Mouthwash Effects on LGG-Integrated Experimental Oral Biofilms.

In order to investigate the effects of mouthwashes on oral biofilms with probiotics, we compared in biofilms the susceptibility to mouthwashes of probiotic Lactobacillus rhamnosus GG (LGG) and oral pathogens Streptococcus mutans, Streptococcus sanguinis, and Candida albicans. We also evaluated these pathogens' susceptibility to the mouthwashes and their recovery after mouthwash-rinsing in biofilms with/without LGG. First, 1-day-/3-day-old LGG-integrated multi-species biofilms were exposed for 1 min to mouthwashes containing chlorhexidine, essential oils, or amine fluoride/stannous fluoride. Cells were plate-counted and relative survival rates (RSRs) of LGG and pathogens calculated. Second, 1-day-/3-day-old multispecies biofilms with and without LGG were exposed for 1 min to mouthwashes; cells were plate-counted and the pathogens' RSRs were calculated. Third, 1-day-old biofilms were treated for 1 min with mouthwashes. Cells were plate-counted immediately and after 2-day cultivation. Recovery rates of pathogens were calculated and compared between biofilms with/without LGG. Live/Dead® staining served for structural analyses. Our results showed that RSRs of LGG were insignificantly smaller than those of pathogens in both 1-day and 3-day biofilms. No significant differences appeared in pathogens' RSRs and recovery rates after treatment between biofilms with/without LGG. To conclude, biofilm LGG was susceptible to the mouthwashes; but biofilm LGG altered neither the mouthwash effects on oral pathogens nor affected their recovery.

Probiotics: Evidence of Oral Health Implications.

The prevalence of common oral diseases, such as dental caries, periodontal diseases and oral candidiasis remains high in the general population. Various preventive strategies have been proposed and included in national health programs promoting oral health. Interest in probiotics in light of oral health has gradually evolved as attractive means in prevention of oral infectious diseases. The aim of the present review is to outline the current evidence on the role of probiotic species on oral health parameters and their beneficial role in contributing to healthier oral environment.

Lactobacillus rhamnosus GG in Experimental Oral Biofilms Exposed to Different Carbohydrate Sources.

Probiotic administration may favour caries prevention, as recent research has shown. This in vitro study aimed to investigate the growth of Lactobacillus rhamnosus GG (LGG) in experimental biofilms exposed to various carbohydrates, and also to assess its cariogenic potential. Multispecies experimental oral biofilms with or without LGG were grown with a sole-carbohydrate source (fructose/glucose/lactose/sorbitol/sucrose). The viable cells of LGG and structure of the biofilms were examined after 64.5 h of incubation, and pH values of spent media were measured at 16.5, 40.5, and 64.5 h. Fermentation profiles of LGG in biofilm media were assessed with study carbohydrate as the sole energy source. Our results showed that LGG reached higher viable cell numbers with glucose and sucrose in 64.5-h multispecies experimental oral biofilms compared to other carbohydrates. When LGG was incorporated in biofilms, no distinct pH changes at any time points were observed under any of the carbohydrates used; the pH values of spent media at each time point were lower when lactose was used, compared to other carbohydrates. The fermentation profiles of LGG in biofilm media were similar to its growth in MRS (no obvious growth with lactose or sucrose). In conclusion, LGG in our in vitro multispecies experimental oral biofilms was capable of surviving and growing well in each carbohydrate source. LGG might not have harmful effects on dental hard tissues. Another finding from our study was that the lowest pH values were observed in the presence of lactose, and the thickest biofilms were in sucrose.

Interactions between Lactobacillus rhamnosus GG and oral micro-organisms in an in vitro biofilm model.

BACKGROUND: Probiotics have shown favourable properties in maintaining oral health. By interacting with oral microbial communities, these species could contribute to healthier microbial equilibrium. This study aimed to investigate in vitro the ability of probiotic Lactobacillus rhamnosus GG (L.GG) to integrate in oral biofilm and affect its species composition. Five oral strains, Streptococcus mutans, Streptococcus sanguinis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Candida albicans were involved. The group setup included 6 mono-species groups, 3 dual-species groups (L.GG + S. mutans/S. sanguinis/C. albicans), and 4 multi-species groups (4/5 species and 4/5 species + L.GG, 4 species were all the tested strains except S. mutans). Cell suspensions of six strains were pooled according to the group setup. Biofilms were grown on saliva-coated hydroxyapatite (HA) discs at 37 °C in anaerobic conditions for 64.5 h. Biofilm medium was added and refreshed at 0, 16.5, and 40.5 h. The pH of spent media was measured. Viable cells of the 16.5 h and 64.5 h biofilms were counted. 64.5 h biofilms were stained and scanned with confocal laser scanning microscopy. RESULTS: Our results showed that L.GG and S. mutans demonstrated stronger adhesion ability than the other strains to saliva-coated HA discs. L.GG, C. albicans, S. mutans and F. nucleatum, with poor ability to grow in mono-species biofilms demonstrated better abilities of adhesion and reproduction in dual- and/or multi-species biofilms. L.GG slightly suppressed the growth of C. albicans in all groups, markedly weakened the growth of S. sanguinis and F. nucleatum in 4sp + L.GG group, and slightly reduced the adhesion of S. mutans in L.GG+ S. mutans group. CONCLUSIONS: To conclude, in this in vitro model L.GG successfully integrated in all oral biofilms, and reduced the counts of S. sanguinis and C. albicans and lowered the biofilm-forming ability of F. nucleatum, but only slightly reduced the adhesion of S. mutans. C. albicans significantly promoted the growth of L.GG.

