Abstract
Introduction Knowledge about the effects of medications, vitamins, and various supplements on orthodontic tooth movement (OTM) is imperative for orthodontists. This study aimed to assess the effect of methotrexate (MTX) injection on OTM in rats. Materials and Methods Twenty-eight male Wistar rats were randomized into four groups (n = 7). The first molar and central incisor were connected using a nickel-titanium (NiTi) coil spring with a 50 g load in each rat. The two experimental groups received 0.75 mg/kg and 1.5 mg/kg MTX, respectively, intraperitoneally for 21 days. The negative control group did not receive any injection and did not undergo orthodontic treatment. The positive control group underwent orthodontic treatment and received 0.9% saline (NaCl) injections for 21 days. All rats were sacrificed with chloroform inhalation after 21 days; their maxilla was resected, and the mean number of Howship's lacunae, blood vessels, osteoclasts, and resorption lacunae was counted. The reduction in bone volume (bone volume to total volume ratio (BV/TV)) at the site of the maxillary molar was quantified by microcomputed tomography (micro-CT). Results OTM, the number of osteoclasts, and the number of blood vessels significantly increased in rats treated with MTX (P < 0.05). However, the increase in the number of Howship's lacunae and resorption lacunae was not significant (P > 0.05). Lower BV/TV in the MTX groups was in agreement with the increased number of osteoclasts. Conclusion Injection of MTX can significantly increase OTM and decrease root resorption in rats.
Highlights
Knowledge about the effects of medications, vitamins, and various supplements on orthodontic tooth movement (OTM) is imperative for orthodontists. is study aimed to assess the effect of methotrexate (MTX) injection on OTM in rats
In the process of OTM, osteoclasts are induced to resorb the old bone while osteoblasts are attracted to the areas requiring bone deposition [3]. e proliferation rate of osteoclasts can be used as an important indicator of the level of OTM [4]. e regeneration of periodontal tissue is the basis of OTM. e pressure applied to the alveolar bone induces OTM and tissue regeneration
Orthodontic treatment often lasts for 1 to 2 years. us, it is imperative for orthodontists to have adequate knowledge about the effects of medications, vitamins, and various supplements on OTM. ey should efficiently communicate with patients in this respect, since many patients take different medications for the prevention or treatment of their medical conditions. ese medications can reach the periodontal tissue, affected by the orthodontic forces, via the International Journal of Dentistry blood circulation and accelerate or decelerate the process of OTM [6]
Summary
Orthodontic tooth movement (OTM) occurs as the result of simultaneous modeling and remodeling of bone and the periodontal tissue. E pressure applied to the alveolar bone induces OTM and tissue regeneration. Ese medications can reach the periodontal tissue, affected by the orthodontic forces, via the International Journal of Dentistry blood circulation and accelerate or decelerate the process of OTM [6]. Its antiproliferative properties are related to its interactions with dihydrofolate reductase, inhibition of DNA synthesis, and prevention of the conversion of folic acid to tetrahydrofolic acid. Is mechanism of action justifies the use of MTX for conditions with high infiltration rates of inflammatory cells such as T-lymphocytes in the target tissues [7, 8]. Osteoporosis occurred in rats under high doses of MTX. Considering the confirmed effects of MTX on bone formation and lack of studies on its effect on OTM, this study aimed to assess the biological and histological effects of intraperitoneal injection of MTX on OTM in rats
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