Cysteine challenge testing: a powerful tool for examining oral malodour processes and treatments in vivo

Simple and Sensitive Detection of Bacterial Hydrogen Sulfide Production Using a Paper-Based Colorimetric Assay

Hydrogen sulfide (H₂S) is known to participate in bacteria-induced inflammatory response in periodontal diseases. Therefore, it is necessary to quantify H₂S produced by oral bacteria for diagnosis and treatment of oral diseases including halitosis and periodontal disease. In this study, we introduce a paper-based colorimetric assay for detecting bacterial H₂S utilizing silver/Nafion/polyvinylpyrrolidone membrane and a 96-well microplate. This H₂S-sensing paper showed a good sensitivity (8.27 blue channel intensity/μM H₂S, R² = 0.9996), which was higher than that of lead acetate paper (6.05 blue channel intensity/μM H₂S, R² = 0.9959). We analyzed the difference in H₂S concentration released from four kinds of oral bacteria (Eikenella corrodens, Streptococcus sobrinus, Streptococcus mutans, and Lactobacillus casei). Finally, the H₂S level in Eikenella corrodens while varying the concentration of cysteine and treatment time was quantified. This paper-based colorimetric assay can be utilized as a simple and effective tool for in vitro screening of H₂S-producing ability of many bacteria as well as salivary H₂S analysis.

Evaluation of halitosis parameters in patients undergoing head and neck radiotherapy

OBJECTIVES

To assess halitosis parameters using OralChromaTM and the correlation with salivary flow, oral hygiene index, radiation dose, and tongue-coating index among irradiated head-and-neck cancer patients compared to patients without cancer.

MATERIALS AND METHODS

This cross-sectional study enrolled irradiated and non-irradiated patients divided into two groups. Hydrogen sulphide, methyl mercaptan, and dimethy sulphide (DMS) levels were measured using a gas chromatograph, and sialometry was performed. The tongue-coating index and simplified oral hygiene index were also assessed.

RESULTS

Thirty-eight patients were allocated to each group. Volatile sulphur compound levels were above the thresholds in both groups. Non-irradiated individuals showed higher levels of hydrogen sulphide and dimethyl sulphide. Patients with asialia had an inexpressive tongue-coating index and increased dimethyl sulphide levels. A decrease in salivary flow rate was followed by a significant increase in volatile sulphur compound levels. Higher doses of radiation to the submandibular salivary glands were associated with higher concentrations of sulphide and methyl mercaptan.

CONCLUSIONS

Head and neck radiotherapy may be important in the development of halitosis. Irradiated patients with asialia presented insignificant lingual biofilm. Consequently, lower levels of volatile sulphur compounds were detected in this group. Asialia, a severe radiation-induced hyposalivation, impacted the levels of DMS (extraoral origin).

Case-control study related to the use of L-Cysteine in the differential diagnosis of halitosis

Halitosis is characterized by a foul, unpleasant breath that emanates from the oral cavity due to local or systemic conditions. Approximately 90% of offensive odors are caused by volatile sulfur compounds (VSCs). L-Cysteine, used as a test solution to control bad breath, induces the formation of VSCs and serves as a preliminary rinse. the study aim was to investigate the effectiveness of L-cysteine solution in differentiating the origin of halitosis using a gas chromatography apparatus. Methods: In total, 37 patients with an average age of 49.56 years were evaluated and divided into two groups: halimetry before the use of L-cysteine (n = 37) and halimetry after the use of L-cysteine (n = 37). Patients over 18 years of age, without severe systemic health impairment or infectious/contagious diseases, and who did not use medicines that influenced their breath were included. halimetry was performed using the OralCroma™ device. In the halimetry before the use of L-cysteine group, 5.40%,10.81%, and 67.56% of the patients had high levels of sulfide, methyl mercaptan, and dimethyl sulfide, respectively. After the use of L-cysteine, 48.64%, 8.10%, and 27.02% of the patients had high levels of sulfide, methyl mercaptan, and dimethyl sulfide. In this study, L-cysteine proved to be important for the assessment of halitosis and effective in differentiating the origin of halitosis; therefore, this compound could be used for the differential diagnosis of halitosis origin using the OralChroma™ device.

