To investigate the effects of submucosal injections of acceleratory orthodontic materials and the subsequent relapse rate. No previous study has compared the effects of different acceleratory agents on post-retention relapse. Orthodontic tooth movement (OTM) in rats was evaluated over 4 weeks, followed by 2 weeks of retention and 2 weeks of relapse.

Randomization: The trial included 105 rats divided randomly with a blinded second author into five equal groups. Interventions: Group I (negative control) rats weren’t subjected to OTM or any acceleratory agents. Group II (positive control) rats underwent OTM without receiving any tested injectable materials. Groups III, IV, and V received the same OTM as Group II, accompanied by injections of corticosteroid, vitamin D, and PGE ₂ , respectively. The primary outcome: Tooth movement was measured at predetermined intervals, and histological assessments were performed after euthanasia. Statistical analysis was done using One-way ANOVA then post-hoc Tukey and paired t -test.

During the acceleration phase, incisor movement was fastest in the corticosteroid group, followed by vitamin D, PGE ₂ , positive control, and negative control ( P < 0.001). In contrast, relapse was lowest in the negative control, positive control, and PGE ₂ groups, and higher in vitamin D and corticosteroid groups ( P < 0.001). Histological findings were in the same line with the dental measurements. No harms were detected.

Local application of corticosteroid, vitamin D, and PGE ₂ enhanced orthodontic tooth movement. While corticosteroid produced the greatest acceleration, PGE ₂ was associated with the least subsequent relapse.