Purpose: This study evaluated the pretreatment influence of occlusal splints and relines on mandibular movements (MM) and vertical dimension of occlusion (VDO) in longstanding complete denture wearers. Materials and Methods: A total of 30 volunteers were randomly assigned to three groups (n = 10): control (C), relining of old denture (RD), and occlusal splints (OS). Individual extent of MM was assessed via intraoral Gothic arch tracings and the VDO using posed frontal images taken at three time points. Results: The OS group showed statistically significant differences when compared with the other groups (P .05). Conclusion: Both MM and VDO were significantly improved by use of occlusal splints pretreatment.