Evaluation of impression accuracy for osseointegrated implant supported superstructures.
BACKGROUND
An often-debated issue still exists concerning implant impression techniques, whether to splint impression copings. Different configurations are available for these copings for a variety of manufacturers' implant systems.


OBJECTIVE
This study evaluated and compared 4 impression techniques in terms of their dimensional accuracy to reproduce implant positions on working casts.


METHODS
A master model was designed to simulate a clinical situation. Impressions were made using 4 techniques: (1) tapered impression copings not splinted; (2) squared impression copings not splinted; (3) squared impression copings splinted with autopolymerizing acrylic resin; and (4) squared impression copings with a lateral extension on one side not splinted. Reference points machined onto the master model and onto special healing abutments were compared after abutments were transferred to casts using the 4 techniques. Measurements were made using a Reflex microscope, capable of recording in the x-, y-, and z-dimensions.


RESULTS
The dimensional accuracy was high and, although statistically significant (P =.022; power > 80%), a maximum distortion difference of only 0.31% was registered.


CONCLUSIONS
The dimensional accuracy of all the techniques was exceptional and the observed differences can be regarded as clinically negligible.
Herbst
D
D
Faculty of Dentistry, University of Pretoria, Pretoria, South Africa.
Nel
J C
JC
Driessen
C H
CH
Becker
P J
PJ
D000704:Analysis of Variance; D003198:Computer Simulation; D000044:Dental Abutments; D003761:Dental Impression Technique; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D006801:Humans; D003765:Models, Dental; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric