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.ObjectiveThis 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 MethodsSpecimens (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).ResultsPorosity 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.ConclusionsThe 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.

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A novel acrylic resin palatal device contaminated with Candida albicans biofilm for denture stomatitis induction in Wistar rats Denture stomatitis is the most frequent oral lesion in removable prosthesis wearers, with high recurrence rates and a complex treatment. Objective: This study describes a protocol to obtain and to contaminate a palatal device with Candida albicans biofilm that could be used for an animal model of denture stomatitis. Methodology: Acrylic resin devices (N=41) were obtained from impressions of the palates of Wistar rats with individual trays and polyether.The efficacy of microwave irradiation (MW), ultraviolet light (UV), or ultrasonic bath (US) was assessed by colony viability and spectrophotometric analyses (n=5) in order to select the most appropriate method for sterilizing the devices. Then, different devices (n=5) were contaminated with C. albicans and evaluated by CFU/mL determination, scanning electron microscopy, and laser confocal microscopy. Device stabilization was assessed with either autopolymerizing acrylic resins or a self-adhesive resin cement (n=2). The spectrophotometric data were analyzed by one-way ANOVA followed by the Tukey's HSD post-hoc test (α=0.05). Results: MW was the only method capable of sterilizing the devices, and the contamination protocol developed a mature and viable C. albicans biofilm (~1.2 x 10 6 CFU/mL). The self-adhesive resin cement was the best stabilization material. Conclusions: This acrylic resin palatal device was designed to be similar to the clinical situation of contaminated prostheses, with easy manufacturing and handling, effective stabilization, and satisfactory contamination. Thus, the acrylic device can be a valuable tool in the development of denture stomatitis in rats.

Considering the high prevalence and recurrence of Candida-associated denture stomatitis (CADS), in vivo studies in animal models are necessary before those in humans to evaluate new therapeutic strategies. This study aimed to review the literature on murine models of CADS induction using acrylic intraoral devices simulating dentures. Rats are recommended as experimental animals in these models as well as the adoption of a pasty diet. For maintenance in the proper position during the experiments, intraoral appliances must be obtained by individual impressions, using and retained exclusively by cementation on the molars. The region of interest for histopathological analysis was standardized as that corresponding to the area between the first molars. However, there is no consensus among the studies on the CADS induction rat models in relation to the Candida albicans inoculation and need for immunosuppression and/or administration of antibacterial drugs of animals. The greatest difficulty of the available models refers to maintaining the course of the lesion for a sufficient period to evaluate the effectiveness of the proposed treatment, considering the rapid and efficient murine immune response to candidal colonization. Therefore, future studies are necessary for the development of a robust and reproducible CADS model.

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The effectiveness of denture stomatitis (DS) treatment should be evaluated by associating clinical and mycological parameters. Although widely used in clinical studies, the Newton classification does not accurately represent the degree of severity of palatal inflammation in terms of extent of the lesions and intensity of the erythema. Therefore, a modified Newton classification has been proposed considering the coverage area of palatal inflammation and the erythema level. This consistent and direct ranking will help standardise randomised clinical trials, as well as the statistical comparison among blind evaluations of the obtained scores within and between studies.

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