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Objective: To evaluate the effectiveness of the WhiteTeeth mobile app, a theory-based mobile health (mHealth) program for promoting oral hygiene in adolescent orthodontic patients. Methods: In this parallel randomized controlled trial, the data of 132 adolescents were collected during three orthodontic check-ups: at baseline (T0), at 6-week follow-up (T1) and at 12-week follow-up (T2). The intervention group was given access to the WhiteTeeth app in addition to usual care (n = 67). The control group received usual care only (n = 65). The oral hygiene outcomes were the presence and the amount of dental plaque (Al-Anezi and Harradine plaque index), and the total number of sites with gingival bleeding (Bleeding on Marginal Probing Index). Oral health behaviour and its psychosocial factors were measured through a digital questionnaire. We performed linear mixed-model analyses to determine the intervention effects. Results: At 6-week follow-up, the intervention led to a significant decrease in gingival bleeding (B = −3.74; 95% CI −6.84 to −0.65) and an increase in the use of fluoride mouth rinse (B = 1.93; 95% CI 0.36 to 3.50). At 12-week follow-up, dental plaque accumulation (B = −11.32; 95% CI −20.57 to −2.07) and the number of sites covered with plaque (B = −6.77; 95% CI −11.67 to −1.87) had been reduced significantly more in the intervention group than in the control group. Conclusions: The results show that adolescents with fixed orthodontic appliances can be helped to improve their oral hygiene when usual care is combined with a mobile app that provides oral health education and automatic coaching. Netherlands Trial Registry Identifier: NTR6206: 20 February 2017.

Rheumatoid arthritis (RA) is an auto-immune disease affecting the synovial joints. The current literature reports several interactions between RA and the orofacial system, such as an increased prevalence of temporomandibular disorders (TMD), reduced saliva production, and increased prevalence of dental plaque and caries. For periodontitis, a chronic inflammatory disease of the tooth-supporting tissues, bidirectional associations are found. Furthermore, it has been suggested that the oral microbiome may play a role in RA onset.Due to the advantages of early intervention, there is an important focus on the timeframe around RA onset in research and clinical practice. However, current knowledge on possible orofacial complications in the preclinical and early stages of RA disease is very limited. Therefore, the main aim of this thesis is to contribute to this knowledge. A protocol for an observational study in early RA patients and individuals at risk of developing RA (chapter 2) and the resulting data on TMD (chapter 3), oral health and oral microbiome (chapter 6), and oral health-related quality of life (chapter 7) are presented. Further, the consequences (chapter 4) and a possible treatment (chapter 5) for TMJ involvement in RA are investigated.In conclusion, the timeframe around RA onset may be considered a window of opportunity for the prevention of future orofacial complications. Screening for TMD and xerostomia in rheumatology care settings is strongly advised, and referral of newly diagnosed RA patients to a dentist – or at least encouragement of regular dental check-ups – seems justified. Accordingly, interprofessional collaboration is essential and thus advised.

Apical periodontitis (AP) is the outcome of host-microbiome interaction at the root-apex. The effect of this interaction on the immune system, translated into changes in concentration of circulatory inflammatory mediators was firstly investigated with two systematic reviews and a meta-analysis. We also investigated the role of reactive oxygen species in the initiation and progression of chronic inflammation, with AP being such. Taking the information from the systematic reviews into consideration, we designed a prospective case-control intervention study, to investigate the impact of the minimum burden (1 AP). The aim of the study was: To explore the influence of apical periodontitis (AP) in inflammatory markers in blood of otherwise healthy individuals. Peripheral blood was drawn at 6 time points, 3 before and 3 after the extraction of the tooth with AP. The teeth were pulverised, DNA extraction and sequencing were performed. The results revealed that AP has an effect on the immune fitness of the individuals. The immunologic profile of chronic apical periodontitis in one tooth and its healing profile reveals a systemic low-grade inflammation through compensatory immunosuppression. The analysis of the microbiome of the teeth with AP, revealed a difference between symptomatic and asymptomatic infections and also between primary and secondary AP. The immunologic profile of patients with asymptomatic infections was different in the concentration of some inflammatory markers, compared to symptomatic. Finally, an association between member of the microbiome of the endodontic infection and blood mediators was found. This correlation was different depending on the presence or absence of pain.

We determined the degradation rates of the herbicides 2,4-D and 2,4,5-T by two different bacterial communities. One of these originated from soil heavily contaminated with herbicides from Bien Hoa airbase, the other from the same soil but amended with additional carbon and Gibbs energy sources. The community from the contaminated, but untreated, soil degraded both 2,4-D and 2,4,5-T within 5 days of cultivation. The one from the amended soil, however, hardly showed any degradation of the compounds throughout 23 days of cultivation. After refreshment of the medium and prolonged culturing, however, this community degraded both herbicides within 25 days with progressively increasing rates. nMDS analysis revealed a highly significant differentiation pattern of the two communities. Cultures inoculated with amended soil showed a significant increase of Bacillus and Paenibacillus upon prolonged exposure to the herbicides. The succession in the culture from untreated soil, on the other hand, was dominated by species from the Proteobacteria. We were able to isolate two of them and they were shown to be related to Bordetella petrii and Sphingomonas histidinilytica, successively. Subsequent PCR analyses of their DNA revealed the presence of key genes involved in the degradation of the herbicides. This study provides a more fundamental understanding of the biodegradation of 2,4-D and 2,4,5-T by displaying part of the bacterial community succession during their breakdown allowing a comprehensive view on potential key degraders.

The indivisible relationship between the human host and its oral microbiome has been shaped throughout the millennia, by facing various changes that have forced the adaptation of oral microorganisms to new environmental conditions. In this constant crosstalk between the human host and its microbiome, a bidirectional relationship has been established. The microorganisms provide the host with functions it cannot perform on its own and at the same time the host provides its microbes with a suitable environment for their growth and development. These host factors can positively affect the microbiome, promoting diversity and balance between different species, resulting in a state of symbiosis and absence of pathology. In contrast, other host factors can negatively influence the composition of the oral microbiome and drive the interaction towards a dysbiotic state, where the balance tilts towards a harmful relationship between the host and its microbiome. The aim of this review is to describe the role host factors play in cultivating and maintaining a healthy oral ecology and discuss mechanisms that can prevent its drift towards dysbiosis.

