Strontium ranelate modulates circular RNA BACH1/microRNA-155-5p to ameliorate root resorption and tooth anchoring during orthodontic tooth movement.

The tooth movement is a fundamental requirement during any orthodontic treatment. This study aimed to investigate the action and mechanism of strontium ranelate (SR) in orthodontic tooth movement (OTM). Rats were given SR by gavage daily, along with lentiviral vectors interfering with circBACH1 or miR-155-5p. Three weeks later, an OTM rat model was established. RANKL and osteoprotegerin (OpG) in serum were measured. The gap between the first and second molar and root resorption were examined. Osteoclast test was used; and root condition was examined. Detection of miR-155-5p, circBACH1, CLC7 and cathepsin K was performed. The binding of circBACH1 to miR-155-5p was verified. In OTM rats, circBACH1 was elevated (p<0.05) and miR-155-5p was silenced (p<0.05). SR reduced osteoclast activity (p<0.05) and improved root resorption (p<0.05) in OTM rats, which was enhanced by silenced circBACH1 (p<0.05) or elevated miR-155-5p (p<0.05). circBACH1 inhibited miR-155-5p expression (p<0.05). Silenced miR-155-5p reversed the ameliorative effect of circBACH1 on tooth root resorption in OTM rats (all p<0.05). SR modulates circBACH1/miR-155-5p to ameliorate root resorption and tooth fixation during OTM.