Matrix Metalloproteinases Inhibitory Effects of Silver Diamine Fluoride: Influence of Time and Potassium Iodide,...

Silver diamine fluoride (SDF) arrests caries, partly by inhibiting matrix metalloproteinases (MMPs). Potassium iodide (KI) is often applied after SDF to mitigate tooth darkening.

This in vitro study evaluated the effects of application time and potassium iodide on SDF-mediated MMP inhibition, and assessed surface microhardness following SDF ± KI application.

Seventy-two carious (ICDAS score 5 or 6) dentine blocks from 34 teeth were randomly assigned to one of four groups: baseline, SDF, SDF + KI and control. Total MMP activity was measured using a colorimetric assay. For enamel lesions, surface microhardness (VHN) was assessed on 20 enamel surfaces from 10 teeth (ICDAS 2).

After 1 week, SDF significantly inhibited total MMP activity by 93% (p < 0.001). SDF + KI showed a lower, not statistically significant level of inhibition of 55.5% (p = 0.07). Surface microhardness of enamel caries lesions increased by 66.8% (p < 0.0001) with SDF and by 71.5% (p < 0.0001) with SDF + KI. No significant difference was observed between 1 and 3 min of SDF application.

In this in vitro model, SDF demonstrated strong MMP inhibition, while SDF + KI showed lower numerical inhibition, suggesting that KI may attenuate the anti-MMP effect of SDF. SDF and SDF + KI produced similar increases in surface microhardness of non-cavitated enamel lesions.