Made available in DSpace on 2019-10-06T16:32:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-09-15 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Percutaneous medical devices are prone to bacterial contamination that causes dramatic clinical conditions. At the percutaneous level of dental implant systems, microbial pathogens induce biofilm formation that may result in bone resorption and dental implant loss. In view of peri-implantitis caused by bacterial inflammation at the percutaneous abutment region, we here establish a novel drug release system based on layer-by-layer (LbL)-deposited poly(acrylic acid) (PAA) and poly-L-lysine (PLL) coatings on titanium (Ti). Detailed multilayer coating characterization was performed by different microscopy and spectroscopy techniques to probe physical and chemical properties. Our data revealed a significant difference in roughness average between ten double layers coated (141 nm ±30) and uncoated Ti discs (115 nm ±40). Although roughness of the coatings increased significantly after immersion in water for 24 h at 37 °C, this physical property remained below 200 nm. Coating stability was confirmed under neutral and acidic pH, mimicking healthy and diseased/inflammatory environments, respectively. LbL coatings supported in vitro human keratinocytes growth, demonstrating absence of cytotoxic effects. Tetracycline (TC) showed an initial burst release under neutral and acidic conditions, which further demonstrated robust antibacterial efficacy against Porphyromonas gingivalis. However, a convenient pH-dependent 2-folds increase in TC release was observed for coatings incubated at pH = 4.5. Sustained TC release was observed from coatings up till 15 days of incubation in both pH conditions. These results demonstrate the potential application of this simple surface modification to leverage anti-bacterial efficacy at the percutaneous abutment region. Regenerative Biomaterials Radboudumc, Philips van Leydenlaan 25 Department of Dental Materials and Prosthodontics School of Dentistry at Araraquara Sao Paulo State University (Unesp), Humaita, Sao Paulo Department of Tumor Immunology Radboudumc and Radboud Institute for Molecular Life Sciences (RIMLS), Geert Grooteplein Zuid Department of Preventive Dentistry Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam, Gustav Mahlerlaan Department of Organic Chemistry Radboud University, Heyendaalseweg 135 Faculty of Applied Sciences Delft University of Technology, Lorentzweg 1 Department of Dental Materials and Prosthodontics School of Dentistry at Araraquara Sao Paulo State University (Unesp), Humaita, Sao Paulo FAPESP: 2015/03567-7 FAPESP: 2016/19650-3

In recent years, the concept of preventing caries-related microbial dysbiosis by enhancing the growth and survival of health-associated oral microbiota has emerged. In this article, the current evidence for the role of oral pre- and probiotics in caries prevention and caries management is discussed. Prebiotics are defined as “substrates that are selectively utilized by host microorganisms conferring a health benefit.” With regard to caries, this would include alkali-generating substances such as urea and arginine, which are metabolized by some oral bacteria, resulting in ammonia production and increase in pH. While there is no evidence that urea added to chewing gums or mouth rinses significantly contributes to caries inhibition, multiple studies have shown that arginine in consumer products can exert an inhibitory effect on the caries process. Probiotics are “live microorganisms which when administrated in adequate amounts confer a health benefit on the host.” Clinical trials have suggested that school-based programs with milk supplemented with probiotics and probiotic lozenges can reduce caries development in preschool children and in schoolchildren with high caries risk. Due to issues with research ethics (prebiotics) and risk of bias (prebiotics, probiotics), the confidence in the effect estimate is however limited. Further long-term clinical studies are needed with orally derived probiotic candidates, including the health-economic perspectives. In particular, the development and evaluation of oral synbiotic products, containing both prebiotics and a probiotic, would be of interest in the future management of dental caries.

Background and Objective: Metal-based dental restorations with a subgingival outline may enhance plaque accumulation and bacterial colonization. This study aimed to investigate whether metal-based restorations influence the composition of subgingival microbiome. Material and Methods: Per subject one site with a metal-based restoration and one contra-lateral site without a restoration were selected on basis of radiographic bone loss ≤2 mm, restoration outline at sulcus level/subgingivally, pocket depth ≤4 mm, and no root canal treatments. Subgingival samples were collected with sterile paper-points, and microbial profiles were obtained by 16S rRNA gene amplicon sequencing. Restorations were sampled with an Arkansas-stone and the metal composition was determined using energy-dispersive X-ray spectroscopy. Results: A total of 22 sites from 11 subjects were included. No significant differences for the clinical parameters were found between the restored and unrestored sites. The average age of the restorations was 14.9 ± 7.1 years. Firmicutes was the most prevalent phylum at the restored sites (32% vs 20% of the reads of the unrestored sites, P = 0.016), and Actinobacteria at the unrestored sites (33% vs 18% of the reads of the restored sites, P = 0.01). Overall, sequences clustered into 573 operational taxonomic units (OTUs). Species richness of the restored sites was significantly higher than species richness of the unrestored sites (117 ± 32 and 96 ± 20 OTUs, respectively, P = 0.013). No associations between the metal composition and bacterial profiles were found. Conclusion: This study shows that metal-based restorations may enhance colonization of Firmicutes and the neighboring pocket may harbor more diverse microbial communities.

Candida albicans and Cutibacterium acnes are opportunistic pathogens that co-colonize the human body. They are involved in biofilm-related infections of implanted medical devices. The objective of this study was to evaluate the ability of these species to interact and form polymicrobial biofilms. SEM imaging and adhesion assays showed that C. acnes adhesion to C. albicans did not have a preference for a specific morphological state of C. albicans; bacteria adhered to both hyphal and yeast forms of C. albicans. C. albicans did not influence growth of C. acnes under anaerobic growth conditions, however under aerobic growth condition, C. albicans enhanced early C. acnes biofilm formation. This favorable impact of C. albicans was not mediated by secreted compounds accumulating in the medium, but required the presence of metabolically active C. albicans. The ability of these microorganisms to interact together could modulate the physiopathology of infections.

Objectives Dental calculus is among the richest known sources of ancient DNA in the archaeological record. Although most DNA within calculus is microbial, it has been shown to contain sufficient human DNA for the targeted retrieval of whole mitochondrial genomes. Here, we explore whether calculus is also a viable substrate for whole human genome recovery using targeted enrichment techniques. Materials and methods Total DNA extracted from 24 paired archaeological human dentin and calculus samples was subjected to whole human genome enrichment using in-solution hybridization capture and high-throughput sequencing. Results Total DNA from calculus exceeded that of dentin in all cases, and although the proportion of human DNA was generally lower in calculus, the absolute human DNA content of calculus and dentin was not significantly different. Whole genome enrichment resulted in up to four-fold enrichment of the human endogenous DNA content for both dentin and dental calculus libraries, albeit with some loss in complexity. Recovering more on-target reads for the same sequencing effort generally improved the quality of downstream analyses, such as sex and ancestry estimation. For nonhuman DNA, comparison of phylum-level microbial community structure revealed few differences between precapture and postcapture libraries, indicating that off-target sequences in human genome-enriched calculus libraries may still be useful for oral microbiome reconstruction. Discussion While ancient human dental calculus does contain endogenous human DNA sequences, their relative proportion is low when compared with other skeletal tissues. Whole genome enrichment can help increase the proportion of recovered human reads, but in this instance enrichment efficiency was relatively low when compared with other forms of capture. We conclude that further optimization is necessary before the method can be routinely applied to archaeological samples. H2020 European Research Council, Grant/Award Number: 319209; Horizon 2020 Framework Programme, Grant/Award Number: 649307DK-TAF 5662; National Science Foundation, Grant/Award Number: BCS 1516633, BCS-1528698

Toothpastes are the most universally accepted form of fluoride delivery for caries prevention. To provide anti-caries benefits, they must be able to release fluoride during the time of tooth brushing or post brushing into the oral cavity. However, there is no standard accepted procedure to measure how much fluoride in a toothpaste may be (bio) available for release. The European Organization for Caries Research proposed and supported a workshop with experts in fluoride analysis in toothpastes and representatives from industry. The objective of the workshop was to discuss issues surrounding fluoride analysis in toothpaste and reach consensus on terminology and best practices, wherever the available evidence allowed it. Participants received a background paper and heard presentations followed by structured discussion to define the problem. The group also reviewed evidence on the validity, reliability and feasibility of each technique (namely chromatography and fluoride electroanalysis) and discussed their strengths and limitations. Participants were able to reach a consensus on terminology and were also able to identify and summarize the advantages and disadvantages of each technique. However, they agreed that most currently available methods were developed for regulatory agencies several decades ago, utilizing the best available data from clinical trials then, but require to be updated. They also agreed that although significant advances to our understanding of the mechanism of action of fluoride in toothpaste have been achieved over the past 4 decades, this clearly is an extraordinarily complex subject and more work remains to be done.