Cysteine challenge test as a novel diagnostic tool to distinguish oral halitosis

BACKGROUND

The cysteine challenge test is often used to check the H₂ S production capacity of the mouth. Patients with oral halitosis group (n = 305) or non-oral halitosis group (n = 191) and healthy individuals (control group, n = 102) were compared with each other to identify any possible relationship between initial and cysteine-induced oral H₂ S concentrations.

SUBJECTS AND METHOD

The medical records of 598 participants were reviewed retrospectively. Oral H₂ S concentrations before (pre-CR) and after cysteine rinse (post-CR) with 5 mL of 20 mmol L-cysteine solution for 30 s were compared.

RESULTS

Pre-CR H₂ S concentrations were >0.8 ppm in 75.1% of oral group patients but less than <0.8 ppm in 87.3% of the non-oral group and 86.9% of controls. After cysteine rinse, oral H₂ S concentrations exceeded 12 ppm in 72% of the oral halitosis patients but were lower in 88% of non-oral group and 99% of controls. Whilst post-CR/pre-CR ratio was >12 in 74.5% of the oral group, it was <12 in 81.7% of the non-oral group and 83.4% of controls.

CONCLUSION

Cysteine challenge test can be used as a diagnostic tool to identify an individual's tendency to produce oral malodor, not only to quantify momentary halitosis level.

Efficacy of Arabic Coffee and Black Tea in Reducing Halitosis: A Randomized, Double-Blind, Controlled, Crossover Clinical Trial

The aim of the study was to objectively evaluate the short-term effect of Arabic coffee and black tea on oral halitosis. This study was a single-center, randomized, double-blind, placebo-controlled, crossover clinical trial on 17 healthy individuals. During the initial visit, pre-treatment breath samples were collected from each subject and analyzed using portable gas chromatography (OralChroma™). Four interventions were evaluated, with Arabic coffee and black tea as the test intervention tools, mouthwash containing a solution (0.05% chlorhexidine, 0.05% cetylpyridinium chloride, and 0.14% zinc lactate (CHX-CPC-Zn)) as a positive control, and drinking water as a negative control. Halitosis was induced by rinsing with 10 mL solution of L-cysteine for 30 s. Twenty minutes later, a breath sample was taken to record the baseline volatile sulfur compounds (VSC) levels (T0). Then, the participants were asked to rinse with 10 mL of a randomly-assigned solution for 30 s. Sixty minutes later, another breath sample was recorded (T1). Finally, after 120 min, the final breath sample was recorded (T2). It was found that rinsing with Arabic coffee decreased the level of H2S both in the first hour (T1) and the second hour (T2). The reduction was significantly greater at T1 (p = 0.017). There was a similar result after the volunteers rinsed with black tea. At T2, Arabic coffee showed a substantially greater reduction in H2S (p < 0.001). On the contrary, using CHX-CPC-Zn showed a significant and continuous decrease in H2S values in the breath throughout the experiment (p < 0.001). Water showed no significant impact on the level of VSC (p = 0.71). This study demonstrates that black tea and Arabic coffee had inhibitory effects on halitosis that was greater in the first hour and was not sustained over a long period. Additionally, Arabic coffee had a greater inhibitory effect on halitosis than black tea.

Alternative therapies in controlling oral malodour: a systematic review

Is there a role for alternative therapies in controlling intra-oral halitosis? Treatments other than tongue cleaning and anti-halitosis products containing zinc, chlorhexidine and cetylpyridinium chloride were considered as alternative therapies. Four databases were searched (PubMed, EMBASE, Web of Science and The Cochrane Library). Inclusion criteria were: examination of alternative halitosis therapies, study population with oral malodour, a (negative or positive) control group and evaluation of breath odour via organoleptic and/or instrumental assessment. Data were extracted for descriptive analysis. The screening of 7656 titles led to the inclusion of 26 articles. Analysis showed heterogeneity concerning the population of interest (from cysteine-induced to genuine halitosis), the examined treatment and the reported outcomes. This made a meta-analysis impossible. Essential oils, fluoride-containing products and herbal substances were the most studied. Results varied enormously and none of the active ingredients had an unambiguously positive effect on the malodour. The risk of bias was assessed as high in all articles. Given the fact that little evidence was found for each of the investigated treatments, it could be concluded that there is currently insufficient evidence that alternative therapies are of added value in the treatment of halitosis.Clinical relevanceScientific rationale:Halitosis is a common problem causing social isolation. Out of embarrassment, patients search the internet, leading to many questions about alternative solutions (e.g. oil pulling, herbs). This is the first systematic review on these alternative therapies.Principal findings: Results varied among studies. Some promising results were found for fluoride-containing toothpastes and probiotics. For other products (such as herbal and antibacterial products and essential oils) results were inconsistent. Long-term follow-up studies on these products are scarce. Moreover, the quality of the studies was poor.Practical implications:No clear evidence was found to support a certain alternative anti-halitosis therapy.

