MicroRNA‑21 serves an important role during PAOO‑facilitated orthodontic tooth movement.

Periodontal accelerate osteogenesis orthodontics (PAOO) is an extension of described techniques that surgically alter the alveolar bone; however, the specific mechanism underlying the technique is not completely understood. The aim of the present study was to evaluate the roles of microRNA (miR)‑21 during PAOO. Sprague‑Dawley rats were divided into the following four groups: i) Group tooth movement (TM), underwent TM and were administered normal saline (NS); ii) Group PAOO, underwent PAOO + TM and were administered NS; iii) Group agomiR‑21, underwent PAOO + TM and were administered agomiR‑21; and iv) Group antagomiR‑21, underwent PAOO + TM and were administered antagomiR‑21. To validate the rat model of PAOO, morphological analyses were performed and measurements were collected. Reverse transcription‑quantitative PCR, western blotting and immunohistochemical staining were performed to examine the expression levels of programmed cell death 4 (PDCD4), activin A receptor type 2B (ACVR2b), receptor activator of NF‑κΒ ligand (RANKL) and C‑Fos. Dual‑luciferase reporter assays were performed to validate PDCD4 as a target of miR‑21 in vitro. Following 7 days of treatment, the TM distance of group PAOO was longer compared with groups TM and antagomiR‑21 (P<0.05), but shorter compared with group agomiR‑21 (P<0.05). Tartrate‑resistant acid phosphatase staining indicated that following treatment with agomiR‑21, osteoclast activity was notably increased, whereas the mRNA and protein expression levels of PDCD4 were notably decreased compared with group PAOO. The mRNA and protein expression levels of RANKL and C‑Fos in group agomiR‑21 were notably increased compared with group PAOO, whereas group antagomiR‑21 displayed the opposite pattern (P<0.05). With regard to ACVR2b, no significant differences were observed among the group agomiR‑21 and antagomiR‑21 compared with group PAOO. Bioinformatics analysis predicted that PDCD4 was a potential target gene of miR‑21, and dual‑luciferase reporter assays demonstrated that miR‑21 directly targeted PDCD4. In conclusion, the present study demonstrated that miR‑21 serves an important role during PAOO‑mediated orthodontic TM.