Experimental orthodontic tooth movement (OTM)

For the induction of experimental orthodontic tooth movement (OTM) it was used nickel-titanium (NiTi) closed-coil springs and a 0.25-mm (MORELLI, Brazil) thick stainless steel tying wire to move the maxillary left molars mesially^7,9,11. The animals were previously anesthetized with ketamine (70 mg/kg administered i.p., 10% Quetamina, VETNIL, São Paulo, SP, Brazil) and xylazine (10 mg/kg administered i.p., 2% CALMIUM, São Paulo, SP, Brazil). All groups, except the naïve group, were submitted to NiTi springs installation in the first left maxillary molar (force of 50gf; Fig. 2A)⁹ allowing OTM for a period of 4 or 21 days. The other end was attached to the maxillary left incisor using a tying wire and composite resin (COLTENE, Brazil). The force produced by the spring was measured and standardized using a tensiometer (MORELLI, Brazil).

Orthodontic tooth movement (OTM) (A) First left upper molar surrounded by a ligature wire and Niti spring and anchored in the upper incisor teeth. (B) Schematic model of the roots of the rat's left upper first molar. (C) Photomicrograph of the roots of the rat's left upper first molar. Five roots (MV, DV, INT, MP and DP) of the maxillary first molar; cross section. Dashed line highlights the DV root, chosen for histomorphometric evaluations. The arrow indicates the direction of the applied force. Bar indicates 500 µm, HE, ×40.