Oral hygiene associated with antimicrobial photodynamic therapy or lingual scraper in the reduction of halitosis after 90 days follow up: A randomized, controlled, single-blinded trial

BACKGROUND

Although antimicrobial photodynamic therapy (aPDT) can reduce halitosis immediately after application, it returns after a week. This probably occurs because bacteria residing in the oral cavity may recolonize the dorsum of the tongue.

OBJECTIVE

Verify if modification of oral hygiene behavior associated with aPDT or lingual scraper can reduce halitosis after a 90-day follow-up.

METHODS

Forty adults with positive halitosis were randomized in G1 (n = 20) -aPDT + oral hygiene behavior (OHB) or G2 (n = 20)- lingual scraper + OHB. G1 group were submitted to 0.005 % methylene blue in the middle and posterior third of the tongue, with pre-irradiation of 1 min. Irradiations were performed with red laser diode (λ =660 nm), 100 mW, 318 J/cm², 3537 mW/cm², 9 J per point at 6 points. In the G2 group, the tongue was scraped 10 times on the right side and on the left side with a tongue scraper. All patients were instructed on OHB at baseline, 7 and 90 days (guidance on the use of dental floss and the Bass technique for brushing). Halitosis was evaluated by gas chromatography (OralChroma®). Values ​​> 112 ppb for Hydrogen sulfide (H₂S) gas was considered positive halitosis. Methylmercaptanes and dimethylsulfide were also measured. The gas measures were assessed at baseline, immediately, and at 7 and 90 days. Paired t-test was used for the statistical analysis. For comparison between groups, the t-test was used. Values of p < 0.05 were considered statistically significant.

RESULTS

There was no difference between groups immediately after treatment (p = .1532) after 7 days (p = 0.9312) and 90 days (p = 0.6642). For the aPDT group, there was a decrease in hydrogen sulfide ​​immediately after treatment (p = 0.0001), after 7 days, values remained 3-fold smaller (p = 0.0088) and 2-fold smaller after 90 days (p = 0.0270). For the scraper group, there was a decrease immediately after treatment (p = 0.0001), the values remains 2-fold smaller ​​(p = 0.0003) after 7 days and 3 months (p = 0.0001).

CONCLUSION

The oral hygiene behavior associated with aPDT or tongue scraper was not able to reduce halitosis after 90-day follow-up. Despite halitosis remaining ​​ higher than 112 ppb in all follow-up periods, the mean values remain 2 or 3 fold smaller than baseline values. Future studies should include other oral hygiene behavior to achieve better results in the treatment of halitosis.

Halitosis, reduced salivary flow and the quality of life in pre-kidney transplantation patients

Background

Halitosis is a condition that affects 50% of adults and one third of patients with chronic kidney disease. The aim of this study was to evaluate oral manifestations and volatile sulfur compounds (VSCs) associated with halitosis and quality of life in pre-kidney transplantation candidates.

Material and Methods

The organoleptic test (OT) and halimetry (HA) (before and after cysteine mouthwash) were performed in patients with the Oralchroma® device, stimulated (SE) and non-stimulated sialometry (SN), Tongue Coating Index (TCI). The OHIP-14 questionnaire was administered to assess the impact of oral health on quality of life.

