J Korean Acad Prosthodont.  2002 Jun;40(3):246-261.

Effect of the surface modifications and the use of washer on the reverse torque of the implant prosthetic gold retaining screw

• Lee JH
• Jang KS
• Kim CW
• Kim YS

Abstract

The screw loosening is one of the complications that happen frequently in dental implant prostheses. The purpose of this study was to evaluate the changes of reverse/loosening (opening) torque of the screw according to the surface modifications by sandblasting and 24K gold electroplating as well as to determine the possibility of the clinical use of a washer in dental implant. The reverse torque of 4 experimental conditions(control, sandblasted, use of washers, electroplasted) was measured by digital torque gauge (Model MGT50Z, Mark-10 Corp., 458 West John Street Hicksville, NY 11801 USA). Electronic torque controller (Nobel Biocare DEA 020) was used in fastening the gold screws into abutment replicas. Mixed Linear Model Analysis method was used for statistical analysis. To examine the changes of screw thread surface, microphotographs were taken by Olympus PME-3 metallurgic microscope (Olympus Optical Co. Ltd., Tokyo, Japan). Within the limitations of this study, the following results were drawn: 1. The surface modifications of the gold screws and the use of a washer have significantly affected the reverse torque value compared to the control group (p<0.01). 2. Sandblasting and electroplating treatments demonstrated significantly higher reverse torque val-ue than that of control group. 3. The use of a washer may be one of the useful clinical methods that prevent the screw loosening. However, further studies are necessary for the material selection and design of the washer.

Keyword

Implant; Gold Screw; Reverse Torque; Sandblasting; Electroplating; Washer

MeSH Terms

Dental Implants
Electroplating
Linear Models
Prostheses and Implants
Torque*
Dental Implants