Microbiome associated with denture malodour

In the past, our inability to cultivate most of the oral microorganisms has limited our view of this complex ecosystem. In the present study, we utilized next generation deep sequencing techniques to revisit the microbiome associated with denture malodour, a growing field with the rise in life expectancy. The study population comprised 26 full dentures patients (mean age 71 ± 6.4, 10 males, 16 females) who visited the Tel Aviv University dental geriatric clinic. Denture malodour was rated organoleptically by a single odour judge, and dentures scoring 2 and above were considered malodour positive. DNA was extracted from the swab samples and analysed using next generation deep sequencing 16 s rDNA technology. Taxa identified could be classified into nine phyla, 29 genera and 117 species. Malodour positive samples showed a higher abundance of the phyla Firmicutes and Fusobacteria and the genera Leptotrichia, Atopobium, Megasphaera, Oribacterium and Campylobacter. Microbiome analysis demonstrated higher bacterial diversity within the malodourous samples and a significant difference in the microbial profile within the two groups. Taken together these results suggest a difference between the microbial populations of malodourous and non-malodourous dentures both in composition and diversity.

β-Galactosidase Activity in Saliva is Associated with Oral Malodor

Deglycosylation of oral mucins may be a critical initial step leading to their subsequent proteolysis and putrefaction. The present study was undertaken to determine whether activity in saliva of a major glycosidic enzyme (β–galactosidase) is associated with oral malodor in a group of 64 subjects. Enzyme activity was detected by the use of a chromogenic substrate (X-Gal) impregnated on paper discs. Malodor-related measurements included two odor judges' assessments of whole-mouth and tongue malodor, and volatile sulfide levels measured by a portable sulfide monitor (Interscan Corp.). β–galactosidase assay scores were significantly associated with both odor judges' scores for whole-mouth (p ≤ 0.002; Spearman) and tongue malodor (p ≤ 0.001; Spearman). β–galactosidase activity and sulfide monitor measurements both factored significantly into multiple regression equations for odor judge scores, yielding multiple r-values ranging from 0.47 (p = 0.0007) to 0.60 (p < 0.0001). Analysis of the data presented indicates that β–galactosidase activity in saliva is correlated with oral malodor.

Streptococcus salivarius Promotes Mucin Putrefaction and Malodor Production by Porphyromonas gingivalis

Although the contribution of the oral microbiota to oral malodor is well-documented, the potential role of Gram-positive micro-organisms is unclear. In the current study, we tested the hypothesis that Gram-positive micro-organisms contribute to malodor production by deglycosylating oral glycoproteins, rendering them susceptible to subsequent proteolysis. To this end, we examined the effect of Streptococcus salivarius on Porphyromonas gingivalis-mediated putrefaction of a model glycoprotein (pig gastric mucin). Malodor was scored by two odor judges, and volatile sulfides were determined with the use of a sulfide monitor. Mucin degradation was followed by electrophoresis on SDS-PAGE. Results showed that the addition of S. salivarius or β-galactosidase promoted mucin degradation and concomitant malodor production. Addition of glycosidic inhibitors (p-APTG and glucose) inhibited this process. These results suggest that Gram-positive micro-organisms such as S. salivarius contribute to oral malodor production by deglycosylating salivary glycoproteins, thus exposing their protein core to further degradation by Gram-negative micro-organisms.

Halitosis management by the general dental practitioner--results of an international consensus workshop

Clinical investigations on patients suffering from halitosis clearly reveal that in the vast majority of cases the source for an offensive breath odor can be found within the oral cavity (90%). Based on these studies, the main sources for intra-oral halitosis where tongue coating, gingivitis/periodontitis or a combination of the two. Thus, it is perfectly logical that general dental practitioners (GDPs) should be able to manage intra-oral halitosis under the conditions found in a normal dental practice. However, GDPs who are interested in diagnosing and treating halitosis are challenged to incorporate scientifically based strategies for use in their clinics. Therefore, the present paper summarizes the results of a consensus workshop of international authorities held with the aim to reach a consensus on general guidelines on how to assess and diagnose patients' breath odor concerns and general guidelines on regimens for the treatment of halitosis.

In vitro CPC retention and VSC adsorption by IPM oil droplets: possible mechanisms of action of a two phase mouthwash

Two phase oil-water mouthwash has been previously shown to efficiently bind oral microorganisms, relying on their cell surface hydrophobicity. The aim of the present in vitro study was to test the cetylpyridinium chloride (CPC) retention and volatile sulfide compounds (VSCs) adsorption abilities of the oil droplets created by mixing of a two phase oil-water solution. VSC adsorption was assayed using a salivary incubation assay and garlic powder solutions, and demonstrated using microscopic sulfide assay. CPC retention was assayed by kinetic and endpoint measurement of Streptococcus salivarius outgrowth using microplate (ELISA) reader. Results showed that the isopropyl myristate (IPM) oil droplets in the two phase solutions were able to adsorb 68-80% of VSCs. CPC at a concentration of 0.05% was most affectively retained by the oil droplets showing a significantly increase in residual antibacterial activity against Streptococcus salivarius. These results taken together, suggests that VSC adsorption and CPC retention by IPM oil droplets may be two additional mechanisms in the activity of the two phase mouthwash formulation.

