Zinc Pretreatment as a Strategy to Improve Silver Diamine Fluoride Therapy: A Translational Approach to Reducing Discoloration and Enhancing Aesthetic Outcomes in Dentistry

Abstract

Silver diamine fluoride (SDF) has gained widespread recognition as a minimally invasive treatment for early childhood caries (ECC), but its aesthetic drawback, permanent black discoloration of carious lesions, remains a significant barrier to broader clinical acceptance. This dissertation explores zinc pretreatment as a translational strategy to mitigate SDF-induced discoloration while maintaining its antimicrobial and functional efficacy. Through a series of in vitro investigations modeled on clinically relevant conditions, this work advances the development of more acceptable, patient-centered alternatives to conventional SDF therapy.

In this dissertation, I conducted three interconnected studies to evaluate the role of zinc pretreatment in modifying SDF outcomes. The first study assessed the effect of zinc pretreatment on sound dentin prior to SDF application. Results demonstrated reduced surface discoloration, with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) confirming modified silver deposition patterns and the presence of zinc on treated dentin. The second study extended these findings to an artificial caries model, simulating cariogenic conditions using dual-species biofilms of Streptococcus mutans and Candida albicans. Zinc pretreatment preserved SDF’s antimicrobial activity while disrupting biofilm structure and reducing biomass, suggesting a potential synergistic effect. The third study focused on primary dentition, where aesthetics are of heightened concern, demonstrating that zinc reduced discoloration on carious and sound dentin of extracted primary teeth, with SEM/EDS corroborating altered silver distribution. Although statistical significance in discoloration reduction was borderline, consistent trends across experiments support the mechanistic role of zinc in modifying silver behavior on dentin surfaces.

The results of this dissertation provide foundational evidence for incorporating zinc into caries-arresting treatments to overcome aesthetic limitations without compromising therapeutic efficacy. In addition to establishing zinc’s potential to reduce staining, this work proposes future directions including nanoparticle-based delivery systems, expanded surface and functional analyses, and clinical trials in pediatric populations.

Collectively, this research bridges the gap between laboratory-based discovery and real-world application. It contributes to the broader mission of translational biomedical science by advancing minimally invasive, aesthetically acceptable, and biologically effective therapies for managing caries, particularly in young children and underserved populations.