Abstract
Purpose: The aim of this investigation was to evaluate and compare the dimensional accuracy of hydrophilic polysiloxane, vinyl polysiloxane (VPS), and polyether (PE) impression materials under dry, moist and wet conditions. Methods: An acrylic master model including 6 implants was formed, and 108 impressions were made up of this acrylic model at total. In this study, the materials of hydrophilic polysiloxane impression material, 1 hydrophilic vinyl polysiloxane impression material and 1 polyether impression material were tested. Twelve impression of each material were created under dry, moist and wet respectively. Two reference distances were evaluated on each study model by using a graphics-editing program whereas for comparison of mean dimensional changes one-way analysis of variance and Student t-test were used. Results: One-way analysis of variance revealed significant differences between impression materials and conditions (P P Conclusions: All impression materials showed a statistically significant difference under dry, moist and wet conditions.
Highlights
The best result is with polyether impression material under dry condition (0.15 mm-mean difference)
The accuracy of the definitive cast is affected by the accuracy of impression so that an accurate impression is necessary for the fabrication of good-fit prosthesis
When the dimensional changes in the three conditions for used material were compared, dry conditions gave a lesser dimensional change value followed by moist and wet conditions (Table 1)
Summary
An inaccurate impression may cause misfit in prosthesis, which may further result in mechanical and/or biological complications [2]-[41]. The possible mechanical complications due to misfits in prosthesis can be observed as screw loosening, screw fracture, implant fracture, and occlusal inaccuracy [2]. The internal stresses in the FPD (fixed partial denture), the implants, and the bone matrix are possibly induced by any visible or invisible misalignment of the FPD to the osseointegrated implants [8] [9]. The little mobility of osseointegrated implants is due to the “elasticity” of the investing bone [11]
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