Adaptation of PMMA/divinyl adipate resin for denture base

Objective: It has been reported that a new powder-liquid type material using the elastic paste prepared by the mixing poly methyl methacrylate (PMMA) powder and a divinyl adipate (DVA) liquid has high flexural property. This investigation seeks to evaluate the adaptation of PMMA/DVA resin for denture base material in comparison with conventional acrylic denture base resin.

Method: The reproducing occlusion rim was fabricated on maxillary working cast. The elastic paste was prepared by mixing of PMMA powder (Acron, GC) and DVA or MMA liquid at P/L ratio of 2.3 (g/ml). The samples (n=6 for each) were polymerized at 70 °C for 30 minutes and 100 °C for 30 minutes. After deflasking, polymerized occlusion rim was replaced on the respective working cast, and embedded in plaster. For the posterior palate border gap measurements, the embedded occlusion rim and working cast was trimmed coronally to 14mm away from the posterior end of working cast using a cutting machine (BS-3000, EXAKT). The adaptation was measured by the posterior border gaps at mid-palatal area. And linear polymerization shrinkage was measured by dimensional change between 5x5x65 mm wax and polymerization specimens (n=6 for each).

Result: Posterior border gap of PMMA/DVA resin was 388±59 µm, and that of PMMA/MMA resin was 398±92 µm. The linear polymerization shrinkage of PMMA/DVA resin was 0.54±0.08 %, and that of PMMA/MMA resin was 0.47±0.03 %. There was no significant difference in the adaptation accuracy between PMMA/DVA resin and PMMA/MMA resin.

Conclusion: It was suggested that PMMA/DVA resin has adaptation accuracy for denture base material.