Results

Fourteen individuals with a mean age of 49.64 ± 13.35 years were evaluated. In the organoleptic test, 57.14% of the individuals presented halitosis. Oralchroma results showed that dimethyl sulfide was above the threshold in 85.71% of the individuals, while hydrogen sulfide and methyl mercaptan were above threshold in 28.57%; after the use of cysteine, hydrogen sulfide was present in 100% of the cases, dimethyl sulfide in 57.14% and methyl mercaptan in 50%. In the non-stimulated sialometry, 57.14% of the individuals presented hyposalivation and 21.42% in the stimulated. Regarding the tongue coating index, 100% of the individuals presented tongue coating, with a mean of 7.64. The assessment of impact of oral health on quality of life showed a negative impact in all dimensions.

Conclusions

Tongue coating, in association with hydrogen sulfide, was the main cause of halitosis in the study subjects, and hyposalivation may contribute to higher tongue-coating indices. These oral changes negatively affect the quality of life for pre-kidney transplantation patients.

Key words:Halitosis, chronic kidney disease, quality of life, kidney transplantation.

The Underestimated Problem of Intra-Oral Halitosis in Dental Practice: An Expert Consensus Review

Approximately 90% of halitosis cases originate within the oral cavity (intra-oral halitosis). With a focus on intra-oral halitosis, this narrative review article provides a current summary of the epidemiology, diagnosis and management of halitosis and discusses practical considerations for healthcare professionals (HCPs), including dentists, dental hygienists, general practitioners, community pharmacists, nurses and medical specialists. MEDLINE and PubMed were searched up to 31 December 2019. Additional information was sourced from reference lists of relevant published literature. Full-text articles which reported on the epidemiology, diagnosis and management of halitosis were considered for inclusion. Halitosis affects substantial numbers of individuals globally and is an underestimated problem in dental practice. Current estimates of the prevalence of halitosis, in addition to diagnostic methods and management considerations for halitosis, are discussed. Although not a life-threatening condition, halitosis has a significant impact on patients’ quality of life and can result in psychological consequences including social, professional and affective limitations. Using a simple step-wise approach for diagnosis and treatment, dentists and dental hygienists are ideally placed to respond to an initial consultation for halitosis.

Clinical effect of toothpaste and mouth rinse containing zinc lactate on oral malodor reduction

Background

This study aimed to investigate the effect of toothpaste and mouth rinse containing 0.14% zinc lactate on the reduction of three volatile oral malodor gases.

Material and Methods

Ten subjects with good health were recruited to take part in a crossover design study with a 7-day washout period. They were randomly assigned to use the test (toothpaste and rinse containing 0.14% zinc lactate) or placebo (negative control) treatment regimens within the two-week period. All subjects were asked to refrain from tooth brushing and eating in the morning prior to the gas collection periods. The assessment of malodor measured the quantity of three volatile sulphur compounds (VSCs) using an OralChromaTM device. Oral gas collecting was divided into four time periods; before breakfast and the morning oral hygiene practice (baseline); after oral hygiene at 30 minutes, 1 hour and 2 hours. After the baseline assessment, each subject used the test or placebo treatment regimen for 7 days. After 7 and 14 days, subjects returned to the study site to repeat the same procedures with different products. Kruskal-Wallis was used to analyze the mean differences of malodor gases between the two test regimens.

Results

The baseline mean of total VSCs in test and control groups was 6.5±3.7 and 1.7±9.3 ng/10 ml, respectively. The percent reduction of H2S at 30 minutes, 1 hour and 2 hours was statistically significant (p<0.005) in both treatments. The percent reduction of (CH3)2S and total VSCs in both treatments after 1 hour was statistically significant (p<0.005).

Conclusions

The test treatment regimen was more effective than the placebo treatment regimen. Key words:Zinc lactate, molodor, volatile sulphur compound, mouth rinse, toothpaste.

