Evaluation of the dimensional stability of epoxi resins for full arch reconstruction
Date
1981
DOI
Authors
Ghirri, Hussein Said
Version
OA Version
Citation
Abstract
The continuous search for new improved die materials is a necessity for crown and bridge work. All existing materials used for dies at the pre sent time suffer from one or more shortcomings. The now widely used epoxy die resins have only been investigated fairly recently.
The objective of this study was to evaluate the dimensional stability of two epoxy die resin systems compared to dental stone. In addition, the surface reproducibility in combination with various impression materials was investigated by means of scanning electron microscopy.
An experimental stainless steel model was made in a machine shop. On this model, which was horseshoe shaped and had four abutments, 30 individual trays of resin were fabricated. These trays were used for im pressions with the following impression materials: Polysulfide, Polyether, Silicone and Vinyl polysiloxane. These models were poured in two epoxy resin materials and dental stone. After the models were retrieved, measure ments were made immediately upon separation according to a predetermined system and after 24 hours, 7 days, 14 days and 28 days, additional measurements were made to determine dimensional stability. Repruction of detail was evaluated by imprinting an experimental model containing Knoop hardness indentations. The quality of reproduction was examined by means of scanning electron microscopy.
The results indicated that the die systems including dental stone suffered from dimensional instability. All epoxy dies contracted due to polymerization shrinkage and all models from dental stone underwent dimensional changes as well.
Certain impression materials in combination with particular die materials produced better dies than other systems. Many times a surface reaction between impression material and die system was observed resulting in a soft sticky surface, unsuitable for clinical practice.
It can be concluded from this study that dimensional changes took place in all die materials tested. Some epoxy resin systems exhibited superior qualities compared to other systems. It is recommended that epoxy dies are used within 7 days after separation.
More research should be devoted to developing an improved material for use of dies in crown and bridge work.
Description
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Colored photographs included.
Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1981 (Prosthodontics)
Bibliography : leaves 87-91.
Colored photographs included.
Thesis (M.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1981 (Prosthodontics)
Bibliography : leaves 87-91.
License
This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.