The progression of caries involves ingestion of dietary sugars, bacterial metabolism, tooth mineral demineralization, and tooth organic matrix degradation. The cariogenic process is initiated by an imbalance in the demineralization and remineralization equilibrium, induced by the presence of acid-producing and acid-tolerant bacteria, shifting to a lower pH, resulting in loss of tooth minerals.18 Therefore, it is important to enhance the protective and minimize the pathologic factors associated with tooth decay. Current strategies for caries treatment focus on the individual’s risk assessment and establishment of preventive and/or restorative treatments.19
Caries progression occurs by simultaneous demineralization of enamel and dentin and degradation of the organic matrix. Once the caries lesion is developed, treatment options include restorative and non-restorative measures.19 Nonrestorative approaches may be invasive, such as preventive resin restorations; or noninvasive, such as SDF, fluoride therapy, or sealants.
Although most studies reported caries arrest in deciduous teeth, the proposed mechanisms by which SDF may help arrest caries would likely apply for permanent teeth.18
In 2018, the ADA Center for Evidence-Based Dentistry conducted a systematic review and network meta-analysis20 informing a clinical practice guideline18 on nonrestorative treatments for carious lesions. The expert panel formulated 11 clinical recommendations, each specific to lesion type (i.e., cavitated, noncavitated), tooth surface (i.e., coronal, root surface [in adults]) and dentition (i.e., primary or permanent). The panel provided recommendations for the use of the most effective treatment options, which included 38% SDF, along with other topical fluoride products. The expert panel recommended that clinicians prioritize the use of 38% SDF solution biannually to arrest advanced cavitated carious lesions on coronal surfaces of primary teeth.18 The expert panel extrapolated these results to suggest that clinicians could also use biannual application of 38% SDF solution to arrest advanced cavitated lesions on coronal surfaces of permanent teeth. Biannual application of 38% solution SDF for advanced cavitated lesions may be relevant if access to care is limited, for uncooperative patients, or for patients when general anesthetic is not considered safe.18
A 2017 guideline11 from the AAPD made a conditional recommendation (based on low-quality evidence) for the use of SDF in the management of caries in children and adolescents, including those with special health care needs. Panel members were confident that given its low cost and the disease burden of caries, the benefits of SDF application in the target populations outweighed the undesirable dark discoloration of carious SDF-treated dentin.
According to an umbrella review, application of 38% SDF prevented root caries in adults with success rates 72% higher than a placebo treatment.21 The same review reported a prevented fraction for successful root caries arrest, between 100% and 725% higher as compared to a placebo treatment.21 Moreover, application of 38% SDF in combination with oral health education was found to be the most effective method for preventing root caries in adults.22
The disadvantages of SDF include potential pulpal and oral soft tissue irritation and dental staining. Attention is needed during the application to avoid contact of the solution with the gingiva, since it may cause irritation.13 Mature and sound enamel is not stained, unless there is any superficial defect, such as hypomineralization, carious/demineralized, or immature enamel, where the porosities allow silver ions to penetrate.23
Further restoration of the arrested caries lesion may be needed to recover form and function of a cavitated tooth, which will also diminish tooth discoloration.12 There is limited evidence on the adhesive performance of traditional restorative options, such as resin composite and glass ionomer cement (GIC), following caries arrest with SDF.12 SDF treatment does not seem to impair GIC bonding.24, 25
A 2019 systematic review by Horst et al. found that once-yearly SDF application was more effective in preventing caries than more frequent application (i.e., 2 to 4 times yearly) of fluoride varnish.23 Whereas when compared to occlusal sealants, SDF was only more effective in preventing caries if continuously applied.23