When both maxillary and mandibular immediate complete dentures are planned, they should be constructed together to ensure proper occlusion and vertical dimension at the time of insertion. Simultaneous fabrication allows accurate registration of centric relation and avoids interferences that may impair function or cause trauma. This also facilitates immediate esthetics and function, preventing collapse of the jaws during healing. Furthermore, coordination reduces the need for extensive adjustments post-insertion, promoting patient comfort and smoother transition to complete denture use.

Reference: Contemporary Fixed Prosthodontics, Rosenstiel, 5th Edition.