# A Concise Review of Silver Diamine Fluoride on Oral Biofilm
## 4 Discussion
As discussed above, the bioactive form of silver in SDF in its ionized form is \"Ag+\". It has been reported that silver particles can inhibit the growth of _C. albicans_ under high concentrations [46]. One of the possible reasons for this is that silver ions can also suppress extracellular phospholipase production, which plays a crucial role in the pathogenicity of _C. albicans_[47]. Phospholipase is associated with the development of hyphae, which plays an essential role in the biofilm's adherence and formation [48]. The blocking transformation from a yeast form to a hyphal form could stop colonization and initiation or pathogenesis. However, variations in inhibition still exist among different species in the yeast. Another possible explanation for this could be the avidity of the biological ligands of the yeast to SDF [49]. Based on the review, the most frequently used approach for assessing biofilm is still the colony-forming unit count and the live-to-dead ratio in the traditional culture method. New molecular biological technology is being adopted into assessments, usually combined with traditional ones. The majority of the studies included in this review were conducted in vitro. As the duration of the selected laboratory studies was relatively short, the long-term caries-arresting effect and the periodicity of the SDF application could not be evaluated. It was not the objective of this review to judge the quality of the studies or to discuss the limitations of each study. This should be taken into consideration when interpreting the results as well as the conclusions of this review. This concise review was intended to provide the best evidence regarding SDF's antimicrobial effect, as presented in 21 selected papers, to obtain a definitive answer to a research question involving antibacterial function. It provides an overview and updated information about the antimicrobial effect of SDF on oral biofilm, as well as its known role in the inhibition of cariogenic bacteria. The major lines of investigation in this review involved 15 laboratory studies and six clinical studies. Some data are quite limited due to the lack of studies on certain topics such as the antibacterial effect of SDF on periodontal pathogens. As a whole, this field shows significant gaps, with only one study so far providing limited information [22]. In addition, only two published papers have shown promising results for SDF's antifungal effect against candida [16; 33]. However, overall, this review provides strong evidence that SDF can, indeed, inhibit the growth of cariogenic bacteria and prevent bacterial adhesion to the tooth surface. This review--the first concise review of the effect of SDF applied directly to biofilm--can be used to guide future research in this area. Even though SDF has been used for decades, its properties remain under-investigated. Thus far, most laboratory studies have focused on its remineralization properties rather than its antimicrobial functions within biofilm. It has been suggested that the concentrations of antibacterial agents required to inhibit biofilm are more than 100 times higher than those needed to inhibit planktonic bacteria, as biofilm is more resistant to antimicrobial agents than planktonic bacteria are [12]. More studies exploring the rationale behind these materials are still needed.