Thomas Thurnheer

Thomas Thurnheer
University of Zurich | UZH · Institut für Orale Biologie

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114
Publications
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Publications

Publications (114)
Article
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Antibacterial properties of toothpastes enable chemical plaque control in limited‐access tooth regions that are mechanically not sufficiently reached by toothbrushes. Therefore, this study aimed to compare different microbial methods to assess antimicrobial toothpaste properties and evaluate different toothpastes in terms of their antibacterial eff...
Article
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Periodontitis and dental caries are two major bacterially induced, non-communicable diseases that cause the deterioration of oral health, with implications in patients' general health. Early, precise diagnosis and personalized monitoring are essential for the efficient prevention and management of these diseases. Here, we present a disk-shaped micr...
Article
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Necrotizing gingivitis (NG) is a necrotizing periodontal disease that differs from chronic gingivitis (CG). To date, both the microbiological causes and the involved host cytokine response of NG still remain unclear. Here, we investigated corresponding interdental plaque and serum samples from two groups of Chinese patients with CG (n = 21) or NG (...
Article
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Antimicrobial peptides have been proposed as antibiofilm agents. Therefore, we evaluated the effect of endodontic irrigants combined or not with the antimicrobial peptide nisin against an endodontic biofilm model composed of eleven bacterial species. Biofilms were grown on hydroxyapatite discs for 3, 15 and 21 days and treated with 1.5% sodium hypo...
Article
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The self-produced matrix of biofilms, consisting of extracellular polymeric substances, plays an important role in biofilm adhesion to surfaces and the structural integrity of biofilms. In dentistry, biofilms cause multiple diseases such as caries, periodontitis, and pulpitis. Disruption of these biofilms adhering to dental hard tissues may pose a...
Article
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Biofilm virulence is mainly based on its bacterial cell surrounding biofilm matrix, which contains a scaffold of exopolysaccharides, carbohydrates, proteins, lipids, and nucleic acids. Targeting these nucleid acids or proteins could enable an efficient biofilm control. Therefore, the study aimed to test the effect of deoxyribonuclease I (DNase I) a...
Article
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This study investigated the potential of salivary bacterial and protein markers for evaluating the disease status in healthy individuals or patients with gingivitis or caries. Saliva samples from caries- and gingivitis-free individuals (n = 18), patients with gingivitis (n = 17), or patients with deep caries lesions (n = 38) were collected and anal...
Article
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New strategies to eradicate endodontic biofilms are needed. Therefore, we evaluated the effect of high-purity nisin alone and in combination with D-amino acids (D-AAs) or chlorhexidine (CHX) against an “endodontic-like” biofilm model. Biofilms were grown on hydroxyapatite discs for 64 h and treated with nisin, eight D-AAs mixture, nisin + eight D-A...
Article
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We asked whether transient Staphylococcus aureus in the oral environment synergistically interacts with orally associated bacterial species such as Actinomyces oris, Candida albicans, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans, and Veillonella dispar (six-species control biofilm 6S). For this purpose, four modified biofilms...
Chapter
More than 700 microbial species inhabit the complex environment of the oral cavity. For years microorganisms have been studied in pure cultures, a highly artificial situation because microorganisms in natural habitats grow as complex ecologies, termed biofilms. These resemble multicellular organisms and are characterized by their overall metabolic...
Article
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The present study aims to assess the initial bacterial adhesion and biofilm formation on different aligner materials. A total of four different aligner materials, CA-medium (CAM), copolyester (COP), Duran (DUR), Erkodur (ERK), were tested. Stimulated human saliva was obtained from six healthy volunteers. Salivary bacteria were harvested by centrifu...
Article
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Oral health is maintained by a healthy microbiome, which can be monitored by state-of-the art diagnostics. Therefore, this study evaluated the presence and quantity of ten oral disease-associated taxa (P. gingivalis, T. forsythia, T. denticola, F. nucleatum, C. rectus, P. intermedia, A. actinomycetemcomitans, S. mutans, S. sobrinus, oral associated...
Article
Introduction As active bacteria present higher abundance of ribosomal rRNA than DNA (rRNA gene), the rRNA/DNA ratio of Next Generation Sequencing (NGS) data was measured to search for active bacteria in endodontic infections. Methods Paired cDNA and DNA samples from 5 root canals of teeth with apical periodontitis were subjected to PCR with barcod...