A key question in microbial ecology is what the driving forces behind the persistence of large biodiversity in natural environments are. We studied a microbial community with more than 100 different types of species which evolved in a 15-years old bioreactor with benzene as the main carbon and energy source and nitrate as the electron acceptor. Using genome-centric metagenomics plus metatranscriptomics, we demonstrate that most of the community members likely feed on metabolic left-overs or on necromass while only a few of them, from families Rhodocyclaceae and Peptococcaceae, are candidates to degrade benzene. We verify with an additional succession experiment using metabolomics and metabarcoding that these few community members are the actual drivers of benzene degradation. As such, we hypothesize that high species richness is maintained and the complexity of a natural community is stabilized in a controlled environment by the interdependencies between the few benzene degraders and the rest of the community members, ultimately resulting in a food web with different trophic levels., Chrats Melkonian and colleagues use metagenomics and transcriptomics to study microbial dynamics in a 15-year old bioreactor. In contrast to what is expected in a system where benzene is the primary carbon and energy source, relatively few members of the microbial community can degrade this compound. The results have implications for understanding interdependencies within such a community.

Oral biofilms are assemblages of microbes which adhere to intra-oral surfaces as structurally and functionally organized microbial communities. They are beneficial for marinating oral health when living in a state of homeostatic balance, or symbiosis, with the host. However, they are also responsible for the development of oral diseases once microbial composition of oral biofilms shifts to an imbalanced dysbiotic state. In this thesis, we aimed to develop biofilm models that can resemble the microbial shift from symbiotic to a pathogen-enriched dysbiotic state using in vitro saliva-derived microcosm biofilms. We first confirmed that oral biofilms were able to regrow shortly after treating by antimicrobial agents that are commonly used in clinic. The regrown biofilms showed reduced diversity and altered microbial composition, which may predispose the oral cavity to more aggressive and complicated infections. This observation highlights the importance of developing novel therapeutic strategies that can favorably modulate the microbial ecology of oral biofilms, rather than focusing solely on biofilm elimination. In view of this, we successfully established a series of biofilm models that can resemble the pathogen-enriched dysbiotic subgingival microbiota, by incorporating important periodontal microbes, such as Porphyromonas gingivalis, into in vitro saliva-derived microcosm biofilms. In addition, we demonstrated that such models can facilitate the evaluation of microbiome modulation strategies beneficial for oral microbial ecology.

Introduction: Previous studies showed that 5-year-old Dutch-Moroccan children had significantly higher dmft scores compared to Dutch children of the same age, even after correction for socio-economic status. The mechanisms underlying this difference are little understood.Aim: To explore cultural factors involved in poorer oral health of Dutch-Moroccan children by identifying knowledge, attitudes and behaviour of their mothers concerning their children's oral health.Methods: In 2012 mothers of Dutch-Moroccan preschool children in two cities in the Netherlands were interviewed in two focus groups (n = 16) or individual semi-structured interviews (n = 13). Semi structured interviews were also conducted with three oral health professionals, working with Dutch-Moroccan children, and one physician from an under-five-clinic. All interviews were voice recorded, transcribed and inductively coded. MAXQDA software was used for data analysis.Results: All mothers mentioned pain complaints, swelling and black front teeth as oral health problems in their children. Although mothers were aware that brushing teeth and reducing sugary snacks are effective preventative strategies, they did not sufficiently implement these measures. This was due to lack of brushing skills, insufficient awareness of the daily sugar intake of their children and their childrearing concerning these measures. Most mothers indicated they felt empowered in making dental care decisions.Conclusions: This research revealed the presence of knowledge on preventive strategies regarding their children's oral health in Dutch-Moroccan mothers, but an inadequate implementation of these measures in their daily lives. Additional qualitative research is needed to gain deeper insight for broader exposure of values, knowledge and culture.

Made available in DSpace on 2018-12-11T17:36:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-05-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Periodontitis is an infectious polymicrobial, immuno-inflammatory disease of multifactorial aetiology that has an impact on the health, production and welfare of ruminants. The objective of the present study was to determine the microbial profiles present in the gingival sulcus of cattle considered periodontally healthy and in the periodontal pocket of animals with periodontitis lesions using high-throughput bacterial 16S rRNA gene sequencing. Subgingival biofilm samples were collected from 40 cattle with periodontitis and 38 periodontally healthy animals. In total, 1923 OTUs were identified and classified into 395 genera or higher taxa. Microbial profiles in health differed significantly from periodontitis in their composition (p < 0.0001, F = 5.30; PERMANOVA) but no statistically significant differences were observed in the diversity of healthy and periodontitis microbiomes. The most prevalent taxa in health were Pseudomonas, Burkholderia and Actinobacteria, whereas in disease these were Prevotella, Fusobacterium and Porphyromonas. The most discriminative taxa in health were Gastranaerophilales, Planifilum and Burkholderia, and in disease these were Elusimicrobia, Synergistes and Propionivibrio. In conclusion, statistically significant difference exists between the microbiome in bovine oral health and periodontitis, with populations showing 72.6% dissimilarity. The diversity of the bacteria found in health and periodontitis were similar and bacteria recognised as periodontal pathogens showed increased abundance in disease. In this context, the main components of bacterial homeostasis in the biofilm of healthy sites and of dysbiosis in periodontal lesions provide unprecedented indicators for the evolution of knowledge about bovine periodontitis. São Paulo State University (Unesp) School of Veterinary Medicine, Araçatuba Campus Dental School University of Glasgow School of Veterinary Medicine University of Glasgow Department of Preventive Dentistry Academic Centre for Dentistry Amsterdam University of Amsterdam and VU University Amsterdam São Paulo State University (Unesp) School of Veterinary Medicine, Araçatuba Campus

The aim of this study was to assess the association between externalizing behaviour problems and dental caries in children. A further objective was to explore direct and indirect pathways between sociodemographic factors, family functioning and parenting factors, oral health behaviours, externalizing behaviour problems, and dental caries using structural equationmodelling. Cross-sectional data were collected on 251, 5- to 8-yr-old children from a paediatric dental practice in the Netherlands. Children's decayed, missing, and filled primary teeth (dmft) scores were obtained from their dental records. Validated self-report questionnaires were used to collect sociodemographic, behavioural, and family-related data. Externalizing problem behaviour was significantly associated with a higher dmft score [incidence risk ratio (IRR)=1.19; 95% CI: 1.06-1.34], but this association did not remain significant after adjustment for sociodemographic factors (IRR=1.11; 95% CI: 0.99-1.26). A valid path model was presented after applying some modifications. Findings from the model suggest that it is plausible that child behaviour problems are directly associated with dental caries via toothbrushing behaviour. The model also provided support that maternal education level, the restrictiveness and warmth of parenting, and the communication of the family, play an indirect role in the association between children's externalizing behavioural problems and dental caries experience.

