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Oral infectious diseases are probably the most common infectious pathologies affecting humankind. They have a significant impact on both people quality of life and costs for the healthcare system. Thus, their prevention should be high priority for governaments and research institutes. There are hundres of bacterial species in the oral environment, however, only a few of them are pathogenic. In fact, the disease begins when there is an imbalance in the oral biofilm with a prevalence of pathogenic species. In order to prevent oral infectious diseases we can eliminate most of the oral biofilm with mechanical and chemical means. However, in this way also many saprophytic species are eradicated. A smart solution could be to induce a selective pressure for ?good? oral bacteria thus hampering pathogenic ones. How can we achive this? Modifying our diet is a possible solution, we demonstrated how cariogenic biofilm development was lowered by using levorotatory carbohydrates instead of dextrorotatory ones. If we already have a carious lesion, it should be removed and the tooth restored with proper materials. However, most of them are methacrylate based and favour biofilm development, moreover, they also seem to select cariogenic species due to the lack of buffering ability. In our study we demonstrated how the use of different materials, the siloranes, could lead to a decrease in the biofilm development, thus theoretically lowering the incidence of secondary caries. If a tooth cannot be recovered and should be extracted, dental implants are probably the best solution for their replacement. However, peri-implantitis is a serious issue affecting up to 50% of the implant and can lead to their loss. The prevention of this oral disease is hence very important. In our study we compared different materials and showed that biofilm formation was similar in all of them. In future studies we will investigate if the biofilm on these materials is similar or not and if they are prevalently pathogenic or saprophytic ones. In conclusion, oral infectious disease are still very common and for decades dentists tried to achieve oral health by eliminating all the biofilm. However, the most innovative strategy is not to eradicate it but to induce selective pressures by using different means thus leading to a beneficial biofilm which does not cause illness but instead promote our health.

This in vitro study evaluated the influence of chlorhexidine diacetate (CDA) when blended within dentin bonding systems (DBSs) on Streptococcus mutans (S. mutans) biofilm formation. One commercially available 0.2% wt CDA-containing DBS (Peak Universal Bond) and five experimental 0.2% wt CDA-containing DBS formulations (experimental Adper Scotchbond 1XT plus experimental resins, R2, R3, R4, R5) were assessed vs their no-CDA containing counterparts. Twenty-eight DBSs disks were prepared for each group (6.4 mm×1.0 mm) and cured for 80 s at 800 mW/cm2 in a nitrogen atmosphere. A modified Drip-Flow Reactor was used to grow S. mutans biofilms on specimen surfaces for 24 h and adherent, viable biomass was evaluated using a tetrazolium salt assay (MTT). Two specimens from each of the tested materials were processed with LIVE/DEAD stain and observed using laser confocal microscopy (CLSM) while two disks from each group were examined by using scanning electron microscopy (SEM). MTT assay, CLSM and SEM observations showed that CDA addition decreased, increased or did not change S. mutans biofilm formation. The lowest biofilm formation was obtained with Peak Universal Bond and R5 (with and without CDA). It may be concluded that the chemical composition of DBSs determines their ability to promote or hamper biofilm formation. Therefore, CDA addition may be helpful in modulating biofilm formation provided that DBS formulation is tuned and optimized.