Article
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Oral bacteria possess the ability to form biofilms on solid surfaces. After the penetration of oral bacteria into the pulp, the contact between biofilms and pulp tissue may result in pulpitis, pulp necrosis and/or periapical lesion. Depending on the environmental conditions and the availability of nutrients in the pulp chamber and root canals, main...
Article
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Modification of oral biofilms adhering to dental hard tissues could lead to new treatment approaches in cariology and periodontology. In this study the impact of DNase I and/or proteinase K on the formation of a simulated supragingival biofilm was investigated in vitro. Six-species biofilms were grown anaerobically in the presence of DNase I and pr...
Article
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Biofilms consist of microbial communities embedded in a 3D extracellular matrix. The matrix is composed of a complex array of extracellular polymeric substances (EPS) that contribute to the unique attributes of biofilm lifestyle and virulence. This ensemble of chemically and functionally diverse biomolecules is termed the ‘matrixome’. The compositi...
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Due to increasing antibiotic resistance, the application of antimicrobial photodynamic therapy (aPDT) is gaining increasing popularity in dentistry. The aim of this study was to investigate the antimicrobial effects of aPDT using visible light (VIS) and water-filtered infrared-A (wIRA) in combination with a Hypericum perforatum extract on in situ o...
Article
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The aim of this study was to determine the antibiotic susceptibility patterns of 57 Aggregatibacter actinomycetemcomitans and 56 Porphyromonas gingivalis strains isolated from subgingival biofilm samples of periodontitis patients in Switzerland from 1980 to 2017. The minimal inhibitory concentrations (MIC) of the most commonly used antibiotics in p...
Article
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Fusobacteria are common obligately anaerobic Gram-negative bacteria of the oral cavity that may act as a bridge between early and late colonizing bacteria in dental plaque and have a role in oral and extra-oral infections. has a crucial role in oral biofilm structure and ecology, as revealed in experimental and clinical biofilm models. The aim of t...
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Aggregatibacter actinomycetemcomitans is a Gram-negative organism, strongly associated with aggressive forms of periodontitis. An important virulence property of A. actinomycetemcomitans is its ability to form tenacious biofilms that can attach to abiotic as well as biotic surfaces. The histone-like (H-NS) family of nucleoid-structuring proteins ac...
Article
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On account of its proven clinical efficacy, the combination of systemically administered amoxicillin and metronidazole is frequently adjuncted to non-operative periodontal therapy and well documented. Potential drawbacks of this regimen, e.g., side effects and problems with the compliance, led to an ongoing search for alternatives. Azithromycin, an...
Article
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In light of increasing resistance toward conventional antibiotics and antiseptics, antimicrobial photodynamic therapy (aPDT) may be a valuable alternative, especially for use in dentistry. In this regard, photosensitizers (PS) based on a phenalen-1-one structure seem to be especially favorable due to their high singlet oxygen quantum yield. However...
Article
Antimicrobial photodynamic therapy (aPDT) may be useful as a supportive antimicrobial measure for caries-active subjects. In this study, the antimicrobial efficacy of aPDT with a phenalen-1-one photosensitizer was evaluated in a novel in vitro biofilm model comprising Actinomyces naeslundii, Actinomyces odontolyticus, and Streptococcus mutans and w...
Article
Objective: Fluoride is widely used as an anti-caries agent, e.g. in toothpastes and mouth rinses. However, the nature of the anti-caries action is not entirely clear. Mechanisms suspected to explain the cariostatic effect include inhibitory effects on acid formation by bacteria, inhibition of extracellular polysaccharide (EPS) production, inhibiti...
Article
Bacteria residing in oral biofilms live in a state of dynamic equilibrium with one another. The intricate synergistic or antagonistic interactions between them are crucial for determining this balance. Using the 6-species Zürich “supragingival” biofilm model, this study aimed to investigate interactions regarding growth and localization of the cons...
Chapter
A biofilm is a structured community of microbial cells embedded in a self-produced (hydrated) matrix extracellular polymeric substance (EPS) and adherent to an inert or living surface, as defined by Costerton [1] and modified in 2012 by IUPAC [2]. Microbial cells growing in a biofilm differ physiologically from planktonic cells of the same organism...
Article
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Anaeroglobus geminatus is a relatively newly discovered putative pathogen, with a potential role in the microbial shift associated with periodontitis, a disease that causes inflammatory destruction of the periodontal tissues, and eventually tooth loss. This study aimed to introduce A. geminatus into a polymicrobial biofilm model of relevance to per...
