The Influence of Abutment Screw Tightening
on the Screw Joint Configuration
Lisa A. Lang, DDS, MS
Rui-Feng Wang, BS
Kenneth B. May, DDS, MS
Abstract: This study examined the relationship of the abutment hexagon to the implant hexagon following tightening of the abutment screw for several abutment systems with and without the use of a counter torque device. Thirty Conical Self-Tapping Brånemark® System implants and ten wide platform Brånemark® System implants along with ten abutment samples of the CeraOne®, EsthetiCone®, Procera®, and AuraAdapt® abutments were selected for this investigation. The implants were placed in a holding device prior to tightening the abutments. When the tightening torque recommended for each abutment system was reached using a torque controller, each implant abutment sample was removed from the holding device and embedded in hard resin medium. The samples were sectioned in a horizontal direction at the level of the hexagons, and cleansed of debris prior to examination. The cross-sections were assessed for the degree and direction of rotation of the abutment hexagon in relation to the implant hexagon centroid (Fig. 1).
Fig. 1. The Degree of Rotation Was Measured
Using the Following Technique
The four abutment systems demonstrated the following mean maximum degrees of hexagonal rotation when the samples were tightened using the counter-torque device: AuraAdapt (2.92°), CeraOne (2.88°), Estheticone (2.60°), and Procera (2.37°) (Table 1).
Table 1. Range of the Maximum Degrees of Rotation
With the Use of a Counter Torque Device
Abutment System
AuraAdapt
CeraOne
EsthetiCone
Procera
Range in Degrees
-1.39 to 1.53
-0.14 to 2.74
-0.75 to 1.85
-2.26 to 0.11
Number of Degrees
2.92
2.88
2.60
2.37
The mean maximum degrees of hexagonal rotation when the samples were tightened without the counter-torque device were: AuraAdapt (1.51°), CeraOne (3.11°), Estheticone (3.28°), and Procera (3.53°) (Table 2).
Table 2. The Range of the Maximum Degrees of Rotation
Without the Use of a Counter Torque Device
Abutment System
AuraAdapt
CeraOne
EsthetiCone
Procera
Range in Degrees
0.38 to 1.13
-0.93 to 2.18
-1.47 to 1.81
-1.70 to 1.83
Number of Degrees
1.51
3.11
3.28
3.53
All abutment systems rotated to some degree following abutment screw
tightening regardless of the abutment group or whether or not the counter
torque device was used. Such randomization observed in the various test
conditions studied would suggests that rotation of the abutment hexagon
around the implant hexagon following screw tightening may in fact be the
product of the operator’s initial positioning of the abutment onto
the implant.
Conclusions: The hexagon to hexagon rotational fit of all abutment
systems studied was less than 3.5° demonstrating the precision of
fit suggested (5°) as optimal for screw joint stability. The absolute
degrees of rotation for all four abutment groups were less than 1.50°
with or without the use of the counter torque device.
Close Window to continue.