Influence of the implant-abutment connection design and diameter on the screw joint stability.
OBJECTIVE
This study was conducted to evaluate the influence of the implant-abutment connection design and diameter on the screw joint stability.


METHODS
Regular and wide-diameter implant systems with three different joint connection designs: an external butt joint, a one-stage internal cone, and a two-stage internal cone were divided into seven groups (n=5, in each group). The initial removal torque values of the abutment screw were measured with a digital torque gauge. The postload removal torque values were measured after 100,000 cycles of a 150 N and a 10 Hz cyclic load had been applied. Subsequently, the rates of the initial and postload removal torque losses were calculated to evaluate the effect of the joint connection design and diameter on the screw joint stability. Each group was compared using Kruskal-Wallis test and Mann-Whitney U test as post-hoc test (α=0.05).


RESULTS
THE POSTLOAD REMOVAL TORQUE VALUE WAS HIGH IN THE FOLLOWING ORDER WITH REGARD TO MAGNITUDE: two-stage internal cone, one-stage internal cone, and external butt joint systems. In the regular-diameter group, the external butt joint and one-stage internal cone systems showed lower postload removal torque loss rates than the two-stage internal cone system. In the wide-diameter group, the external butt joint system showed a lower loss rate than the one-stage internal cone and two-stage internal cone systems. In the two-stage internal cone system, the wide-diameter group showed a significantly lower loss rate than the regular-diameter group (P<.05).


CONCLUSIONS
The results of this study showed that the external butt joint was more advantageous than the internal cone in terms of the postload removal torque loss. For the difference in the implant diameter, a wide diameter was more advantageous in terms of the torque loss rate.
Department of Prosthodontics, Dental Research Institute, Pusan National University, Yangsan, Republic of Korea.
Hyon-Mo
HM
Shin
Department of Prosthodontics, Dental Research Institute, Pusan National University, Yangsan, Republic of Korea.
Jung-Bo
JB
Huh
Department of Prosthodontics, Dental Research Institute, Pusan National University, Yangsan, Republic of Korea.
Mi-Jeong
MJ
Yun
Department of Prosthodontics, Dental Research Institute, Pusan National University, Yangsan, Republic of Korea.
Young-Chan
YC
Jeon
Head and Neck Institute, Cleveland Clinic, Cleveland, Ohio, USA.
Brian Myung
BM
Chang
Department of Prosthodontics, Dental Research Institute, Pusan National University, Yangsan, Republic of Korea.
Chang-Mo
CM
Jeong
External butt joint connection; Internal connection; Platform switching; Postload removal torque value