EVOLUTION: Of Mice . . .

Dental biofilms produce acids from carbohydrates that result in caries. According to the extended caries ecological hypothesis, the caries process consists of 3 reversible stages. The microflora on clinically sound enamel surfaces contains mainly non-mutans streptococci and Actinomyces, in which acidification is mild and infrequent. This is compatible with equilibrium of the demineralization/remineralization balance or shifts the mineral balance toward net mineral gain (dynamic stability stage). When sugar is supplied frequently, acidification becomes moderate and frequent. This may enhance the acidogenicity and acidurance of the non-mutans bacteria adaptively. In addition, more aciduric strains, such as ‘low-pH’ non-mutans streptococci, may increase selectively. These microbial acid-induced adaptation and selection processes may, over time, shift the demineralization/remineralization balance toward net mineral loss, leading to initiation/progression of dental caries (acidogenic stage). Under severe and p...

The Role of Bacteria in the Caries Process: Ecological Perspectives

Biomineralization is a dynamic, complex, lifelong process by which living organisms control precipitations of inorganic nanocrystals within organic matrices to form unique hybrid biological tissues, for example, enamel, dentin, cementum, and bone. Understanding the process of mineral deposition is important for the development of treatments for mineralization-related diseases and also for the innovation and development of scaffolds. This review provides a thorough overview of the up-to-date information on the theories describing the possible mechanisms and the factors implicated as agonists and antagonists of mineralization. Then, the role of calcium and phosphate ions in the maintenance of teeth and bone health is described. Throughout the life, teeth and bone are at risk of demineralization, with particular emphasis on teeth, due to their anatomical arrangement and location. Teeth are exposed to food, drink, and the microbiota of the mouth; therefore, they have developed a high resistance to localized demineralization that is unmatched by bone. The mechanisms by which demineralization-remineralization process occurs in both teeth and bone and the new therapies/technologies that reverse demineralization or boost remineralization are also scrupulously discussed. Technologies discussed include composites with nano- and micron-sized inorganic minerals that can mimic mechanical properties of the tooth and bone in addition to promoting more natural repair of surrounding tissues. Turning these new technologies to products and practices would improve health care worldwide.

/pdf/demineralization-remineralization-dynamics-in-teeth-and-bone-4qz7fpfvch.pdf

Demineralization–remineralization dynamics in teeth and bone

In some diseases, a very important role is played by the ability of bacteria to form multi-dimensional complex structure known as biofilm. The most common disease of the oral cavity, known as dental caries, is a top leader. Streptococcus mutans, one of the many etiological factors of dental caries, is a microorganism which is able to acquire new properties allowing for the expression of pathogenicity determinants determining its virulence in specific environmental conditions. Through the mechanism of adhesion to a solid surface, S. mutans is capable of colonizing the oral cavity and also of forming bacterial biofilm. Additional properties enabling S. mutans to colonize the oral cavity include the ability to survive in an acidic environment and specific interaction with other microorganisms colonizing this ecosystem. This review is an attempt to establish which characteristics associated with biofilm formation—virulence determinants of S. mutans—are responsible for the development of dental caries. In order to extend the knowledge of the nature of Streptococcus infections, an attempt to face the following problems will be made: Biofilm formation as a complex process of protein–bacterium interaction. To what extent do microorganisms of the cariogenic flora exemplified by S. mutans differ in virulence determinants “expression” from microorganisms of physiological flora? How does the environment of the oral cavity and its microorganisms affect the biofilm formation of dominant species? How do selected inhibitors affect the biofilm formation of cariogenic microorganisms?

https://link.springer.com/content/pdf/10.1007%2Fs10096-013-1993-7.pdf

The virulence of Streptococcus mutans and the ability to form biofilms.

https://deepblue.lib.umich.edu/bitstream/handle/2027.42/94273/idj12007.pdf;sequence=1

Minimal intervention dentistry for managing dental caries - a review: report of a FDI task group.

The number of products containing probiotics, viable bacteria with proven health benefits, entering the market is increasing. Traditionally, probiotics have been associated with gut health, and most clinical interest has been focused on their use for prevention or treatment of gastrointestinal infections and diseases; however, during the last decade several investigators have also suggested the use of probiotics for oral health purposes. The aim of this review is to examine potential mechanisms of probiotic bacteria in the oral cavity and summarize observed effects of probiotics with respect to oral health. The review focuses on probiotic lactobacilli and bifidobacteria, genera that are most used in various probiotic products.

/pdf/probiotics-and-oral-health-piantzdadt.pdf

Probiotics and Oral Health

Introduction: Most probiotic products are consumed orally and hence it is feasible that the bacteria in these products may also attach to oral surfaces; however, the effects of these bacteria on the oral ecosystem are mostly unknown. Our aim was to evaluate the oral colonization potential of different probiotic, dairy, and fecal Lactobacillus and Bifidobacterium strains in vitro.



