a potential cause of the disease. The citrullinating enzyme and other major virulence factors of P. gingivalis, including some that were implicated in the etiology of rheumatoid arthritis, are targeted to the host tissue as secreted or outer-membrane-bound proteins. These targeting events play pivotal roles in the interactions between the pathogen and its human host. Accordingly, the overall protein sorting and secretion events in P. gingivalis are of prime relevance for understanding its full disease-causing potential and for developing preventive and therapeutic approaches. The aim of this review is therefore to offer a comprehensive overview of the subcellular and extracellular localization of all proteins in three reference strains and four clinical isolates of P. gingivalis, as well as the mechanisms employed to reach these destinations.

Untargeted metabolomics of the bacterial tongue coating of intra-oral halitosis patients.

Intra-oral halitosis (IOH) refers to an unpleasant odor from the oral cavity that is mainly caused by the tongue coating. Although the tongue coating microbiome is thought to play an essential role in IOH, the exact aetiology of IOH remains unclear. Here we investigated and compared the metabolic profiles of the tongue coating microbiomes of patients with IOH versus healthy control. The metabolic profiles were significantly different in IOH patients than in healthy controls. Healthy controls showed higher selenoamino acid and nicotinamide metabolism; these metabolic pathways are mainly involved in maintaining the oxidation-reduction potential and redox state. A total of 39 putative metabolites were associated with IOH. Remarkably, 3 of the metabolites, branched-chain fatty acids (BCFA), 3-fumaryl pyruvate, and acetyl phosphate, are potential key players in IOH. Interestingly, the predominant metabolite in IOH is BCFAs, which might underlie tongue coat formation. In addition, the key metabolite acetyl phosphate has a clear association with the hydrogen sulfide- (H2S-) producing metabolic pathway and anaerobic fermentation. These novel metabolomic findings provide insights into the formation of the tongue coating and the production of H2S, which causes bad breath.

Talk to your gut: the oral-gut microbiome axis and its immunomodulatory role in the etiology of rheumatoid arthritis.

Microbial communities inhabiting the human body, collectively called the microbiome, are critical modulators of immunity. This notion is underpinned by associations between changes in the microbiome and particular autoimmune disorders. Specifically, in rheumatoid arthritis, one of the most frequently occurring autoimmune disorders worldwide, changes in the oral and gut microbiomes have been implicated in the loss of tolerance against self-antigens and in increased inflammatory events promoting the damage of joints. In the present review, we highlight recently gained insights in the roles of microbes in the etiology of rheumatoid arthritis. In addition, we address important immunomodulatory processes, including biofilm formation and neutrophil function, which have been implicated in host-microbe interactions relevant for rheumatoid arthritis. Lastly, we present recent advances in the development and evaluation of emerging microbiome-based therapeutic approaches. Altogether, we conclude that the key to uncovering the etiopathogenesis of rheumatoid arthritis will lie in the immunomodulatory functions of the oral and gut microbiomes.

A Secreted Bacterial Peptidylarginine Deiminase Can Neutralize Human Innate Immune Defenses.

The keystone oral pathogen Porphyromonas gingivalis is associated with severe periodontitis. Intriguingly, this bacterium is known to secrete large amounts of an enzyme that converts peptidylarginine into citrulline residues. The present study was aimed at identifying possible functions of this citrullinating enzyme, named Porphyromonas peptidylarginine deiminase (PPAD), in the periodontal environment. The results show that PPAD is detectable in the gingiva of patients with periodontitis, and that it literally neutralizes human innate immune defenses at three distinct levels, namely bacterial phagocytosis, capture in neutrophil extracellular traps (NETs), and killing by the lysozyme-derived cationic antimicrobial peptide LP9. As shown by mass spectrometry, exposure of neutrophils to PPAD-proficient bacteria reduces the levels of neutrophil proteins involved in phagocytosis and the bactericidal histone H2. Further, PPAD is shown to citrullinate the histone H3, thereby facilitating the bacterial escape from NETs. Last, PPAD is shown to citrullinate LP9, thereby restricting its antimicrobial activity. The importance of PPAD for immune evasion is corroborated in the infection model Galleria mellonella, which only possesses an innate immune system. Together, the present observations show that PPAD-catalyzed protein citrullination defuses innate immune responses in the oral cavity, and that the citrullinating enzyme of P. gingivalis represents a new type of bacterial immune evasion factor.IMPORTANCE Bacterial pathogens do not only succeed in breaking the barriers that protect humans from infection, but they also manage to evade insults from the human immune system. The importance of the present study resides in the fact that protein citrullination is shown to represent a new bacterial mechanism for immune evasion. In particular, the oral pathogen P. gingivalis employs this mechanism to defuse innate immune responses by secreting a protein-citrullinating enzyme. Of note, this finding impacts not only the global health problem of periodontitis, but it also extends to the prevalent autoimmune disease rheumatoid arthritis, which has been strongly associated with periodontitis, PPAD activity, and loss of tolerance against citrullinated proteins, such as the histone H3.

