Parotid saliva 1 H-NMR analysis for colon cancer metabolomics: A case report.

BACKGROUND: A key priority in colon cancer research is the identification of molecular biomarkers to improve early diagnosis, guide prognosis, and the design of new therapeutic approaches. Saliva is a powerful diagnostic biofluid that can be used to detect systemic alterations. This study aimed to investigate the parotid saliva (PS) metabolic Proton Nuclear Magnetic Resonance (1 H-NMR) profile of a patient diagnosed with colon cancer, and the subsequent changes 1 year after the end of chemotherapy. CASE REPORT: We describe the 1 H-NMR PS spectrum of a 65-year-old woman diagnosed with colon cancer (G3 pT3 pN1c) (T0), and the changes in the spectrum from PS collected 1 year after the end of chemotherapy (XELOX: capecitabine plus oxaliplatin) (T1). The data was co-analyzed with blood test cancer antigens (S-CEA; S-CA19-9) and thyroid peroxidase antibody (TPOAb) measurements obtained simultaneously in order to identify peaks and interpret the spectra. The blood cancer antigens (S-CEA; S-CA19-9) and the PS 1 H-NMR peaks for fatty acids, lactate, acetate, N-acetyl sugars, citrate, tyrosine, saccharides, and formate decreased at T1 compared to T0. Whereas, the thyroid peroxidase antibody (TPOAb) blood values increased at T1 compared to T0 reflecting the changes in the 1 H-NMR spectral window of 1-3.5 ppm. CONCLUSION: PS 1 H-NMR profiling identified modified metabolites that revealed cancer cells metabolism disturbances that subsequently decreased with time throughout treatment. These altered metabolites are potential biomarkers, providing a molecular diagnostic approach for clinical diagnosis, and prognosis of human colon cancer.

Impact of Demographic Factors, Obesity, and Oral Health Status on Self-esteem among School-going Children in United Arab Emirates: A Cross-sectional Study.

OBJECTIVES: The objective of this study was to determine if oral health, obesity, and demographic factors have an impact on self-esteem among school-going children in United Arab Emirates. MATERIALS AND METHODS: Ten schools (six private and four public) were selected using random digit table. Decayed, missing, and filled teeth index according to the World Health Organization criteria was used to assess dental caries. Obesity was measured by body mass index (BMI = weight [kg]/height [m2]). Data related to demographic details and toothbrushing were collected and entered into assessment forms. The mental well-being was assessed using Rosenberg Self-esteem Scale. RESULTS: Self-esteem score was 19.8 (standard deviation [SD], ±3.8) mean, and ranged from 19.1 to 20.5. The presence or absence of dental caries or their body shape (obesity/overweight/normal weight) had no impact on the self-esteem scores. Of the participants, 93% brushed daily, whereas the brushing frequency was significantly greater in female children (98%) (P < 0.001) and children with higher self-esteem scores (P = 0.066). The self-esteem scores of school children was positively associated with age as elder children had higher scores (P = 0.001). Children of Indian origin had lower self-esteem (P = 0.004). BMI was negatively associated (P = 0.006). CONCLUSION: Rosenberg Self-esteem Scale scores were found to be lower in young children and Indian children. The child's obesity and dental caries status had no significant influence on their self-esteem. High self-esteem in older children can be linked with increased toothbrushing frequency.

A core curriculum in the biological and biomedical sciences for dentistry.

INTRODUCTION: The biomedical sciences (BMS) are a central part of the dental curriculum that underpins teaching and clinical practice in all areas of dentistry. Although some specialist groups have proposed curricula in their particular topic areas, there is currently no overarching view of what should be included in a BMS curriculum for undergraduate dental programmes. To address this, the Association for Dental Education in Europe (ADEE) convened a Special Interest Group (SIG) with representatives from across Europe to develop a consensus BMS curriculum for dental programmes. CURRICULUM: This paper summarises the outcome of the deliberations of this SIG and details a consensus view from the SIG of what a BMS curriculum should include. CONCLUSIONS: Given the broad nature of BMS applied to dentistry, this curriculum framework is advisory and seeks to provide programme planners with an indicative list of topics which can be mapped to specific learning objectives within their own curricula. As dentistry becomes increasingly specialised, these will change, or some elements of the undergraduate curriculum may move to the post-graduate setting. So, this document should be seen as a beginning and it will need regular review as BMS curricula in dentistry evolve.

