Effect of Cross-linker on Fracture Toughness of Denture Base Material

*3253 Effect of Cross-linker on Fracture Toughness of Denture Base Material*
S. KONDO¹, Y. NODASAKA², T. KAMADA², and H. SHIMOKOBE³, ¹Private Laboratory, Sapporo, Japan, ²Hokkaido University, Graduate School of Dental Medicine, Sapporo, Japan, ³Meirin College, Niigata, Japan Objective: The primary objective was to examine the effect of cross-linker on fracture toughness of PMMA/MMA-based denture base material. Methods: The cross-linkers used in the study were dimethacrylate (Gylcerine dimethacrylate, GDMA), trimethacrylate (Trimethylolpropane trimethacrylate, TMPT),and tetramethacrylate (Glycerine dimethacrylate hexamethylene diisocyanate,UTMA), as compared with monomethacrylate (MMA). The experiments were carried out for a heat-cure type PMMA/MMA-based denture base material (Acron, GC) with the liquid incorporated 1-10 contents by mol.% of three cross-linkers. Fracture toughness was measured using single-edge notched specimen defined in ASTM E399-1983. Dental flask packed at the dough stage was cured in water bath at 65 degree for 30 min and in boiling water for 1h. The specimen was wet polished with a waterproof abrasive paper (2000CC-Cw) finally and stored in a deionized water at 37 degree for 24 h. Prior to fracture toughness test, a precrack was created on the notch bottom exerting one slide under a constant hand pressure with a fresh cutter blade. Fracture toughness test was carried out at a crosshead speed of 0.5 mm/min for wet specimen in the atmosphere at 23 degree. Fracture toughness was calculated from a maximum fracture load. Results were statistically analyzed with one-way ANOVA and t-test. Results: Fracture toughness values, mean (SD) of n = 6, MPa¥m1/2 for the liquid of 10 mol.% incorporation of GDMA, TMPT, and UTMA was 1.299 (0.231), 1.376 (0.256), and 1.519 (0.166), respectively and one for MMA was 1.610 (0.148). The fracture toughness values for 10 mol.% incorporation of the three cross-linkers showed a decreased mean values as compared to one of non-cross-linked material. There was also a significant difference in the fracture toughness between GDMA and MMA (p < 0.05). Conclusion: The constraint of plastic deformation at crack tip is influenced the content, number of methacrylate and chemical structure of cross-linker.
Seq #344 - Prosthodontic Polymers 10:15 AM-11:30 AM, Saturday, 13 March 2004 Hawaii Convention Center Exhibit Hall 1-2
Back to the Dental Materials: VI - Polymer Materials-Mechanical Properties and Degradation Program Back to the IADR/AADR/CADR 82nd General Session (March 10-13, 2004)
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