Recombinant Sox Enzymes from Paracoccus pantotrophus Degrade Hydrogen Sulfide, a Major Component of Oral Malodor

Hydrogen sulfide (H₂S) is emitted from industrial activities, and several chemotrophs possessing Sox enzymes are used for its removal. Oral malodor is a common issue in the dental field and major malodorous components are volatile sulfur compounds (VSCs), including H₂S and methyl mercaptan. Paracoccus pantotrophus is an aerobic, neutrophilic facultatively autotrophic bacterium that possesses sulfur-oxidizing (Sox) enzymes in order to use sulfur compounds as an energy source. In the present study, we cloned the Sox enzymes of P. pantotrophus GB17 and evaluated their VSC-degrading activities for the prevention of oral malodor. Six genes, soxX, soxY, soxZ, soxA, soxB, and soxCD, were amplified from P. pantotrophus GB17. Each fragment was cloned into a vector for the expression of 6×His-tagged fusion proteins in Escherichia coli. Recombinant Sox (rSox) proteins were purified from whole-cell extracts of E. coli using nickel affinity chromatography. The enzyme mixture was investigated for the degradation of VSCs using gas chromatography. Each of the rSox enzymes was purified to apparent homogeneity, as confirmed by SDS-PAGE. The rSox enzyme mixture degraded H₂S in dose- and time-dependent manners. All rSox enzymes were necessary for degrading H₂S. The H₂S-degrading activities of rSox enzymes were stable at 25–80°C, and the optimum pH was 7.0. The amount of H₂S produced by periodontopathic bacteria or oral bacteria collected from human subjects decreased after an incubation with rSox enzymes. These results suggest that the combination of rSox enzymes from P. pantotrophus GB17 is useful for the prevention of oral malodor.

A new measurement protocol to differentiate sources of halitosis

OBJECTIVE

Three sources of halitosis exist, potentially in any combination: mouth, nasal cavity or alveolar breath. There has been no universally accepted protocol which differentiates and quantifies each odour source separately. In this study a new gas measurement protocol is described and tested to determine whether each odour source can be separately detected without contamination.

MATERIALS AND METHODS

Ninety healthy volunteers were divided into three groups. Hydrogen sulphide (H2S), volatile organic compounds (VOCs) and hydrogen (H2) were artificially generated in the mouth, nose and pulmonary alveoli, respectively. VOC, ammonia (NH3), sulphur dioxide (SO2), H2S and H2 gas readings from mouth, nose and alveolar air were measured and compared. Measurements were taken before and during gas generation.

RESULTS

Contamination of nasal air (2.8%) and alveolar air (5.0%) by oral H2S; alveolar air (2.06%) and oral air (4%) by nasal organic gas; nasal air (18.43%) and oral air (9.42%) by alveolar H2 was calculated.

CONCLUSION

The results demonstrated that artificially generated oral H2S nasal VOC and alveolar H2 can be individually quantified. This gas measurement protocol can be used diagnostically or to gauge response to therapy in any medical or dental setting.

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.

Immediate results of photodynamic therapy for the treatment of halitosis in adolescents: a randomized, controlled, clinical trial

Light with or without chemical agents has been used to induce therapeutic and antimicrobial effects. With photodynamic therapy, the antimicrobial effect is confined to areas covered by a photosensitive dye and irradiated with light. The aim of the present study was to evaluate the effect of photodynamic therapy for the treatment of halitosis in adolescents through the analysis of volatile sulfur compounds, especially sulfide. A controlled, clinical trial was conducted with 45 adolescents randomly allocated to three groups: group 1, photodynamic therapy administered to the dorsum of the tongue; group 2, treatment with a tongue scraper; and group 3, treatment with a tongue scraper combined with photodynamic therapy. The diagnosis of halitosis was performed using gas chromatography before and after treatment. Comparisons were made using the Kruskal-Wallis test followed by the Student-Newman-Keuls test, with the level of significance set at 5 % (p < 0.05). After treatment, a statistically significant reduction in halitosis was found in all groups (p < 0.001). The greatest reduction in total sulfides (median = 0) occurred with the combination of tongue scraper and photodynamic therapy. The present study describes a novel option for the treatment of halitosis in adolescents with an immediate effect that does not involve the mechanical aggression of the lingual papillae that occurs with conventional treatment.

TRIAL REGISTRATION

Photodynamic Therapy in Adolescents Halitosis ( https://clinicaltrials.gov/ct2/show/NCT02007993?term=NCT02007993&rank=1 )Number: NCT02007993FUNDING:FAPESPNumber: 2013/13032-8.

Efficacy of different mouthrinse formulations in reducing oral malodour: a randomized clinical trial

AIMS

The aim of this study was to assess the efficacy of mouthrinses formulations in oral malodour.

