OBJECTIVES To evaluate the efficiency of injectable platelet-rich fibrin (i-PRF) in accelerating canine tooth movement and to examine levels of the matrix metalloproteinase-8 (MMP-8), interleukin-1β (IL-1β), receptor activator of nuclear factor kappa-light-chain-enhancer of activated B cells ligand (RANKL), and osteoprotegerin (OPG) in the gingival crevicular fluid during orthodontic treatment. MATERIALS AND METHODS Twenty patients (mean age = 21.4 ± 2.9
years) with Class II Division 1 malocclusion were included in a split-mouth study. The treatment plan for all patients was extraction of maxillary first premolars followed by canine distalization with closed-coil springs using 150 g of force on each side. The study group received i-PRF two times, with a 2-week interval, on one side of the maxilla. The contralateral side served as the control and did not receive i-PRF. Maxillary canine tooth movement was measured at five time points (T1-T5) on each side. Also, the activity of inflammatory cytokines was evaluated at three time points in the gingival crevicular fluid samples. RESULTS There was a significant difference in canine tooth movement between the two groups (P < .001). i-PRF significantly increased the rate of tooth movement, and stimulation in the levels of inflammatory cytokines supported this result (P < .001). The levels of cytokines changed in both groups between T1 and T2. The IL-1β, MMP8, and RANKL values were significantly increased in the study group compared with the control group, while the OPG values were significantly decreased. CONCLUSIONS i-PRF-facilitated orthodontics is an effective and safe treatment modality to accelerate tooth movement, and this method can help shorten orthodontic treatment duration.