Unlike other fluoride-based caries preventive agents, silver diamine fluoride (SDF) can simultaneously prevent and arrest coronal and root dentine caries. The profound clinical success of SDF has drawn many clinicians and researchers to study the mechanism of SDF in arresting dentine caries. This critical review discusses how silver and fluoride contribute to caries arrest, in terms of their effects on bacteria as well as on the mineral and organic content of dentine. Silver interacts with bacterial cell membrane and bacterial enzymes, which can inhibit bacterial growth. Silver can also dope into hydroxyapatite and have an antibacterial effect on silver-doped hydroxyapatite. Furthermore, silver is also a strong inhibitor of cathepsins and inhibits dentine collagen degradation. Early studies proposed that silver hardened caries lesions by forming silver phosphate. However, recent studies found that little silver phosphate remained on the arrested dentine lesion. The principal silver precipitate was silver chloride, which could not contribute to the significant hardening of the arrested lesions. On the other hand, fluoride enhances mineral formation by forming fluorohydroxyapatite with reduced solubility. A significant increase in microhardness occurs with an elevated level of calcium and phosphorus but not silver on the surface layer of the arrested dentine caries lesion following SDF treatment. Fluoride also inhibits matrix metalloproteinases activities and therefore inhibits dentine collagen degradation. The combination of silver and fluoride in an alkaline solution has a synergistic effect in arresting dentine caries. The alkaline property of SDF provides an unfavorable environment for collagen enzyme activation. Understanding the mechanisms of SDF in arresting dentine caries helps clinicians to develop appropriate protocols for the use of SDF in clinical care.

In a water fluoridated area, annual application of SDF solution or SDF/KI solution can arrest dental root caries in elders. In the long term, application of KI does not reduce the blackening of arrested caries lesions caused by SDF.

Oral health status had become worse from childhood to early adulthood in the study cohort. Economic circumstance of the subjects was found to be positively related to their utilization of dental services and through this contributed to the subjects' caries experience. Oral health at younger ages was positively associated with succeeding oral health conditions.

New caries development of Hong Kong preschool children was low. Children's feeding, snaking and brushing habits, and parents' education attainment were the significant predictors for new caries development of preschool children.

sumptive therapeutic effect of chlorhexidine digluconate in a population with untreated gingivitis and presence of abundant calculus. SETTING AND STUDY DESIGN: Sixty subjects (ෂ mean Despite the preventive role of chlorhexidine in the devel-CONCLUSION: In conclusion, there was a significant opment of gingivitis, the therapeutic potential of this agent effect of chlorhexidine on gingivitis, although the effect in long-standing, untreated, well-established gingivitis and may be too limited to assure prognostic benefits in the in the presence of dental calculus has not been explored. prevention of future disease progression.The potential compatibility of gingival tissue with the presence of large amounts of plaque and calculus was suggested in some of the epidemiological studies on Asian popu-