Effect of 38% Silver Diamine Fluoride on the Discoloration of Sound Primary and Permanent Enamel: A Spectrophotometric Study

Objectives: Silver diamine fluoride (SDF) is widely recognized as an effective, minimally invasive agent for caries management. Despite its cariostatic and preventive benefits, the main drawback is the dark discoloration of dental hard tissues. This in vitro study aimed to evaluate the discoloration potential of 38% SDF on sound enamel surfaces of primary and permanent teeth, and to assess the mitigating effects of potassium iodide (KI) and post-treatment rinsing.Materials and Methods: A total of 120 extracted molars (primary and permanent, n = 60 each) with intact enamel were randomly allocated into eight groups (n = 15) according to treatment protocol: SDF without rinsing, SDF with rinsing, SDF + KI without rinsing, and SDF + KI with rinsing. Color measurements (CIE Lab* system) were recorded using a spectrophotometer at baseline, immediately after application, 24 hours, 72 hours, and 1 week. Color change (ΔE) values were calculated, with ΔE ≥ 3.7 considered clinically perceptible. Statistical analysis was performed with significance set at p < 0.05.Results: SDF without rinsing produced the greatest discoloration in both dentition types (p < 0.001), with ΔE values exceeding the perceptibility threshold at all time points. The combination of SDF + KI followed by rinsing resulted in the lowest ΔE values, remaining below clinical significance during early intervals. Groups treated with KI alone or rinsing alone exhibited intermediate levels of staining, without significant differences between them (p > 0.05). Permanent teeth generally showed more pronounced darkening than primary teeth.Conclusions: Within the limitations of this in vitro study, 38% SDF caused clinically perceptible discoloration on sound enamel of both primary and permanent teeth, especially without rinsing. The adjunctive use of KI with immediate rinsing effectively minimized staining. Clinicians should exercise caution when applying SDF to esthetically sensitive areas, and inform patients or caregivers of potential discoloration risks.