Effects of Stromal Cell‐Derived Factor 1 on Osteoblast Activity During Orthodontic Tooth Movement

OBJECTIVE: This study aimed to clarify the relationship between stromal cell‑derived factor 1 (SDF‑1) and osteoblast-related responses in periodontal ligament (PDL) during orthodontic tooth movement (OTM) after tooth extraction, based on the hypothesis that local inhibition of SDF‑1/C‑X‑C chemokine receptor type 4 (CXCR4) signaling with the CXCR4 antagonist AMD3100 would attenuate osteoblast differentiation and alveolar bone remodeling during OTM. METHODS: Thirty-six 6-week-old Wistar/Sprague-Dawley male rats were randomly divided into control and experimental groups. After the extraction of the maxillary left first molar, the maxillary left second molar (M2) was moved mesially with a 10-gf force following the local injection of phosphate-buffered saline or AMD3100 into the buccal and palatal gingiva adjacent to the M2 in the control and experimental group, respectively. Micro-computed tomography was performed to assess tooth movement and alveolar bone changes. Histological and immunohistochemical analyses were performed to evaluate periodontal tissue morphology and the percentages of SDF-1-, CXCR4-, RUNX2-, and BGLAP-positive cells on the tension side of the PDL. Quantitative reverse transcription PCR was used to assess expression levels of SDF-1, CXCR4, RUNX2, and BGLAP. RESULTS: OTM distance and mesial tilt angle were significantly reduced in the experimental group. RT-PCR showed that SDF-1, CXCR4, and RUNX2 expression levels were significantly downregulated from Day 1 through Day 7, whereas BGLAP expression was significantly decreased only on Day 1. Immunohistochemical analysis of the tension side of the PDL demonstrated significantly reduced SDF-1- and CXCR4-positive cells on Day 3 and RUNX2-positive cells on Day 7 in the experimental group. In contrast, the BGLAP-positive cells did not differ significantly at any time point. CONCLUSION: Local inhibition of SDF-1/CXCR4 signaling reduced OTM and altered early alveolar bone remodeling after tooth extraction. The combined gene expression and immunohistochemical findings suggest that the SDF-1/CXCR4 axis may contribute to osteoblast differentiation, particularly through RUNX2-related responses during the early phase of OTM. TRIAL REGISTRATION: Not applicable.