New Insights on the Scalping Phenomenon of Volatile Sulphur Compounds on Micro-Agglomerated Wine Closures.

Flavour scalping in wine is a well-known phenomenon that is defined as the sorption of flavour compounds on wine closures. While the impact of closure type was the object of several studies, no research has addressed the impact of wine closure permeability on flavour scalping. For that purpose, the adsorption of volatile sulphur compounds (VSCs) on four micro-agglomerated wine cork closures was investigated by soaking them in model and Shiraz wines for 7 days. From a kinetic point of view, most of the VSCs were quickly scalped after 1 h of soaking, and this effect increased after 6 h until reaching a plateau. Most importantly, no significant impact of the closure on the kinetics and adsorption rates of the VSCs was found. As to the quantitative aspects, VSC sorption on closures accounted for 1% to 5% of the initial VSCs present in the wines only, meaning that the impact was negligible under oenological conditions.

Effectiveness of oral care interventions on malodour in dogs.

BACKGROUND: Oral malodour is identified by pet owners as an unpleasant inconvenience, but they may not recognise this likely indicates underlying disease. The primary cause of oral malodour relates to the presence of bacteria in the oral cavity often associated with gingivitis and periodontitis. The purpose of this study was to determine the effect of feeding two oral care chews with different textural properties on oral malodour and the proportion of bacterial species involved in the production of volatile sulphur compounds (VSCs). METHODS: Fourteen dogs (9 Petit Basset Griffon Vendéen (PBGV) and 5 Beagle dogs) participated in the randomised cross-over study for a total of 14 weeks. The cohort was divided into four groups with each exposed to a different intervention per week: chew A, chew B, tooth brushing control or a no intervention control. An induced malodour method was used to assess VSCs in breath samples using a portable gas chromatograph (OralChroma™). Microbiological samples (supragingival plaque and tongue coating scrapes) were analysed for VSC-producing bacteria using Oral Hydrogen Sulfide agar with lead acetate. RESULTS: VSCs were detected in the dogs' breath samples and levels of hydrogen sulphide and methyl mercaptan were found to be reduced following an intervention. Chew B significantly reduced the levels of both hydrogen sulphide (p < 0.001) and methyl mercaptan (p < 0.05) compared to no intervention. Reductions in methyl mercaptan were also observed for chew A and tooth brushing but these were not statistically significant. When compared to no intervention, all interventions significantly reduced the total bacterial load and VSC producing bacterial load in plaque (p < 0.001). For tongue samples, only chew B significantly reduced the total bacterial load and VSC-producing bacterial load (p < 0.001) compared to no intervention. CONCLUSIONS: By inducing oral malodour and subsequently applying the one-time interventions, significant reductions in the levels of VSCs were observed. The use of oral care chews texturally designed to deliver a deep, all-round cleaning action can be particularly effective at managing oral malodour in dogs, likely through an enhanced ability to remove bacteria.

Nitrogen metabolism in three non-conventional wine yeast species: A tool to modulate wine aroma profiles.

The positive impact of certain non-Saccharomyces yeasts on the aromatic profile of wines has been well documented in literature and their industrial use in association with S. cerevisiae is now recommended. Competition between non-Saccharomyces species and Saccharomyces cerevisiae for various nutrients, especially nitrogen sources, greatly impacts the production of aroma compounds. In this study, we further explored the impact of different nitrogen nutrition strategies on the production of carbon and sulphur volatile compounds of three non-Saccharomyces strains, namely Pichia burtonii, Kluyveromyces marxianus, Zygoascus meyerae sequentially inoculated with S. cerevisiae in Sauvignon blanc and Shiraz grape musts. Nitrogen additions were implemented according the specific requirement of each species. At the end of fermentation, we observed specific metabolic signatures for each strain in response to the nature of the nitrogen source suggesting strain-specific metabolic fluxes present. Overall, these results confirmed and further explored the interconnection between nitrogen sources and aroma metabolism (including that of higher alcohols, fatty acids, esters and volatile sulphur compounds), and their variations according to species and the nature of the nitrogen source. The knowledge generated provides new insights to modulate the aroma profile of wines produced with non-Saccharomyces species.

The long-term effect of a zinc acetate and chlorhexidine diacetate containing mouth rinse on intra-oral halitosis-A randomized clinical trial.

