Dimensional stability and accuracy of epoxy resin materials

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1994 (Prosthodontics).Includes bibliographical references: (leaves 89-98).In this study three epoxy resin die materials were evaluated and compared with respect to their dimensional stability and accuracy under controlled circumstances. An experimental stainless steel round test block (ADA approved) was used to produce 35 impressions which were divided into three groups: Group 1: 11 impressions were poured with 3M epoxy resin die material Group 2: 11 impressions were poured with Die-Epoxy epoxy resin die material Group 3: 13 impressions were poured with Epoxydent epoxy resin die material The distance between two vertical lines on the ruled surface of the dies was measured and compared to the same distance on their respective impressions and the standard model at different time intervals: 0, 1, 24, 48, 72 hours and 1 week by using a Nikon travelling measuring microscope. For all three die materials tested the results revealed a significant linear shrinkage with time. The effect of epoxy resins was also examined using two different resins (3M Epoxy and Die-Epoxy) in two die systems (Zeiser and Pindex). A stainless steel experimental model with four evenly spaced abutments was fabricated. Forty polyinylsiloxane (President) impressions were made of the standard model using acrylic custom trays. Twenty of these impressions were poured with 3M epoxy resin die material and twenty with Die-Epoxy resin material. They were then divided into four groups of combinations of epoxy resin dies and die systems: Group 1: Die-Epoxy / Zeiser (10 casts) Group 2: 3M / Zeiser (10 casts) Group 3: Die-Epoxy / Pindex (10 casts) Group 4: 3M / Pindex (10 casts) All groups were measured and evaluated before and after segmentation. The distance between two vertical lines on both anterior and posterior abutments was measured with a travelling measuring microscope. Both resins exhibited shrinkage before segmentation of the casts. After segmentation of the casts both materials underwent an apparent expansion