MATERIAL & METHODS

This single-centre, double-blind, randomized, parallel group clinical trial compared the efficacy of Halita™ and meridol(®) with and without zinc lactate versus negative and positive control. Volunteers with confirmed oral malodour (18/group) rinsed with one mouthrinse during 7 days (15 ml, 2x/day for 1 min.). 15 min. after a first rinse (masking effect), and after 7 days (therapeutic effect) the change in organoleptic scores and level of sulphur compounds was recorded.

RESULTS

All rinses showed a masking effect (OLS 1 to 2 values reduced), only the rinses with antimicrobial ingredients showed a therapeutic effect (OLS 1 to 1.5 value less). The addition of zinc resulted in a more pronounced masking effect. Halita™ and meridol(®) with zinc showed the best therapeutic effect.

CONCLUSION

Although the masking effect of the rinses can be attributed partially to a dilution and the effect of aromas, the therapeutic effect should be linked to the anti-microbial action of active ingredients and counter action of zinc ions on VSC. A complete resolution of the unpleasant breath by additional mechanical intervention remains to be proven.

Effect of chewing gums containing the probiotic bacterium Lactobacillus reuteri on oral malodour

OBJECTIVE

To evaluate the effect of chewing gums containing probiotic bacteria on oral malodour. The null hypothesis was that no difference would be displayed compared with placebo gums.

MATERIALS AND METHODS

Twenty-five healthy young adults with self-reported malodorous morning breath completed this randomized double-blind placebo-controlled cross-over trial. The design included run-in and wash-out periods interspersed by two intervention periods of 14 days each. The subjects were instructed to chew one gum in the morning and one in the evening containing either two strains of probiotic lactobacilli (L. reuteri DSM 17938 and L. reuteri ATCC PTA 5289) or placebo. The outcome measures were (i) organoleptic scores (0-5) by a certified test panel, (ii) concentration of volatile sulphur compounds (VSC) measured with a Halimeter and (iii) concentration of VSC after a cysteine rinse. Registrations were made at baseline and after each intervention period. Differences between the groups were assessed by non-parametric paired statistics and chi-square test.

RESULTS

The median organoleptic score was similar (score 2) in both groups at baseline. After 14 days of treatment, the organoleptic scores were significantly lower in the probiotic group compared with the placebo group (p < 0.05). Assessments of the VSC levels displayed no significant differences between the groups, either before or after rinsing with L-cysteine. No adverse effects were registered.

CONCLUSION

The results demonstrated that probiotic chewing gums may have some beneficial effect on oral malodour assessed by organoleptic scores. The results indicate that the probiotic gum may affect bacteria that produce malodourous compounds other than VSCs.

A review of the current literature on management of halitosis

Halitosis is an unpleasant or offensive odour, emanating from the oral cavity. In approximately 80% of all cases, halitosis is caused by microbial degradation of oral organic substrates. Major degradation products are volatile sulphur-containing compounds. In this review, the available management methods of halitosis and their effectiveness and significance are presented and discussed. Undoubtedly, the basic management is mechanically reducing the amount of micro-organisms and substrates in the oral cavity. Masking products are not, and antimicrobial ingredients in oral healthcare products are only temporary effective in reducing micro-organisms or their substrates. Good short-term results were reported with chlorhexidine. Triclosan seems less effective, essential oils and cetylpyridinium chloride are only effective up to 2 or 3 h. Metal ions and oxidizing agents, such as hydrogen peroxide, chlorine dioxide and iminium are active in neutralizing volatile sulphur-containing compounds. Zinc seems to be an effective safe metal at concentrations of at least 1%. The effectiveness of active ingredients in oral healthcare products is dependent on their concentration and above a certain concentration the ingredients can have unpleasant side effects. Tonsillectomy might be indicated if (i) all other causes of halitosis are managed properly; (ii) halitosis still persists and (iii) crypts in tonsils are found to contain malodorous substrates.

A review of the current literature on aetiology and measurement methods of halitosis

OBJECTIVES

This work reviews the current knowledge of aetiology and measurement methods of halitosis.

DATA

Halitosis is an unpleasant or offensive odour emanating from the breath. The condition is multifactorial and may involve both oral and non-oral conditions.