Dropping anchor: attachment of peptidylarginine deiminase via A-LPS to secreted outer membrane vesicles of Porphyromonas gingivalis.

The periodontal pathogen Porphyromonas gingivalis has been invoked in the autoimmune disease rheumatoid arthritis (RA). This association relates to the peptidylarginine deiminase of P. gingivalis (PPAD), an enzyme capable of citrullinating human proteins and potentially contributing to loss of tolerance to citrullinated proteins in RA. PPAD is both retained in the outer membrane (OM) of P. gingivalis cells and secreted into the extracellular milieu, where it is detected in a soluble form and in association with outer membrane vesicles (OMVs). Recent studies showed that certain P. gingivalis proteins are retained in the OM through modification with an A-type lipopolysaccharide (A-LPS). Here, we investigated the possible involvement of A-LPS modification in the association of PPAD to the OM and OMVs. The results indicate that the OM- and OMV-associated PPAD is A-LPS-modified. The modified PPAD species is of low abundance in particular clinical isolates of P. gingivalis, which is not due to defects in the overall synthesis of A-LPS-modified proteins but, rather, to particular traits of the respective PPAD proteins. Lastly, we show that OMV association protects the A-LPS-modified PPAD from proteolytic degradation. Altogether, our observations show that A-LPS modification contributes to OM(V) sorting and 'protective secretion' of PPAD.

There's no place like OM: Vesicular sorting and secretion of the peptidylarginine deiminase of Porphyromonas gingivalis.

The oral pathogen Porphyromonas gingivalis is one of the major periodontal agents and it has been recently hailed as a potential cause of the autoimmune disease rheumatoid arthritis. In particular, the peptidylarginine deiminase enzyme of P. gingivalis (PPAD) has been implicated in the citrullination of certain host proteins and the subsequent appearance of antibodies against citrullinated proteins, which might play a role in the etiology of rheumatoid arthritis. The aim of this study was to investigate the extracellular localization of PPAD in a large panel of clinical P. gingivalis isolates. Here we show that all isolates produced PPAD. In most cases PPAD was abundantly present in secreted outer membrane vesicles (OMVs) that are massively produced by P. gingivalis, and to minor extent in a soluble secreted state. Interestingly, a small subset of clinical isolates showed drastically reduced levels of the OMV-bound PPAD and secreted most of this enzyme in the soluble state. The latter phenotype is strictly associated with a lysine residue at position 373 in PPAD, implicating the more common glutamine residue at this position in PPAD association with OMVs. Further, one isolate displayed severely restricted vesiculation. Together, our findings show for the first time that neither the major association of PPAD with vesicles, nor P. gingivalis vesiculation per se, are needed for P. gingivalis interactions with the human host.

The tongue microbiome in healthy subjects and patients with intra-oral halitosis.

Intra-oral halitosis (IOH) is an unpleasant odor emanating from the oral cavity. It is thought that the microbiota of the dorsal tongue coating plays a crucial role in this condition. The aim of the study was to investigate the composition of the tongue microbiome in subjects with and without IOH. A total of 26 subjects, 16 IOH patients and 10 healthy subjects were recruited based on their organoleptic score and volatile sulfur compound (VSC) measurements. The composition of the tongue microbiome was studied using the 16s amplicon sequencing of the V3-V4 hyper variable region with an Illumina MiSeq. The sequenced data were analyzed using QIIME, and the sequences obtained were distributed across 7 phyla, 27 genera and 825 operational taxonomic units (OTUs). At a higher taxon level, TM7 was associated with IOH patients whereas Gemellaceae was significantly abundant in the healthy subjects. At OTU level, we found several significant OTUs that differentiated the IOH patients from the controls. These included Aggregatibacter (OTU id 4335776), Aggregatibacter segnis (A. segnis), Campylobacter, Capnocytophaga, Clostridiales, Dialister, Leptotrichia, Parvimonas, Peptostreptococcus, Peptococcus, Prevotella, Selenomonas, SR1, Tannerella, TM7-3 and Treponema in the IOH group. In the control group, Aggregatibacter (OTU id 4363066), Haemophilus, Haemophilus parainfluenza (H. parainfluenza), Moryella, Oribacterium, Prevotella, several Streptococcus, Rothia dentocariosa (R. dentocariosa) and OTU from Gemellaceae were significantly abundant. Based on our observation, it was concluded that the bacterial qualitative composition of the IOH and the control group was almost the same, except for the few above-mentioned bacterial species and genera.

