الفهرس 
Denture Base MaterialOnly 14 pages are availabe for public view
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Abstract
This study was carried out on four groups of upper acrylic dentures. Group 1, included upper unrelined dentures, Group 2, included upper dentures relined by heat cured acrylic resin, Group 3, included upper dentures relined by self cured acrylic resin, Group 4, included upper dentures relined by resilient silicone based permanent liner, (Molloplast –B).
Dentures were constructed on a standard stone model. First, a metal spacer 2mm in thickness (thickness of relining material) was constructed on the stone model. The stone model was duplicated into acrylic resin cast. The surface of the acrylic cast was covered by a uniform layer of silicon rubber base to simulate the oral mucosa.
Two sheets of vacuum formed base plate material were adapted directly on the stone model to form the trial denture base of the first group dentures. While for the second, third and fourth groups only one sheet of base plate was adapted to the stone model. Wax rim was placed on the trial denture base, teeth were set up and waxing up was then carried out to obtain a waxed-up denture.
A stone key was formed to act as a guide for duplication of twenty three waxed-up dentures.
The waxed-up dentures for the second, third and fourth groups were placed on the metal spacer and flasked. Then the metal spacer was removed, the relining material was packed, and then processing was carried out. The waxed-up dentures for Group 3 were processed. The finished dentures were relined with self cure resin.
A specially constructed metal load applicator was then mounted to the upper jaw of the universal testing machine. The load applicator was attached to the dentures in the planed position at the premolar molar area. An acoustic sensor was placed at the mid palatal area of the dentures for counting the acoustic events. Load was applied till midline fracture occurred.
Statistic results for deformation and work at failure showed that Molloplast-B relined dentures required more load to fracture. As regards acoustic emission, self cure relined dentures recorded the highest value than the other groups of dentures. However, no statistical significant difference was noted between Molloplast-B relined dentures and self cure relined dentures when measuring acoustic emission at failure.
To assess the gap distance between acrylic base and different relining materials, three groups of rectangular heat cure acrylic resin samples having the same denture thickness were constructed. The samples were relined with heat cure acrylic resin relining material, self cure acrylic resin relining material, and Molloplast-B relining material. Also, samples were taken from the fractured relined dentures. Samples were tested under the stereomicroscope to assess the gap distance. The results revealed no gap distance in both the constructed samples and samples from the fractured relined dentures.