An Approach to Determine the Scannability of Dental Impression Materials

Objective: Aim of this study was to develop a method for measuring the scannability of impression materials in commercial red-light impression scanners. STL (surface tesselation language) files created by the scanners define the surface of 3D objects as triangles. Here we present a first approach and initial measurements to describe the scannability of impression materials as the ratio of number of triangles and surface.

Method: Impressions of the same model dye (Frasaco) made with four materials - polyether (ImP, Impregum Penta,3M ESPE,#441251-Base,#417456-Katalyst), vinyl polyether silicone material optimized for scannability (IdS, Identium Scan Heavy,#110141-05/Identium Scan Light,#110021,Kettenbach), and two vinylpolysiloxane materials (AqX,Aquasil UltraXLV,Dentsply;#100803, T1A,Take1Advanced LightBody FastSet,Kerr,#0-1124) - were scanned in a red-light impression scanner (iSeries, Dentalwings,n=5). STL files were analyzed with 3D software (3D-Tool-FreeViewer).

Result:  The ratio of the number of triangles in the STL file and the surface of the impression scan was calculated (table). All data were analyzed by 1-way-ANOVA with general linear model and pairwise comparison using Tukey test (p<0.05). All materials were found to be significantly different from each other.

 

Material:	ImP	IdS	AqX	T1A
Triangle/Surface-Ratio	52.3 (1.23)b	47.6 (0.32)a	61.9 (0.40)c	74.6 (1.71)d

 Conclusion: Within the limitation of this study it can be concluded that a low Triangle/Surface-Ratio indicates good scannability. More triangles in relation to a constant surface will be generated when a material is harder to scan. The Surface/Triangle-Ratio was lowest for the scannable material IdS, followed by ImP. Standard VPS impression materials showed less scannability. Further investigations are needed to better understand the scannability of dental impression materials especially in a clinical setting.