SOURCES

A private, monthly with keywords halitosis, malodo(u)r, (a)etiology, measurement, and management from Medline and Pubmed updated database of literature was reviewed.

CONCLUSIONS

In approximately 80-90% of all cases, halitosis is caused by oral conditions, defined as oral malodour. Oral malodour results from tongue coating, periodontal disease, peri-implant disease, deep carious lesions, exposed necrotic tooth pulps, pericoronitis, mucosal ulcerations, healing (mucosal) wounds, impacted food or debris, imperfect dental restorations, unclean dentures, and factors causing decreased salivary flow rate. The basic process is microbial degradation of organic substrates. Non-oral aetiologies of halitosis include disturbances of the upper and lower respiratory tract, disorders of the gastrointestinal tract, some systemic diseases, metabolic disorders, medications, and carcinomas. Stressful situations are predisposing factors. There are three primary measurement methods of halitosis. Organoleptic measurement and gas chromatography are very reliable, but not very easily clinically implemented methods. The use of organoleptic measurement is suggested as the 'gold standard'. Gas chromatography is the preferable method if precise measurements of specific gases are required. Sulphide monitoring is an easily used method, but has the limitation that important odours are not detected. The scientific and practical value of additional or alternative measurement methods, such as BANA test, chemical sensors, salivary incubation test, quantifying beta-galactosidase activity, ammonia monitoring, ninhydrin method, and polymerase chain reaction, has to be established.

Anaerobic bacteria cultured from the tongue dorsum of subjects with oral malodor

The bacteria on the dorsum of the tongue are the most frequent cause of oral malodor; however, the bacterial flora of the tongue has not been well defined. Although recent studies have used DNA probes to detect the presence of certain periodontal pathogens, cultural studies have been limited because of the complexity of the flora of the tongue dorsum. The purpose of this study was to grow and to identify maximum numbers of capnophylic Gram-negative bacilli and anaerobic micro-organisms by culturing tongue samples on to several selective and non-selective media. The most frequently isolated species included Peptostreptococcus anaerobius, Collinsella aerofaciens, Eubacterium group, Actinomyces spp., Eikenella corrodens, Veillonella spp., Fusobacterium nucleatum, pigmented Prevotella spp. and Selenomonas spp. Reported for the first time are Actinomyces turicensis, Collinsella aerofaciens, Eubacterium saburreum, E. timidum, Prevotella tannerae, Campylobacter concisus, Campylobacter mucosalis, Leptotrichia buccalis, Selenomonas flueggei, and Centipeda periodontii. Species not previously reported in studies that used only molecular techniques were identified in the present study.

Volatile sulfur compounds produced by Helicobacter pylori

GOALS

To assess the volatile sulfur compounds produced by three strains of Helicobacter pylori in broth cultures mixed with sulfur-containing amino acids.

BACKGROUND

Halitosis has been reported in H. pylori-positive patients, and volatile sulfur compounds such as hydrogen sulfide and methyl mercaptan are known to be responsible for inducing oral malodor. Whether H. pylori produces these volatile sulfur compounds has yet to be established.

STUDY

Three strains of H. pylori (ATCC 43504, SS 1, DSM 4867) were cultured with 5 mM cysteine and methionine. After 72 hours of incubation, the headspace air was aspirated and injected directly into a gas chromatograph. The concentrations of hydrogen sulfide and methyl mercaptan were analyzed and compared between experimental and control cultures

RESULTS

In broth containing 5 mM cysteine, hydrogen sulfide was increased by ATCC 43504 (P < 0.01) and SS 1 (P < 0.05), while methyl mercaptan was elevated only by SS 1 (P < 0.05). In broth containing 5 mM methionine, methyl mercaptan increases were significant for SS 1 (P < 0.05) and DSM 4867 (P < 0.05). In broth containing 5 mM cysteine and 5 mM methionine, the concentration of hydrogen sulfide was higher than in controls for all three strains (P < 0.01); that of methyl mercaptan was higher only for SS 1 (P < 0.01). Cysteine addition to cultures containing methionine increased hydrogen sulfide and methyl mercaptan for ATCC 43504 (P < 0.05) and SS 1 (P < 0.05). Conversely, addition of methionine to cultures containing cysteine increased methyl mercaptan only for DSM 4867 (P < 0.01).

