Removal resistance of locking taper implant-abutment connections at different strike numbers: An in vitro study

The consistency of the placement force provided by striking friction-locked abutments remains uncertain.

The purpose of this in vitro study was to evaluate different strikes and repeated reconnection-disconnection cycles on the connection strength of a locking taper implant system with varying wells.

Sixty-three implant-abutment replica specimens (IARSs) with 2-, 2.5-, and 3-mm wells with a 1.5-degree locking taper design were fabricated from grade 5 titanium (Ti). Specimens were divided into 3 striking groups (3T, 6T, 12T, n=21/group) and 3 well subgroups (3T2, 3T2.5, 3T3; 6T2, 6T2.5, 6T3, and 12T2, 12T2.5, 12T3, n=7/subgroup). For subgroups 3T2, 3T2.5, and 3T3, the abutments were seated in the implants with finger load and then struck 3 times with a calibrated striker. The abutments were then disconnected using rotational movements and the removal torque values were recorded with a digital torque meter in newton centimeter (Ncm). This seating, striking, and removal cycle was repeated 7 times by the same operator. The same procedure was applied to the second and third subgroups with 6 and 12 strikes respectively. ANOVA and post hoc Bonferroni tests were used to analyze the data. Repeated measures ANOVA with the Greenhouse-Geisser correction was applied when the sphericity assumption was violated (α=.05).

Removal torque values varied significantly with well diameter and the number of strikes (P<.001), peaking at 3 mm with 12 strikes. Torque values were statistically similar after repeated disconnection-reconnection cycles (P>.05).

Although wider wells and higher striking cycles tended to increase the removal torque and repeated disconnection-reconnection tended to decrease it, the values remained statistically similar.