Abstract
Objective: To compare the effect of two construction techniques and two pattern materials on the fit of resin-bonded cast restorations.
Design: In-vitro study carried out by one operator.
Setting: Postgraduate university hospital.
Subjects and Methods: 65 nickel-chrome castings were constructed using refractory die and lift-off techniques with wax and acrylic resin pattern material. They were cemented onto master silver dies, embedded in self-curing acrylic resin and sectioned along their long axes. Interfacial distance between the master silver die and casting was measured.
Results: A significant different between the range of figures in each group (Mann-Whitney Test, P < 0.01) was found. Construction techniques can be ranked in order of fit of castings: 1. Refractory die, wax patterns: 42.6 microns (SD 12.03). 2. Refractory die, acrylic resin patterns: 53.7 microns (SD.16.06).3. Conventional technique, acrylic resin patterns: 85.5 microns (SD 31.62). 4. Lift-off technique, wax patterns: 139 microns (SD 53.15).5. Lift-off technique, acrylic patterns: 172.8 microns (SD 74.04).
Conclusions: Castings constructed using refractory die technique and subsequently cemented resulted in a more accurate and less variable fit than those produced with the lift-off technique. Wax patterns lead to more accurate castings than acrylic resin and locating indentations may interfere with the cementation of castings when lift-off techniques are used
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Chana, H., Pearson, G. & Ibbetson, R. A laboratory evaluation of the construction of resin-bonded cast restorations. Br Dent J 183, 130–134 (1997). https://doi.org/10.1038/sj.bdj.4809443
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DOI: https://doi.org/10.1038/sj.bdj.4809443