Gingival Crevicular Fluid MMP‑۹ Levels and Orthodontically Induced Root Resorption During Anterior Retraction With or Without Mini‑Implant‑Assisted Intrusion: A Non‑Randomized Controlled Clinical Trial

AimThis study aimed to compare changes in gingival crevicular fluid (GCF) matrix metalloproteinase‑۹ (MMP‑۹) levels and radiographically assessed orthodontically induced root resorption (OIRR) in patients undergoing maxillary anterior retraction with or without mini‑implant–assisted intrusion.MethodsIn this clinical trial, ۱۴ participants were allocated into two groups (n = ۷ each). Group ۱ underwent anterior retraction following first premolar extraction, whereas Group ۲ received simultaneous intrusion and retraction using a midline mini‑implant. GCF samples were collected at three time points: T۰ (baseline), T۱ (initiation of retraction), and T۲ (three months after retraction). MMP‑۹ concentrations were quantified using an ELISA assay. Radiographic evaluation of OIRR via standardized RadioVisioGraphy (RVG) was performed at T۰ and T۲ using the Modified Malmgren Criteria. Statistical analyses using Fisher Exact, independent and paired t‑tests. P-value<۰.۰۵ was considered as significant.ResultsBaseline MMP‑۹ concentrations were comparable between the two groups (Group ۱: ۰.۹۹ ± ۰.۳۷ ng/mL; Group ۲: ۰.۹۶ ± ۰.۱۰ ng/mL; P > ۰.۰۵). Both groups showed a significant increase in GCF MMP‑۹ levels from T۰ to T۱ and from T۱ to T۲. At T۲, mean MMP‑۹ levels were significantly higher in Group ۲ (۲.۸۲ ± ۰.۶۲ ng/mL) compared with Group ۱ (۲.۱۲ ± ۰.۴۹ ng/mL) (P = ۰.۰۳), corresponding to percentage increases of ۱۹۳.۷% and ۱۱۴.۱%, respectively.Radiographic assessment revealed no evidence of root resorption at baseline in either group. At T۲, both groups demonstrated a statistically significant increase in root resorption scores compared with baseline (P = ۰.۰۰۰۱). The Pearson correlation test for Group ۱ showed a moderate negative correlation between T۲ MMP-۹ values and T۲ root resorption grade (r = -۰.۴۶, p = ۰.۲۹۹). In Group ۲ , the Pearson correlation test showed a strong negative correlation between T۲ MMP-۹ values and T۲ root resorption grade (r = -۰.۸۹, p = ۰.۰۰۷).Conclusion Both orthodontic retraction alone and retraction combined with mini‑implant–assisted intrusion were associated with increases in GCF MMP‑۹ levels and mild radiographic root resorption over the three‑month period. Although the intrusion group showed higher MMP‑۹ levels, this did not lead to clear radiographic differences between the groups. This study showed a strong and statistically significant negative correlation between T۲ MMP‑۹ levels and root resorption grade , but the overall clinical relevance of this pattern remains uncertain.

کلیدواژه ها:

Fixed Orthodontic Treatment ، Gingival crevicular fluid ، Matrix Metalloproteinase-۹ ، Root Resorption