The central nucleus of the amygdala lesion attenuates orthodontic pain during experimental tooth movement in rats

Abstract

IntroductionOrthodontic pain is the most common adverse side effect reported in the context of tooth movement. Given its central role in processing pain and negative emotion, the central nucleus of the amygdala (CeA) is thought to be a key site involved in orthodontic pain sensation.MethodsIn the present study, we therefore explored whether the CeA is involved in contributing to orthodontic pain in a rat model of tooth movement. For this study, we utilized adult male rats with bilateral sham or electrolytic CeA lesions (400 μA; 25 s), and then we analyzed face grooming behavior as a measure of pain sensation.ResultsThrough this approach, we found that there were time‐ and force‐dependent factors influencing pain levels in these rats. We further found that bilateral CeA lesions markedly reduced tooth movement‐induced orofacial pain and that unilateral CeA lesions did so to a lesser extent.ConclusionsAs such, these results suggest the CeA is a key area of orthodontic pain, with the results of this study highlighting potential avenues for achieving pain relief in those suffering from orthodontic pain.

Effect of Methotrexate Injection on Orthodontic Tooth Movement: An Experimental Study on Rats

“…Several factors can affect this process [25]. In recent years, many studies have assessed the effect of different supplements, vitamins, and medications on OTM [1,26,27]. Some materials such as vitamin C and vitamin E have no local or systemic effect on the speed of OTM.…”

“…Orthodontic tooth movement (OTM) occurs as the result of simultaneous modeling and remodeling of bone and the periodontal tissue. Orthodontic force application also alters the blood vessels in the periodontal tissue and subsequently the blood supply, resulting in local synthesis and release of different molecules [1]. e balanced activity of osteoclasts and osteoblasts plays a fundamental role in this respect [2].…”

Increased expression of TRPV1 in the central nucleus of the amygdala is involved in orthodontic pain during experimental tooth movement in rats

“…The CeA processes nociceptive input from the spinalparabrachial-amygdala pathway and transmits the resulting information to the hypothalamus, substantia innominate dorsalis and brainstem nuclei that control responses to defensive behaviour [10,11]. Our previous research revealed the role of the CeA in orthodontic pain during tooth movement [12]. Speci cally, after electrolytic destruction of the CeA, pain during tooth movement was signi cantly reduced.…”

“…Based on our previous ndings [12], this study aimed to investigate pain behaviour and TRPV1 expression in the CeA during tooth movement using behavioural and molecular biology techniques in order to elucidate the complex pain regulation network and identify effective interventional measures for orthodontic pain.…”