Detection of Fusobacterium in oral and head and neck cancer samples: A systematic review and meta-analysis.

AIMS: This systematic review aimed to analyse: a) the presence and the abundance of Fusobacterium; b) the Fusobacterium species most often found, and c) the most common methods used for their identification in oral/head and neck cancer samples. DESIGN: A protocol was registered on PROSPERO database. This review was conducted following PRISMA guidelines. Literature search was performed on five electronic biomedical databases, namely Pubmed, Scopus, Web of Science, Embase, and Cochrane from their start dates to 30 August 2018. Two reviewers independently assessed the eligibility for inclusion; extracted the data; and evaluated the risk of bias. RESULTS: From 118 unique abstract records, 88 full-text articles were assessed for eligibility. According to inclusion and exclusion criteria, 17 publications were included in this review. Meta-analysis showed an increased prevalence of 6 % (95 % CI, 3-9) of Fusobacterium in tumour lesions than in non-tumour lesions (Fusobacterium prevalence of 16 % in tumour lesions and of 10 % in non-tumour lesions), and a 2.93 higher chance of Fusobacterium being present in tumour lesions (95 % CI, 1.47-5.81). The most common detection methods were based on molecular evidence (64.70 %) (95 % CI, 37.7-84.7). F. nucleatum was the most prevalent species (47.06 %) (95 % CI, 23.5-72). CONCLUSION: In conclusion, Fusobacterium is present and in higher abundance in oral/head and neck cancer samples when compared to non-cancer samples, suggesting that Fusobacterium may contribute to oral/head and neck cancer development.

Correlation between parotid saliva composition and dental caries using 31P-NMR and ICDAS score.

OBJECTIVES: The preservation of enamel mineral is influenced by the supersaturation of salivary secretions with respect to calcium phosphate salts. The aim was to measure the chemical environmental state of phosphate ions in a subject's parotid saliva, and to correlate this with their dental caries score, by means of 31P-Nuclear Magnetic Resonance Spectroscopy (31P-NMR) and the International Caries Detection and Assessment System (ICDAS). DESIGN: Unilateral paraffin wax stimulated parotid saliva samples were collected from 21 healthy adult subjects using a Lashley cup. The flowrate was recorded during collection. Clinical caries scores of each subject were classified using the ICDAS score. The pH was recorded for each saliva sample. 31P-NMR spectra of each saliva sample were obtained to determine the phosphorus chemical environment. All the collected data were analysed by Pearson's correlation. RESULTS: Parotid saliva flow rates were in the range from 0.07 to 0.56 ml/min. The pH varied from 5.9 to 7.6. Each 31P-NMR spectrum showed a single broad line with a chemical shift between 0.07 and 2.38 ppm. At neutral pH the maximum chemical shift was 2.05 ppm, whereas at a lower pH values the phosphorous chemical shift reduced, to 0.34 at pH 5.9. The flowrate and the 31P-NMR chemical shift correlated positively (r = 0.71; p < 0.05). The ICDAS score correlated negatively with the 31P-NMR chemical shift (r = 0.43; p < 0.05). CONCLUSIONS: This parotid saliva 31P-NMR study has shown that different phosphate states exist within saliva, which significantly influence its inorganic chemical behaviour, and therefore its cariostatic activity.

Age estimation using canine pulp volumes in adults: a CBCT image analysis.

Secondary dentine deposition is responsible for the decrease in the volume of the pulp cavity with age. Therefore, the volume of the pulp cavity can be considered as a predictor for estimating age. The aims of this study were to investigate the relationship strength between canine pulp volumes and chronological age from homogenous (approximately equal numbers of individuals in each age range) age distribution and to assess the effect of sex as predictor in age estimation. This study was performed on 719 subjects of Pakistani origin. Cone beam computed tomography images of 521 left maxillary and 681 left mandibular canines were collected from 368 females and 349 males aged from 15 to 65 years. Planmeca Romexis® software was used to trace the outline of the pulp cavity and to calculate pulp volumes. Regression analysis was performed to assess the correlation between pulp volumes considering with and without sex as a predictor with chronological age. The obtained results showed that mandibular canine pulp volume and sex have the highest predictive power (R2 = 0.33). The relationship between mandibular canine pulp volume and sex with chronological age demonstrates an odd S-shaped non-linear relationship. A statistically significant difference in volumes of pulp was found (p = 0.000) between males and females. The conclusion was that predictions using the pulp volume of the mandibular canine and sex produced the best estimates of chronological age.

