The regulatory role of oxidative stress in the tooth movement process of rats with chronic fluorosis

Abstract Background Clinically, fluorosis patients exhibit delayed orthodontic tooth movement and compromised retention. Experimental studies in fluorosis-exposed rats demonstrate suppressed tooth movement, impaired periodontal angiogenesis, and downregulated VEGF/PI3K/AKT/eNOS signaling. Oxidative stress is critical in periodontal remodeling during orthodontic treatment, yet its role in fluorosis-related movement alterations remains unclear. Methods Seventy 3-week-old Sprague-Dawley rats (body weight 60 ± 5 g) were randomly allocated into experimental groups. Ten rats served as a baseline group (0 day). The remaining 60 were randomized into three groups: control (C), orthodontic (O), and fluorosis orthodontic (FO), ( n = 20 rats), subdivided into 3, 7, 14, and 21 days subgroups. C, O groups and blank baseline subgroup received purified water (fluoride < 0.08 mg/L, below the national standard of 1 mg/L), the FO group and fluorosis baseline subgroup drank 150 mg/L NaF water to establish a fluorosis model. After 3 months, orthodontic appliances were applied to O and FO groups. Fluoride accumulation (blood/urine), tooth movement rate and oxidative stress markers (SOD, CAT, MDA, and 8-OHdG) were analyzed. Results 1 FO group showed elevated blood/urine fluoride levels with C group ( P < 0.05). Successful tooth movement was confirmed by interdental expansion.2 FO group exhibited slower tooth movement rate than O group ( P < 0.05)0.3 Oxidative stress dynamics: Intergroup Difference: SOD and CAT levels were lowest in the FO group before 7 days, while MDA and 8-OHdG levels were highest in the FO group ( P < 0.05), with differences narrowing in later stages.Intragroup Comparisons: SOD: C group: Levels initially increased, peaked at 14 days, and subsequently declined.O group: Levels consistently decreased over time.FO group: Levels exhibited a continuous upward trend.CAT: C group: Levels fluctuated in the early phase and sharply increased in the later phase.O group: Levels initially rose and then declined.FO group: Levels persistently increased throughout the study.MDA: C and FO groups: Levels continuously decreased.O group: Levels first increased, then decreased with fluctuations.8-OHdG: C group: Levels initially rose and later declined.O group: Levels fluctuated markedly.FO group: Levels first decreased and then slightly rebounded. Conclusion Fluorosis inhibits early-stage tooth movement (3–7 days) through aggravated oxidative stress, with diminishing effects over time as compensatory antioxidant mechanisms emerge.