Volume Error of The Abutment Teeth by Laboratory Impression Scanning

Objectives: The purpose of this study was to evaluate the volume error of the abutment teeth in the direct 3D optical scanning of the silicone dental impression compared with the scanning of the stone cast.
Methods: The artificial tooth of maxillary left central incisor (21) and mandibular right first molar (46) were prepared for CAD/CAM prosthesis. For each of 21 and 46 tooth, 6 silicone bite impressions were taken on the typodont, and 6 stone definitive casts were fabricated. The original abutment teeth (21 and 46), silicone bite impressions and stone casts were measured by the blue LED scanner and the STL morphological data were obtained. The STL data of the original abutment tooth was superimposed on the die of impression and the die of stone cast using the marginal area .The volume of the protrusion and recession part of the die compared with the original abutment tooth were calculated, and the sum of them was defined as the volume error. For each of 21 and 46 tooth, comparison of the volume error between the die of impression and the die of stone cast were carried out. The paired t-test was used for statistical analysis.
Results: No significant differences was observed in the average of the volume error between the die of impression and the die of stone cast for both of 21 and 46 tooth (p 〉.05). The volume of the protrusion part was larger and recession part was smaller for the die of impression compared with the die of stone cast.
Conclusions: We concluded that the negative shape of the die of impression was measured slightly larger than the positive shape of the die of stone cast.