Methods:  The binding of 17 Lactobacillus and seven Bifidobacterium strains to hydroxyapatite and microtitre wells coated with human saliva was tested. Binding of selected strains to human buccal epithelial cells and co-adherence with Fusobacterium nucleatum were also investigated. In addition, the survival in sterilized human whole saliva was examined.



Results:  There was a large variation in binding to saliva-coated surfaces and buccal epithelial cells but all strains survived in saliva. The binding pattern of the probiotics did not differ from the binding of the fecal strains. F. nucleatum altered the binding of both the low-binding bifidobacteria and the high-binding lactobacilli.



Conclusion:  The differences in binding in vitro may indicate that there are also differences in the persistence of the different probiotic strains in the oral cavity in vivo.

Oral adhesion and survival of probiotic and other lactobacilli and bifidobacteria in vitro.

Introduction: The use of probiotic bacteria is increasing worldwide and at least some of them can transiently colonize the oral cavity. Several studies have shown that probiotic bacteria, which are often thought of in relation only to intestinal health, can also affect the oral ecology, but the mechanisms for this are largely unknown. The aim of this study was to investigate in vitro if the probiotic bacteria used in commercial products affect the protein composition of the salivary pellicle and the adherence of other oral bacteria.



Methods:  Salivary pellicle on hydroxyapatite and the adhesion of two oral streptococci, Streptococcus mutans and Streptococcus gordonii, were used as a model.



Results:  Probiotic bacteria that bound to saliva-coated hydroxyapatite reduced the adhesion of S. mutans but the inhibitory effect on the adherence of S. gordonii was weaker. Salivary pellicle protein composition was modified by all the strains tested. The modifications in the pellicle affected the adherence of S. mutans but not of S. gordonii. Two of the proteins missing from the pellicles made of saliva-treated with the probiotic bacteria were identified as salivary agglutinin gp340 and salivary peroxidase. All bacterial strains bound salivary agglutinin gp340. The ability of the probiotic bacteria to degrade peroxidase was demonstrated with purified bovine lactoperoxidase and two of the probiotic strains.



Conclusion:  This in vitro study showed that probiotic strains used in commercial products may affect the oral ecology by specifically preventing the adherence of other bacteria and by modifying the protein composition of the salivary pellicle.

Probiotic bacteria affect the composition of salivary pellicle and streptococcal adhesion in vitro

In clinical studies, probiotic bacteria have decreased the counts of salivary mutans streptococci (MS). We compared the effects of probiotic Lactobacillus strains on the biofilm formation of Streptococcus mutans. The bacterial strains used included four S. mutans strains (reference strains NCTC 10449 and Ingbritt and clinical isolates 2366 and 195) and probiotic strains Lactobacillus rhamnosus GG, L. plantarum 299v, and L. reuteri strains PTA 5289 and SD2112. The ability of MS to adhere and grow on a glass surface, reflecting biofilm formation, was studied in the presence of the lactobacilli (LB). The effect of LB culture supernatants on the viability of the MS was studied as well. All of the LB inhibited the biofilm formation of the clinical isolates of MS (P < 0.001). The biofilm formation of the reference strains of MS was also inhibited by the LB, but L. plantarum and L. reuteri PTA 5289 showed a weaker inhibition when compared to L. reuteri SD2112 and L. rhamnosus GG. Viable S. mutans cells could be detected in the biofilms and culture media only when the experiments were performed with the L. reuteri strains. The L. reuteri strains were less efficient in killing the MS also in the tests performed with the culture supernatants. The pHs of the supernatants of L. reuteri were higher compared to those of L. rhamnosus GG and L. plantarum; P < 0.001. In conclusion, our results demonstrated that four commonly used probiotics interfered with S. mutans biofilm formation in vitro, and that the antimicrobial activity against S. mutans was pH-dependent.

Probiotic lactobacilli interfere with Streptococcus mutans biofilm formation in vitro

Some probiotic bacterial strains have been suggested to improve oral health. However, lactobacilli and bifidobacteria are associated with the progression of dental caries. The pH fall caused by 14 probiotic and dairy bacterial strains from glucose, lactose, sucrose, sorbitol and xylitol was followed. All strains used glucose, nine lactose and seven sucrose. Six of the lactobacilli caused a small decrease in pH with sorbitol and two with xylitol. None of the bifidobacteria fermented sugar alcohols. As all the strains could be considered acidogenic, more long-term clinical trials are needed before recommendations for oral health purposes can be made.

Anna Haukioja

Papers

Probiotics and Oral Health

Oral adhesion and survival of probiotic and other lactobacilli and bifidobacteria in vitro.

Probiotic bacteria affect the composition of salivary pellicle and streptococcal adhesion in vitro

Probiotic lactobacilli interfere with Streptococcus mutans biofilm formation in vitro

Acid Production from Sugars and Sugar Alcohols by Probiotic Lactobacilli and Bifidobacteria in vitro