AIM: To evaluate the long-term effects of a zinc acetate and chlorhexidine diacetate mouth rinse (Zn/CHX) on intra-oral halitosis. MATERIALS AND METHODS: Forty-six adults with intra-oral halitosis were randomized into a 6-month, double-blind, placebo-controlled clinical study. The presence of intra-oral halitosis was evaluated at baseline, 3 and 6 months after treatment by assessment of organoleptic score (OLS) and by total volatile sulphur compounds (T-VSC), hydrogen sulphide (H2 S) and methyl mercaptan (MM) concentrations in exhaled air. RESULTS: A Zn/CHX mouth rinse provided significantly better control of intra-oral halitosis than a placebo mouth rinse. At 3 and 6 months, individuals rinsing with the Zn/CHX rinse presented with reductions of the OLS, T-VSC (p < .01, respectively), H2 S (p < .001), and MM (p < .01) in subjects' exhaled air. At 6 months, 68.2% of individuals using the Zn/CHX rinse experienced a 1 or 2 category improvement in OLS compared with 19.1% of placebo-treated subjects. 91% of subjects in the Zn/CHX group were categorized as being effectively treated for intra-oral halitosis (i.e. H2 S < 112 ppb), compared to 43% in the placebo group. CONCLUSION: Zn/CHX mouth rinse provides effective long-term efficacy against intra-oral halitosis, assessed both objectively and subjectively. With regular rinsing, the effect was sustained for 6 months.

Subjective and objective halitosis among patients with Parkinson's disease.

OBJECTIVES: Parkinson's disease (PD) affects oral health, but prevalence of subjective and objective halitosis and the influence of hyposalivation remain unclear. We aimed to explore whether patients with PD suffer from halitosis and to define correlations between halitosis and hyposalivation. We hypothesised that patients with PD suffer more often from halitosis compared to healthy controls, influenced by dry mouth. MATERIALS AND METHODS: Subjective (halitosis, xerostomia visual analogue scale [VAS], short German Oral Health Impact Profile [OHIPG]-14) and objective scales (e.g., organoleptic score, volatile sulphur compounds [VSCs], stimulated whole saliva [SWS]) were assessed from 26 patients with PD and 26 healthy controls. RESULTS: The mean organoleptic score was 0.7 (SD: 0.7) in all patients, and VSCs were either comparable or significantly lower (dimethyl sulphide, P = .010) in PD patients compared with controls, yet more patients with PD perceived halitosis to be stronger (77% vs 54%, respectively; P = .059). Dry mouth was significantly more likely in patients with PD than controls: mean xerostomia VAS 4 (SD: 2) vs 1 (SD: 2), P = .010; SWS 0.4 (SD: 0.4) vs 0.7 (SD: 0.6) mL/min, P < .05); SWS did not correlate with subjective or objective halitosis. Oral health-related quality of life (OHRQoL) was lower in patients with PD than controls (mean OHIPG-14 score 12 (SD: 0.2) vs 5 (SD: 7.0), respectively; P < .05). CONCLUSIONS: Patients with PD suffer from subjective and objective halitosis, dry mouth and impaired OHRQoL. Dry mouth problems do not correlate with prevalence or intensity of halitosis.

A randomized controlled trial evaluating the efficacy of a 67% sodium bicarbonate toothpaste on gingivitis.

INTRODUCTION: In previous studies, toothpastes with high levels of sodium bicarbonate (>50%) have reduced gingival inflammation and oral malodour. This study compared the effects of brushing for 6 weeks with 67% (test group) or 0% (control group) sodium bicarbonate toothpaste on gingival health. METHODS: This was a single-centre, single examiner-blind, randomized, controlled, two-treatment, parallel-group study. Eligible subjects (≥18 years) had ≥20 gradable teeth, mild-to-moderate gingivitis, a positive response to bleeding on brushing and ≥20 bleeding sites. The primary objective was to compare the number of bleeding sites following twice-daily use of 67% sodium bicarbonate toothpaste or 0% sodium bicarbonate toothpaste after 6 weeks. Secondary endpoints included Modified Gingival Index (MGI), Bleeding Index (BI) and volatile sulphur compounds (VSC), assessed after 6 weeks. Safety was assessed by treatment-emergent oral soft tissue abnormalities and adverse events. RESULTS: Of 148 patients randomized (74 to each treatment), 66 (89.2%) completed the study in the test group, compared with 69 (93.2%) in the control group. Compared with the control group, the test group had a significant reduction in the number of bleeding sites at Week 6 (absolute difference - 11.0 [-14.0, -8.0], P < 0.0001; relative difference - 25.4%), together with significant reductions in MGI and BI (both P < 0.0001). Although the median reductions from baseline for VSC were numerically greater in the test group, the difference did not reach statistical significance (P = 0.9701). CONCLUSIONS: This 67% sodium bicarbonate toothpaste provided statistically significant improvements in gingival health and bleeding after 6 weeks of use.

