RESUMO
STATEMENT OF PROBLEM: Fracture and dimensional change of an acrylic resin denture are a rather common occurrence. PURPOSE: The purpose of this study was to compare differences in dimensional changes and flexural strength of separate maxillary complete dentures after immediate deflasking by injection molding and conventional compression processing. MATERIAL AND METHOD: To evaluate dimensional stability, the maxillary dentures were fabricated by using different materials and methods. Lucitone 199(Dentsply Trubyte, york, pennsylvania, USA) and Vertex(Dentimex, zeist, Netherlands) were used as materials. Compression and injection packing methods were used as processing methods. The impression surface of the dentures was measured by 3D Scanning System(PERCEPTRON, USA) and overlapped original impression surface of the master cast. To evaluate flexural strength, resin specimens were made according to the different materials, powder/liquid ratio and processing methods. Flexural strength of the complete resin specimens (64mm*10mm*3.3mm) were measured by INSTRON 467.(INSTRON, England) The data was analyzed by ANOVA, t-test and Tukey test.(p<.05 level of significance) RESULT: The results were as follows: 1. There was no significant differences between master model and denture base for each group in overall dimensional changes. 2. Palatal area was more stable than flange or alveolar area in dimensional stability. but, there was no significant differences among each area. 3. Materials and power/liquid ratio had an effect on flexural strength.(p<.05) Especially materials was most effective.(p<.05) 4. Lucitone 199(powder/liquid ratio followed by manufacturer's direction) showed higher flexural strength than Vertex. CONCLUSION: Dimensional stability or flexural strength are affected by materials rather than packing techniques.