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The accuracy of computer-guided implant placement decreases when the remaining teeth are poorly distributed. This clinical report demonstrates a protocol for using a superimposition-anchor microscrew (SAM) system to improve the accuracy of computer-guided implant surgery in a posterior unilateral edentulous area. The SAM functioned as a fiducial marker for image superimposition and as an anchor for guide positioning. Applying the SAM system to computer-guided implant surgery enhances the accuracy of implant placement by minimizing possible errors occurring during image registration and guide positioning., (Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of this study was to evaluate the effect of a computer-aided design/computer-assisted manufacturing (CAD/CAM) guide on drilling the screw-access channel for lingually placed implants., Materials and Methods: Screw-channel drilling guides were fabricated on lingually placed implant models using CAD/CAM technology. The screw channels were prepared with guided or freehand drilling by 20 dental graduates. The accuracy of each screw channel was assessed for drilling entry point, channel volume, and angulation (α = .05)., Results: The guided drilling group showed smaller deviations than the freehand drilling group, and prosthesis position influenced the guide effect (P < .001)., Conclusion: The CAD/CAM guide facilitated the screw channel preparation of cement-retained prostheses supported by lingually placed implants.

The difficulty of retrieving the abutment screw is a major disadvantage of cement-retained implant restorations. Conventional methods for locating the screw-access hole are based largely on radiography or manual labor, which limits accuracy and clinical feasibility. This clinical report describes a non-radiological method for fabricating an accurate drilling guide for location of the screw channel using intraoral optical scanning, 3D superimposition, and computer-aided design and computer-aided manufacturing (CAD/CAM) technologies. The present technique not only improves the guide fabrication process and the accuracy of screw-channel drilling, but also has wide indications for implant restorations., (© 2016 by the American College of Prosthodontists.)

Limited retrievability is a major disadvantage of cement-retained implant restorations. Despite great progress in locating the abutment screw within crowns, the existing techniques are based on prior data or prefabricated devices and require significant work. This study introduces a new procedure for fabricating a guide template to drill a screw access hole using a double-step superimposition technique that incorporates intraoral optical scanning, cone beam computed tomography, and dental design software. The double-step superimposition technique with computer-aided design/computer-assisted manufacturing technology can enhance the convenience and accuracy of drilling the screw-access hole.