This study evaluated the inhibitory effects of lactams on Streptococcus mutans, Enterococcus faecalis, and Candida glabrata multispecies biofilm formation. γ-Alkylidene-γ-lactams 1, 2, and 3 [solubilized in 3.5% dimethyl sulfoxide (DMSO)] were tested. Glass coverslips were conditioned with either the lactams or 3.5% DMSO (control) for 1 h, inoculated with microbial cultures, and incubated for 48 h. To assess the effect of the lactams on biofilm formation, the following parameters were determined: the biofilm biomass (by both crystal violet staining and protein determination); the amount of insoluble polysaccharides of the extracellular matrix; and the number of viable and total cells [by both colony-forming unit counting and quantitative real-time PCR (qPCR)]. Data were analysed using one-way anova and post-hoc Tukey tests. Lactams 1, 2, and 3 promoted a statistically significant reduction in the amount of biofilm biomass, but only lactam 3 resulted in a statistically significant reduction in the number of attached viable E. faecalis. Both total protein content and the amount of extracellular polysaccharides decreased significantly. The effects of γ-alkylidene-γ-lactams 1, 2, and 3 on the inhibition of multispecies biofilm formation were evident by their ability to reduce the amount of protein and extracellular polysaccharides.

Previous studies have shown that Streptococcus oligofermentans inhibits the growth of cariogenic Streptococcus mutans in biofilms in vitro and is considered a probiotic candidate for caries prevention. This study aimed to examine the effects of various environmental factors on the competition between S. oligofermentans and S. mutans in a dual-species biofilm model. Single or dual S. oligofermentans and S. mutans biofilms were grown in a 96-well active attachment model for 48 h. Several growth conditions were examined in the model, namely: S. oligofermentans was inoculated 24 h before S. mutans or vice versa; the growth medium was supplemented with 0.2% sucrose or 0.4% glucose; biofilms were grown under a constantly neutral pH or pH-cycling condition, which included 8 h of neutral pH and 16 h of pH 5.5. The 48-h biofilms were examined for viable cell counts and lactic acid and hydrogen peroxide production ability. When S. oligofermentans was inoculated first, it clearly inhibited the growth of S. mutans and reduced the biofilm lactic acid production by up to 8-fold through hydrogen peroxide production, independently of sugar supply and pH conditions. When S. mutans was inoculated first, the level of inhibition by S. oligofermentans varied depending on the sugar supply and pH conditions. Thus, the inhibition efficacy of S. oligofermentans against S. mutans in dual-species biofilms is influenced by environmental factors. This study provides practical information on how to maximize the efficacy of S. oligofermentans.

Background Alkali production via arginine deiminase system (ADS) of oral bacteria plays a significant role in oral ecology, pH homeostasis and inhibition of dental caries. ADS activity in dental plaque varies greatly between individuals, which may profoundly affect their susceptibility to caries. Objective To investigate the effect of arginine on the growth and biofilm formation of oral bacteria. Methods and results Polymicrobial dental biofilms derived from saliva were formed in a high-throughput active attachment biofilm model and L-arginine (Arg) was shown to reduce the colony forming units (CFU) counts of such biofilms grown for various periods or biofilms derived from saliva of subjects with different caries status. Arg hardly disturbed bacterial growth of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus gordonii in BHI medium, but only inhibited biofilm formation of S. mutans. Scanning electron microscope (SEM) showed S. mutans biofilms harboured fewer cells grown with Arg than that without Arg, even in the initial 2 h and 8 h phase. Confocal laser scanning microscope (CLSM) images of poly-microbial dental and S. mutans biofilms revealed the biofilms grown with Arg had lower exopolysaccharide (EPS)/bacteria ratios than those without Arg (P = 0.004, 0.002, respectively). Arg could significantly reduce the production of water-insoluble EPS in S. mutans biofilms (P < 0.001); however, quantitative real-time PCR (qRT-PCR) did not show significantly influence in gene expression of gtfB, gtfC or gtfD (P = 0.32, 0.06, 0.44 respectively). Conclusions Arg could reduce the biomass of poly-microbial dental biofilms and S. mutans biofilms, which may be due to the impact of Arg on water-insoluble EPS. Considering the contribution to pH homeostasis in dental biofilms, Arg may serve as an important agent keeping oral biofilms healthy thus prevent dental caries.

Introduction: This study investigated the effect of force feedback (FFB) on student performance in a virtual learning environment (VLE) using the Simodont dental trainer (Moog, Nieuw-Vennep, the Netherlands) and evaluated the students' satisfaction with and without FFB. Methods: The Simodont dental trainer, which was used as a VLE, was randomly assigned to 101 first-year dental students with no previous experience in cutting a tooth or working in a VLE with FFB. This study was designed as a crossover study. One half of the students practiced without FFB, whereas one half practiced with FFB. Both groups practiced four sessions lasting 45 minutes on a cross preparation. In the fifth session, test 1 was scheduled. After test 1, the same practicing and testing protocol was followed, although the environment was switched. After test 2, participants filled out a questionnaire. For the statistical analysis, only the questionnaires of the students who participated in both tests were processed. Results: The results of test 1 and test 2 revealed that only students who used FFB were able to pass the tests. The questionnaire outcomes supported the results of both tests; 100% of the students preferred working with FFB. Conclusions: The results suggest that FFB is important for performance in a VLE and essential for satisfaction.

Background and Aims: The scope of this working group was to review (1) ecological interactions at the dental biofilm in health and disease, (2) the role of microbial communities in the pathogenesis of periodontitis and caries, and (3) the innate host response in caries and periodontal diseases. Results and Conclusions: A health-associated biofilm includes genera such as Neisseria, Streptococcus, Actinomyces, Veillonella and Granulicatella. Microorganisms associated with both caries and periodontal diseases are metabolically highly specialized and organized as multispecies microbial biofilms. Progression of these diseases involves multiple microbial interactions driven by different stressors. In caries, the exposure of dental biofilms to dietary sugars and their fermentation to organic acids results in increasing proportions of acidogenic and aciduric species. In gingivitis, plaque accumulation at the gingival margin leads to inflammation and increasing proportions of proteolytic and often obligately anaerobic species. The natural mucosal barriers and saliva are the main innate defence mechanisms against soft tissue bacterial invasion. Similarly, enamel and dentin are important hard tissue barriers to the caries process. Given that the present state of knowledge suggests that the aetiologies of caries and periodontal diseases are mutually independent, the elements of innate immunity that appear to contribute to resistance to both are somewhat coincidental.

Non restorative cavity control (NRCC) is a non to minimally invasive dental approach in dentine caries management which can be applied to cavitated dentine lesions in the primary and permanent dentition. This approach could be supported by topical fluoride applications to enhance caries arrestment. Caries arrestment is a clinical sign of the success of the NRCC approach. The overall aim of this thesis was to understand more closely the chemical and histological (microradiographic) aspects of this fluoride induced arrestment. Therefore, this thesis has investigated these aspects in dentine lesions after treatment with various topically applied fluoride products (SDF, NaF, TiF4 and SnF2), and to examine which product performs best in dentine caries arrestment in an in vitro de- and remineralization model. The current finding showed that all fluoride products used in the current thesis were effective in inhibiting demineralization or enhancing remineralization, depending on the formulas and concentration of the product. SDF, however, was the most effective product in dentine caries management. Therefore, it was of interest to compare the effect of equal fluoride concentrations as either SDF or KF on dentine lesions to examine whether the superior effect of the SDF is due to both the fluoride and silver components, or only to the high fluoride concentration. The results suggest that the effect depended on the high fluoride concentration. In conclusion, the chemical and histological results of these products confirmed the superiority of the SDF treatment in inhibiting dentine demineralization and enhancing dentine remineralization during the pH-cycling.