Article
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Objectives: Anaeroglobus geminatus is a gram-negative species belonging to the family of Veillonellaceae and close associate to genus Megasphaera. The role of the species within dysbiotic microbial communities is not yet clear. However, this putative pathogen has been identified in a number of anaerobic infections, including periodontal diseases. T...
Article
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The periodontopathogen Tannerella forsythia has a characteristic cell surface (S-) layer modified with a unique O-glycan. This structure was analyzed for its role in biofilm formation employing an in vitro multispecies biofilm model, into which different T. forsythia strains and mutants with a modified cell surface composition were incorporated tog...
Article
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Objective The aim of this study is to assess the effects of ultrasonic tip distance and orientation on the removal of a multispecies biofilm under standardized conditions in vitro. Methods Six-species biofilms were grown on hydroxyapatite discs for 64 h and treated with a magnetostrictive ultrasonic tip (Cavitron) placed either on contact or at 0.2...
Article
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As a member of subgingival multispecies biofilms, Tannerella forsythia is commonly associated with periodontitis. The bacterium has a characteristic cell surface (S-) layer modified with a unique O-glycan. Both the S-layer and the O-glycan were analyzed in this study for their role in biofilm formation by employing an in vitro multispecies biofilm...
Article
This study investigated the possibility to depict individual taxa in clinically relevant biofilms using fluorescent in situ hybridization (FISH). Gutta-percha samples were collected from the apical aspect of root canals associated with a chronic apical abscess (test samples, n = 8). Corresponding control samples were obtained from previously filled...
Article
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Purpose: To measure the release of an antibiotic mixture of ciprofloxacin, cerfuroxim and metronidazole (TreVitaMix, TVM) through human dentine and to assess the growth inhibition of Fusobacterium nucleatum. Material and methods: Twenty-four extracted human incisors were scaled and endodontically treated. Root canals were either filled with anti...
Article
Objectives: Staphylococcus spp. are postulated to play a role in peri-implantitis. This study aimed to develop a "submucosal" in vitro biofilm model, by integrating two staphylococci into its composition. Materials and methods: The standard "subgingival" biofilm contained Actinomyces oris, Fusobacterium nucleatum, Streptococcus oralis, Veillonel...
Article
This study aims to assess the potential of a mixture of three antibiotics (TreVitaMix, TVM) as an intracanal dressing to disinfect the outer root surface by applying a new in vitro model. Fifty freshly extracted bovine roots were endodontically treated. Forty samples were then thoroughly scaled, mounted to petri dishes, gas sterilized, and randomly...
Article
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Periodontitis is an infectious inflammatory disease that destroys the tooth-supporting tissues. It is caused by the formation of subgingival biofilms on the surface of the tooth. Characteristic bacteria associated with subgingival biofilms are the Gram-negative anaerobes Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola, collec...
Article
To determine in vitro the antibacterial properties of propolis toothpaste and mouthrinse against an in vitro multispecies biofilm model. Six-species biofilms grown anaerobically on pellicle-coated hydroxyapatite disks were fed with glucose/sucrose-supplemented medium 3 times daily for 45 min and incubated in 37°C saliva between feedings for up to 6...
Article
The development of dental caries and periodontal diseases result from distinct shifts in the microbiota of the tooth-associated biofilm. This in vitro study aimed to investigate changes in biofilm composition and structure, during the shift from a "supragingival" aerobic to a "subgingival" anaerobic profile. Biofilms consisting of Actinomyces oris,...
Article
Periodontitis is the chronic inflammatory destruction of the periodontal tissues, as a result of bacterial biofilm formation on the tooth surface. Proteins secreted by the gingival epithelium challenged by subgingival biofilms represent an important initial response for periodontal inflammation. The aim of this in vitro study was to characterize th...
Article
Full-text available
Periodontitis is an infectious disease that causes the inflammatory destruction of the tooth-supporting (periodontal) tissues, caused by polymicrobial biofilm communities growing on the tooth surface. Aggressive periodontitis is strongly associated with the presence of Aggregatibacter actinomycetemcomitans in the subgingival biofilms. Nevertheless,...
Article
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Background: Periodontal diseases are polymicrobial diseases that cause the inflammatory destruction of the tooth-supporting (periodontal) tissues. Their initiation is attributed to the formation of subgingival biofilms that stimulate a cascade of chronic inflammatory reactions by the affected tissue. The Gram-negative anaerobes Porphyromonas gingi...
Article
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Abstract Biofilms are polymicrobial communities that grow on surfaces in nature. Oral bacteria can spontaneously form biofilms on the surface of teeth, which may compromise the health of the teeth, or their surrounding (periodontal) tissues. While the oral bacteria exhibit high tropism for their specialized ecological niche, it is not clear if bact...
