Fig. 6. Linear intermolar measurements obtained to assess the effects of nicotine on orthodontic tooth movement and bone remodeling in rats. Representative images for each group showing the intermolar distance (amount of orthodontic tooth movement, M1-M2, mm) on the left side of maxilla at 3, 7, and 14 days after insertion of a 30-g orthodontic force application device (image magnification × 10). A-C, Control group (saline 0.5 mL daily). D-F, Experimental group (nicotine 0.83 mg/kg daily). G-I, Experimental group (nicotine 1.67 mg/kg daily). M1, first molar; M2, second molar; M3, third molar.