Effects of Lithium Chloride and Nitric Oxide Inhibitor on Orthodontic Tooth Movement in the Rat

Abstract

Orthodontic tooth movement in a rodent model is reduced by lithium chloride (LiCl), a mood-stabilizing agent with antithyroid effects. Considering the established inhibitory effect of N(omega)-nitro-L-arginine methyl ester (L-NAME) on orthodontic tooth movement and the possible role of nitric oxide synthase in LiCl mechanism of action, the question arises if these two mechanisms are synergistic. To answer this question, 70 male Sprague Dawley rats were randomly divided into seven groups: untreated group without any interventions (i), and the orthodontic tooth movement groups receiving daily saline injection (ii), 300 (iii), and 600 mg/kg (iv) of LiCl per os, 10 mg/kg of L-NAME (v) and the combinations of 300 (vi) and 600 mg/kg LiCl (vii) with L-NAME. The first molar was moved towards the incisor with 60 g of mesial tipping force applied by an activated fixed coil spring for two weeks. The resulted distance between the first and the second molar was measured using a feeler gauge. The serum parameters were also determined. We report here that both concentrations of LiCl significantly decreased tooth movement. Even though L-NAME was capable of reducing orthodontic tooth movement, no synergistic effects with LiCl were observed. Moreover, L-NAME had no impact on the robust and significant increase of thyroid-stimulating hormone (TSH) and decrease of triiodothyronine (T3) and thyroxine (T4) in the LiCl treated rats. These findings suggest LiCl significantly decreases the orthodontic tooth movement in rats; however, this ability seems not to be principally mediated through nitric oxide synthase.

Korean Panax Ginseng Reduces Orthodontic Tooth Movement in Rats

“…Another limitation is that we did not include a control group where an agonist of Nrf2-HO1 signaling pushes OTM. It would further be interesting to link the decreased OTM observed with LiCl, an agonist of the canonical Wnt signaling and the hypothalamus-pituitary-adrenal axis, and L-NAME, an inhibitor of nitric oxide synthases activity [35], to the Nrf2-HO1 axis and to our present findings observed with G115 ginseng extracts. In general, there is a great demand to understand how we can modulate and particularly stimulate OTM by means of herbal medicine.…”

“…Based on previous research in the same field [35][36][37], considering a type I α-error of 0.05, and to reach a power of 80%, the fewest number of animals per group was eleven. The nonparametric Kruskal-Wallis test with post hoc Dunn's test for multiple comparisons of the data was applied to analyze the data.…”

“…Although relatively old, it is considered a standard method for measurement of the space between the adjacent teeth [42]. Different experiments and a similar method we applied to measure the gap resulting from orthodontic tooth movements have already benefited from using a Feeler Gauge [6,[32][33][34][35]; however, based on the available equipment and techniques, micro-CT and newer techniques may provide more accurate and reliable results.…”

“…Using a calibrated Feeler Gauge (Mitutoyo Co. Kawasaki-Shi, Japan) with 0.01 mm increments, OTM was measured directly in the mouth to reveal the distance between reference points of the disto-occlusal and mesio-occlusal tips of the first and second maxillary molars, respectively (Figure 1D,E). This manual method has been widely used also in previous preclinical models of rat OTM [6,[32][33][34][35]. To prevent any potential relapse of tooth movement before removing the appliances, a silicone impression (Zermack, Mahl, Germany) was taken and ultra-strength dental stone (Velmix, Gildand, Germany) was poured into a mold to create a model.…”