β-Galactosidase activity and H(2)S production in an experimental oral biofilm

We recently suggested that oral malodor production involves two steps: (i) deglycosylation of glycoproteins and (ii) proteolysis and amino acid utilization of the protein core to yield volatiles such as volatile sulfide compounds (VSCs). Our aim was to test the hypothesis that β-galactosidase activity and VSC production occur in distinct areas of the biofilm by two different bacterial populations. Biofilms were grown anaerobically for seven days with or without antibiotics (i.e. vancomycin and metronidazole). Biofilms were stained for β-galactosidase activity and VSC production and studied using confocal laser scanning microscopy. Results showed that β-galactosidase activity occurs in the outer layers and disappears following vancomycin addition, whereas VSC production occurs deeper within the biofilm and disappears following metronidazole application. These findings suggest that β-galactosidase activity is produced mainly by Gram-positive oral bacteria at the outer portion of the biofilm, and VSC production occurs in the deeper layers by Gram-negative oral bacteria.

A novel microscopic assay for oral malodor-related microorganisms

Previous research has shown that the production of volatile sulfide compounds (VSC) by oral bacteria is associated with oral malodor. In the present study, we report a novel technique (microscopic sulfide assay (MSA)) for the quantification of VSC-producing oral microorganisms. The MSA was performed by overnight incubation of saliva samples in the presence of ferrous sulfate and sodium thiosulfate, followed by digital analysis of cells stained black due to cell-associated precipitation of ferric sulfide. This method was found to correlate significantly with oral malodor parameters, including mean odor judge scores (two judges, r = 0.48 and p = 0.001) and Halimeter® readings (r = 0.53 and p < 0.001), in a group of 42 subjects. As compared with odor judge scores as the gold standard, the new MSA technique yielded a diagnostic accuracy of 0.7 (ROC, p = 0.023). Results indicate that the MSA may serve as a diagnostic technique for assessing oral malodor levels and aid in identifying the particular bacteria involved in this condition.

Effect of deglycosylation of salivary glycoproteins on oral malodour production

Putrefaction of saliva is commonly used as an in-vitro assay in oral malodour investigations.

AIM

To exam the hypothesis that deglycosylation of salivary glycoproteins promotes oral malodour production.

DESIGN

Porphyromonas gingivalis-mediated putrefaction of salivary glycoproteins was tested following preincubation of saliva in the presence of beta-galactosidase with or without glycosidic inhibitor (galactosamine), and in the presence of glucose with or without a non-glycosylated protein (bovine serum albumin).

METHODS

Malodour was determined by two odour judges, and volatile sulphides by using a sulphide monitor. Salivary glycoprotein degradation was measured densitometrically following electrophoresis on SDS-PAGE.

RESULTS

The addition of beta-galactosidase promoted salivary glycoprotein degradation and concomitant malodour production, whereas addition of a glycosidic inhibitor (D-galactosamine) inhibited this process. Glucose inhibited salivary glycoproteins putrefaction, but this inhibitory effect was mitigated when a non-glycosylated protein (BSA) was added.

CONCLUSIONS

Deglycosylation of salivary glycoproteins may be an initial step in oral malodour production. This process exposes the protein core of the glycoprotein, which is then further degraded by Gram-negative microorganisms under anaerobic conditions.

Beta-galactosidase activity in saliva is associated with oral malodor

Deglycosylation of oral mucins may be a critical initial step leading to their subsequent proteolysis and putrefaction. The present study was undertaken to determine whether activity in saliva of a major glycosidic enzyme (beta-galactosidase) is associated with oral malodor in a group of 64 subjects. Enzyme activity was detected by the use of a chromogenic substrate (X-Gal) impregnated on paper discs. Malodor-related measurements included two odor judges' assessments of whole-mouth and tongue malodor, and volatile sulfide levels measured by a portable sulfide monitor (Interscan Corp.). Beta-galactosidase assay scores were significantly associated with both odor judges' scores for whole-mouth (p < or = 0.002; Spearman) and tongue malodor (p < or = 0.001; Spearman). Beta-galactosidase activity and sulfide monitor measurements both factored significantly into multiple regression equations for odor judge scores, yielding multiple r-values ranging from 0.47 (p = 0.0007) to 0.60 (p < 0.0001). Analysis of the data presented indicates that beta-galactosidase activity in saliva is correlated with oral malodor.

Reduction of oral malodor by oxidizing lozenges

The main purpose of the study was to examine the anti-malodor properties of oxidizing lozenges, as compared to breath mints and chewing gum. Healthy, young adult volunteers (N = 123; mean age 24.5 years) were measured for oral malodor-related parameters (whole mouth odor measured by 2 judges; tongue dorsum posterior odor using the spoon test; volatile sulphide levels; salivary levels of cadaverine and putrescine; and 2 versions of an oral rinse test) on the first afternoon of the study. They were then assigned randomly to one of 6 groups (2 brands of breath mints, chewing gum with no active ingredients, regular and full-strength oxidizing lozenges, and a no-treatment control), and instructed to employ the treatment before bedtime, the next morning, and in the early afternoon 3 hours prior to measurements, which were carried out 24 hours following baseline measurements. Volunteers also estimated the level of their own whole mouth and tongue odors at baseline and post-treatment. The data showed that, among treatments, only the full-strength oxidizing lozenge significantly reduced tongue dorsum malodor, as determined by the spoon test. The full-strength lozenge also yielded a significant increase in the modified oral rinse test, presumably due, at least in part, to residual oxidizing activity retained in the oral cavity. Self-estimations of whole mouth and tongue malodor by volunteers were significantly correlated with corresponding-judge assessments, suggesting some degree of objectivity in assessing one's own oral malodor.