A computer-implemented method for generating a virtual CAD model of a superstructure (10, 10', 10", 10′′′) for a customized dental prosthesis of a group of teeth or a dental arch which is adapted to be fixed to a plurality of dental implants which are fixed below a gingival plane in order to replace multiple teeth or a dental arch, wherein said superstructure (10, 10', 10", 10′′′) comprises a vestibular face, adapted to be directed toward the vestibular side of the oral cavity in the anatomical configuration for use, and a lingual/palatal face, adapted to be directed toward the lingual/palatal side of the oral cavity in the anatomical configuration for use, said computer-implemented method comprising the following steps: a. having an initial virtual CAD model of said superstructure (10, 10', 10", 10′′′) in which a plurality of implant holes are defined, each one of which: - has a longitudinal extension along a respective implant axis and - is adapted to be aligned with a respective dental implant in order to be fixed thereto by means of a fixing element which passes through said implant hole; b. sectioning said initial virtual CAD model along one or more cutting surfaces so as to subdivide said CAD model into an extra-gingival component (20, 21, 22, 23) and into one or more intra-gingival connecting components (31, 32, 33, 34, 35, 36), generating respectively a virtual CAD module of said extra-gingival component (20, 21, 22, 23) and a CAD model of each one of said one or more intra-gingival connecting components (31, 32, 33, 34, 35, 36), each one of said one or more intra-gingival connecting components (31, 32, 33, 34, 35, 36) comprising at least two of said implant holes; c. for each one of said intra-gingival connecting components (31, 32, 33, 34, 35, 36), defining, in said CAD model of said extra-gingival component (20, 21, 22, 23), at least one connecting hole which is adapted to be engaged by a connecting element for fixing said extra-gingival component (20, 21, 22, 23) to said intra-gingival connecting component (31, 32, 33, 34, 35, 36). a. having an initial virtual CAD model of said superstructure (10, 10', 10", 10′′′) in which a plurality of implant holes are defined, each one of which: - has a longitudinal extension along a respective implant axis and - is adapted to be aligned with a respective dental implant in order to be fixed thereto by means of a fixing element which passes through said implant hole; - has a longitudinal extension along a respective implant axis and - is adapted to be aligned with a respective dental implant in order to be fixed thereto by means of a fixing element which passes through said implant hole; b. sectioning said initial virtual CAD model along one or more cutting surfaces so as to subdivide said CAD model into an extra-gingival component (20, 21, 22, 23) and into one or more intra-gingival connecting components (31, 32, 33, 34, 35, 36), generating respectively a virtual CAD module of said extra-gingival component (20, 21, 22, 23) and a CAD model of each one of said one or more intra-gingival connecting components (31, 32, 33, 34, 35, 36), each one of said one or more intra-gingival connecting components (31, 32, 33, 34, 35, 36) comprising at least two of said implant holes; c. for each one of said intra-gingival connecting components (31, 32, 33, 34, 35, 36), defining, in said CAD model of said extra-gingival component (20, 21, 22, 23), at least one connecting hole which is adapted to be engaged by a connecting element for fixing said extra-gingival component (20, 21, 22, 23) to said intra-gingival connecting component (31, 32, 33, 34, 35, 36).