Effect of axial wall modification of short titanium abutments on the retention of implant supported zirconia crowns

Abstract

Abstract: Background: retention is an essential factor in the success of cement-retained implant supported restorations. Achieving adequate retention for short abutments (<4 mm) remains major challenge. Purpose: this study was designed to investigate the effect of modifications of short abutment in order to increase retention.

Materials and methods: 72 implant abutments were designed and milled and divided in 6 group (12 abutment each group).a control group without modification , one axial wall removal , two opposing wall , axial groove , frustum groove and circumferential groove. 72 zirconia crown were prepared using ( CAD/CAM ) to fit all abutments. All crowns were cemented with dual cure resin cement. A pull -out test using universal machine test was applied until separation

Results: the main retentive value : first group 155/93 N , second group 194/33 N, third group 201/94 N , forth group 198/55N , fifth group 191/65 N and sixth group 220/05 N. the retention of group with circumferential groove and removal of two opposing wall was significantly higher than control group ( P< 0/05) Conclusion : According to the results of study , modifications of abutment design including circumferential groove and removal of opposing wall improve the retention of zirconia restoration cemented to short abutments.