Changes of volatile sulphur compounds during therapy of a case series of patients with chronic periodontitis and halitosis.

AIM: To assess the effect of different stages of intervention on volatile sulphur compounds (VSCs) of periodontitis patients with halitosis, before and after non-surgical periodontal therapy. MATERIAL & METHODS: This clinical trial included 18 adults with chronic periodontitis and halitosis. After initial examination, patients received oral hygiene (OH) instructions and tongue cleaner. One week later, non-surgical periodontal therapy was completed within 48 h. Measurements were at baseline, 1 week after OH, 1 and 6 weeks post therapy. These included simplified plaque index (sPlI), probing pocket depth (PPD), bleeding on probing (BoP), Winkel Tongue Coating Index (WTCI), organoleptic scores (OLSs) of nose and mouth air and VSCs. RESULTS: sPlI, BoP, WTCI, OLS of the mouth air and VSCs showed significant differences (p < 0.05), even after 1 week of OH. A further significant decrease was determined 1 week after non-surgical therapy for WTCI, OLS (nose and mouth air) and methyl mercaptan concentration. A significant decrease, 6 weeks post therapy, was observed for sPlI, BoP, WTCI, PPD, OLS of the nose and mouth air and VSCs (p < 0.05). CONCLUSIONS: Oral hygiene and tongue cleaning improve the OLSs of the mouth air and reduce VSCs. Periodontal therapy further improves the OLSs and reduces the concentration of VSCs.

The effect of periodontal therapy on intra-oral halitosis: a case series.

AIM: The aim of this study was to evaluate the effects of non-surgical periodontal therapy on intra-oral halitosis 3 months after therapy. MATERIAL AND METHODS: Sixty-eight adults with intra-oral halitosis were included in a case series. Intra-oral halitosis was evaluated at baseline, and at 3 months after treatment using the organoleptic scores (OLS), Halimeter® , and a gas chromatograph. RESULTS: Significant reductions for OLS (p < 0.01), total sum of volatile sulphur compounds (T-VSC) (p < 0.01) and methyl mercaptan (MM) (p < 0.05) values were found after treatment. Hydrogen sulphide (H2 S) levels were not significantly reduced. The numbers of probing pockets 4 mm, 5 mm and 6 mm were significantly reduced as a result of therapy (p < 0.001). Bleeding on probing (BOP) and plaque indices were also significantly reduced (p < 0.001). For the 34 individuals with successful periodontal treatment (BOP<20% and a ≥50% reduction of total pocket depth) reductions in OLS (p < 0.01) and T-VSC scores (p < 0.01) were found. Eleven individuals were considered effectively treated for intra-oral halitosis presenting with a T-VSC value <160 ppb, a H2 S value <112 ppb and a MM value <26 ppb. CONCLUSION: Non-surgical periodontal therapy resulted in reduction of OLS, MM and T-VSC values 3 months after therapy. Few individuals were considered as effectively treated for intra-oral halitosis.

Comparative effect of a new mouthrinse containing chlorhexidine, triclosan and zinc on volatile sulphur compounds: a randomized, crossover, double-blind study.