In this thesis we investigate host-microbe interactions on reconstructed human gingiva (RHG) in vitro. Our results suggest: 1) The multi-species commensal microcosm biofilm promotes the barrier function of RHG, mimicking the beneficial influence of the oral microbiome on the host in vivo. 2) The underlying mechanisms by which the commensal biofilm influence RHG are different from that of the gingivitis and cariogenic (pathogenic) biofilms, e.g. TLR signaling pathways are differentially regulated. 3) That crosstalk occurs, with microbes constantly influencing the host, and host factors e.g. nutrients and different oral surfaces, also constantly influencing the community structures of the local microbiome. 4) Host-commensal interactions also influence other host events: when living commensal bacteria Streptococcus mitis is exposed to RHG/RHS (reconstructed human skin), the host tissues respond differentially to metals nickel and titanium, with regards to the innate immune response. Taken together, our results describe host-microbe interplay in a human organotypic model which mimics both physiological and pathological conditions in vitro. This model can therefore now be used as a valid animal free human model to investigate in further detail, the complex host-microbe interactions and mechanisms involved in oral health and disease.

Sugar is added to food for a multitude of functions: fermentation, preservation, physical and chemical, and also to satisfy the consumer’s preference for sweetness. Unfortunately, sugar consumption is also a main aetiological factor for dental caries. The relationship between sugar and caries was established in the latter half of the 19th century. Many factors influence this relationship: the availability of sugar for bacterial digestion, the presence of acidogenic bacteria in the plaque on teeth, and the ability of fluoride and saliva to counteract bacteria and acids. The importance of the frequency of administering sugars over the amount has been demonstrated in various studies in humans. Through guidelines, world and national health organizations advocate the reduction of sugar consumption to below 10E% (daily dietary energy percentage consumption per capita), but voluntary implementation on an individual basis is difficult for many, and maybe more compulsory strategies that aim to reduce both the amount and frequency of sugar intake are needed.

The dental clinic is a potential site for the transmission of pathogenic microorganisms between patients and dental health care workers (DHCW), originating from the oral cavity and of dental unit waterlines (DUWL). There is a risk of transmission of pathogens due to the exposure to aerosols and spats, generated during dental treatment of infectious patients, which are dispersed in the environment. The air and surfaces within 80cm from the patient’s oral cavity are substantially contaminated by microorganisms from water and human origin. These microorganisms are in low numbers also found up to 2 meters from the head of the patient. Biofilms in the DUWL contribute to the microbial contamination of the effluent water from the dental unit. If these biofilms are treated with high concentrations of hydrogen peroxide or chlorine followed by a low dose of the same chemical disinfectants, these DUWL-biofilms can be controlled successfully. Prolonged exposure to chemicals may result in a shift of the microbial composition of DUWL biofilms leading to a selection of microbes which could lead to potentially pathogenic alterations of the composition in time. Airborne pathogens pose a risk for DHCW, which varies from very low to almost 100%, depending on the characteristics of the microorganism, the level of air-ventilation in the treatment room and the level of personal protection (mainly respiratory protection). This thesis reports on the risk of pathogen transmission in the dental clinic. The risk of infection for DHCW can be reduced by strict application of hygiene and infection control protocols.

Invasive Staphylococcus aureus infections account for 15 to 50% of fatal bloodstream infections annually. These disseminated infections often arise without a defined portal of entry into the host but cause high rates of mortality. The fungus Candida albicans and the Gram-positive bacterium S. aureus can form polymicrobial biofilms on epithelial tissue, facilitated by the C. albicans adhesin encoded by ALS3. While a bacterium-fungus interaction is required for systemic infection, the mechanism by which bacteria disseminate from the epithelium to internal organs is unclear. In this study, we show that highly immunogenic C. albicans hyphae attract phagocytic cells, which rapidly engulf adherent S. aureus and subsequently migrate to cervical lymph nodes. Following S. aureus-loaded phagocyte translocation from the mucosal surface, S. aureus produces systemic disease with accompanying morbidity and mortality. Our results suggest a novel role for the host in facilitating a bacterium-fungus infectious synergy, leading to disseminated staphylococcal disease.

Een correcte persoonlijke hygiëne draagt bij aan het voorkomen van de overdracht van micro-organismen (bacteriën, schimmels en virussen) in de mondzorgpraktijk. Dan hebben we het over onderwerpen als: haar, handen en nagels, sieraden en werkkleding.

Background This systematic scoping review aimed to identify changes in biomarkers of microbiological, immunological and biochemical origin during experimental gingivitis (EG) studies that might indicate resistance and resilience. Methods The term ‘experimental gingivitis’ was run in PubMed from inception to April 11th, 2018. From the 411 studies retrieved, 22 studies were included for this review. Results Studies reporting data on biomarker changes during and after full mouth EG trial were included. Two studies reported findings on changes in biomarkers of microbiological, 12 on immunological and eight on biochemical origin. Changes were reported in the induction phase, and occasionally in the resolution phase. The microbiological composition of both supragingival and subgingival dental plaque changed over the course of EG to a more pathogenic direction, but showed a shift back to a more normal composition. This indicates resilience of the oral microbiome. For immunological biomarkers, it was challenging to retrieve a robust pattern of changes across multiple studies. IL-1β and IL-6 in saliva and in gingival crevicular fluid increased during induction phase and returned in the resolution phase below baseline values. The biochemical parameters cystatin-SN, cystatin-S and lactoferrin in saliva were increased at the end of induction phase, however also here no clear pattern emerged based on all available studies. Conclusions More research is needed to investigate which microbiological, immunological, and biochemical biomarkers can be useful for future investigations into the resistance and resilience of the oral cavity to experimental gingivitis.

In dit artikel wordt de huidige kennis over prebiotica voor de mondgezondheid besproken. Op basis van hun biochemische eigenschappen en hun ecologische effecten in de mond zijn er twee natuurlijke stoffen – ureum en arginine – die in aanmerking komen als anticariës-prebioticum. Er blijkt echter onvoldoende bewijs te zijn om ureum als prebioticum voor cariëspreventie te bestempelen. Wel is er klinisch bewijs dat arginine in fluoridetandpasta een toegevoegde waarde heeft in vergelijking met een tandpasta die alleen fluoride bevat. De gepubliceerde klinische studies met argininetandpasta worden echter geassocieerd met een hoog risico op bias doordat de producent van de onderzochte tandpasta betrokken is bij het onderzoek en de bijbehorende publicaties. Er zijn op dit moment geen prebiotica bekend die een ontstekingsremmend effect veroorzaken, maar er wordt actief gewerkt in deze richting.

Tandartsen schrijven regelmatig een antibioticum voor. Hoewel antibiotica levensreddend kunnen zijn, leidt onnodig gebruik ervan tot meer antibioticaresistentie. Door wereldwijd reizen is de verspreiding van resistentie bovendien versneld. Hoewel resistentie steeds meer aandacht krijgt, heeft een antibioticumkuur, ook nadat het antibioticum uit het lichaam is verdwenen, invloed op onze microflora. Een kuur met ciprofloxacine of clindamycine veroorzaakt zelfs een maandenlange verandering van de microflora in onze darmen.

Tijdens de zwangerschap treden natuurlijke hormonale en immunologische veranderingen op. Door een geleidelijke stijging van de hormoonspiegel en toename van ontstekingsmediatoren gedurende de zwangerschap komt de bevalling op gang. Onder invloed van deze veranderingen kunnen mondbacteriën gemakkelijker een lokale ontstekingsreactie veroorzaken, die kan leiden tot zwangerschapscomplicaties. Een goede mondgezondheid is dan ook van groot belang om de invloed van virulente bacteriën te beperken.

