Mibianto: ultra-efficient online microbiome analysis through k-mer based metagenomics.

Quantifying microbiome species and composition from metagenomic assays is often challenging due to its time-consuming nature and computational complexity. In Bioinformatics, k-mer-based approaches were long established to expedite the analysis of large sequencing data and are now widely used to annotate metagenomic data. We make use of k-mer counting techniques for efficient and accurate compositional analysis of microbiota from whole metagenome sequencing. Mibianto solves this problem by operating directly on read files, without manual preprocessing or complete data exchange. It handles diverse sequencing platforms, including short single-end, paired-end, and long read technologies. Our sketch-based workflow significantly reduces the data volume transferred from the user to the server (up to 99.59% size reduction) to subsequently perform taxonomic profiling with enhanced efficiency and privacy. Mibianto offers functionality beyond k-mer quantification; it supports advanced community composition estimation, including diversity, ordination, and differential abundance analysis. Our tool aids in the standardization of computational workflows, thus supporting reproducibility of scientific sequencing studies. It is adaptable to small- and large-scale experimental designs and offers a user-friendly interface, thus making it an invaluable tool for both clinical and research-oriented metagenomic studies. Mibianto is freely available without the need for a login at: https://www.ccb.uni-saarland.de/mibianto.

Skin treatment with non-thermal plasma modulates the immune system through miR-223-3p and its target genes.

Non-thermal plasma, a partially ionized gas, holds significant potential for clinical applications, including wound-healing support, oral therapies, and anti-tumour treatments. While its applications showed promising outcomes, the underlying molecular mechanisms remain incompletely understood. We thus apply non-thermal plasma to mouse auricular skin and conducted non-coding RNA sequencing, as well as single-cell blood sequencing. In a time-series analysis (five timepoints spanning 2 hours), we compare the expression of microRNAs in the plasma-treated left ears to the unexposed right ears of the same mice as well as to the ears of unexposed control mice. Our findings indicate specific effects in the treated ears for a set of five miRNAs: mmu-miR-144-5p, mmu-miR-144-3p, mmu-miR-142a-5p, mmu-miR-223-3p, and mmu-miR-451a. Interestingly, mmu-miR-223-3p also exhibits an increase over time in the right non-treated ear of the exposed mice, suggesting systemic effects. Notably, this miRNA, along with mmu-miR-142a-5p and mmu-miR-144-3p, regulates genes and pathways associated with wound healing and tissue regeneration (namely ErbB, FoxO, Hippo, and PI3K-Akt signalling). This co-regulation is particularly remarkable considering the significant seed dissimilarities among the miRNAs. Finally, single-cell sequencing of PBMCs reveals the downregulation of 12 from 15 target genes in B-cells, Cd4+ and Cd8+ T-cells. Collectively, our data provide evidence for a systemic effect of non-thermal plasma.

Extracellular Release of a Disintegrin and Metalloproteinase Correlates With Periodontal Disease Severity.

AIM: Periodontal disease is driven by oral pathogens, including Porphyromonas gingivalis, and the release of inflammatory cytokines. These cytokines (e.g., TNF) or their receptors (e.g., IL-1R) are substrates of a disintegrin and metalloproteinases (ADAMs). In this study, we aimed to determine the effects of ADAMs on periodontal disease phenotypes. MATERIALS AND METHODS: Western blot and FRET-based activity measurements of the gingival crevicular fluid (GCF) of patients were compared with those of infected (P. gingivalis) or cytokine-stimulated oral keratinocytes and primary human neutrophils, respectively. This was accompanied by an analysis of the released extracellular vesicles and MMP9 activity. RESULTS: In the GCF of patients, ADAM8 protein expression and activity were correlated with disease stage, whereas ADAM10 protein expression was inversely correlated with disease stage. Infection and the resulting cytokine release orchestrated the release of soluble ADAM8 by oral keratinocytes and primary neutrophils as soluble ectodomain and on exosomes, respectively. Furthermore, ADAM8 regulated the release of ADAM10 and MMP9. CONCLUSION: Dysregulation of cell-associated and extracellular ADAM proteolytic activity may be an essential regulatory element in the progression of periodontal disease driven by ADAM8. The influence of ADAM8 on disease onset and the evaluation of targeting ADAM8 as a potential and novel local treatment option should be addressed in future translational in vivo studies.

