In vitro assessment of stainless steel orthodontic brackets coated with titanium oxide mixed Ag for anti-adherent and antibacterial properties against Streptococcus mutans and Porphyromonas gingivalis.

Orthodontic brackets made from stainless steel were introduced in dentistry, though they have less ability in reducing enamel demineralization and are not successful in preventing microbial as well as biofilm growth. In this study, we evaluated the significant role of different brackets in reducing enamel demineralization indirectly. Results from different tests indicate the significant reduction in adhesion, biofilm formation and slow growth of tested bacterial species on brackets coated with Ag + TiO2 and found to be statistically significant lower than control. There was no loss in cell viability in all brackets indicating that the cells are biocompatible with different bracket materials. Scanning electron microscopy showed less bacteria attached with the surface coated with Ag + TiO2 indicated that bacteria were losing adherent nature on coated surface. In conclusion, TiO2+Ag coating on stainless steel brackets possessed anti-adherent properties and also have demonstrable antibacterial properties therefore helps in preventing dental caries and plaque accumulation indirectly. The cell compatibility of TiO2+Ag coated brackets is superior to the uncoated samples therefore can be used in orthodontics as it not only provide suitable antimicrobial activity and resistance to biofilm formation but also sustained the cell viability of human gingival fibroblast (HGF) cell lines.

In situ assessment of effects of the bromide- and fluoride-incorporating adhesive systems on biofilm and secondary caries.

AIM: This in situ study assessed the effects of adhesive systems containing or not fluoride and/or the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) on the microbiological composition of dental biofilm and enamel demineralization. MATERIALS AND METHODS: During two phases of 14 days, ten volunteers wore intraoral palatal appliances containing two slabs of human enamel according to a double-blind, crossover design. The slabs were randomly restored using a composite resin and one of the following adhesive systems: All-Bond SE(TM) (self-etch, fluoride/MDPB free adhesive, AB) and Clearfl Protect Bond (self-etch containing fluoride and MDPB adhesive, CB). The biofilm formed on the slabs was analyzed with regard to total and mutans streptococci and lactobacilli counts. Demineralization represented by integrated area of hardness × lesion depth Delta S ( ΔS) was determined on enamel by analysis of cross-sectional microhardness, at 20 and 70 µm from the restoration margin. Data were analyzed by ANOVA. RESULTS: No statistically significant difference was found either in enamel demineralization or in the microbiological composition of dental biofilm. CONCLUSION: All adhesive systems containing or not fluoride and/or MDPB tested were unable to inhibit secondary caries in the in situ model used in the present research.

Does assessment of microbial composition of plaque/saliva allow for diagnosis of disease activity of individuals?

Microbiological tests are limited in their applicability in the assessment of caries activity and in caries prediction. They can be effective in group of persons with high or low caries experience. The reasons for the limitation of microbiological tests rests with unique characteristics of the microflora and local environments of the oral cavity, which will modify the cariogenicity of plaque in an individual. Thus, high numbers of S. mutans may be associated with the development of a lesion at a site, while a second susceptible site with high levels of this organism in the same subject will remain caries free. This paper identifies some aspects of oral bacteria which can contribute to the unique nature of the microflora associated with plaque in an individual. Firstly, the range of bacteria potentially involved in caries has widened and now includes, for example, 'low pH' non-mutans streptococci. The presence of such organisms in plaque in an individual may influence early enamel demineralization. Most significantly, Streptococcus mutans, Streptococcus mitis and Actinomyces naeslundii have been shown to be comprise many distinct clones, with different distribution among subjects. Little is known of the impact of clonal diversity on caries activity but in some bacterial diseases particular clones are associated with virulence. Therefore, possession of a particular clone or clones by an individual could be related to caries activity. Also, the extent of clonal diversity may reflect the nature of the oral environment. Recent studies suggest that cells are released from biofilms, during adherence and growth, i.e. the early phases of development. Thus, determination of the numbers of a given species in non-stimulated saliva may indicate whether it is actively growing in plaque. Microbiological tests on the oral flora should perhaps be used to monitor the status of the oral cavity, after establishing a norm for the individual patient. Research on species and clonal diversity of oral bacteria among human populations; diversity and its role in the caries process; and the liberation of biofilm cells could provide data to allow better appreciation and evaluation of the results of microbiological testing.