Oral health-related quality of life and satisfaction of edentulous patients using conventional complete dentures and implant-retained overdentures: An umbrella systematic review.

BACKGROUND: Loss of teeth has a negative influence on essential oral functions. It is important to understand edentulous patients' perceptions about the impacts of treatment options on their oral health-related quality of life (OHRQoL) and satisfaction. AIMS: To appraise the systematic reviews (with/without meta-analysis) that investigate the impacts of complete conventional dentures (CCDs) and/or implant-retained overdentures (IRODs) on the oral health-related quality of life (OHRQoL) and satisfaction among edentulous patients. METHODS: The Joanna Briggs Institute (JBI) methodology for conduct of an umbrella systematic review was followed. Three database systems were used: Medline, Google Scholar and Cochrane Library. PROSPERO was searched for ongoing or recently completed systematic reviews. The reviews must report OHRQoL and patients' satisfaction as outcomes. RESULTS: A total of eight reviews were included in data synthesis (six were systematic reviews without meta-analysis, one was systematic review with meta-analysis, and one was meta-analysis). The level of evidence of all included reviews based on the Scottish Intercollegiate Guidelines Network ranged between 1+ and 1-. CONCLUSION: The results of this umbrella systematic review demonstrate the superiority of using IRODs compared with CCDs on the OHRQoL and patients' satisfaction outcomes. However, this positive impact is more accentuated when patients demand implant treatment or cannot adapt to CCDs treatment. Financial factors and adaptive capability indeed affect patient tolerance to both treatment modalities.

Evaluating the risk factors that link obesity and dental caries in 11-17-year-old school going children in the United Arab Emirates.

OBJECTIVE: The objective is to study the effect of obesity on dental caries among schoolchildren in Sharjah, United Arab Emirates. MATERIALS AND METHODS: The sample comprised 803, 11-17-year-old schoolchildren. The study was in the form of a randomized cross-sectional manner. Method used was two questioners. The first assessed socioeconomic and general health and the second detailed their demographic, oral hygiene, and dietary habits. Dental examination included dental caries assessment using the World Health Organization 1997 criteria and gingival health valuation. Clinical examination consisted of height, weight, and body mass index (BMI). Data analysis was done by descriptive, univariate, and multiple regressions. RESULTS: In this sample, 75% had dental caries and the mean decayed, missing, and filled teeth (DMFT) was 3.19 (standard deviation: 2.9). Obesity was seen in 15% of the adolescents and the mean BMI was 21. The link between DMFT and BMI, when evaluated using univariate analysis, showed a significant correlation (r = 0.097, P = 0.006), indicating that the rise in BMI by 10 points resulted in an increase in DMFT by 0.57. However, in the multivariate analysis, a significant relationship was observed only between father's education (P < 0.001), adolescent's age (P < 0.001), gender (P = 0.008), ethnicity (P = 0.001), and soft drink consumption with DMFT while BMI showed a significant association with age (P < 0.001), school fees (P = 0.005), obesity in family (P < 0.001), and soft drink consumption (P < 0.001). CONCLUSIONS: Obesity and dental caries were not significantly associated. The most important predictor for obesity and dental caries was soft drink consumption.

The relationship between childhood body weight and dental caries experience: an umbrella systematic review protocol.

BACKGROUND: Obesity and dental caries are global public health problems which can impact in childhood and throughout the life course. In simple terms, childhood dental caries and body weight are linked via the common risk factor of diet. An association between dental caries and obesity has been described in a number of studies and reviews. However, similarly, a relationship has also been noted between low body weight and caries experience in children. This protocol will provide the framework for an umbrella review to address the following question: Does the available evidence support a relationship between dental caries experience and body weight in the child population? METHODS: This review protocol outlines the process to carry out an umbrella systematic review which will synthesise previous reviews of childhood dental caries experience and body weight. An umbrella review methodology will be used to examine the methodological and reporting quality of existing reviews. DISCUSSION: The final umbrella review aims to aggregate the available evidence in order to provide a summary for policymakers and to inform healthcare interventions. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42016047304.

The timing of mandibular tooth formation in two African groups.

