Preventing dental erosion using silver diamine fluoride

Abstract

Dental erosion is the dissolution of the mineralised tooth surface caused by non-bacterial acids. Erosive tooth wear (ETW) is a result of demineralisation caused by erosive acid and abrasion. All populations suffer from dental erosion. This thesis started with a literature review of salivary pellicle and oral diseases. The review provided an overview of the composition of salivary pellicle and its role in oral diseases. The review found that salivary pellicle is a protective factor against dental erosion. The salivary pellicle is formed when saliva contacts the tooth surface. It mainly consists of adsorbed salivary proteins and other macromolecules. The salivary pellicle acts as the protective barrier between erosive acids and the tooth surface. However, salivary pellicle could not protect the tooth surface from severe erosive acids. A second review was performed to investigate topical agents for nonrestorative management of dental erosion. The most commonly used topical anti-erosive agent is fluoride. Fluoride can form a protective layer, modify hydroxyapatite to fluorapatite, and modify salivary pellicle. These properties of fluoride contribute to anti-erosive potential. Silver diamine fluoride (SDF) is one of the polyvalent metal fluorides. SDF has not been widely investigated on dental erosion prevention. The first study was a cross-sectional survey to investigate ETW and its association with oral hygiene habits among non-institutionalised older adults in Hong Kong. All 433 participants had ETW, and over half had severe ETW. An increase in age and untreated dental caries were positively associated with severe ETW. The second study was a laboratory study, which investigated the preventive effect of 38% SDF-modified salivary pellicle. After SDF application, a precipitated layer was formed and silver compounds, such as silver phosphate, silver chloride, and silver fluoride, were formed. These compounds enhanced acid resistance on SDF-treated surfaces. The results confirmed that SDF had a positively synergistic effect with salivary pellicle to reduce surface loss and decrease percentage surface microhardness loss (%SMHL) on human enamel and dentine surfaces. The third was a laboratory study, which examined the preventive effect of a single application of 38% SDF compared to stannous-containing fluoride against a 7-day erosive challenge. The results showed that a single application of 38% SDF was effective in reducing surface loss and %SMHL on human enamel and dentine surfaces. However, the application of experimental agents may differ from that of clinical scenarios. Therefore, the fourth and fifth studies were conducted to simulate clinical scenarios on human enamel and dentine surfaces, respectively. These laboratory studies investigated the preventive effect of different frequencies of SDF application and its discolouring effects. The results showed that two weekly applications of SDF was more effective in preventing erosive demineralisation during a 14-day erosive challenge. However, using SDF more frequently caused discolouration on human enamel and dentine surfaces.