Probiotics and oral health : myth or reality?

A. Probiotics and dental caries

Dental caries is a multifactorial disease of bacterial origin that is characterized by acid demineralization of the tooth enamel^{( 9)}. To have a beneficial effect in limiting or preventing dental caries, a probiotic must be able to adhere to dental surfaces and integrate into the bacterial communities making up the dental biofilm. The advantage of incorporating probiotics into dairy products lies in their capacity to neutralize the acidic conditions⁽¹⁰⁾.

Comelli and colleagues reported that out of 23 bacterial strains used in the dairy industry, Streptococcus thermophilus and Lactobacillus lactis ssp. lactis were the only ones with the capacity to integrate into a biofilm present on the hydroxyapatite surface and to interfere with thedevelopment of cariogenic species Streptococcus sobrinus ⁽¹¹⁾.

Several clinical studies have demonstrated the regular consumption of milk or cheese containing probiotics led to a decrease in the number of cariogenic streptococci in the saliva and a reduction in dental plaque ^{(12, 19)}. More recently it was demonstrated that Weissela cibaria had the capacity to inhibit, both in vitro and in vivo, biofilm formation by Streptococcus mutans and to prevent proliferation of this bacterial strains⁽¹³⁾.

B. Probiotics and periodontal disease

Periodontal disease is classified into 2 types: gingivitis and periodontitis. Gingivitis is characterized by inflammation limited to the unattached gingival(terminal edge or border of the gingiva surrounding the teeth in a collar- like fashion), whereas periodontitis is a progressive, destructive disease that affect all supporting tissues of the teeth, including the alveolar bone ⁽¹⁴⁾. There are few experimental studies exploring probiotics use in periodontal diseases, partly reflecting a poorer understanding of the precise etiology of the disease and of the conditions that promote health.

Riccia and colleagues recently studied the antiinflammatory effects of Lactobacillus brevis in a group of patients with chronic periodontitis. The treatment which involved sucking lozenges containing L. brevis over a period of 4 days, led to improvement in the targeted clinical parameters (plaque index, gingival index, bleeding on probing) for all patients. In that study a significant reduction in salivary levels of prostaglandins and matrix metalloproteinases (MMPs) was also observed. The authors suggested that the beneficial effects of L. brevis could be attributed to its capacity to prevent the production of nitric oxide and, consequently, the release of prostaglandins and activation of MMPs induced by nitric oxide⁽¹⁵⁾.

Various studies have reported the capacity of Lactobacilli to inhibit the growth of periodontopathogens, including Porphyromonus gingivalis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans⁽¹⁶⁾

C. Probiotics and Halitosis

Halitosis has many causes (including consumption of particular foods, metabolic disorders, respiratory tract infections), but in most cases it is associated with the imbalance in the commensal micro flora in the oral cavity. More specifically, halitosis results from the action of anaerobic bacteria that degrade salivary and food proteins to generate amino acids, which are in turn transformed into volatile sulphur compounds, including hydrogen sulphide and methanethiol. There have also been clinical and laboratory studies of probiotics in their potential of preventing halitosis ⁽¹⁷⁾.

Kang and colleague reported the capacity of various strains of W.cibaria to inhibit the production of volatile sulphur compounds by Fusobacterium nucleatum. They concluded that this beneficial effect resulted from the production of hydrogen peroxide by W.cibaria, which inhibited the proliferation of F.nucleatum. These authors also found that gargling with a solution containing W.cibaria was associated with the net reduction in the production of hydrogen sulphide and methanethiol and consequently a reduction in a bad breath ⁽¹⁸⁾.