Implant decontamination with phosphoric acid during surgical peri-implantitis treatment: a RCT.

BACKGROUND: Peri-implantitis is known as an infectious disease that affects the peri-implant soft and hard tissue. Today, scientific literature provides very little evidence for an effective intervention protocol for treatment of peri-implantitis. The aim of the present randomized controlled trial is to evaluate the microbiological and clinical effectiveness of phosphoric acid as a decontaminating agent of the implant surface during surgical peri-implantitis treatment. METHODS: Peri-implantitis lesions were treated with resective surgical treatment aimed at peri-implant granulation tissue removal, bone recontouring, and pocket elimination. Fifty-three implant surfaces in 28 patients were mechanically cleaned and treated with either 35% phosphoric etching gel (test group) or sterile saline (control group). Microbiological samples were obtained during surgery; clinical parameters were recorded at baseline and at 3 months after treatment. Data were analyzed using multi-variable linear regression analysis and multilevel statistics. RESULTS: Significant immediate reductions in total anaerobic bacterial counts on the implant surface were found in both groups. Immediate reduction was greater when phosphoric acid was used. The difference in log-transformed mean anaerobic counts between both procedures was not statistical significant (p = 0.108), but there were significantly less culture-positive implants after the decontamination procedure in the phosphoric acid group (p = 0.042). At 3 months post-surgery, 75% of the implants in the control group and 63.3% of the implants in the test group showed disease resolution. However, no significant differences in clinical and microbiological outcomes between both groups were found. CONCLUSIONS: The application of 35% phosphoric acid after mechanical debridement is superior to mechanical debridement combined with sterile saline rinsing for decontamination of the implant surface during surgical peri-implantitis treatment. However, phosphoric acid as implant surface decontaminant does not seem to enhance clinical outcomes on a 3-month follow-up. TRIAL REGISTRATION: Netherlands National Trial Register, NTR5185 (www.trialregister.nl).

Extracellular Proteome and Citrullinome of the Oral Pathogen Porphyromonas gingivalis.

Porphyromonas gingivalis is an oral pathogen associated with the inflammatory disease periodontitis. Periodontitis and P. gingivalis have been associated with rheumatoid arthritis. One of the hallmarks of rheumatoid arthritis is the loss of tolerance against citrullinated proteins. Citrullination is a post-translational modification of arginine residues, leading to a change in structure and function of the respective protein. This modification, which is catalyzed by peptidylarginine deiminases (PADs), plays a role in several physiological processes in the human body. Interestingly, P. gingivalis secretes a citrullinating enzyme, known as P. gingivalis PAD (PPAD), which targets bacterial and human proteins. Because the extent of P. gingivalis protein citrullination by PPAD was not yet known, the present study was aimed at identifying the extracellular proteome and citrullinome of P. gingivalis. To this end, extracellular proteins of two reference strains, two PPAD-deficient mutants, and three clinical isolates of P. gingivalis were analyzed by mass spectrometry. The results uncovered substantial heterogeneity in the extracellular proteome and citrullinome of P. gingivalis, especially in relation to the extracellular detection of typical cytoplasmic proteins. In contrast, the major virulence factors of P. gingivalis were identified in all investigated isolates, although their citrullination was shown to vary. This may be related to post-translational processing of the PPAD enzyme. Altogether, our findings focus attention on the possible roles of 6 to 25 potentially citrullinated proteins, especially the gingipain RgpA, in periodontitis and rheumatoid arthritis.

Regulatory CD4+ T-Cell Subsets and Anti-Citrullinated Protein Antibody Repertoire: Potential Biomarkers for Arthritis Development in Seropositive Arthralgia Patients?