Om een antwoord te vinden op vragen met betrekking tot biofilmgerelateerde processen in de mond is sinds de jaren tachtig het kweken van micro-organismen binnen de mondzorgpraktijk veelvuldig uitgevoerd. Het is echter al jaren duidelijk dat het uitvoeren van microbiologische diagnostiek bij cariës een zinloze missie is voor zowel patiënt als behandelaar. Er is met diagnostiek niet méér te zien dan de behandelaar al ziet bij het klinisch onderzoek. Wat parodontitis betreft is de literatuur ook duidelijk. Sinds we parodontitis zien als een ontstekingsziekte in plaats van een infectieziekte, weten we dat er meer aan de hand is bij deze patiënten dan alleen de aanwezigheid van pathogene bacteriën. Deze paradigmaverschuiving moet leiden tot een betere, op de individuele patiënt gerichte behandeling. De enige zinvolle diagnostiek binnen een mondzorgpraktijk is die naar de kwaliteit van het unitwater. Als het resultaat boven een bepaalde norm uitkomt, is er een grotere kans op de aanwezigheid van longpathogenen in het unitwater en moeten er maatregelen worden genomen om de waterbiofilm aan te pakken.

The balance between the host and microbe is pivotal for oral health. A dysbiotic oral microbiome and the subsequent host inflammatory response are causes for the most common dental problems, such as periodontitis and caries. Classically, toll-like receptors (TLRs) are known to play important roles in host-microbe interactions by recognizing pathogens and activating innate immunity. However, emerging evidence suggests that commensals may also exploit TLRs to induce tolerance to the benefit of the host, especially in oral mucosa which is heavily colonized by abundant microbes. How TLRs and downstream signaling events are affected by different oral microbial communities to regulate host responses is still unknown. To compare such human host-microbe interactions in vitro, we exposed a reconstructed human gingiva (RHG) to commensal or pathogenic (gingivitis, cariogenic) multi-species oral biofilms cultured from human saliva. These biofilms contain in vivo like phylogenic numbers and typical bacterial genera. After 24 h biofilm exposure, TLR protein and gene expression of 84 TLR pathway related genes were investigated. Commensal and pathogenic biofilms differentially regulated TLR protein expression. Commensal biofilm up-regulated the transcription of a large group of key genes, which are involved in TLR signaling, including TLR7, the MyD88-dependent pathway (CD14, MyD88, TIRAP, TRAF6, IRAKs), MyD88-independent pathway (TAB1, TBK1, IRF3), and their downstream signaling pathways (NF-κB and MAPK pathways). In comparison, gingivitis biofilm activated fewer genes (e.g., TLR4) and cariogenic biofilm suppressed CD14, IRAK4, and IRF3 transcription. Fluorescence in situ hybridization staining showed the rRNA of the topically applied and invaded bacteria, and histology showed that the biofilms had no obvious detrimental effect on RHG morphology. These results show an important role of TLR signaling pathways in regulating host-microbe interactions: when a sterile gingival tissue is exposed to commensals, a strong immune activation occurs which may prime the host against potential challenges in order to maintain oral host-microbe homeostasis. In contrast, pathogenic biofilms stimulate a weaker immune response which might facilitate immune evasion thus enabling pathogens to penetrate undetected into the tissues.

A single biomineralization of demineralized dentin is significant to restore the demineralized dentin due to dental caries or erosion. In recent years, meaningful progress has been made regarding the mechanisms involved in the biomineralization of dentin collagen. Concepts changing from the classical ion-based crystallization to non-classical particle-based crystallization, inspired a different strategy to infiltrate the demineralized dentin collagen. The remarkable discovery was the report of liquid-like amorphous calcium phosphate as nanoprecursor particles to carbonated hydroxyapatite. The non-collagenous proteins and their analogues are widely investigated, for their key role in controlling mineralization during the process of crystal nucleation and growth. The in-depth studies of the gap zone provided significant improvements in our understanding of the structure of collagen and of the intrafibrillar remineralization of collagen fibrils. The collagen is not a passive substrate as previously supposed, and the active role of guiding nanoprecursor infiltration and mediating its nucleation has been demonstrated. Furthermore, recovery of mechanical properties has been evaluated to determine the effectiveness of dentin remineralization. Finally, the problems regarding the origin formation of the calcium phosphate that is deposited in the collagen, and the exact interactions between the non-collagenous proteins, amorphous calcium phosphate and collagen are still unclear. We reviewed the importance of these findings in enriching our understanding of dentin biomineralization, while addressing certain limitations that are inherent to in vitro studies.

The discovery and implementation of fluoride in the prevention of dental caries is often praised as one of the most important achievements in health care. In the early 20th century, it took 30 y to identify fluoride as the cause of enamel mottling but also of reduced caries prevalence in a population drinking water containing fluoride. Similarly, from 1960 to 1990, it took major efforts to unravel the working mode of fluoride in such detail that a rational scheme of caries prevention could be formulated. This article describes the scientific struggle leading to a consensus on the topic. For a historic purpose, the field, the actors, and their main research achievements are described. Ultimately it was generally agreed that the effect of fluoride is primarily topical by fluorides in the oral fluids rather than systemic by incorporation of fluoride in the enamel mineral crystals. Fluoride concentrations, even

Objective To evaluate dentist-related factors associated with the use of vital pulp therapy (VPT) for the treatment of pulp exposures in permanent teeth. Methods This survey-based study sent an online questionnaire to collect data on the demographics of the respondents, the use of VPT and the choice of materials for VPT, to all members of the Society of Endodontology of Guangdong, China. Results A total 183 of 380 members responded (48.2%). The majority (89.6%; 164 of 183) had performed direct pulp capping (DPC) while 55.2% (101 of 183) had performed partial pulpotomy (PP) at least once. The most-cited reason for not performing VPT was unfamiliarity with the technique. Mineral trioxide aggregate was the most commonly used material for both DPC (67.1%; 110 of 164) and PP (73.3%; 74 of 101). Endodontists, compared with general practitioners, preferred to perform DPC and chose calcium silicate materials (CSMs) for VPT (odds ratios 5.81 and 8.07, respectively). DPC and CSMs for VPT were also favoured more by respondents who had practised for > 5 years. Senior respondents were more likely to use PP. Conclusions Speciality, years of practise and age of dentists influenced the decision making and the choice of materials for VPT. Continuing education is essential to promote the clinical use of VPT.

Objective Considering the diverse mechanisms by which fluoride could affect oral bacteria, this study evaluated the effect of sodium fluoride onStreptococcus mutans transcriptome in the presence of sucrose. Methods S. mutans UA159 was cultured in 3 different types of media: medium control[TY], sucrose control[TY_S], and sodium fluoride sucrose test[TY_S_NaF]. Triplicates of each group were sampled at exponential phase 3 h after inoculation, total RNA was isolated, mRNA enriched and cDNA paired-end sequenced (Illumina Hi-Seq2500). Results Genes related toS. mutans adhesion(gtfB and gtfC), acidogenicity and sugar transport were up-regulated in the presence of sucrose(TY_S) and sucrose/fluoride(TY_S_NaF), whereas gene dltA, D-alanine-activating enzyme, which is related to regulation of non-PTS sugar internalization was down-regulated. Up-regulation of the scrA gene and the PTS fructose-and mannose system, as well as functions such as those involved in stress and defence responses and peptidases; and down-regulation of lacACDG and pyruvate formate-lyase were observed in the TY_S_NaF group, as compared to TY_S group. Conclusions The presence of NaF has decreased the overall gene expression level inS. mutans. However, its major effect seems to be the inducing of expression of genes involved in some PEP:PTS systems and other metabolic transporters which imply specific cellular internalisation of sugars.

