Comparison of time-dependent two-dimensional and three-dimensional stability with micro-computerized tomography and wettability of three impression materials
Objectives: The objective of this study is to explore time‑dependent dimensional stability of three different elastomeric impression materials – vinyl polyether silicone (VPES), vinyl polysiloxane (VPS), and polyether (PE) – through micro‑computerized tomography (µ‑CT) imaging, allows three‑dimensional (3D) imaging and measurement without sample preparation or chemical fixation.
Materials and Methods: Thirty specimens were created using 3 mm high, 30 mm wide Teflon molds (n = 10). Specimens were scanned with µ‑CT on the 1st (T1) h and 1st (T2), 7th (T3), and 14th (T4) days. 3D models were created at the above‑mentioned times, volumetric measurements were conducted and dimensional changes were calculated. Diameters and heights of each impression material were measured with 2D analyses. Furthermore, contact angle measurements of these elastomeric impression materials were collected using the sessile drop method during and after polymerization at 0, 2, 5, 20, 60, 120, and 240 s These measurements were made on specimens (n = 10) prepared in standard sizes using a 50 µm deep stainless steel die with dimensions of 62 mm × 20 mm × 3 mm.
Results: Evaluation of the dimensional volume changes of the VPES, VPS, and PE measurements showed there to be no statistically significant differences between the T1, T2, T3, and T4 (P > 0.05). Only the decreases in the volume averages of T3 and T4 in the VPES were statistically significant (P < 0.05). As a result of binary comparisons, the evaluation of contact angle measurements of VPES, VPS, and PE materials during and after polymerization were compared. The average contact angle measurements of the VPS group were statistically significantly lower than the averages of the VPES and PE groups (P < 0.01).
Conclusions: VPS was found to be the most stable impression material concerning dimensional change and wettability.
Keywords: Contact angle, dimensional stability, elastomeric impression materials, micro‑computerized tomography