Effects of Iron Salts on Demineralization and Discoloration of Primary Incisor Enamel Subjected to Artificial Cariogenic Challenge versus Saline Immersion

Abstract

This study aimed to assess the effects of iron salts on the demineralization and discoloration of primary incisor enamel subjected to artificial cariogenic challenge (ACC) versus saline immersion. In this in vitro experimental study, 90 primary incisors were evaluated in 10 groups (n = 9). Five groups were subjected to ACC, and the other five were immersed in saline. Ferrous sulfate, ferrous fumarate, ferrous ammonium citrate, and ferrous gluconate were added to both saline and cariogenic solutions. The solutions were refreshed every 48 h. After 14 days, the teeth were removed from the media and their demineralization was inspected via scanning electron microscopy (SEM). Energy-dispersive X-ray spectroscopy (EDX) was also performed. The color of the specimens was measured at baseline and after the intervention using the Vita Shade Guide. Data were analyzed by the Kruskal-Wallis test, one-way ANOVA, and Tukey's test. The color change of specimens subjected to ACC was greater than the color change of those in saline (p = 0.083). The teeth subjected to ACC showed greater iron uptake than did those in saline (p = 0.023). SEM assessment revealed a regular pattern of enamel prisms, with some broken prisms and superficial cracks in the teeth immersed in saline. The teeth subjected to ACC showed numerous fractures and cracks, which were greater in the ferrous sulfate group. Immersion in ACC increased the structural porosities and led to greater iron uptake and, consequently, higher discoloration. The maximum structural changes and subsequent staining were noted in the ferrous sulfate group, followed by ferrous ammonium citrate, ferrous fumarate, and ferrous gluconate.