Bacteriën bestonden lang voordat alle andere levensvormen – waaronder de mens – zich ontwikkelden. Hierdoor zijn wij als mens geëvolueerd in aanwezigheid van micro-organismen. Bacteriën leveren een belangrijke bijdrage aan verschillende processen in het menselijk lichaam. Voor de afbraak van bepaalde voedingsstoffen zijn wij zelfs afhankelijk van de aanwezigheid van bacteriën. Bij gezondheid leven micro-organismen in symbiose met het menselijk lichaam. Onder bepaalde omstandigheden kan deze symbiose echter veranderen in dysbiose, waardoor ziekte ontstaat. Gedurende het leven zijn er bepaalde factoren die gezonde mondmicrobiota in de weg staan, of juist bevorderen. In dit artikel bespreken we de belangrijkste factoren die van invloed zijn op ontwikkeling en samenstelling van de mondmicrobiota gedurende het leven, in relatie met algemene gezondheid en mondgezondheid.

Speeksel als medicijn klinkt misschien gek, maar de instinctieve reactie om een verwonde vinger direct in je mond steken lijkt wel degelijk een positief effect te hebben op wondgenezing. Uit onderzoek bij ratten is inderdaad gebleken dat wonden waaraan dieren gelikt hadden sneller genezen dan wonden waaraan niet gelikt werd (1). Verder is bekend dat door de aanwezigheid van speeksel, wonden in de mond sneller genezen en minder littekens vormen dan de huid (2). Deze bevinding zijn aanleiding voor een onderzoek naar de toepassing van speeksel als behandeling bij brandwonden. Dit onderzoek wordt uitgevoerd in het Academisch Centrum Tandheelkunde Amsterdam samen met het Amsterdam UMC, locatie VUmc en het brandwondencentrum van het Rode Kruis Ziekenhuis in Beverwijk.

The World Health Organization guideline to use less sugar may be an opportunity and support for dentistry in its goal to get the message of using less sugar across to the public. Two ways (with all the combinations of these) to achieve a reduction of sugar consumption are the reduction of the amount of sugar in products or the reduction of the frequency of consumption of sugar-containing products. Which sugar-reducing strategy is best for caries prevention? To answer this question, this manuscript discusses the shape of the dose-response association between sugar intake and caries, the influence of fluoridated toothpaste on the association of sugar intake and caries and the relative contribution of frequency and amount of sugar intake to caries levels. The results suggest that when fluoride is appropriately used, the relation between sugar consumption and caries is very low or absent. The high correlation between amount and frequency hampers the decision related to which of both is of more importance, but frequency (and stickiness) fits better in our understanding of the caries process. Reducing the amount without reducing the frequency does not seem to be an effective caries preventive approach in contrast to the reciprocity. Goals set in terms of frequency may also be more tangible for patients to follow than goals set in amount. Yet, in sessions of dietary counselling to prevent dental caries, the counsellor should not forget the importance of quality tooth brushing with fluoride toothpaste.

Periodontal diseases and dental caries are the most common diseases of humans and the main cause of tooth loss. Both diseases can lead to nutritional compromise and negative impacts upon self‐esteem and quality of life. As complex chronic diseases, they share common risk factors, such as a requirement for a pathogenic plaque biofilm, yet they exhibit distinct pathophysiologies. Multiple exposures contribute to their causal pathways, and susceptibility involves risk factors that are inherited (e.g. genetic variants), and those that are acquired (e.g. socio‐economic factors, biofilm load or composition, smoking, carbohydrate intake). Identification of these factors is crucial in the prevention of both diseases as well as in their management. Aim. To systematically appraise the scientific literature to identify potential risk factors for caries and periodontal diseases. Methods. One systematic review (genetic risk factors), one narrative review (role of diet and nutrition) and reference documentation for modifiable acquired risk factors common to both disease groups, formed the basis of the report. Results & Conclusions. There is moderately strong evidence for a genetic contribution to periodontal diseases and caries susceptibility, with an attributable risk estimated to be up to 50%. The genetics literature for periodontal disease is more substantial than for caries and genes associated with chronic periodontitis are the vitamin D receptor (VDR), Fc gamma receptor IIA (Fc‐γRIIA) and Interleukin 10 (IL10) genes. For caries, genes involved in enamel formation (AMELX, AMBN, ENAM, TUFT, MMP20, and KLK4), salivary characteristics (AQP5), immune regulation and dietary preferences had the largest impact. No common genetic variants were found. Fermentable carbohydrates (sugars and starches) were the most relevant common dietary risk factor for both diseases, but associated mechanisms differed. In caries, the fermentation process leads to acid production and the generation of biofilm components such as Glucans. In periodontitis, glycaemia drives oxidative stress and advanced glycation end‐products may also trigger a hyper inflammatory state. Micronutrient deficiencies, such as for vitamin C, vitamin D or vitamin B12, may be related to the onset and progression of both diseases. Functional foods or probiotics could be helpful in caries prevention and periodontal disease management, although evidence is limited and biological mechanisms not fully elucidated. Hyposalivation, rheumatoid arthritis, smoking/tobacco use, undiagnosed or sub‐optimally controlled diabetes and obesity are common acquired risk factors for both caries and periodontal diseases.

Objective Denaturing Gradient Gel Electrophoresis (DGGE) is suggested to predict caries risk in young children. Such a tool would be valuable in orthodontic patients undergoing treatment with fixed appliances. In this cross-sectional study the applicability of DGGE and conventional microbiology for caries risk assessment in orthodontic patients were assessed. Design Dental plaque was obtained from orthodontic patients immediately prior to bracket removal. Presence of white spot lesions (WSL) was assessed immediately post debracketing. DGGE-patterns and band counts were assessed using varying automated band detection settings and compared to visually detected bands to determine optimum settings. Optimum settings were used to compare band patterns in subjects with or without WSL. Microbiological samples were assessed for total colony forming units (CFU’s) and percentages of aciduric flora, Streptococcus mutans, Lactobacillus spp. and Candida albicans . Results Thirty-seven subjects were included with a mean age of 15.4 yr (SD 1.6 yr; 28 with WSL; 9 without WSL). Depending on settings, DGGE outcomes were different. Optimum minimum profiling absolute to the most intense band of 4% showed no significant difference in band numbers for subjects with or without WSL (p = 0.845). Optimum settings for minimum profiling relative to the most intense band of 15% showed significant lower band numbers for subjects with WSL than those without (p = 0.007). No differences between groups were observed for microbiological parameters. Conclusion The analysis of DGGE-patterns is ambiguous. Software settings significantly affected outcomes. DGGE-patterns and band numbers like CFU counts were not predictive with respect to WSL formation in these orthodontic patients.