OBJECTIVE: Seropositive arthralgia patients (SAP) are at high risk of developing rheumatoid arthritis (RA). This prospective study aimed to determine whether altered peripheral regulatory T-cells (Tregs) and defined subsets, besides a broadened anti-citrullinated protein antibody (ACPA) response, may qualify as biomarkers for RA development in SAP. METHODS: Thirty-four consecutive SAP were prospectively assessed every 6 months for minimally 2 years. At inclusion, peripheral Treg (CD4+CD25+FoxP3+) numbers and subsets, defined as CD45RA+FoxP3low naive Tregs (Fr I), CD45RA-FoxP3high activated Tregs (Fr II) and CD45RA-FoxP3low non-Tregs (Fr III), were compared to age- and sex-matched healthy controls (HC, n = 16) and treatment-naive RA patients (n = 12). SAP that developed RA were compared to non-switchers and analyzed for Treg numbers and Treg subsets at inclusion. Also, Treg numbers and subsets were compared in switched SAP before and at diagnosis. To assess the ACPA repertoire, IgG and IgA reactivity was measured against citrullinated peptides from fibrinogen, α-enolase and vimentin. RESULTS: Treg numbers were similar between HC, SAP and RA patients. Although the bonafide Treg subsets Fr I and Fr II were comparable between groups, Fr III was increased in SAP compared to HC (p = 0.01). Fourteen (41%) SAP developed RA during follow-up. Their Treg numbers and subsets were comparable to non-switched SAP. At RA diagnosis, Treg numbers in switched SAP were similar to 6 months before. Switched SAP displayed a more diverse IgG ACPA repertoire compared to non-switched SAP (p = 0.046) and showed more IgA reactivity than non-switched SAP reaching significance for Fib1 only (p = 0.047). CONCLUSION: Numbers of Total Treg and bonafide Treg subsets are not indicative for RA development in SAP, opposed to the ACPA repertoire.

Prognostic indicators for surgical peri-implantitis treatment.

OBJECTIVES: Objective of this study was to identify prognostic indicators for the outcome of resective peri-implantitis treatment, by an analysis of the pooled data of two previously conducted randomized controlled trials. MATERIAL AND METHODS: Data of 74 patients with peri-implantitis (187 implants) who had received resective surgical treatment were available. Primary outcome variable was failure of peri-implantitis treatment after 12 months. Multilevel univariable and multiple logistic regression analyses were performed to evaluate the effect of various potentially prognostic indicators on the primary outcome. RESULTS: Peri-implantitis treatment was unsuccessful in 106 implants (57%) and 48 patients (67%) after 12 months. In the multiple regression analysis, the variables "order of inclusion" (P = 0.016) and mean bone loss at baseline (P = 0.030) were significant prognostic indicators for treatment failure. To eliminate the effect of "order of inclusion," post hoc analyses were carried out in a subgroup of patients. The univariable post hoc analysis showed a significant association for smoking (P = 0.015), maximum pocket depth at baseline (P = 0.073), mean bone loss at baseline (P = 0.003), and presence of plaque (P = 0.100). In the multiple regression post hoc analysis, only the variables smoking (P = 0.044) and mean bone loss (P = 0.043) remained statistically significant. CONCLUSIONS: The outcome of surgical peri-implantitis treatment is influenced by the experience of the surgical team with the surgical procedure. The observed learning effect has consequences for clinical practice and for conducting and interpreting clinical trials on peri-implantitis treatment. Other prognostic indicators are amount of peri-implant bone loss at baseline and smoking, and to a lesser extent, probing pocket depth at baseline and presence of plaque during follow-up. Early diagnosis of peri-implantitis and control of behavioral factors are crucial in achieving peri-implantitis treatment success.

The peptidylarginine deiminase gene is a conserved feature of Porphyromonas gingivalis.

Periodontitis is an infective process that ultimately leads to destruction of the soft and hard tissues that support the teeth (the periodontium). Periodontitis has been proposed as a candidate risk factor for development of the autoimmune disease rheumatoid arthritis (RA). Porphyromonas gingivalis, a major periodontal pathogen, is the only known prokaryote expressing a peptidyl arginine deiminase (PAD) enzyme necessary for protein citrullination. Antibodies to citrullinated proteins (anti-citrullinated protein antibodies, ACPA) are highly specific for RA and precede disease onset. Objective of this study was to assess P. gingivalis PAD (PPAD) gene expression and citrullination patterns in representative samples of P. gingivalis clinical isolates derived from periodontitis patients with and without RA and in related microbes of the Porphyromonas genus. Our findings indicate that PPAD is omnipresent in P. gingivalis, but absent in related species. No significant differences were found in the composition and expression of the PPAD gene of P. gingivalis regardless of the presence of RA or periodontal disease phenotypes. From this study it can be concluded that if P. gingivalis plays a role in RA, it is unlikely to originate from a variation in PPAD gene expression.