Effect of Polyphenols on the Ultrastructure of the Dentin Pellicle and Subsequent Erosion.

INTRODUCTION: Erosive tooth wear is a highly prevalent dental condition that is modified by the ever-present salivary pellicle. The aim of the present in situ study was to investigate the effect of polyphenols on the ultrastructure of the pellicle formed on dentin in situ and a subsequent erosive challenge. METHODS: The pellicle was formed on bovine dentin specimens for 3 min or 2 h in 3 subjects. After subjects rinsed with sterile water (negative control), 1% tannic acid, 1% hop extract, or tin/fluoride solution containing 800 ppm tin and 500 ppm fluoride (positive control), specimens were removed from the oral cavity. The erosive challenge was performed on half of the specimens with 1% citric acid, and all specimens were analyzed by transmission electron microscopy. Incorporation of tannic acid in the pellicle was investigated by fluorescence spectroscopy. RESULTS: Compared to the negative control, ultrastructural analyses reveal a thicker and electron-denser pellicle after application of polyphenols, in which, according to spectroscopy, tannic acid is also incorporated. Application of citric acid resulted in demineralization of dentin, but to a lesser degree when the pellicle was pretreated with a tin/fluoride solution. The pellicle was more acid-resistant than the negative control when modified with polyphenols or tin/fluoride solution. CONCLUSION: Polyphenols can have a substantial impact on the ultrastructure and acid resistance of the dentin pellicle, while the tin/fluoride solution showed explicit protection against erosive demineralization.

Effects of apical periodontitis treatment on hyperglycaemia in diabetes: A prospective cohort study.

AIM: This prospective cohort study was undertaken to evaluate the success rate of root canal treatment (RCT) in type 2 diabetes mellitus (T2DM) patients with targeted level and unachieved targeted level of glycaemic control as well as the impact of RCT on the glucose blood level in T2DM patients. METHODOLOGY: Patients needing RCT were divided into three groups: these without T2DM, that is, the control group (CG), those with targeted level of glycated haemoglobin HbA1c < 7% (TL A1c) and the third ones with unachieved targeted level (UTL A1c), that is, with HbA1c ≥ 7%. Before RCT, HbA1c and the periapical index (PAI) score were assessed, as well as 1 year later. RESULTS: Our results showed less favourable treatment results of RCT such as a reduction of radiographic lesions in T2DM patients, particularly in subjects with UTL A1c. The intergroup analysis of PAI score at the 12-month follow-up revealed a significant difference in TL A1C (p = .022) and CG (p = .001) with respect to UTL A1c. Total number of healed teeth (PAI≤2) at the 12-month after RCT in UTL A1c was significantly lower in comparison to CG (p = .008). Contrariwise, RCT may improve the glycaemic control in diabetic patients with UTL A1c after 12 months of posttreatment. Regression analysis showed that UTL A1c patients were more likely to have AP persistence after endodontic treatment (OR = 4.788; CI: 1.157-19.816; p = .031). CONCLUSIONS: T2DM retards the AP healing and conversely AP contributes to increasing the inflammatory burden in T2DM. RCT reduces the cumulative inflammatory burden in T2DM and thus may contribute to improvement of glycaemic control particularly in patients with UTL A1c.

Bacterial contamination potential of personal protective equipment itself in dental aerosol-producing treatments.