AIM: The aims of this study were to compare the volatile sulphur compounds (VSC)-reducing effect of two commercial mouthrinses using a morning bad breath model and to assess the role of mechanical plaque control (MPC) when performed previously to mouthrinse use. PATIENTS AND METHODS: Eleven volunteers with good oral health were enrolled in a double-blind, randomized, six-step crossover design study with a 7-day washout period. Two commercial mouthrinses were tested using a saline solution (NaCl 0.9%) as a negative control: one mouthrinse contained 0.05% chlorhexidine, 0.05% cetylpyridinium chloride and 0.14% zinc lactate (CHX-CPC-Zn), while the other contained 0.05% chlorhexidine, 0.15% triclosan and 0.18% zinc pidolate (CHX-triclosan-Zn). A portable sulphide monitor (Halimeter(®) ) was used for VSC quantification. Measurements were made at baseline, and 1, 3 and 5 h after rinsing. Significant differences were detected by analysis of variance. RESULTS: No significant differences between groups were detected at baseline. We were unable to demonstrate a significant influence of mechanical plaque control on the reduction of VSC levels when performed before mouthrinse use (P = 0.631). Both mouthrinses effectively lowered VSC levels in all test intervals (P < 0.05). No statistically significant differences were found between mouthrinses in any of the test intervals (P = 0.629, 0.069 and 0.598 at 1, 3 and 5 h). CONCLUSION: This study demonstrated that CHX-CPC-Zn and CHX-triclosan-Zn have significant and similar effects in reducing VSC levels, which persist for at least 5 h. Such effects were independent of previous MPC, which failed to improve on the results of mouthrinse use alone.

The effect of different mouth rinse products on intra-oral halitosis.

AIM: To evaluate the effect of different mouth rinses 12 h after rinsing on genuine intra-oral halitosis. MATERIALS AND METHODS: Twenty-four adults with halitosis were included in a double-blind, crossover, randomized clinical trial. Halitosis was evaluated 12 h after rinsing with placebo and five mouth rinse products containing zinc acetate and chlorhexidine diacetate; zinc lactate, chlorhexidine and cetylpyridinium chloride; zinc acetate and chlorhexidine diacetate with reduced amounts of mint and menthol; zinc chloride and essential oil; and chlorine dioxide using the organoleptic method and a gas chromatograph. Test periods were separated by 1 week. RESULTS: Hydrogen sulphide (H2 S), methyl mercaptan (MM) and the organoleptic scores (OLS) were significantly reduced 12 h following rinsing with all substances compared to placebo (P < 0.05). H2 S was more effectively reduced after rinsing with zinc acetate and chlorhexidine diacetate and zinc acetate and chlorhexidine diacetate with reduced amounts of mint and menthol compared to rinsing with zinc chloride and essential oil (P < 0.05), and significantly lower values of MM were obtained after rinsing with zinc acetate and chlorhexidine diacetate compared to zinc lactate, chlorhexidine and cetylpyridinium chloride (P < 0.05). The percentage effectively treated individuals (H2 S (<112 ppb), MM (<26 ppb) and OLS score <2) varied from 58% percentage (zinc acetate and chlorhexidine diacetate) to 26% (zinc chloride and essential oil). CONCLUSION: All treatments resulted in reduction in halitosis 12 h after rinsing compared to placebo. H2 S and MM were most effectively reduced by zinc acetate and chlorhexidine diacetate.

Volatile sulphur compound levels and related factors in patients with chronic renal failure.

AIMS: To analyse specific volatile sulphur compound(VSC) levels in a group of chronic renal failure (CRF) patients and determine the relationship between these VSC levels and organoleptic measurements, blood urea nitrogen (BUN) levels, dental and periodontal conditions, salivary flow rate, and tongue coating scores. MATERIALS AND METHODS: One examiner performed organoleptic and VSC measurements on fifty patients with CRF before and after haemodialysis (HD) and controls. DMFT and CPITN indexes, tongue coating scores, salivary flow rates were measured. Comparisons were performed using the Mann-Whitney U, Wilcoxon signed-ranks, and chi-square tests. Spearman correlation coefficient was used to analyse correlations. RESULTS: Before HD, the mean dimethyl sulphide level was 1.04 ± 1.20 in the CRF patients and 0.51 ± 0.65 in controls, with a significant difference. The mean hydrogen sulphide, methyl mercaptan and dimethyl sulphide levels in CRF patients were 1.47 ± 3.04, 1.03 ± 1.85, and 1.04 ± 1.20, respectively, before HD; and 0.53 ± 1.65, 0.48 ± 1.27, and 0.56 ± 0.85, respectively, after HD; with the differences being significant. Methyl mercaptan levels increased with an increase in HD duration. Tongue coating and organoleptic measurements were significantly correlated with methyl mercaptan. CONCLUSIONS: Dimethyl sulphide is the main VSC in extraoral blood-borne halitosis; but methyl mercaptan may also contribute to this type of halitosis. A decreased salivary flow rate and an increased pH of the biofilm matrix may be a significant parameter for VSC levels in CRF patients.