Article
Honey is an ancient natural remedy for the treatment of infected wounds. It has regained attention in the medical profession, as it has recently been reported to have a broad-spectrum inhibitory effect against bacteria. Data concerning Manuka honey of New Zealand origin, which is claimed to provide additional non-peroxide antimicrobial activity (so...
Article
Objectives Biofilm formation on tooth surface results in colonization and invasion of the juxtaposed gingival tissue, eliciting strong inflammatory responses that lead to periodontal disease. This in vitro study investigated the colonization of human gingival multi-layered epithelium by multi-species subgingival biofilms, and evaluated the relative...
Article
Full-text available
This study screened the available evidence for the in vitro antimicrobial efficacy of propolis, a natural herbal resin bee product, against a selection of three bacterial species of relevance to oral diseases. For this purpose, papers dealing with laboratory studies assessing minimum inhibitory concentration (MIC), minimum bactericidal concentratio...
Conference Paper
Objective: The development of subgingival biofilms is the causative factor of periodontal disease. Metabolic and spatial interactions between multiple species are crucial for biofilm formation. Species-specific virulence factors may regulate the interaction between bacteria within biofilms, altering the ecological niche. Porphyromonas gingivalis, a...
Conference Paper
Objective: The development of caries and periodontal diseases result from distinct shifts in the balance of the microbiota of dental plaque. In this study we aimed to investigate the changes in the biofilm composition and structure when shifting from an in vitro six-species aerobic to twelve-species anaerobic biofilm. Method: Biofilms consisting...
Conference Paper
Objectives: The gingival epithelium responds to the challenge of the biofilm by a number of cellular changes. This study investigated the secreted proteome of gingival epithelial cell cultures in response to in vitro subgingival biofilms, and identified the relative effects of the three “red complex” species. Methods: A 10-species subgingival biofi...
Article
Objectives: To investigate the cleaning efficacy of a mechanical and a hydrodynamic homecare device on biofilm-coated titanium surfaces with and without chlorhexidine. Material and methods: Six-species biofilms were grown on 108 SLA-titanium discs, which were cleaned as follows: sonic toothbrush alone (i) or in combination with either a 0.2% chl...
Article
The antimicrobial effects of red wine and its inherent components on oral microbiota were studied by using a 5-species biofilm model of the supragingival plaque that includes Actinomyces oris, Fusobacterium nucleatum, Streptococcus oralis, Streptococcus mutans and Veillonella dispar. Microbiological analysis (CFU counting and confocal laser scannin...
Article
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Background: There is evidence that advanced infectious chronic periodontal inflammatory disease may have an impact on general health including cardiovascular diseases. The aim of this clinical study was to evaluate the ability of Porphyromonas gingivalis to colonize heart valves and, subsequently, to assess whether there is an association between t...
Article
Full-text available
Periodontitis is an infectious inflammatory disease that results in the destruction of the tooth-supporting (periodontal) tissues. The Gram-negative anaerobic species Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola, (also known as the "red complex" species) are highly associated with subgingival biofilms at periodontitis-affe...
Article
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This study aims to investigate the biofilm removal capacity of two ultrasonic tips under standardized conditions using a multi-species biofilm model. Six-species biofilms were grown on hydroxyapatite discs for 64.5 h and were treated for 15 s with a standardized load of 40 g with a piezoelectric or magnetostrictive device. Tips were applied either...
Article
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The aim of this study was to investigate the impact of early colonizing species on the structure and the composition of the bacterial community developing in a subgingival 10-species biofilm model system. The model included Streptococcus oralis, Streptococcus anginosus, Actinomycesoris, Fusobacterium nucleatum subsp. nucleatum, Veillonella dispar,...
Chapter
Contemporary Restorative and Regenerative Dentistry mandates the use of implantable devices, as part of the overall treatment plan. The ultimate aim is to restore missing teeth or regenerate defective tissues. This can be achieved by the implementation of devices such osseointegrated dental implants or tissue regeneration materials, respectively. T...
Article
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The Triggering Receptor Expressed on Myeloid cells 1 (TREM-1) is a cell surface receptor of the immunoglobulin superfamily, with the capacity to amplify pro-inflammatory cytokine production and regulate apoptosis. Polymorphonuclear neutrophils (PMNs) are the first line of defence against infection, and a major source of TREM-1. Porphyromonas gingiv...