RESUMO
OBJECTIVES: Primary objective: To evaluate the effect of L-PRF on the rate of maxillary canine retraction. SECONDARY OBJECTIVE: To validate the rate of maxillary canine retraction by identifying the levels of Interleukin-1ß (IL-1ß) and Tumour Necrosis Factor-α (TNF-α) in the Gingival Crevicular Fluid (GCF). MATERIALS AND METHOD: Fifteen females (age range, 18-25 years) with Class I bimaxillary dentoalveolar protrusion malocclusions were included. After levelling and alignment of maxillary arches, 1st premolars were extracted from both sides. Canines were retracted immediately after the extraction of 1st premolars in control sides and placement of L-PRF plugs in the experimental sides. The amount of canine retraction was evaluated from study models recorded before the extraction of 1st premolars (T0) and at 1-week (T1), 2-weeks (T2), 4-weeks (T3), and 8-weeks (T4) after the beginning of canine retraction by using digital model superimpositions. The concentrations of IL-1ß and TNF-α were evaluated from the GCF collected at T0, T1, T2, T3, and T4 by using commercially available human IL-1ß and TNF-α ELISA kits. RESULTS: The amount of canine retraction in the experimental sides was statistically greater during T0-T1 (P=0.038),T1-T2 (P=0.002), and T2-T3 (P=0.011) periods. Total canine retraction during T0-T4 was statistically greater in experimental sides (2.43±0.46mm) than control sides (2.08±0.28mm) (P=0.001). The concentration of IL-1ß increased significantly in the experimental sides at T1 (P=0.000),T2 (P=0.000), and T3 (P=0.032). The concentration of TNF-α increased both in the control and experimental sides, but it was statistically greater in the experimental sides compared to control sides at T1 (P=0.000) and T2 (P=0.006). A positive but not statistically significant correlation was noted between the rate of canine retraction and the concentrations of cytokines such as IL-1ß and TNF-α in GCF. CONCLUSION: Over an 8-week period, autologous L-PRF statistically accelerated the rate of maxillary canine retraction, but only by 0.35mm. This small acceleration occurred mainly in the first 4 weeks. During the following 4 weeks, the amount of canine retraction was comparable on the experimental and control sides.
