An angularly adjustable dental implant abutment mounting system for supporting an abutment on a dental implant at any of a number of selectable orientations of varying degree of alignment between a longitudinal abutment axis and a longitudinal implant axis in order to situate the longitudinal abutment axis on a desired axis for suitable positioning of a dental prosthetic structure on the abutment, the system comprising: a transmucosal collar comprising a lower portion configured to coaxially engage an upper end of the dental implant, a cylindrical upper portion having external threading thereon, and an axial bore passing fully through the transmucosal member from an upper end of the upper portion to a lower end of the lower portion; a fixation screw comprising an externally threaded shaft for threaded engagement into the implant via the axial bore of the transmucosal collar to secure the transmucosal collar to the implant at a position situating an upper end of the fixation screw adjacent an upper end of the upper portion of the transmucosal collar; a mounting head having a threaded blind-hole extending thereinto from a bottom end thereof and an upper portion located above the bottom end and presenting a contoured exterior, the threaded blind-hole being configured to thread onto the cylindrical upper portion of the transmucosal collar to position a closed end of the blind hole over the upper end of the upper portion of the transmucosal collar when threaded thereonto, the threaded blind-hole of the mounting head and the cylindrical upper portion of the transmucosal collar being threaded in a direction opposite the threaded shaft of the fixation screw; and an abutment member defining the longitudinal abutment axis and having a bottom end thereof configured to fit onto the upper portion of the mounting head in slidable engagement with the contoured exterior thereof to allow shifting of the abutment member relative to the mounting head to change a degree of alignment between the longitudinal abutment axis and the longitudinal implant axis; wherein the mounting head comprises a first portion made of a first material and a second portion made of a different second material, the first portion defining the threaded-blind hole for engagement to the transmucosal collar and the second portion defining the contoured exterior for receiving the abutment and wherein the first material of the first portion of the mounting head is a cast-to material, and the abutment and the second portion of the mounting head are castable. a transmucosal collar comprising a lower portion configured to coaxially engage an upper end of the dental implant, a cylindrical upper portion having external threading thereon, and an axial bore passing fully through the transmucosal member from an upper end of the upper portion to a lower end of the lower portion; a fixation screw comprising an externally threaded shaft for threaded engagement into the implant via the axial bore of the transmucosal collar to secure the transmucosal collar to the implant at a position situating an upper end of the fixation screw adjacent an upper end of the upper portion of the transmucosal collar; a mounting head having a threaded blind-hole extending thereinto from a bottom end thereof and an upper portion located above the bottom end and presenting a contoured exterior, the threaded blind-hole being configured to thread onto the cylindrical upper portion of the transmucosal collar to position a closed end of the blind hole over the upper end of the upper portion of the transmucosal collar when threaded thereonto, the threaded blind-hole of the mounting head and the cylindrical upper portion of the transmucosal collar being threaded in a direction opposite the threaded shaft of the fixation screw; and an abutment member defining the longitudinal abutment axis and having a bottom end thereof configured to fit onto the upper portion of the mounting head in slidable engagement with the contoured exterior thereof to allow shifting of the abutment member relative to the mounting head to change a degree of alignment between the longitudinal abutment axis and the longitudinal implant axis; wherein the mounting head comprises a first portion made of a first material and a second portion made of a different second material, the first portion defining the threaded-blind hole for engagement to the transmucosal collar and the second portion defining the contoured exterior for receiving the abutment and wherein the first material of the first portion of the mounting head is a cast-to material, and the abutment and the second portion of the mounting head are castable.