Effect of fangchinoline on root resorption during rat orthodontic tooth movement

Abstract

Objective: To evaluate the short-term effect of fangchinoline, an antiinflammatory drug widely used in Asia, on root resorption that is associated with orthodontic tooth movement.

Methods: Twenty-four Wistar rats were randomly divided into 6 groups. Mesial forces of 0, 50, or 100 g were applied to the maxillary first molar of the rats in each group for 14 days by activating nickel-titanium closed-coil springs. One-half of the rats receiving each of these treatments also received injections of 200 µL fangchinoline every 2 days. Finally, movement of the maxillary first molars was measured using digitized radiographs. The molars were extracted and the surfaces of the root resorption craters were recorded using a scanning electron microscope. The distance the molars moved and resorptionarea ratio was measured, and results were analyzed using 2-way ANOVA tests.

Results: There were no statistical differences in the distances the first molars moved under 50 or 100 g force, regardless of treatment with fangchinoline. However, the resorption area ratios were significantly smaller in those rats that were treated with both tension and fangchinoline than in those rats treated by tension alone.

Conclusions: Fangchinoline reduced the resorption area ratio in rats and is therefore an important means of alleviating root resorption.

Keywords: Root resorption; SEM; Tooth movement.

Figure 1

Rat tooth movement model. A nickel-titanium coil spring was activated after insertion between the first molar and incisors in order to move the molar mesially.

Figure 2

Calculation of the resorption area ratio in the molars of Wistar rats. A, Representative scanning electron microscope micrograph of the mesial surface of the distopalatal root. B, Diagram indicating the area of the crater (black) as compared to the total root surface area (gray). The resorption area ratio was calculated by dividing the area of the crater by the total root surface area (resorption area ratio = black area/gray area).

Figure 3

Representative scanning electron microscope micrographs of the distal root surface of molars from Wistar rats. A, 50 g force and no fangchinoline; B, 50 g force with injection of 40 µL of 5 µg/µL fangchinoline every 2 days; C, 100 g force and no fangchinoline; D, 100 g force with injection of 40 µL of 5 µg/µL fangchinoline every 2 days. Different sizes of resorption craters can be observed on the mesial surface of the root image from each group. Craters are found primarily on the cervical and middle one third of each root (white arrow).