Oral prophylaxis and its effects on halitosis-associated and inflammatory parameters in patients with chronic periodontitis.

OBJECTIVE: A controlled clinical trial was conducted to evaluate the effects of oral prophylaxis on halitosis-associated, immunological and microbiological parameters. METHODS: Thirty subjects were included in this controlled clinical trial (patients with generalized chronic periodontitis and controls without clinical attachment loss; each n = 15). Before oral prophylaxis and 14 days after (including tongue cleaning) volatile sulphur compounds (VSC), organoleptic scores and a tongue coating index were evaluated. The levels of IL-1ß, IL-8, IL-10 and MMP-8 were measured in GCF, and also major periodontal pathogens were detected. Data were statistically analysed using anova and paired t-test. RESULTS: Supragingival plaque and calculus removal with combined tongue cleaning was able to reduce significantly (P < 0.05) the VSC values in both groups (no significant differences between both groups). Two weeks after periodontal debridement, the VSC values were observed in the periodontitis group, but not in the control group, similar to the baseline values. The difference between the groups was statistically significant (P < 0.05). Only a repeated prophylaxis session in the periodontitis group was able to reduce VSC values significantly in comparison with baseline (P < 0.05). Organoleptic scores (10 and 30 cm) were significantly different (P < 0.05) between both groups before and after the treatment. Periodontal pathogens and host-derived markers were not significantly affected by a single prophylaxis session. CONCLUSIONS: Oral prophylaxis may result in a significant decrease in VSC values. However, in periodontal diseases, a more complex treatment seems to be necessary.

A retrospective analysis of patients suffering from halitosis over a 17-year period.

Halitosis is a socially avoided topic with an increasing worldwide prevalence. This study aimed to investigate the correlation between the different forms of halitosis and factors such as: gender, smoking, stress, and oral hygiene. We analysed data from patients registered at the Center of Salivary Diagnostics, Hyposalivation and Halitosis at the University Center for Dental Medicine Basel over a 17-year period, using both subjective and objective approaches to determine the presence of halitosis. The data was statistically analysed using chi-squared and Wilcoxon rank-sum tests. Although halitosis is of multifactorial origin, an oral cause was found in 3 out of 4 patients. Men showed higher values of volatile sulfur compounds (VSC) (p = 0.002) indicative of halitosis than women, while women displayed better oral hygiene (p < 0.001), yet were twice as likely to suffer from halitophobia than males. Patients with higher tongue coating scores (p < 0.001) and periodontitis (p < 0.001) had higher levels of VSC, contributing to bad breath, whereas patients with symptoms such as stress (p = 0.81) or smoking (p = 0.28) did not reveal significantly altered measurements. This study sheds light on the complex and multifactorial nature of halitosis over a long period of time. It further underlines the importance of individualized treatment strategies, given halitosis' multifactorial nature, in order to contribute to the patients' treatment needs.

Concerning perceived and clinically-measured levels of halitosis.

The different types of self-reported halitosis complaints include those where one feels that one's breath smells bad, where one feels that one has bad breath because of the attitudes of others, and where others have pointed out the presence of bad breath. The results of previous studies comparing the objective and subjectives measures of halitosis are inconsistent, and few studies have used gas chromatography (GC) to measure halitosis in a large sample. This study aimed to examine the objectively measured halitosis levels based on the reasons individuals are concerned about halitosis. We included 2063 patients who visited the halitosis clinic at a university dental hospital. Halitosis was assessed using GC, self-administered questionnaires, and oral examinations. Levels of volatile sulphur compounds (VSCs; H2S, CH3SH, and (CH3)2S) were set as objective measures of halitosis. Patients were grouped based on their answers to 'What made you concerned about bad breath?' into groups: 'self-perceived,' 'attitudes of others,' 'told by others,' and other reasons. Univariate and multivariable linear regression analyses were performed to examine factors associated with VSCs and objective halitosis levels. Age, sex, oral health status, smoking, drinking, and breakfast habits were used as confounders. Patients who answered 'told by others' (n= 691, 33.5%) showed the highest VSCs. Individuals whose halitosis was pointed out by others had higher objectively measured halitosis levels, while those concerned about the attitudes of others or perceived their own halitosis had lower objectively measured halitosis levels. These results suggest that the objective level of halitosis can differ on the basis of the reason underlying an individual's concern about their bad breath. Categorizing halitosis complaints and comparing them with objective halitosis levels may help reduce the anxiety of those who are concerned about halitosis and confirm the need for intervention for those with objective halitosis.