Personal protective equipment (PPE) has long been a high priority in dental aerosol-producing treatments. Since COVID-19 pandemic, its importance has increased yet again. While importance of PPE in preventing transmission and thus possible infection of pathogens is well known, contamination potential of PPE after treatment itself is less investigated. This review aims to give an overview of the current literature and contamination potential (viral, blood, bacterial) of components of protective equipment itself. The literature search was performed using the Medline database; furthermore, a hand search was conducted. Last search took place on 23 November 2022. Two categories of hygiene-related keywords were formed (category A: mask, face shield, goggles, eyewear, personal protective equipment; category B: contamination, aerosol). Each keyword from one category was combined with all keywords from the other one. In addition, the keyword "dental" was always added. First, a title and abstract screening was performed. Afterward, a full-text analysis was followed for the included studies. A total of 648 search hits were found in the Medline database. 47 were included after title and abstract screening. 22 studies were excluded after full-text analysis, 25 studies were included. The hand search resulted in 4 studies that were included. Bacterial contamination of PPE after treatment has been adequately studied, contamination with blood less. Microorganisms mainly originate from the oral and cutaneous flora; however, a transmission of potential pathogens like Staphylococcus aureus or Escherichia coli was also described. Studies showing transmission pathways starting from PPE and its various components are lacking. No measures have yet been described that fully protect the protective equipment from contamination. There is growing awareness that PPE itself can be a source of pathogen transmission, and thus possible infection. Therefore, not only wearing of protective clothing, but also conscious handling of it is crucial for transmission and possible infection prevention. However, studies showing transmission pathways starting from PPE and its various components are lacking. Several studies have investigated what measures can be taken to protect the protective equipment itself. So far, none of the methods evaluated can prevent contamination of PPE.

Vesicular Messages from Dental Biofilms for Neutrophils.

The encounter between dental biofilm and neutrophils in periodontitis remains elusive, although it apparently plays a crucial role in the periodontal pathology and constitutes a key topic of periodontology. Dental biofilm and neutrophils were isolated from orally healthy persons and patients with periodontitis. We investigated biofilm and its particle-shedding phenomenon with electron microscopy and nanoparticle tracking analysis (NTA); biofilm shedding-neutrophil interactions were examined ex vivo with epi-fluorescence microscopy. For this purpose, we used acellular dental biofilm shedding, purified lipopolysaccharide (LPS), and phorbol 12-myristate 13-acetate (PMA) as activators, and the interleukin 8 receptor beta (CXCR2) inhibitor and the anti-interleukin 8 receptor alpha (CXCR1) antibody as modulators. The shedding of acellular dental biofilms overwhelmingly consists of bacterial extracellular vesicles (BEVs). The latter induced the moderate formation of neutrophil extracellular traps (NETs) in orally healthy subjects and a strong formation in patients with periodontitis. A CXCR2 inhibitor and an anti-CXCR1 antibody had a minor effect on NET formation. Neutrophils from patients with periodontitis exhibited NET hyper-responsiveness. BEVs were stronger inducers of NET formation than purified LPS and PMA. A plateau of neutrophil responsiveness is reached above the age of 40 years, indicating the abrupt switch of maladaptive trained immunity (TI) into the activated modus. Our results suggest that dental biofilms consist of and disseminate immense amounts of outer membrane vesicles (OMVs), which initiate NET formation via a non-canonical cytosolic LPS/caspase-4/11/Gasdermin D pathway. This modus of NET formation is independent of neutrophil elastase (NE), myeloperoxidase (MPO), peptidylarginine deiminase 4 (PAD4), and toll-like receptors (TLR). In periodontitis, the hyper-responsiveness of neutrophils to BEVs and the increased NET formation appear to be a consequence of TI.

Dental aerosol-producing treatments: Comparison of contamination patterns of face shields and surgical masks.