BACKGROUND: Ethnic differences in the timing of human tooth development are unclear. AIM: To describe similarities and differences in the timing of tooth formation in two groups of Sudanese children and young adults. SUBJECTS AND METHODS: The sample consisted of healthy individuals from Khartoum, Sudan, aged 2-23 years. The Northern group was of Arab origin (848 males, 802 females) and the Western group was of African origin (846 males, 402 females). Each mandibular left permanent tooth from first incisor to third molar was assessed from dental radiographs into one of 15 development stages. Mean ages at entry for 306 tooth stages were calculated using probit regression in males/females in each group and compared using a t-test. RESULTS: Mean ages were not significantly different in most tooth stage comparisons between ethnic groups for both males (61/75) and females (56/76), despite a tendency of earlier mean ages in the Western group. Mean ages for most tooth stage comparisons between males and females (137/155) were not significantly different within ethnic groups suggesting low sexual dimorphism. CONCLUSION: The mean ages of most mandibular tooth formation stages were generally not significantly different between ethnic groups or between males and females in this study.

Mother's Perception of General Family Functioning and Sugar Consumption of 3- and 4-Year-Old Children: The East London Family Study.

Frequent consumption of sugary foods is a common risk factor for chronic diseases such as dental caries and obesity. Dietary patterns are acquired at home during early life and form a blueprint for dietary behaviours in later life. A favourable family environment can provide a supportive context that enhances the adoption of healthy dietary habits. The aim of this study was to identify the contribution of general family functioning towards the frequent consumption of sugary foods by 3- and 4-year-old children in Outer North East London. The research question was explored with data from the East London Family study, which collected data through home visits from a representative sample of adults and children living in Outer North East London in 2008-2010. This study analysed data from 3- and 4-year-old children (n = 698) and their mothers and included logistic regression, conceptual hierarchical modelling and mediation analysis. The results showed that 17% of the sample consumed sugary foods more than 4 times per day, and that effective general family functioning may help reducing frequent consumption of sugary foods. There was a 67% reduction in children's frequent consumption of sugary foods with every unit increase in the general family functioning score. Mother's higher education may also help reduce the frequent consumption of sugary foods by children. The negative impact of mother's lower education was buffered by the effect of effective general family functioning. The study findings underscore the prospect of identifying factors that contribute to the acquisition of good dietary behaviours.

Controlled, prospective trial of psychosocial function before and after mandibular advancement splint therapy.

INTRODUCTION: The aim of the study was to investigate psychosocial function in patients with obstructive sleep apnea/hypopnea syndrome (OSAHS), before and after mandibular advancement splint (MAS) therapy. METHODS: In a prospective, parallel-group study, changes in psychosocial scores were compared before and after MAS therapy for OSAHS. Patients from the top (MAS treated, n = 40) or bottom (conservatively treated n = 35) of a MAS waiting list rated quality of life (Short Form 36 [SF-36] Health Survey) and sleepiness (Epworth Sleepiness Scale [ESS]). Both groups' ratings at baseline were completed while on conservative therapy. RESULTS: Baseline variables did not differ between groups. At follow-up, psychosocial scores showed improvement in MAS-treated patients, with odds ratios (confidence interval) of 0.26 (0.09, 0.75) and 0.36 (0.14, 0.92) for sleepiness and energy/vitality domain, respectively. Statistically significant improvement in the median (range) sleepiness score (10 [1 to 18] to 6 [1 to 14]; P <0.001) and energy/vitality domain (18 [7 to 20] to 19 [14 to 20]; P = 0.03) were observed with MAS therapy. Reductions were detected in median apnea-hypopnea index (median [range] 16 [5.2 to 30] to 4.6 [0.8 to 17.2] events/hour; P <0.001), and oxygen desaturation index (ODI) (11 [3 to 16] to 0 [0 to 5] events/hour; P <0.001) at follow-up with MAS therapy. Similar changes were observed in the comparison group when they went on to be treated with MAS. CONCLUSIONS: This study demonstrated that treatment with MAS produced statistically and clinically significant psychosocial and cardio-respiratory improvements.

How I remember my parents' divorce: a phenomenological investigation.

In order to examine the experience of parental divorce for adult women, a phenomenological method was used. Ten women were interviewed and the interviews were transcribed verbatim and thematized. The themes that came from the texts of the interviews transcripts and the researchers' reflections on the phenomenological research group analysis were: Before the Divorce, During the Divorce, and After the Divorce. These themes were centered on a contextual ground of Time Frame of the Divorce. The results of this study can provide individuals with a context for understanding their own experiences of parental divorce. These results could also be helpful for mental health clinicians in anticipating the themes that clients will discuss relative to the stages of their parents' divorce.

