Pretreatment with occlusal splints is a crucial step in a structured treatment approach for a complex rehabilitation that changes the vertical dimension of occlusion. Meticulous patient compliance is one of the essential prerequisites for overall treatment success. However, patient compliance is all too often insufficient due to esthetic, phonetic, and functional limitations when using conventional occlusal splints in one arch. Modern production technologies now allow the use of tooth-colored occlusal splints made of polycarbonate, whose quality and material properties are quite distinct from those of conventionally manufactured splints made of transparent polymethyl methacrylate (PMMA). These materials, produced under standardized polymerization conditions, are extremely homogenous, which provides benefits such as a greater accuracy of fit by eliminating the polymerization shrinkage, greater long-term stability of shapes and shades, better biocompatibility, less wear, and a more favorable esthetic appearance. In addition, tooth-colored polycarbonate splints can be fabricated very thin without significantly increasing the fracture risk, thanks to the flexibility of the material. The improved wearing comfort combined with acceptable esthetics result in significantly improved patient compliance in terms of a "23-hour splint." Conclusion: By providing separate splints for the maxilla and mandible in the case of major alterations of the vertical dimension of occlusion, the esthetic and functional aspects defined by the wax-up can be completely transferred to the removable splints for a "test drive" by the patient, reversibly, and under realistic conditions. This dual-splint approach additionally facilitates segmental transfer into the definitive restoration. Keywords: altered vertical dimension of occlusion, CAD/CAM, complex rehabilitation, esthetic and functional evaluation, polycarbonate, pretreatment phase, tooth-colored splints, wax-up