During the COVID-19 pandemic, dental face shields were recommended to protect the eyes. This study aimed to examine to what extent face shield and mask contamination differ when a pre-procedural mouth rinsing with Chlorhexidine (CHX) is conducted before treatment. In this prospective, randomized study, three groups of subjects were formed (rinsing with 0.1% CHX, water, or no rinsing (control) before aerosol-producing treatments). After each of the 301 treatments, the practitioner's face shield was swabbed with eSwab and the mask was brought into contact with agar plates. Sampling was done from the exterior surface only. Samples were cultured for 48 h at 35 °C under aerobic and anaerobic conditions. Bacteria were classified by phenotypic characteristics, biochemical test methods, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Colony-forming units were counted and mean values were compared (WSR, H-test, U-test, p < 0.05). Within each subject group, face shields showed significantly more contamination than surgical masks (control group: 350 CFU, 50 CFU; intervention water: 270 CFU, 40 CFU; intervention CHX: 250 CFU, 30 CFU). Comparison of face shields of the different subject groups did not reveal any statistically significant differences. However, CHX resulted in a statistically significant bacterial reduction on surgical masks compared to the water and control group (control: 50 CFU, intervention water: 40 CFU, intervention CHX: 30 CFU). Contamination of face shields and surgical masks was highest in the control group, followed by the water group, and lowest in the intervention group with CHX. Streptococcus spp. and Staphylococcus spp. dominated, representing the oral and cutaneous flora. Contamination of masks worn with or without face shields did not differ. Presumably, face shields intercept first splashes and droplets, while the masks were mainly exposed to bioaerosol mist. Consequently, face shields protect the facial region and surroundings from splashes and droplets, but not the mask itself. A pre-procedural mouth rinse with CHX had no statistically significant reducing effect on contamination of the face shield, but a statistically significant reducing effect was observed on contamination of the mask.

Prevention of Dental Biofilm Formation with Polyphenols: A Systematic Review.

Polyphenols are plant secondary products with health-promoting properties against various degenerative or infectious diseases, and thus may help in the prevention of oral diseases. The aim of the present systematic review was to investigate polyphenols as a possible adjuvant in inhibiting dental biofilm formation, which is an important precondition for the most prevalent oral disease - caries and periodontitis. A literature search was conducted using the databases PubMed, CENTRAL and Scopus. Only studies with oral healthy participants and plaque level as outcome were included. Data search and extraction was conducted by two authors independently. Of the 211 initially identified studies, only six met all inclusion criteria. Meta-analysis was performed with five studies using the random effect model. Treatment with polyphenols reduced the plaque level in comparison to a negative control, but not significantly. Strong evidence of heterogeneity was observed. The diversity and complexity of polyphenols and their preparation need to be considered. There is no clear evidence that clinical use of polyphenols can prevent dental biofilm formation. Additional research with more and larger randomized controlled trials are required.

Salivary pellicle modulates biofilm formation on titanium surfaces.

OBJECTIVES: The present study aimed to evaluate the potential of the salivary pellicle (SP) formed on titanium (Ti) surfaces to modulate the formation of a biofilm composed of Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis. MATERIALS AND METHODS: Ti substrates were incubated for 2 h with a pool of saliva samples obtained from 10 systemically and periodontally healthy subjects. Enamel substrates were included as a biological reference. Scanning electron microscopy (SEM) and Raman spectroscopy analysis were used to analyze the formation of the salivary pellicle. After the SP formation, the surfaces were incubated for 12 h with a mix of Streptococcus gordonii, Actinomyces naeslundii, Fusobacterium nucleatum, and Porphyromonas gingivalis. The number of bacterial cells attached to each surface was determined by the XTT assay while bacterial viability was analyzed by fluorescence microscopy using the LIVE/DEAD® BacLightTM kit. RESULTS: The SEM and Raman spectroscopy analysis confirmed the presence of a salivary pellicle formed on the tested surfaces. Regarding the biofilm formation, the presence of the SP decreases the number of the bacterial cells detected in the test surfaces, compared with the uncover substrates. Even more, the SP-covered substrates showed similar bacterial counts in both Ti and enamel surfaces, meaning that the physicochemical differences of the substrates were less determinant than the presence of the SP. While on the SP-uncover substrates, differences in the bacterial adhesion patterns were directly related to the physicochemical nature of the substrates. CONCLUSIONS: The salivary pellicle was the main modulator in the development of the biofilm consisting of representative oral bacteria on the Ti substrates. CLINICAL RELEVANCE: The results of this study provide valuable information on the modulatory effect of the salivary pellicle on biofilm formation; such information allows us to understand better the events involved in the formation of oral biofilms on Ti dental implants.

