Three-dimensional analysis of dual-arch impression trays.
OBJECTIVE
The objective of this investigation was to measure and compare the dimensions of casts made using four types of impression trays and two impression materials to the dimensions of the original master model. This study differed from previous studies by using three-dimensional measurement.


METHODS
Vinyl polysiloxane and polyether impressions were made of two crown preparations of ivorine teeth cemented into an acrylic master model. Two grooves were placed into each of the preparations. In addition, six points were placed on each occlusal surface and six were placed on each finish line. Impressions were poured with a Type IV dental stone at 48 hours. A three-dimensional measuring system was used to determine coordinates of 32 points on the master model and resulting casts. Inter- and intratooth dimensions were calculated from the measured coordinates.


RESULTS
The accuracy and precision of the impression techniques were assessed using analysis of variance (ANOVA) and Dunnett's t test. The ANOVA and Dunnett's t test indicated that only the custom tray did not detect any inaccuracies and was as reproducible as the master model.


CONCLUSIONS
This study suggests that the custom tray technique is most accurate, even though all other techniques evaluated apparently produce clinically acceptable results.
Medical University of South Carolina, College of Dental Medicine, Department of Prosthodontics, Charleston, South Carolina 29425, USA. cayouetm@musc.edu
Monica J
MJ
Cayouette
John O
JO
Burgess
Robert E
RE
Jones
Cheng H
CH
Yuan
D000704:Analysis of Variance; D002119:Calcium Carbonate; D003760:Dental Impression Materials; D003761:Dental Impression Technique / Q000295:instrumentation*; D004987:Ethers; D006801:Humans; D021621:Imaging, Three-Dimensional; D003765:Models, Dental; D011145:Polyvinyls; D015203:Reproducibility of Results; D012833:Siloxanes
D003760:Dental Impression Materials; D004987:Ethers; D011145:Polyvinyls; D012833:Siloxanes; C034183:vinyl polysiloxane; D002119:Calcium Carbonate