Establishment of an implant selection protocol for predetermined success

Previously, implant selection was confined to radiographs and to plastic implant templates for evaluation of existing bone. The aim of this study was to determine implant support areas in a compressive mode and to establish a standard via an implant selection protocol. Successful implant selection, regardless of the device design, is relevant to a patient's muscular efficiency and implant support values based on bone quality and size of prescribed bridge. The compressive areas of support, in mm2, of 15 implant designs were computer-analyzed and graph-evaluated. Major/minor diameters and the lengths of screws and cylindrical types of devices were calculated. In addition, the length, width, vents, and any lateral support areas of blade types were recorded. Average muscular force data, provided by clinical transducer studies, and literature reports of the mechanical properties of trabecular bone were correlated with computer bone analyses. These studies determined the quality of maxillary and mandibular bone to be 10 MPa and 15 MPa, respectively. Results indicated that four-unit bridges, at 50 lbs of applied force, require an area 31.14 mm2 of implant support in a compressive mode in the maxilla, and a support area of 20.76 mm2 in the mandible. Five-unit bridges require 40.84 mm2 in the maxilla and 27.23 mm2 for the mandible, because of the moment force, or torque, on the implant. Findings indicated that by determining: (1) the patient's muscular efficiency at implant sites (quantifying dynamic values of the forces and moments on implants supporting functioning bridges); (2) implant support values based on the compressive strength of the cancellous bone at implant sites; and (3) the size of the prescribed bridge, it is possible for the success (or failure) of a selected implant to be predetermined.