The impact of general medical health status, demographical, and patient-specific variables on need for dental treatment of children and adolescents under general anesthesia.

OBJECTIVES: Aim of this retrospective study was to examine the influence of general medical, demographical, and other patient-specific factors on the need for dental treatment under general anesthesia in children and adolescents at Saarland University Hospital. For assessment of the clinical treatment need, a mixed dt/DT (decayed teeth) was introduced. MATERIALS AND METHODS: A total of 340 patients under 18 years of age who received restorative-surgical dental treatment between 2011 and 2022 were anonymously enrolled. Demographic and other patient-specific data, general medical health, oral health, and treatment related data were recorded. In addition to descriptive analysis, Spearman-Rho-test, Mann-Whitney-U-test, Kruskall-Wallis-test and Chi-square-test were used. RESULTS: More than half of the patients (52,6%) were in general health, but non-cooperative. The majority of the patients (66.8%) was between 1 and 5 years of age (p < 0,001). Mean dmft was 10.95 ± 4.118, mean DMFT was 10.09 ± 7.885, and mean dt/DT was 10.79 ± 4.273. Analysis showed that communication difficulties significantly influenced dmft (p = 0.004), DMFT (p = 0.019), and dt/DT (p < 0.001). Type of insurance significantly affected dmft (p = 0.004) and dt/DT (p = 0.001). There was no significant effect of ASA on caries experience, however on prevalence of severe gingivitis (p < 0.001), number of extractions (p = 0.002), and need for repeated treatment (p < 0.001). CONCLUSIONS: Need for dental treatment in the present collective was high, independent of the considered variables. Non-Cooperativeness along with ECC was the main indication for dental general anesthesia. The mixed dt/DT was the most precise survey to evaluate clinical treatment needs. CLINICAL RELEVANCE: Given the enormous demand for these rehabilitations with strict selection, it is imperative to create more treatment capacities for patients mandatorily requiring general anesthesia by avoiding it in healthy patients.

Cytotoxic effects of different mouthwash solutions on primary human articular chondrocytes and normal human articular cartilage - an in vitro study.

OBJECTIVES: To compare the cytotoxicity of octenidine dihydrochloride and chlorhexidine gluconate at different concentrations on primary human articular chondrocytes and cartilage. MATERIALS AND METHODS: Primary cultures of human normal adult articular chondrocytes were exposed to octenidine dihydrochloride (0.001562%, 0.003125%, 0.00625%, 0.0125%, 0.025%, 0.05%, and 0.1%), chlorhexidine gluconate (0.003125%, 0.00625%, 0.0125%, 0.025%, 0.05%, 0.1%, and 0.2%), and control (Dulbecco's modified Eagle medium or phosphate-buffered saline) for 30 s. Normal human articular cartilage explants were exposed to octenidine dihydrochloride (0.1% versus control) and chlorhexidine gluconate (0.1% versus control) for 30 s. The viability of human articular chondrocytes was measured by Trypan blue staining, Cell Proliferation Reagent WST-1, and Live/Dead staining. The proliferation of human chondrocytes was measured using the Cell Proliferation Reagent WST-1. The viability of human articular cartilage explants was measured by using Live/Dead staining. RESULTS: Octenidine dihydrochloride and chlorhexidine gluconate exposure decreased cell viability and proliferation in a dose-dependent manner in primary human articular chondrocytes. Octenidine dihydrochloride and chlorhexidine gluconate exposure decreased cell viability in human articular cartilage explant cultures. CONCLUSION: The degree of toxicity varied between octenidine dihydrochloride and chlorhexidine gluconate, with chlorhexidine gluconate being less toxic than octenidine dihydrochloride at the same concentration. Additionally, both octenidine dihydrochloride and chlorhexidine gluconate evaluation had cytotoxic effects on human articular cartilage. Therefore, dosing for the antimicrobial mouthwash ingredients administration would ideally be determined to remain below IC50. CLINICAL RELEVANCE: These data support the in vitro safety of antimicrobial mouthwashes on primary adult human articular chondrocytes.

