Preventing and arresting dentine caries with casein phosphopeptide-amorphous calcium phosphate and silver diamine fluoride

Abstract

A literature search was conducted to identify publications in five languages on investigating the mechanisms of actions of silver diamine fluoride (SDF) to arrest dental caries. The review found that the possible mode of action of SDF for arresting caries may be attributed to its bacteriostatic and bactericidal effects on cariogenic bacteria, inhibition of mineral demineralisation, promotion of mineral remineralisation and protection of the collagen matrix from degradation. Since SDF has not yet been approved for use in caries control in many European countries, other simple and noninvasive treatments are required as alternative strategies. The first laboratory study of this project was performed to compare the caries-arresting ability of silver nitrate solution followed by sodium fluoride varnish to that of SDF. The results of this laboratory study indicate that the use of silver nitrate solution and sodium fluoride varnish is as effective as SDF in inhibiting dentine demineralisation and dentine collagen degradation. SDF can not only halt caries progress, but also can prevent caries formation. Secondary caries has been considered a major reason for failure of direct restorations. Therefore, the second laboratory study of this project was conducted to investigate the effects of SDF treatment on the prevention of secondary caries formation around resin composite and glass ionomer cement (GIC) restorations. The results of this study illustrate that SDF can increase resistance of GIC and resin composite restorations to secondary caries. However, the anti-caries capability of conventional GIC is limited. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), as a new bioactive agent, has been introduced and incorporated into conventional GIC. The third laboratory study of this project aimed to investigate the effect of SDF treatment and CPP-ACP modified GIC to prevent secondary caries. It has been found that SDF treatment and incorporation of CPP-ACP into GIC restorative materials can prevent the development of secondary caries. Nevertheless, the adhesion and remineralising effect of CPP-ACP modified GIC to caries-affected dentine is not well understood. Therefore, the fourth laboratory study of this project was performed to investigate the effect of CPP-ACP modified GIC on the shear bond strength and remineralisation on demineralised (artificial caries-affected) dentine. The results suggest that the incorporation of CPP-ACP into GIC does not adversely affect the adhesion to artificial caries-affected dentine. Furthermore, CPP-ACP modified GIC is superior to conventional GIC in promoting remineralisation on artificial caries-affected dentine. Previous studies reported that SDF is effective in preventing secondary caries around GIC restorations. A significant disadvantage of SDF use, however, is black staining on teeth which can cause aesthetic concern. A suggested method of managing this problem is to apply a saturated solution of potassium iodide (KI) immediately after the application of SDF. Thus, the fifth laboratory study of this project was to assess whether SDF+KI treatment could prevent tooth discolouration and secondary caries formation. The results show that SDF+KI treatment could partly reduce the staining. It can also inhibit secondary caries development on GIC restorations, but is not as effective as SDF alone.