Objectives:Galla chinensiswater extract (GCE) has been demonstrated to inhibit dental caries by favorably shifting the demineralization/remineralization balance of enamel and inhibiting the biomass and acid formation of dental biofilm. The present study focused on the comparison of composition and anticaries effect ofGalla chinensisextracts with different isolation methods, aiming to improve the efficacy of caries prevention.Methods:The composition of water extract (GCE), ethanol extract (eGCE) and commercial tannic acid was compared. High performance liquid chromatography coupled to electrospray ionization-time of flight-mass spectrometry (HPLC-ESI-TOF-MS) analysis was used to analyze the main ingredients.In vitropH-cycling regime and polymicrobial biofilms model were used to assess the ability of differentGalla chinensisextracts to inhibit enamel demineralization, acid formation and biofilm formation.Results:All the GCE, eGCE and tannic acid contained a high level of total phenolics. HPLC-ESI-TOF-MS analysis showed that the main ingredients of GCE were gallic acid (GA), while eGCE mainly contained 4-7 galloylglucopyranoses (GGs) and tannic acid mainly contained 5-10 GGs. Furthermore, eGCE and tannic acid showed a better effect on inhibiting enamel demineralization, acid formation and biofilm formation compared to GCE.Conclusions:Galla chinensisextracts with higher tannin content were suggested to have higher potential to prevent dental caries.

A selection of commercially available products containing stannous fluoride (SnF2)/sodium fluoride (NaF), SnF2/amorphous calcium phosphate (ACP), SnF2/NaF/ACP, tin (Sn)/fluorine (F)/chitosan were compared with phytosphingosine (PHS) with respect to their anti-erosive properties in vitro. One-hundred and twenty bovine enamel specimens were immersed in the respective product slurries for 2 min, twice daily. The formulations were diluted with either remineralization solution or artificial saliva. After each treatment, an erosive challenge was performed for 10 min, twice daily, using citric acid, pH 3.4. The specimens were stored in remineralization solution or artificial saliva until the next treatment-erosion challenge. After 10 d, tissue loss was determined using profilometry. Enamel softening was determined through surface microhardness measurements. Tissue-loss values (measured in μm and expressed as mean ± SD) for PHS, SnF2/NaF, SnF2/ACP, SnF2/ACP/NaF, and Sn/F/chitosan treatment groups and for the negative-control group, were, respectively, 35.6 ± 2.8, 15.8 ± 1.8, 22.1 ± 2.0, 22.9 ± 1.8, 16.2 ± 1.2, and 51.2 ± 4.4 in the presence of remineralization solution and 31.7 ± 3.3, 15.6 ± 2.9, 16.5 ± 2.7, 16.8 ± 2.1, 13.1 ± 3.0, and 50.7 ± 2.8 in the presence of artificial saliva. There were no significant differences in surface microhardness measurements between the treatment groups. In conclusion, PHS resulted in a significant reduction of tissue loss compared with the negative control, but in comparison, the toothpastes containing Sn2+ and F− ions were significantly more effective compared with PHS.

Birth by Caesarian section is associated with short- and long-term respiratory morbidity. We hypothesized that mode of delivery affects the development of the respiratory microbiota, thereby altering its capacity to provide colonization resistance and consecutive pathobiont overgrowth and infections. Therefore, we longitudinally studied the impact of mode of delivery on the nasopharyngeal microbiota development from birth until six months of age in a healthy, unselected birth cohort of 102 children (n = 761 samples). Here, we show that the respiratory microbiota develops within one day from a variable mixed bacterial community towards a Streptococcus viridans-predominated profile, regardless of mode of delivery. Within the first week, rapid niche differentiation had occurred; initially with in most infants Staphylococcus aureus predominance, followed by differentiation towards Corynebacterium pseudodiphteriticum/propinquum, Dolosigranulum pigrum, Moraxella catarrhalis/nonliquefaciens, Streptococcus pneumoniae, and/or Haemophilus influenzae dominated communities. Infants born by Caesarian section showed a delay in overall development of respiratory microbiota profiles with specifically reduced colonization with health-associated commensals like Corynebacterium and Dolosigranulum, thereby possibly influencing respiratory health later in life., Highlights • The respiratory microbiota is highly dynamic during the first six months of life. • The microbiota develops rapidly from a maternal/environmental-derived flora towards several niche-specific profiles. • Mode of delivery affects early respiratory microbiota development, especially colonization of potential protective commensals. Birth by Caesarian section is associated with increased prevalence of respiratory diseases. We hypothesized that mode of delivery affects the micro-community of bacteria residing in the respiratory tract (microbiota), thereby influencing its ability to prevent invasion and outgrowth of potential pathogenic bacteria that can cause respiratory disease. We followed children during their first six months of life and show that the microbiota develops rapidly from a maternal/environmental-derived flora towards several niche-specific microbial profiles. Mode of delivery significantly affects respiratory microbiota development and interacts with breastfeeding, especially regarding the early presence of potential protective bacteria, which may contribute to respiratory health later in life.

Emerging antibiotic resistance among human pathogens has galvanized efforts to find alternative routes to combat bacterial virulence. One new approach entails interfering with the ability of bacteria to coordinate population‐wide gene expression, or quorum sensing (QS), thus inhibiting the production of virulence factors and biofilm formation. We have recently developed such a strategy by targeting LasR, the master regulator of QS in the opportunistic human pathogen Pseudomonas aeruginosa, through the rational design of covalent inhibitors closely based on the core structure of the native ligand. We now report several groups of new inhibitors, one of which, fluoro‐substituted ITC‐12, displayed complete covalent modification of LasR, as well as effective QS inhibition in vitro and promising in vivo results. In addition to their potential clinical relevance, this series of synthetic QS modulators can be used as a tool to further unravel the complicated QS regulation in P. aeruginosa.

This article investigates whether giving students control over preparing for and the moment of taking a test affects their test results in comparison with when the school is in control of the amount of training followed by a predetermined test moment. The students participated in training for manual dexterity. After the training, the students performed a test. The results of the test were stored in a database. Students from the group with freedom to select the moment of the test performed much better than those in the other group who did not have the freedom to select the moment for the test, with significantly fewer students requiring three attempts to pass the test. The fact that students when given the responsibility to develop manual skills performed better than when guided by the policy of the school is hopeful in the sense that students can learn in an early stage of their study to take responsibility for learning.

Introduction: Disruption of the matrix of endodontic biofilms will aid in their removal from a root canal. Therefore, the aim of this study was to investigate the efficacy of EDTA and a modified salt solution (MSS) to detach bacteria from biofilms.Methods: Forty-eight-hour-old Enterococcus faecalis biofilms were grown on glass coverslips and then treated for 1 hour by immersion in 17% EDTA or MSS. Phosphate-buffered saline served as a negative control. Then, residual biofilm cells on the substrate and the detached cells in the supernatant were collected. Viability was verified by the colony-forming unit (CFU) counting method. Propidium monoazide (PMA) treatment in conjunction with quantitative polymerase chain reaction (qPCR) was also performed to detect the presence of E. faecalis 16S ribonucleic RNA genes. Data were analyzed using 1-way analysis of variance and Tukey or Kruskal-Wallis and Dunn tests. The Pearson R test evaluated the correlation between results from CFU and PMA (α = 5%).Results: qPCR showed that EDTA detached 99% of biofilm cells, and MSS detached 94% of biofilm cells (both P < .001). In contrast to EDTA, MSS was highly antimicrobial. The treatment promoted an ample log 7 reduction of the attached cells (P < .001), and almost no live cells were detected in the supernatant (P < .001). Positive correlations between CFU and qPCR with PMA were observed (r = 0.959 and r = 0.729).Conclusions: EDTA detached cells in biofilms with a minor antimicrobial effect. Besides a great antimicrobial effect, MSS also detached biofilm cells. These dispersals of biofilms give insights into new endodontic biofilm removal strategies.