A vitro study of retained screw stability by various connection designs between fixture and abutment in implant dentistry

Yang, Jae Sik; Vang, Mong Sook; Jo, Gyu Jong

Abstract

STATEMENT OF PROBLEM: Since the concept of osseointegrated dental implant by Branemark et al was first applied to mandibular full edentulous patients. Recently it is considerated the first treatment option on missing teeth. A common problem associated with dental implant restorations is loosening of screws that retain the prosthesis to the abutment and the abutment to the implant fixture. PURPOSE: This study is to examine the influence on screw loosening of implant-abutment designs. MATERIAL AND METHODS: External hex, cone screw, beveled hex, cam cylinder, cylinder hex by means of evaluating the loosening torques, with respect to a range of tightening torques after repeated loading. RESULT: 1. Cone screw, beveled hex groups are the highest initial tightening rate and cylinder hex, external hex groups are the lowest initial tightening rate(p<0.05). 2. Cone screw groups are the highest after repeated loading tightening rate and cylinder hex groups are lowest after repeated loading tightening rate(p<0.05). 3. Cone screw groups have the highest initial stability and final stability. 4. All groups are decreased tightening rate after repeated loading.