Emission of volatile sulphur compounds during swine manure composting: Source identification, odour mitigation and assessment.

This study aimed to identify the sources of volatile sulphur compounds (VSCs) and evaluate their mitigation by ferric oxide (Fe2O3) during swine manure composting. Four chemicals, including l-cysteine, l-methionine, sodium sulphite, and sodium sulphate, were further added to simulate organic and inorganic sulphur-containing substances in swine manure to track VSC sources during composting. Results show that sulphur simulants induced the emission of six common VSCs, including methyl sulphide (Me2S), dimethyl sulphide (Me2SS), carbonyl sulphide (COS), carbon disulphide (CS2), methyl mercaptan (MeSH), and ethyl mercaptan (EtSH), during swine manure composting. Of them, COS, CS2, MeSH and Me2SS were predominantly contributed by the biodegradation of methionine and cysteine, while Me2S and EtSH were dominated by the reduction of sulphite and sulphate. Further Fe2O3 addition at 1.5 % of total wet weight of composting materials immobilized elemental sulphur and inhibited sulphate reduction to reduce the emission of VSCs by 46.7-80.9 %. Furthermore, odour assessment indicated that adding Fe2O3 into composting piles significantly reduced the odour intensity level to below 4, the odour value of VSCs by 47.1-81.3 %, and thus the non-carcinogenic risk by 68.4 %.

Relationship between Fixed Dental Crowns and Volatile Sulphur Compounds.

OBJECTIVES: The aim of this study was to investigate and compare the level of halitosis in patients with/without fixed crowns and in addition the influence of various crown parameters on halitosis was also explored. METHODS: In total, 96 subjects (fixed crowns = 52; no crowns = 44) participated in the study. The levels volatile sulphur compounds (VSCs) of hydrogen sulphide (H2S), methyl mercaptan (CH3SH), and dimethyl sulphide (CH3SCH3) were evaluated with breath samples using gas chromatography and used for classification as presence or absence of halitosis. The periodontal clinical parameters for all the participants as well as the crown parameters for participants with fixed crowns were also evaluated. Cross tabulation, Chi-square test, and one-way analysis of variance tests were used for the statistical analysis and comparisons. RESULTS: Breath samples revealed, 50 (52.1%) participants were suffering from halitosis. Out of VSCs, the level of CH3SCH3 (62.5%) was found to be the most prevalent. Significant correlations were observed between the presence of fixed crowns and oral halitosis (p < 0.001). Statistically significant difference in the concentration of H2S and CH3SH (p < 0.001) and no significance for CH3SCH3 (p = 0.075) between patients with/without fixed crowns was found. The presence of halitosis was more prevalent in the subjects with crown parameters (subgingival margin, over-contoured margin, open-crown margin, over-contoured and under-contoured crowns) considered clinically defective/unacceptable (p < 0.05). CONCLUSIONS: Presence of fixed dental crowns significantly contributes to the oral halitosis. Dental crowns with defects significantly impair the hygienic conditions and oral microflora resulting in high prevalence of halitosis.

Alleviation of halitosis by use of probiotics and their protective mechanisms in the oral cavity.

Regarding the relation of halitosis with oral infections and its effects on social relations between humans, the present study investigated the positive effects of probiotics on prevention or treatment of halitosis. The causative agents of halitosis are volatile sulphur compounds (VSCs), and halitosis is divided into oral and non-oral types according to the source of the VSCs. H2S and CH3SH are two main halitosis metabolites-produced following the degradation of proteins by bacteria in the mouth-however, CH3SCH3 has a non-oral origin, and is a blood neutral molecule. Just as much as halitosis is important in medicine, its psychological aspects are also considered, which can even lead to suicide. Today, the use of probiotics as a new therapeutic in many roles is in progress. Most probiotics are used for the treatment of gastrointestinal tract disorders, but various studies on the alleviation of halitosis by use of probiotics have reported satisfactory results. The genera Lactobacillus, Streptococcus and Weissella are among the most useful probiotics for the prevention or treatment of halitosis in the oral cavity.

