[Three-dimensional accuracy of plaster casts obtained using three impression materials].
OBJECTIVE
To evaluate the accuracy of 3 impression materials in reproductions of simian dental arches using a 3-dimensional optical digitizer.


METHODS
Two simian dental arches were prepared as the master models. Impressions were made for stone casts using three impression materials, including alginate impression materials, C-silicone materials and Impregum-Penta polyether rubber. Five plaster replication models for each master model, as well as for each impression materials were made. The master models and the casts were digitized using a 3-dimensional optical scanner and digitizer. The images of each plaster cast and its original master model were superimposed to obtain the setting cross-section volume of the dental crown. The ratios of the plaster cast volume change and discrepancy distribution patterns were analyzed.


RESULTS
Compared with the volume of the master models, the discrepancies of the plaster casts volume were -5.84%, -3.21%, and -0.63% for alginate impression materials, silicone materials and Impregum-Penta polyether rubber, respectively. The discrepancy between the master models and casts from alginate material was statistically significant (P<0.05), but not for silicone materials or Impregum-Penta polyether rubber. Maximal deviation of image fitting was located in the cervix and the gingival areas.


CONCLUSIONS
The volumes of all the plaster casts from the 3 impression material are smaller than that of the master model. Impregum-Penta polyether rubber allows the most precise and silicone material the relatively accurate reproduction of the denture model, while alginate can not. The major error areas are in the dental cervix and gingival region.
Sun
Li
L
Department of Stomatology, General Hospital of PLA, Beijing 100853, China. sunli112@sina.com
Li
Hong-bo
HB
Chu
Bing-feng
BF
D003735:Dental Casting Technique; D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D003765:Models, Dental
D003760:Dental Impression Materials