Zinc pretreatment reduces silver diamine fluoride-induced discoloration in primary teeth: an in vitro study

Objective: Silver diamine fluoride (SDF) is increasingly recognized as a minimally invasive and effective treatment for early childhood caries. However, the dark discoloration from its application significantly limits its acceptability among parents, especially for anterior teeth. Zinc, with known antimicrobial and biofilm-modulating properties, has recently been proposed as a potential adjunct to reduce SDF-induced staining. This study aimed to evaluate the effectiveness of zinc pretreatment in reducing SDF-induced discoloration on primary tooth caries lesions that involved dentin. This study also aimed to examine surface morphology and elemental composition changes associated with zinc adjunct SDF treatments. Method and materials: Extracted human primary teeth were allocated into three groups: untreated control, positive control (38% SDF alone), and experimental group (20 mol/L zinc pretreatment followed by 38% SDF). Tooth color changes were assessed using grayscale intensity analysis via standardized photography at baseline, immediately posttreatment, and up to 14 days. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were employed to investigate morphologic and compositional changes in both sound and naturally carious dentin areas. Statistical analyses included two-sample t tests, linear regression, and likelihood ratio tests. Results: Teeth pretreated with zinc demonstrated less discoloration compared to the SDF-only group. Although this difference was not statistically significant (P =.125), it may have potential clinical relevance. Scanning electron microscopy images revealed modified silver deposition patterns characterized by dispersed and less densely packed silver aggregates in zinc-pretreated groups. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of zinc, suggesting its interaction with silver deposition processes. Conclusion: Zinc pretreatment effectively reduces SDF-induced discoloration in primary dentition, potentially improving esthetic outcomes and parental acceptance. This approach represents a promising advancement in minimally invasive pediatric dental care and warrants further clinical exploration.