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| Author(s): |
Gisseli Bertozzi de Avila
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2009-08-27 |
| Examining board members: |
Heitor Panzeri;
Rossana Pereira de Almeida Antunes;
Fabiano Perez;
José Carlos Rabelo Ribeiro;
Camila Tirapelli
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| Advisor: | Heitor Panzeri |
| Abstract | |
This study evaluated the high performance polyurethane resin 6470 and hardener Dt 082 (Huntsman Advanced Materials Química Brasil Ltda., supplied by Maxepoxi, Santo Amaro, São Paulo, Brazil) loaded with 30 % diatomite, for use in dental modeling. The material was manipulated in the ratio of 1:8 between resin and hardener, with the addition of the polyurethane accelerator in the proportion of one drop for each 200 grams of resin. Samples of pure resin, modified with diatomite type IV plaster (Fuji Rock EP), GC America Inc-USA, were obtained for the following tests: resistance to compression; diametral compression test ASTM D 695 2(a) to obtain tensile strength, and resistance to fracture by impact ISO 179-1: 2000., three point bending flexural test (ISO 1567:1999); resistance to wear by abrasion, Standard ASTM D 4060. Samples were analyzed with regard to dimensional behavior in a profile projector (Mitutoyo PJ-A3000 Japan); surface roughness Ra, and capacity to copy details were analyzed in a Roughness meter (Mitutoyo Surftest SJ-301 - Japan), surface hardness was analyzed in a Sussen Wolpert durometer Type Tester HT1, with the Rockwell Hardness method. The compatibility of the resin with molding elastomers was analyzed by the criteria of modeling material adherence to the mold and color alteration of the model obtained. The resistance to compression test and diametral compression test for tensile strength were performed in a Universal Test Machine EMIC DL2000, with a 2000 Kgf load cell and speed of 1.3 mm/min. The bending flexural test was performed in the same equipment with a distance of 52 mm between the supports, 2000 Kgf load cell and speed of 5 mm/min. The resistance to fracture by impact was tested in a CEAST Impact Machine model Resil 25 using the Charpy type test. The test for resistance to wear by abrasion was performed in a TABER abrasimeter, which determines the loss of mass per 1000 cycles, using the standard CS-17 abrasive wheel (grindstone) with a 1000g load, ASTM D 4060. The data obtained were statistically analyzed by the analysis of variance and Tukey tests at the level of significance of 95%, and it was verified that: The pure or diatomite-modified polyurethane resin, considering the two criteria adopted, is compatible with condensation and addition silicone; the copying capacity of the resin was reduced with the addition of diatomite, but remained superior to that of type IV plaster; the diatomite interfered in the surface roughness of the polyurethane resin, but the values were lower than those presented by the type IV plaster; diatomite added to the polyurethane resin increased the surface hardness, resistance to compression, traction resistance to diametral compression, resistance to wear by abrasion, impact, and to three point bending flexure. The pure and diatomite-modified polyurethane resin were superior to type IV plaster for resistance to compression, traction resistance to diametral compression, resistance to wear by abrasion, impact and three point bending flexure. Similar dimensional behavior was verified for type IV plaster and diatomite-modified polyurethane resin; the pure resin contracted, and the diatomite reduced polyurethane resin contraction. Conducting this study enabled the following conclusions to be drawn: The pure or diatomite-modified polyurethane resin is compatible with the condensation and addition silicone elastomers; the diatomite load of silicone percent increases the surface hardness, resistance to compression, traction resistance to diametral compression, resistance to fracture by impact, resistance to three point bending flexure, and resistance to wear by abrasion of polyurethane resin; when polyurethane resin is modified with 30% diatomite it has a dimensional behavior similar to that of type IV plaster; the diatomite reduced the polyurethane resin capacity to copy and increased its surface roughness, but the loaded resin presented less surface roughness and greater capacity to copy than the type IV plaster; in view of the results found by modifying the polyurethane resin with 30% diatomite, it is feasible to use this material in dental modeling. (AU) | |