Porosity, water sorption and solubility of denture base acrylic resins polymerized conventionally or in microwave

Abstract The proper selection of polymerization cycle is important to prevent overheating of the monomer that could cause degradation, porosity and, consequently, deleterious effects on the denture base properties. Objective This study evaluated the porosity, water sorption and solubility of acrylic resins (Vipi Cril-VC and Vipi Wave-VW) after conventional or microwave polymerization cycles. Material and Methods Specimens (n = 10) were made and cured: 1-WB = 65°C during 90 min + boiling during 90 min (VC cycle - control group); 2-M25 = 10 min at 270 W + 5 min at 0 W + 10 min at 360 W (VW cycle); 3-M3 = 3 min at 550 W; and 4-M5 = 5 min at 650 W. Afterward, they were polished and dried in a dessicator until a constant mass was reached. Specimens were then immersed in distilled water at 37°C and weighed regularly until a constant mass was achieved. For porosity, an additional weight was made with the specimen immediately immersed in distilled water. For water sorption and solubility, the specimens were dried again until equilibrium was reached. Data were submitted to 2 way-ANOVA and Tukey HSD (α=0.05). Results Porosity mean values below 1.52% with no significant difference among groups for both materials were observed. Resins showed water sorption and solubility values without a significant difference. However, there was a significant difference among groups for these both properties (P<0.013). The highest sorption (2.43%) and solubility (0.13%) values were obtained for WB and M3, respectively. Conclusions The conventional acrylic resin could be polymerized in a microwave since both the materials showed similar performance in the evaluated properties. Shorter microwave cycles could be used for both the materials without any detectable increase in volume porosity.

Montagem de modelos de próteses removíveis em articulador semiajustável / Mounting casts from removable prostheses in semi adjustable articulator

Introdução: O relacionamento dos modelos de diagnóstico ou de trabalho em articulador semiajustável é um dos procedimentos mais importantes no tratamento reabilitador com próteses removíveis parciais ou totais. Objetivo:  Este trabalho descreve as diversas etapas da montagem em articulador semiajustável em situações de dois pacientes com arcos parcial ou totalmente edêntulos. Material e método: Foram discutidos os materiais e as técnicas que são indicados para registro das relações intermaxilares, inclusive em situações diferentes dos casos apresentados. Conclusão: A montagem de modelos de pacientes parcialmente edêntulos em articulador é de grande importância e apresenta uma ampla variação de indicação de acordo com diferentes situações.

Introduction: Articulating preliminary or working casts in semiadjustable articulators is one of the most important procedures in the prosthetic rehabilitation of partially and fully edentulous patients. Objective: This work described the several steps involving mounting casts in semiadjustable articulator in cases of two patients presenting partial and fully edentulous arcs. Material and method: It was discussed the recommended material and techniques for recording the maxilomandibular positions, including a range of situations different from the presented cases. Conclusion: The fitting of models of the edentulous patients in articulator is of great importance and presents a wide range of indication according to different situations.