An in vitro scanning microradiography study of the reduction in hydroxyapatite demineralization rate by statherin-like peptides as a function of increasing N-terminal length.

Enamel demineralization is slowed by salivary proteins that inhibit calcium hydroxyapatite (HA) demineralization. Statherin (StN43), a 43-residue phosphorylated salivary protein with primary sequence similarities to osteopontin and caseins, binds calcium and HA. The aim of this study was to identify the minimum length of the functional domain of the statherin molecule required for cariostatic function by measuring the efficacy of peptides of progressively shorter length (i.e. containing only the N-terminal 21 (StN21), 15 (StN15), 10 (StN10), or 5 (StN5) residues) to reduce HA demineralization rates (RD(HA) ). Porous HA blocks were used as enamel analogues, and were exposed to 0.1 M acetic acid at pH 4 for 120 h, rinsed, and treated with StN21, StN15, StN10, or StN5 peptides (1.88 × 10(-5) M) for 24 h, then demineralized for a further 120 h. The RD(HA) was measured, before and after peptide treatment, using scanning microradiography. Hydroxyapatite blocks treated with StN21 and StN15 demonstrated a 50-60% reduction in the RD(HA) . However, no reduction in the RD(HA) was observed following treatment with either StN10, StN5, or buffer only. The mechanism by which statherin-like peptides reduce RD(HA) may be associated with their binding to HA surfaces. Comparisons with previously published binding energies of statherin to HA also suggest that statherin-like peptides containing 15 N-terminal residues or more, are required for binding, suggesting a link between binding and demineralization reduction.

The influence of proteins on demineralization kinetics of hydroxyapatite aggregates.

Salivary proteins influence the biomineralization of hydroxyapatite (HAp) within enamel. Their effect on the crystal growth has been extensively studied, but, their effect on demineralization kinetics is less well investigated. In this study bovine serum albumin (BSA) was used as a model protein to measure its effect on demineralization kinetics of hydroxyapatite aggregates using scanning microradiography (SMR). HAp aggregates (8 and 20% porous) were cut into 5 x 5 x 2 mm blocks. SMR cells were prepared containing hydroxyapatite blocks. BSA was added to demineralising solutions (0.1 mol L(-1) acetic acid, buffered to pH 4.0; degree of saturation zero and 0.062 respectively) at a concentration range 0.76-75.8 micromol L(-1). Demineralising solution without added BSA was used as a control. The demineralising solutions were circulated past the samples at 0.4 mL min(-1). SMR was used to measure the rate of mineral loss (RML(HAp)) at 14 points in each sample repeatedly for 3 weeks. The results show that BSA increases or decreases the RML(HAp) depending on; BSA concentration, HAp porosity, and the degree of saturation of the demineralising solution. It is suggested that BSA influences demineralization kinetics of HAp either by modifying solution properties, or, by affecting the surface energy of hydroxyapatite.

Activities related to the occurrence of traumatic dental injuries in 15- to 18-year-olds.

OBJECTIVE: To assess the activities related to the occurrence of traumatic dental injuries (TDI) in order to establish the relationship between gender, socio-economic status (SES) and major TDI related events, using classification and examination procedures suitable for epidemiological purposes, in a sample of 15- to 18-year-old students in Taiwan. METHODS: A random sample of 6312 15- to 18-year-old senior high school students in southern Taiwan was selected. Each was examined with standard clinical procedures and a questionnaire. RESULTS: The prevalence of TDI was 19.9%. The major TDI related events included sports and leisure activities (30.8%), eating (20.5%), falls (19.4%), traffic accidents (10.2%) and collisions (7.1%). Within TDI victims, sports and leisure related TDI were more prevalent among males (P = 0.001, OR = 1.640, 95% CI = 1.225, 2.195) and high SES adolescents (P = 0.014, OR = 1.991, 95% CI = 1.149, 3.449). The occurrence of non-accidental TDI was not related to age, gender and SES (P > or = 0.643). CONCLUSION: Traumatic dental injuries have become an important issue in public health and dentistry. Prevention and treatment of TDI should be emphasised to the public, the health professional and the policy maker. Future investigations into the relationship between TDI related events and their determinants are indicated.