CONCLUSIONS

The production of volatile sulfur compounds by H. pylori is not only very complicated but also strain-specific. Nevertheless, H. pylori was shown to produce hydrogen sulfide and methyl mercaptan, which suggests that this microorganism can contribute to the development of halitosis.

Oral malodor reduction by a combination of chemotherapeutical and mechanical treatments

Bacterial proliferation and plaque accumulation on the surface of the tongue are major factors contributing to oral malodor. In this research, we used subjective and objective methods to evaluate the breath benefit of a triclosan-containing dentifrice (Blend-a-Med Complete Night) with and without tongue brushing in a randomized, examiner-blinded, three-period crossover clinical trial. Twenty-nine adults (mean age 40.2 years) with morning malodor were randomly assigned to a treatment sequence: triclosan dentifrice, triclosan dentifrice plus tongue brushing, and a control dentifrice (Crest Cavity Protection). The subjects used each product four times in 27 h with a 2-day wash-out period between treatments. Halimeter measurements were taken at baseline and at 3, 24 and 27 h. Subject questionnaire data assessing the breath quality were collected at 24 and 27 h. Both triclosan regimens showed significant improvement in oral malodor (p < 0.03) relative to the control. Significant (p = 0.035) malodor benefit was observed when tooth brushing with triclosan dentifrice was supplemented with tongue brushing. The triclosan dentifrice was associated with significant improvement (p < 0.05) in morning mouth feel and feeling of clean and fresh breath during the day relative to the control. There were no adverse events reported. The triclosan dentifrice was effective against overnight and daytime oral malodor. Supplementing routine brushing with tongue brushing resulted in additional breath improvement and breath benefits of the triclosan dentifrice were first-person noticeable.

Inhibition of orally produced volatile sulfur compounds by zinc, chlorhexidine or cetylpyridinium chloride--effect of concentration

Zinc ions, chlorhexidine (CHX) and cetylpyridinium chloride (CPC) are all known to inhibit production of volatile sulfur compounds (VSCs). The objective was to examine the anti-VSC dose-response effects of each of the above agents. Oral malodor was induced in 13 test subjects using the cysteine challenge method. The oral VSC response to rinses with 6 mm l-cysteine (pH 7.2) before and 1, 2 and 3 h after rinsing with zinc ions (Zn2+: 0.1, 0.3 and 1.0%), CHX and CPC (0.025 and 0.2%) was measured. Mouth air was analysed for VSC by gas chromatography (GC) according to current methodology. Zinc had a marked dose- and time-dependent anti-VSC effect. Zinc at 1% concentration had a somewhat unpleasant taste, whereas the lowest concentration was found acceptable. Chlorhexidine maintained a moderate anti-VSC effect over time. At 3 h, 0.2% CHX was the most effective agent but tasted relatively unpleasant. Cetylpyridinium at a concentration of 0.2% was only marginally more effective than 0.025% CHX over the 3 h, while 0.025% CPC had no better anti-VSC effect than water at both 2 h and 3 h. It was concluded that the three test agents demonstrated different anti-VSC kinetics. Although Zn had the best anti-VSC effect at 1 h, 0.2% CHX was at least as effective as 1% Zn at 3 h, most likely as a result of its unique substantivity.

Cloning and expression of a pectate lyase from the oral spirocheteTreponema pectinovorumATCC 33768

The pelA gene, encoding a pectate lyase, from Treponema pectinovorum ATCC 33768 was isolated by heterologous expression of a cosmid library in Escherichia coli. In vitro transposon mutagenesis identified an open reading frame of 1293 bp capable of encoding a protein of 430 amino acids with a predicted amino-terminal signal sequence of 21 amino acids. Analysis of the amino acid sequence suggested that it is a member of the polysaccharide lyase family 10 of which all characterized members show pectate lyase activity. An amino-terminal His-tagged recombinant form of PelA was expressed and purified from E. coli. The recombinant enzyme has characteristics common to other bacterial pectate lyases such as an alkaline pH optimum, dependence on calcium ions for activity, and inhibition by zinc ions.