Breaking the Gingival Barrier in Periodontitis.

The break of the epithelial barrier of gingiva has been a subject of minor interest, albeit playing a key role in periodontal pathology, transitory bacteraemia, and subsequent systemic low-grade inflammation (LGI). The significance of mechanically induced bacterial translocation in gingiva (e.g., via mastication and teeth brushing) has been disregarded despite the accumulated knowledge of mechanical force effects on tight junctions (TJs) and subsequent pathology in other epithelial tissues. Transitory bacteraemia is observed as a rule in gingival inflammation, but is rarely observed in clinically healthy gingiva. This implies that TJs of inflamed gingiva deteriorate, e.g., via a surplus of lipopolysaccharide (LPS), bacterial proteases, toxins, Oncostatin M (OSM), and neutrophil proteases. The inflammation-deteriorated gingival TJs rupture when exposed to physiological mechanical forces. This rupture is characterised by bacteraemia during and briefly after mastication and teeth brushing, i.e., it appears to be a dynamic process of short duration, endowed with quick repair mechanisms. In this review, we consider the bacterial, immune, and mechanical factors responsible for the increased permeability and break of the epithelial barrier of inflamed gingiva and the subsequent translocation of both viable bacteria and bacterial LPS during physiological mechanical forces, such as mastication and teeth brushing.

Olive Oil as a Transport Medium for Bioactive Molecules of Plants?-An In Situ Study.

(1) Caries and erosions still remain a challenge for preventive dentistry. Certain plant extracts have shown beneficial effects in preventive dentistry. The aim of this study was to evaluate the antibacterial, anti-adherent and erosion-protective properties of ellagic acid (EA) as a polyphenolic agent. The combination with olive oil was investigated additionally to verify a possible improved bioactive effect of EA. (2) An in situ study was carried out with six subjects. Individual splints were prepared with bovine enamel specimens. The splints were worn for 1 min (pellicle formation time). Thereafter, 10 min rinses were performed with EA in water/in oil. Bacterial adherence was evaluated by fluorescence microscopy (DAPI, ConA, BacLight) after an 8 h oral exposition time. Additionally, the splints were worn for 30 min to quantify demineralization processes. The ultrastructure of the pellicle was investigated after an oral exposure time of 2 h under a transmission electron microscope. Statistical analysis was performed by Kruskal-Wallis tests, Mann-Whitney U tests and Bonferroni-Holm correction. (3) Rinsing with EA led to a significant reduction of adherent vital and dead bacteria. The combination with olive oil did not improve these outcomes. The assessment of glucan structures after rinsing with EA in water showed significant effects. Significant differences were observed for both rinses in calcium release at pH 3.0. After rinsing with EA in oil, significantly less calcium was released compared to rinsing with EA in water (pH = 3.0). (4) Olive oil is not suitable as a transport medium for lipophilic polyphenols. EA has anti-adherent and antibacterial properties in situ. EA also shows erosion-protective effects, which can be enhanced in combination with olive oil depending on the pH value. Ellagic acid has a neutral pH and could be an opportunity in the treatment of specific patient groups (xerostomia or mucositis).

[Introduction of "professional field exploration" for Saarland University dentistry students]. / Einführung des Fachs "Berufsfelderkundung" für Studierende der Zahnmedizin an der Universität des Saarlandes.

The new dental licensing regulations (ZApprO) have been in effect since the 2021/2022 winter semester and stipulate that a "professional field exploration course" be offered in the dentistry degree program. At Saarland University, the course consists of five parts: (I) introduction, (II) practicum, (III) reflection report, (IV) symposium, and (V) evaluation. The practicum is designed to provide students with earlier exposure to clinical reality, give them more confidence in dealing with patients, motivate them, and teach them about the professional role in the healthcare profession. In addition, the reflection report and symposium will initiate the development of scientific competencies. The evaluation, together with the evaluation of the reflection reports, serves to verify the success of the introduction of the course. The purpose of this paper is to describe the new course and to present the results of the result of the evaluation of the two courses in 2021 and 2022.