Diffusive transport within dentinal tubules: an X-ray microtomographic study.

The hydrodynamic theory of dentine hypersensitivity proposes that external stimuli cause dentinal fluid movement within dentinal tubules thereby triggering mechanosensitive nerves and eliciting a pain response. The aim of this study was to employ X-ray microtomography (XMT) to monitor diffusion of caesium acetate through dentine to investigate the extent to which transport occurs within the primary tubules compared to that through branched microtubules believed to run perpendicular to the direction of the primary dentinal tubules. 2.0-mm thick coronal dentine disks masked to leave half of the upper surface exposed were imaged by XMT, initially in water, which was then replaced with an aqueous solution of 0.50 mol l(-1) caesium acetate. Further XMT images were acquired after 1 and 6 days immersion. The XMT images were used to measure the change in the X-ray linear attenuation coefficient resulting from caesium acetate ingress into dentine. There was clearly considerable ingress of caesium acetate into the dentine lying below the exposed surface, but considerably less beneath the sealed surface, suggesting that diffusive transport occurs predominantly in the direction of the primary dentinal tubules, with no significant lateral transport. Primary tubules are clearly the dominant transmission route for triggering the mechanosensitive nerves present at the dentine-pulp interface, and for delivery of nerve desensitising agents.

Adsorption behavior of statherin and a statherin peptide onto hydroxyapatite and silica surfaces by in situ ellipsometry.

The salivary protein statherin is known to adsorb selectively onto hydroxyapatite (HA), which constitutes the main mineral of the tooth enamel. This adsorption is believed to be crucial for its function as an inhibitor of primary (spontaneous) and secondary (crystal growth) precipitation of calcium phosphate salts present in saliva. A fragment corresponding to the first 21 N-terminus amino acids of statherin (StN21) was previously found to reduce the rate of demineralization of HA. Therefore, the interfacial properties of this peptide and statherin onto silica, hydrophobized silica and HA discs was studied by in situ ellipsometry. Their reversibility induced by dilution and elutability induced by buffer and sodium dodecyl sulfate (SDS) was also determined. The results revealed that statherin adsorbed at a greater extent onto the HA as compared to StN21, suggesting that the hydrogen bonding between the uncharged polar residues at the C-terminal region of statherin and HA contributes to its adsorption. However, on both silica surfaces the peptide adsorption appeared to proceed in a similar way. Onto the hydrophobized silica the adsorption of both peptides was suggested to occur either via multilayer formation or adsorption of aggregates from solution, while onto the hydrophilic silica adsorption of peptide aggregates from solution was the suggested mechanism. Further, both peptides were observed to be strongly adsorbed onto HA, even after SDS treatment, in comparison to the layers adsorbed onto hydrophobized silica. Both peptide layers were found to be weakly adsorbed onto the hydrophilic silica surface as they were totally removed by buffer dilution.

Evaluation of bacterial nitrate reduction in the human oral cavity.

It is hypothesized that the enterosalivary nitrate circulation encourages nitrate reducing bacteria to reside within the oral cavity. Nitrite production may then limit the growth of acidogenic bacteria as a result of the production of antimicrobial oxides of nitrogen, including nitric oxide. This study was carried out with 10 subjects to characterize oral nitrate reduction and identify the bacteria responsible. Nitrate reduction varied between individuals (mean 85.4 +/- 15.9 nmol nitrite min(-1) with 10 ml 1 mm KNO(3) mouth wash) and was found to be concentrated at the rear of the tongue dorsal surface. Nitrate reductase positive isolates identified, using 16S rDNA sequencing, from the tongue comprised Veillonella atypica (34%), Veillonella dispar (24%), Actinomyces odontolyticus (21%), Actinomyces naeslundii (2%), Rothia mucilaginosa (10%), Rothia dentocariosa (3%) and Staphylococcus epidermidis (5%). Nitrite production rates, using intact and permeabilized cells, of the major tongue nitrate reducers were determined in the presence of methyl and benzyl viologen. Under anaerobic conditions in the presence of nitrate, rates in decreasing order were: A. odontolyticus > R. mucilaginosa > R. dentocariosa > V. dispar > V. atypica. In conclusion, Veillonella spp. were found to be the most prevalent taxa isolated and thus may make a major contribution to nitrate reduction in the oral cavity.