Salivary β-galactosidase activity affects physiological oral malodour

Salivary β-galactosidase, halitosis parameters in periodontal health and disease, and their changes after periodontal treatment

BACKGROUND

In this study, we aimed to evaluate the salivary β-galactosidase and Halimeter values (HMV), organoleptic scores (OLS) and Winkel tongue coating index (WTCI) in periodontal health and periodontitis (P), and also their changes after phase I periodontal therapy and tongue cleaning.

METHODS

The participants were separated as follows: 25 P with halitosis (Group 1), 25 P without halitosis (Group 2) and 25 healthy controls (Group 3). Periodontal recordings, HMV, OLS and WTCI scores were recorded, and whole saliva β-galactosidase levels were measured colorimetrically in the samples at baseline and 1 month after the therapy.

RESULTS

The baseline values of HMV, OLS, WTCI and salivary β-galactosidase levels were significantly higher in Group 1 than in Group 2 (P < 0.05). There was a statistically significant decrease in periodontal recordings, HMV, OLS, WTCI and salivary β-galactosidase levels in all P patients by the therapy (P < 0.05). However, major reductions in halitosis measurements and saliva enzyme levels were observed in Group 1 after the treatment.

CONCLUSION

Our results showed that salivary β-galactosidase was associated with halitosis parameters and phase I periodontal therapy played an important role to reduce this enzyme level and halitosis parameters in P.

Salivary β-glucosidase as a direct factor influencing the occurrence of halitosis

β-Glucosidases are enzymes present in all living organisms, playing a pivotal role in diverse biological processes. These enzymes cleave β-glycosidic bonds between carbohydrates, or between a carbohydrate and a non-carbohydrate moiety, which may result in the liberation of volatile aglycones. Released compounds execute diverse physiological roles, while the industry takes advantage of exogenously added β-glucosidases for aroma enrichment during food and beverage production. β-Glucosidase enzymatic activity has been reported in human saliva and given the fact that these enzymes are involved in aroma release, we investigated here the correlation between β-glucosidase activity in human saliva and the occurrence of halitosis. Measurement of salivary enzyme activity of 48 volunteers was performed using p-nitrophenyl-β-d-glucopyranoside as substrate. Each volunteer was clinically evaluated by a dental surgeon and clinical and laboratorial data were statistically analyzed. Gas-chromatography of saliva headspace allowed the analysis of the direct role of exogenous β-glucosidase on aromatic /volatile profile of saliva samples. The data demonstrated a positive correlation between halitosis and enzymatic activity, suggesting that the enzyme exerts a direct role in the occurrence of bad breath. Gas-chromatography analysis demonstrated that exogenously added enzyme led to the alteration of volatile organic content, confirming a direct contribution of β-glucosidase activity on saliva volatile compounds release. Although halitosis is a multifactorial condition, the complete understanding of all governing factors may allow the development of more effective treatment strategies. Such studies may pave the way to the use of β-glucosidase inhibitors for halitosis clinical management.

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β-Glucosidases are capable of altering the aromatic profile of saliva.

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Increased salivary β-glucosidase is associated with halitosis.

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Increased salivary β-glucosidase is associated with dental biofilm.

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Salivary β-glucosidases are produced by oral microrganisms.

Small, but smelly: the importance of Solobacterium moorei in halitosis and other human infections

Solobacterium moorei (S. moorei) has been described as Gram-positive, non spore forming, obligate anaerobic bacillus from human feces. The traditional culture and identification of these strains is very difficult (as the strains are often not cultivable or they grow only relatively slowly, in addition to producing only a very few positive biochemical reactions in commercially available identification kits); thus, reliable identification may only be carried out using methods, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and DNA sequencing. Regarding its pathogenic role, the relevance of S. moorei in halitosis (oral malodor) has a good standing, as it has been suggested by multiple studies, while the isolation of these bacteria from invasive infections is very rare; there are only a few reports available in the literature, regarding infections outside the oral cavity. Based on these reports, affected patients are predominantly characterized compromised immunity and are frequently associated with a dental focus of infection. The aim of our present review is to summarize the currently available knowledge on the pathogenic role of S. moorei in halitosis and other infections and to emphasize the relevance of this neglected anaerobic pathogen.