Probiotics: health benefits in the mouth.

Probiotics or health-beneficial bacteria have only recently been introduced in dentistry and oral medicine after years of successful use in mainly gastro-intestinal disorders. The concept of bacteriotherapy and use of health-beneficial micro-organisms to heal diseases or support immune function was first introduced in the beginning of the 20th century. Later the concept lead to the development of modem dairy industry and even today most probiotic strains are lactobacilli or bifidobacteria used in milk fermentation. The mechanisms of probiotic action are mainly unknown but the inter-microbial species interactions are supposed to play a key role in this together with their immuno-stimulatory effects. The introduction of probiotic bacteria in the mouth calls for ascertainment of their particular safety. Since acid production from sugar is detrimental to teeth, care must be taken not to select strains with high fermentation capacity. The first randomized controlled trials have nevertheless shown that probiotics may control dental caries in children due to their inhibitory action against cariogenic streptococci. Less evidence exists on their role in periodontal disease or oral yeast infections. Furthermore the best vehicles for oral probiotic applications need to be assessed. So far mainly dairy products have been investigated but other means such as probiotics in chewing gums or lozenges have also been studied. From the clinical practitioner's point of view direct recommendations for the use of probiotics cannot yet be given. However, scientific evidence so far indicates that probiotic therapy may be a reality also in dentistry and oral medicine in the future.

Safety issues of Lactobacillus bulgaricus with respect to human gelatinases in vitro.

In oral medicine and dentistry probiotics have shown promising results in controlling dental diseases and yeast infections. This study was made to investigate the effect of eight strains of Lactobacillus bulgaricus and their effects on human matrix metalloproteinase-9 (MMP-9). The hypothesis was that these bacteria used in yoghurt production for centuries are not proteolytic and thus can be safely used in the development of probiotic preparations. Bacterial cell fractions and supernatant specimens were prepared and studied with gelatinase zymography and MMP-9 activation was assessed by immunoblotting. The effect of synthetic MMP inhibitors and a serine protease inhibitor (Pefabloc) on bacterial proteinases was studied with zymography. The results showed very low gelatinolytic activity. There was a slight difference between the supernatant and cell fractions so that the supernatant specimens produced weak gelatinolytic bands in zymography while hardly anything was seen in the cell fraction series. The tested synthetic MMP inhibitors and Pefabloc did not affect the proteolytic activity of the lactobacilli strains. The lactobacilli did not seem to induce the conversion of proMMP-9 to its active form. Consequently, our study hypothesis was confirmed and the studied Lactobacillus strains are not likely to degrade host tissue components.

Early results of the use of ProRoot MT and Titan cement for furcation perforation repair--a comparative experimental study.

UNLABELLED: The aim of the present experimental study was to follow up the connective tissue response after using ProRoot MTA and Titan cement to repair furcation perforations in dogs. MATERIAL AND METHODS: Four animals aged 12 to 18 months were used in the study. Perforation defects were created in the center of the pulp chamber of mandibular premolars P2, P3 and P4, right and left. The defects on the left side were repaired with ProRoot MTA, and those on the right side--with Titan cement in all dogs. After 30 days bone fragments with teeth included were fixed in formalin and decalcified in 50% formic acid. Serial sections of 10 microm thickness were prepared, stained with hematoxylin and eosin and studied under light microscopy. RESULTS: The connective tissue response in the Titan cement repaired teeth was a fibrous capsule in contact with the material, with single or aggregated lymphocytes seen in the vicinity. The response to ProRoot MTA was similar, but the fibrous capsule was thinner and without any aggregation of lymphocytes. CONCLUSIONS: The connective tissue response was similar for both tested materials. The tissues tolerated both of them well; it formed a fibrous capsule, which is indicative of the start of a healing process.

The smear layer in the root canal and its removal.

Instrumentation of the root canal during endodontic treatment produces a smear layer which is not uniformly attached to the canal wall. Its morphological structure comprises dentin particles, organic debris, odontoblast processes, microorganisms and their metabolic products. The view that has currently gained wide popularity holds that leaving the smear layer in the root canal contradicts the principles of efficient treatment as this might compromise the optimal progression of the healing process. The proven unfavorable effects of the smear layer on treatment outcome bring forward the necessity for additional application of agents aimed at its complete removal. As the smear layer has a complex structure, these agents should possess a potential for dealing with both its organic and inorganic components. The wide range of used medications includes different concentrations of sodium hypochlorite as a major irrigant of the root canal, chlorhexidine gluconate, chelating agents (EDTA), organic acids, combined preparations (MTAD), combined use of agents that can tackle both the organic and inorganic components. Lasers find manifold applications in various medical fields and can be regarded as a future solution to the problem of total smear layer removal. In the present review we have made a critical analysis of currently used agents placing the emphasis on the potential use of new medications, capable of attacking the smear layer.