Journal of Oral Implantology April 2012 - (Page 165)

CLINICAL A Modified Technique for Removing a Failed Abutment Screw From an Implant With a Custom Guide Tube Yohsuke Taira, DDS, PhD* Takashi Sawase, DDS, PhD Fracture of abutment screw is a serious prosthodontic complication. When the abutment screw is fractured at the junction of the screw shank and screw thread, removal of the fractured screw fragment from the screw hole can be difficult. This article describes a modified technique for removing the failed abutment screw with a custom guide tube and tungsten carbide bur. The failed screw can be removed speedily without damaging the screw hole of the implant body or the screw threads. Key Words: implant, prosthodontic complication, abutment screw, removal INTRODUCTION n implant-supported prosthesis is a useful treatment option for replacement of a missing tooth. However, clinicians occasionally encounter complications, such as abutment screw loosening and fracture.1–4 The incidence of abutment screw fracture was reported to range from 0.5% to 8%.2 Abutment screw fractures are related to the design of the implant-abutment connection, poorly fitting framework, bone remodeling and release of pretension in the screw joint, reduced clamping force and screw joint movement, heavy occlusal forces, and metal fatigue after screw loosening.2,3,5 The screw shank is defined as the cylindrical length of the screw that extends Department of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan. * Corresponding author, e-mail: yohsuke@nagasaki-u. ac.jp DOI: 10.1563/AAID-JOI-D-10-00162 A from the underside of the head to the first thread (Figure 1). Fractures mostly occur at the junction of the screw head and screw shank or at the junction of the screw shank and screw thread.6 Once a tightened screw fails at the junction of the screw shank and screw thread, it is difficult to remove the remaining screw from the screw hole. Furthermore, the threads of the screw hole should not be damaged during the removal of the fragment so that the superstructure can be replaced. Although some manufacturers supply instruments, for example, Retrieval Instruments (Nobel Biocare, Zurich, Switzerland) and Neo Screw Remover kit (Neobiotech Co Ltd, Seoul, Korea), to remove failed abutment screws with a low-speed micro-motor hand piece or with a hand driver, the procedure is often time consuming. The purpose of this article was to describe a simple and accurate clinical technique for removing a fractured abutment screw fragment from the implant body using a custom guide tube. Journal of Oral Implantology 165

Table of Contents for the Digital Edition of Journal of Oral Implantology April 2012

Research Letters: A New Editorial Format for the Rapid Disclosure of Innovative Data and Concepts, Didactic Demonstrations, and Scientific Discussions
Effect of Defective Collagen Synthesis on Epithelial Implant Interface: Lathyritic Model in Dogs. An Experimental Preliminary Study
Presence of Aspartate Aminotransferase in Peri-Implant Crevicular Fluid With and Without Mucositis
Deformation of Implant Abutments After Framework Connection Using Strain Gauges
Implant-Retained Mandibular Bar-Supported Overlay Dentures: A Finite Element Stress Analysis of Four Different Bar Heights
The Efficacy of Mylohyoid Nerve Anesthesia in Dental Implant Placement at the Edetulous Posterior Mandibular Ridge
Metal-Ceramic Screw-Retained Implant Fixed Partial Denture With Intraoral Luted Framework to Improve Passive Fit
A Relaxed Implant Bed: Implants Placed After Two Weeks of Osteotomy With Immediate Loading: A One Year Clinical Trial
A Modified Technique for Removing a Failed Abutment Screw From an Implant With a Custom Guide Tube
Therapy for Missing Lower Medial Incisor by Means of Reduced Diameter Implants
Simplifying the Implant Treatment Plan for an Elderly Patient
The Use of Leukocyte- and Platelet-Rich Fibrin During Immediate Postextractive Implantation and Loading for the Esthetic Replacement of a Fractured Maxillary Central Incisor
Atraumatic Removal of an Asymptomatic Migrated Dental Implant Into the Maxillary Sinus: A Case Report
Tooth-Implant Connection: A Review

Journal of Oral Implantology April 2012