New insight into the effect of thermal hydrolysis on high solid sludge anaerobic digestion: Conversion pathway of volatile sulphur compounds.

Untreated sludge (total solids = 10%) and thermally hydrolysed sludge (total solids = 10%) were subjected to high-solid anaerobic digestion (HSAD) to study the effect of thermal hydrolysis pre-treatment (THP) on the conversion pathways of volatile sulphur compounds (VSCs). Typical VSCs were detected in the gas produced by THP at 160 °C for 30 min, including H2S, methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). After THP, the organic sulphide ratio in the treated sludge had decreased from 96% to 90%, and inorganic sulphide had increased from 4% to 10%. In the THS (THP + HSAD) group, the productivity and total volume of VSCs were significantly increased. These results suggest that THP directly promotes converting organic sulphur (OS) into VSCs. Further tests revealed that THP increased the activity of reductases (adenine phosphate sulphate reductase and sulphite reductase), OS hydrolysis was the main source of VSCs in biogas, and MM could be converted into H2S (78%), DMS (18%) and DMDS (4%). These findings are used to elucidate the conversion pathway of sulphides in HSAD.

Comparative Evaluation of SmartMouth Clinical DDS Advanced Oral Rinse and Chlorhexidine Mouthrinse.

PURPOSE: To evaluate the efficacy of SmartMouth Clinical DDS compared with 0.12% chlorhexidine and placebo mouthrinses. MATERIALS AND METHODS: Seventy-six subjects with gingivitis or chronic periodontitis were enrolled in a double-blind, placebo-controlled, clinical study. Examinations included Gingival Index (GI), Bleeding Score (BS), Plaque Index (PI), Tooth Stain Index (TSI), and Calculus Index (CI). Subjects were given a prophylaxis and oral hygiene instructions at the time of enrolment. Subjects were assigned to one of three groups: SmartMouth Clinical DDS (SM), 0.12% chlorhexidine (CHX), or placebo (PL). Subjects were examined at 3 and 6 weeks. Data were evaluated as differences from baseline for each group. Analysis of variance (ANOVA), t tests or non-parametric alternatives were used to analyse data. RESULTS: The GI, BS and PI decreases from baseline were statistically significant at both 3 and 6 weeks for all three groups (p ≤ 0.025). Differences between groups were not statistically significant, except that the PI decrease for CHX was significantly greater than PL at 6 weeks (p = 0.048). At 6 weeks there was a statistically significant increase in TSI for CHX (p ≤ 0.001). CI decreased significantly for all groups at 3 weeks (p ≤ 0.004) and for PL at 6 weeks (p ˂ 0.001). At 3 weeks and 6 weeks, the percentages for compliance were significantly higher for SM and PL than for CHX (p ˂ 0.001). SM had less taste alteration reported than CHX (p = 0.003). CONCLUSION: While all three groups were shown to improve GI, BS and PI scores; non-prescription SM resulted in less taste alteration, less tooth stain and better compliance than CHX.

Effects of physicochemical parameters on volatile sulphur compound formation from L-methionine catabolism by non-growing cells of Kluyveromyces lactis.

The present study investigated for the first time the effects of various physicochemical parameters on the production of volatile sulphur compounds (VSCs) by non-growing cells of Kluyveromyces lactis supplemented with L-methionine. The results showed that the production of VSCs positively correlated with the cell biomass, but it seemed that no clear relationship with L-methionine concentration existed. Temperature and pH significantly affected the formation of VSCs with more production at 30 °C and pH 5, respectively. Nitrogen supplementation (in the form of diammonium phosphate, DAP) repressed the production of VSCs. It is interesting to note that DAP and yeast extract supplementation induced the production of methional, but not Mn2+ supplementation. The presence of Mn2+ improved the production of methionol and dimethyl disulphide, but inhibited the formation of S-methyl thioacetate. The study indicated that optimization of physicochemical conditions and media composition would be crucial for producing L-methionine-derived VSC bioflavor.