J Korean Acad Prosthodont.  2020 Oct;58(4):321-327. 10.4047/jkap.2020.58.4.321.

Analysis of implant strain value exerted using different screw tightening protocols in screw-retained 3-unit prostheses

• Kim SB
• Lee DH
• Lee CH

• KMID: 2508374
• DOI: http://doi.org/10.4047/jkap.2020.58.4.321

Abstract

Purpose
The purpose of this study was to measure and compare the strain value exerted on the cervical area using different screw tightening protocols in implant-supported, screw-retained 3-unit prostheses.
Materials and methods
Strain gauges were attached to four implants: two external and two internal. Thereafter, two study model were designed each type using acrylic resin. CAD-CAM was used to design hex and nonhex abutments for each group (EH, ENH, IH, and INH group) and Screw-cement-retained prostheses were also designed using a nonprecious base metal. Abutment was fixed with 10 Ncm torque, and the prosthesis was cemented. Screws were fixed with 30 Ncm torque using different three protocols. After 5 min, the strain gauge level was measured, and group analysis was performed (α=.05).
Results
External group showed significantly lower strain values than internal group and the EH group showed significantly lower strain values than the ENH group (P<.05). There was no difference in strain value based on the types of screw tightening protocols in same group (P>.05). The IH group exhibited significantly higher strain values than the INH group and the IH group showed a significant difference in strain values based on the types of screw tightening protocols used (P<.05).
Conclusion
There was no significant effect on the external type in the implant-supported, screw-retained prostheses. However, strain values were high in the internal type, and the types of screw tightening protocol significantly affected these implants.

Keyword

Screw-cement-reatined prostheses; Screw tightening protocols; Strain value