The use of a 3D laser scanner using superimpositional software to assess the accuracy of impression techniques.
OBJECTIVE
Several studies have made comparisons in the dimensional accuracy of different elastomeric impression materials. Most have used two-dimensional measuring devices, which neglect to account for the dimensional changes that exist along a three-dimensional surface.


OBJECTIVE
The aim of this study was to compare the dimensional accuracy of an impression technique using a polyether material (Impregum) and a vinyl poly siloxane material (President) using a laser scanner with three-dimensional superimpositional software.


METHODS
Twenty impressions, 10 with a polyether and 10 with addition silicone, of a stone master model that resembled a dental arch containing three acrylic posterior teeth were cast in orthodontic stone. One plastic tooth was prepared for a metal crown. The master model and the casts were digitised with the non-contacting laser scanner to produce a 3D image. 3D surface viewer software superimposed the master model to the stone replica and the difference between the images analysed.


RESULTS
The mean difference between the model and the stone replica made from Impregum was 0.072mm (SD 0.006) and that for the silicone 0.097mm (SD 0.005) and this difference was statistically significantly, p=0.001.


CONCLUSIONS
Both impression materials provided an accurate replica of the prepared teeth supporting the view that these materials are highly accurate.
Department of Prosthodontics, Guy's, King's and St Thomas' Dental Institute, Guy's Tower, London Bridge SE1 9RT, UK.
Sinal
S
Shah
Geeta
G
Sundaram
David
D
Bartlett
Martyn
M
Sherriff
D003760:Dental Impression Materials / Q000737:chemistry*; D003761:Dental Impression Technique; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D003765:Models, Dental; D015203:Reproducibility of Results; D012117:Resins, Synthetic / Q000737:chemistry; D012680:Sensitivity and Specificity; D012828:Silicones
D003760:Dental Impression Materials; C022821:Impregum; D012117:Resins, Synthetic; D012828:Silicones; C118335:president, silicone impression material