Objective: Iron deficiency, a leading cause of anemia in children under five, is treated by iron supplementation. However, iron syrups prescribed for children aged 6–24 months, may cause extrinsic staining of primary teeth, raising esthetic concerns. This in vitro experimental study aimed to evaluate the impact of syrup dilution and tooth brushing on iron-induced staining of primary anterior teeth.
Materials and Methods: After ethical approval, 90 anterior primary teeth with intact crowns were collected, disinfected, and mounted in acrylic resin molds. Samples were randomly assigned to six groups (n=15). Groups either received undiluted or diluted ferrous sulfate syrup (PediaFer®, 15 mg/mL elemental iron), with or without brushing using a children’s fluoride tooth-paste (500 ppm) (Aquafresh® milk teeth, GSK Consumer Healthcare, Brentford, UK). Artificial saliva served as control. Immer-sion simulated three years of clinical exposure by incubating samples for 36 days at 37°C. Color measurements were recorded at baseline and after 12, 24 and 36 days using the CIE Lab* system and a spectrophotometer (VITA Easyshade®, VITA Zahnfab-rik, Bad Säckingen, Germany). Color change (ΔE) was calculated and interpreted according to ISO/TR 28642:2016 standards. Analysis was performed using RStudio (version 2024.12.1). Repeated-measures ANOVA or the Friedman tests assessed within-group time effects; t-tests or Wilcoxon tests examined brushing effects; and ANOVA or Kruskal-Wallis tests analyzed dilution effects. Significance was set at p≤0.05.
Results: Teeth exposed to concentrated iron syrup without brushing showed the highest ΔE values, rising significantly from T1 to T3 (p<0.001), indicating progressive staining. Diluted syrup without brushing caused significant discoloration (p=0.015). Brushing reduced early staining only in the diluted group at T1 (p=0.002), but this effect was not sustained. Pooled analysis showed no significant effect of brushing by T3 (p=0.08), while syrup concentration had an overall strong and consistent effect (p<0.001). Concentrated syrup led to significantly higher ΔE values than diluted and control groups (adjusted p<0.001). Mean ΔE values for concentrated syrup exceeded the clinical visibility threshold (ΔE>6) confirming its marked staining potential.
Conclusion: These findings suggest that dilution is a more consistently effective strategy than brushing alone for minimizing iron-induced staining in primary teeth.