Direct and indirect effects of different dentifrices on the initial bacterial colonization of enamel in situ overnight.

OBJECTIVE: The aim of this study was to investigate the direct and indirect influence of fluoridated toothpastes and fluoride-free toothpaste with hydroxyapatite (HAP) as active ingredient on initial bacterial colonization on enamel in situ. METHODS: For this clinical-experimental pilot study, eight subjects were instructed to brush their teeth with three different toothpastes (Elmex® : 1400 ppm AmF, Meridol® : 1400 ppm AmF +SnF2, Karex® : HAP), using each for two consecutive days. As a control, brushing without toothpaste was performed. To evaluate bacterial colonization, subject wore splints with buccally placed bovine enamel platelets overnight. Two modes were tested. In a first pass (regimen A), the splints were inserted after toothbrushing to examine the indirect effects of the dentifrices. In order to investigate the direct effects, the specimens were brushed in situ in a second pass (regimen B). Biofilm formation was visualized and quantified using fluorescence microscopy (DAPI and BacLight) and transmission electron microscopy (TEM). RESULTS: For brushing regimen A (indirect effect of dentifrices), no statistical differences were detected between any of the tested dentifrices or the control. Likewise, no statistically significant differences were recorded for brushing regimen B (direct effect of dentifrices). Furthermore, no differences between the different brushing techniques were determined with regard to the ultrastructure of the overnight biofilm. CONCLUSION: Within the limitations of the present pilot study, it can be concluded that in patients with good oral hygiene, dentifrices and their chemical composition have no statistically significant effect on the initial bacterial colonization of enamel platelets in situ, irrespectively of the mode of application.

Ultrastructure of the Dentin Pellicle and the Impact of Erosion.

While the ultrastructure of the enamel pellicle and its erosion protective properties are well studied, the dentin pellicle is still neglected in dental research. Therefore, the ultrastructure and erosion protective properties of a pellicle formed on bovine dentin specimens were investigated in the present study. The dentin pellicle was formed in situ for 3, 30, 120, and 360 min at buccal or palatal oral sites of 3 subjects and analyzed by transmission electron microscopy. In order to clarify the impact of an erosive challenge to the ultrastructure of the pellicle and the underlying dentin, specimens were exposed to the oral cavity and eroded in vivo with 0.1% or 1% citric acid either immediately or after 30 min of pellicle formation. Specimens that were eroded without exposure to the oral cavity served as control. In another trial, specimens with a 30-min pellicle were exposed to the oral cavity for a further 60 min after the erosive challenge to investigate the effect of saliva on the impaired pellicle and dentin. Transmission electron micrographs reveal a globular and granular structured pellicle layer, which was thicker when the pellicle was formed buccally or with longer formation times. Erosion with citric acid reduced the thickness of the pellicle and interrupted its continuity. The dentin was also affected by erosion, which was represented by a lower electron density and formation of demineralized lacunae. These were infiltrated by a granular structured material when specimens were exposed to the oral cavity. After further intraoral exposure, the infiltration was more pronounced, indicating a significant impact of saliva on the demineralized dentin. A reformation of the dentin pellicle on the other hand did not occur. In conclusion, the dentin pellicle is neither acid-resistant nor able to effectively protect dentin from erosion.

Expression of inflammatory mediators in biofilm samples and clinical association in inflammatory bowel disease patients-a preliminary study.