Induction and inhibition of oral malodor

Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H₂ S) and methyl mercaptan (CH₃ SH) are the main components of oral malodor, and are produced as the end products of the proteolytic processes of oral microorganisms. The main pathway of proteolysis is the metabolism of sulfur-containing amino acids by gram-negative anaerobic bacteria. Gram-positive bacteria may promote VSC production by gram-negative anaerobes by cleaving sugar chains from glycoproteins and thus providing proteins. A large variety of bacteria within the oral microbiota are thought to be involved in the complex phenomenon of halitosis. Oral microbiota associated with a lack of oral malodor, oral microbiota associated with severe and H₂ S-dominant oral malodor, and oral microbiota associated with severe and CH₃ SH-dominant oral malodor have been distinguished through molecular approaches using the 16S rRNA gene. Pathological halitosis may primarily be addressed through treatment of causative diseases. In all cases, plaque control is the basis of oral malodor control, and dentifrices, mouthwashes, and functional foods play a supplementary role in addition to brushing. Recently, the use of natural ingredients in products tends to be favored due to the increase in antibiotic-resistant strains and the side effects of some chemical ingredients. In addition, probiotics and vaccines are expected to offer new strategies for improving the oral conditions through mechanisms other than antibacterial agents.

Reliability, Accuracy, and Use Frequency of Evaluation Methods for Amount of Tongue Coating

OBJECTIVE

To classify the evaluation methods for amount of tongue coating (TC) and investigate their reliability, accuracy, and frequency of use.

METHODS

Articles published from 1985 to 2015 were searched for evaluation methods for the amount of TC in PubMed and the Cochrane Library. Only clinical researches were included except protocol articles. The methods were classified according to their characteristics.

RESULTS

Finally, 113 articles were selected. The evaluation method for the amount of TC from the articles was classified into 4 types: intuitive, specificative, computerized, and weighing TC. The reliability in the intuitive and specificative methods (κ =0.33-0.92) showed varying levels among the studies. In general, the amount of TC calculated by the specificative method (Spearman's r=0.68-0.80) was more strongly related to the directly measured value than to the value estimated by the computerized method (Pearson's r=0.442). The number of articles published on this topic has increased consistently, and the specificative method was the most frequently used. Despite the higher reliability of the computerized method, it has not been widely used.

CONCLUSIONS

The high prevalence of the specificative method would continue in clinical practice because of its convenience and accuracy. However, to establish higher reliability, the limitation of the subjectivity of the assessors should be overcome through calibration training. In the computerized method, novel algorithms are needed to obtain a higher accuracy so that it can help the practitioners confidently estimate the amount of TC.

Biology of the Tongue Coating and Its Value in Disease Diagnosis

Tongue diagnosis is one of the most important diagnostic tools in traditional Chinese medicine and has been verified for thousands of years. However, its subjectivity and repeatability has been disputed continuously. The tongue coating as the primary coverage of tongue diagnosis provides more objectivity and reproducibility due to its relatively clear molecular basis; it also has a close relationship with many system diseases and may be used as a potentially valuable disease diagnostic tool. This article describes the material basis of the tongue coating, including its biology (epithelial cells, blood cells, vascular endothelial cells, and bacteria) and its metabolites; moreover, we summarize the diseases that are most correlated with the tongue coating. This will be valuable not only for fundamental research of tongue diagnosis but also for the diagnosis and differential diagnosis of disease. We suppose that the tongue coating could serve as a valuable auxiliary diagnosis tool in many diseases, and more research should focus on how to colligate the various information about the tongue and provide useful information for disease diagnosis.

Characterization of volatile sulfur compound production by Solobacterium moorei

OBJECTIVE

Solobacterium moorei is a Gram positive bacterium that has been specifically associated with halitosis. The aim of this study was to characterize volatile sulfur compound (VSC) production by S. moorei.

METHODS

S. moorei was either grown or incubated in the presence of various supplements prior to determining VSC production with a Halimeter sulfide monitor. The effect of exogenous proteases or glycosidase inhibitors on VSC production by S. moorei was examined.

RESULTS

We first showed that S. moorei can convert cysteine into hydrogen sulfide. The capacity of S. moorei to produce VSCs from serum, saliva, and mucin was dependent on the presence of an exogenous source of proteases such as pancreatic trypsin or Porphyromonas gingivalis gingipains. VSC production from mucin was inhibited by the presence of a β-galactosidase inhibitor, thus suggesting that deglycosylation of mucin by S. moorei is critical for VSC production.

CONCLUSION

Our study suggests that S. moorei can be a major source of malodorous compounds in halitosis by producing VSCs through a process involving the β-galactosidase activity of the bacterium and an exogenous source of proteases.