A study on surface alteration of implant screws after function

Han, Myung Ju; Chung, Chae Heon; Choi, Han Cheol

Abstract

STATEMETN OF PROBLEM: Surface alteration of the implant screws after function may be asso-ciated with mechanical failure. Theses metal fatigue appears to be the most common cause of structural failure. PURPOSE: The purpose of this study was to evaluate surface alteration of the implant screws after function through the examination of used and unused implant screws in SEM(scanningelectron microscope). MATERIAL AND METHODS: In this study, abutment screws(Steri-oss, 3i), gold retaining screw(3i) and titanium retaining screw(3i) were retrieved from patients. New, unused abutment and retain-ing screws were prepared for control group. Each of the old, used screws was retrieved with a screwdriver. And retrieved implant complex of Steri-oss system was prepared for this study. Then, SEM investigation and EDS analysis of abutment and retaining screws were per-formed. And SEM investigation of cross-sectioned sample of retrieved implant complex was performed.
RESULTS
In the case of new, unused implant screws, as maunfactured circumferential grooves are regularly examined and screw thread are sharply remained. Before ultrasonic cleans-ing of old, used implant screw, a lot of accumulation and corrosion products were existed. After ultrasonic cleansing of old, used implant screws, circumferential grooves as examined before function were randomly deepened and scratches increased. Also, dull screw thread was examined. More surface alterations after function were examined in titanium screw than gold screw. And more surface alteration was examined when retrieved with driver than retrieved without driver.
CONCLUSIONS
These surface alteration after function may result in the screw instability. Regularly cleansing and exchange of screws was recommended. We recommend the use of gold screw rather than titanium screw, and careful manipulation of the driver.