OBJECTIVES: Inflammatory bowel disease (IBD) has multiple impacts on soft and hard tissues in the oral cavity. The aim of this study was to analyze the expression of cytokines in biofilm samples from patients suffering from IBD and compare them to healthy patients. It was hypothesized that different cytokine expression levels and clinical associations might be drawn. MATERIAL AND METHODS: A total of 56 biofilm samples from three different patient cohorts (group 0 = healthy, HC n = 30; group 1 = Crohn's disease, CD, n = 19; group 2 = ulcerative colitis, UC, n = 7) were examined for the expression levels of the cytokine interleukins IL-2, -6, and -10; matrix metalloproteinases 7 and 9; and surface antigens CD90/CD11a by quantitative real-time PCR and according to clinical parameters (plaque index, BOP, PD, DMFT, CAL). Relative gene expression was determined using the ∆∆CT method. RESULTS: The mean BOP values (p = 0.001) and PD (p = 0.000) were significantly higher in the CD group compared to controls. Expression of IL-10 was significantly higher in the CD (p = 0.004) and UC groups (p = 0.022). Expression of MMP-7 was significantly higher in the CD group (p = 0.032). IBD patients treated with TNF inhibitors (p = 0.007) or other immunosuppressants (p = 0.014) showed significant overexpression of IL-10 compared to controls. CONCLUSION: Different expression levels of IL-10 and MMP-7 were detected in plaque samples from IBD patients. As only BOP was significantly increased, we conclude that no clinical impairment of periodontal tissue occurred in IBD patients. CLINICAL RELEVANCE: With the worldwide increasing incidence of IBD, it is important to obtain insights into the effects of the disease on the oral cavity. The study was registered (01.09.2020) at the German clinical trial registry (DRKS00022956). CLINICAL TRIAL REGISTRATION: The study is registered at the German clinical trial registry (DRKS00022956).

Bioadhesion on Textured Interfaces in the Human Oral Cavity-An In Situ Study.

Extensive biofilm formation on materials used in restorative dentistry is a common reason for their failure and the development of oral diseases like peri-implantitis or secondary caries. Therefore, novel materials and strategies that result in reduced biofouling capacities are urgently sought. Previous research suggests that surface structures in the range of bacterial cell sizes seem to be a promising approach to modulate bacterial adhesion and biofilm formation. Here we investigated bioadhesion within the oral cavity on a low surface energy material (perfluorpolyether) with different texture types (line-, hole-, pillar-like), feature sizes in a range from 0.7-4.5 µm and graded distances (0.7-130.5 µm). As a model system, the materials were fixed on splints and exposed to the oral cavity. We analyzed the enzymatic activity of amylase and lysozyme, pellicle formation, and bacterial colonization after 8 h intraoral exposure. In opposite to in vitro experiments, these in situ experiments revealed no clear signs of altered bacterial surface colonization regarding structure dimensions and texture types compared to unstructured substrates or natural enamel. In part, there seemed to be a decreasing trend of adherent cells with increasing periodicities and structure sizes, but this pattern was weak and irregular. Pellicle formation took place on all substrates in an unaltered manner. However, pellicle formation was most pronounced within recessed areas thereby partially masking the three-dimensional character of the surfaces. As the natural pellicle layer is obviously the most dominant prerequisite for bacterial adhesion, colonization in the oral environment cannot be easily controlled by structural means.

Apical periodontitis after intense bruxism.

BACKGROUND: Bruxism is known to cause masticatory muscle pain, temporomandibular joint pain, headaches, mechanical tooth wear, prosthodontic complications and cracked teeth. Less known to the practitioner, and described only experimentally in literature, is that bruxism can also damage the pulp. To our knowledge, this is the first known clinical case of a patient developing apical periodontitis due to bruxism. CASE PRESENTATION: This article presents the case and successful treatment of a 28-year-old healthy male patient with apical periodontitis on teeth 36 and 46 requiring root canal treatment after an intense phase of bruxism. Due to an unclear diagnosis, treatment had been delayed. CONCLUSIONS: Incomprehensible tooth pain can be the result of bruxism. Practitioners need to be informed that intense bruxism can possibly lead to apical periodontitis. It is important, therefore, that a thorough anamnesis is collected and taken into account during diagnostics.