Despite the large number of studies addressing the effect of microwave polymerization on the properties of acrylic resin, this method has received limited clinical acceptance. This study evaluated the influence of microwave polymerization on the flexural strength of a denture base resin. A conventional heat-polymerized (Clássico), a microwave-polymerized (Onda-Cryl) and a autopolymerizing acrylic (Jet) resins were used. Five groups were established, according to polymerization cycles: A, B and C (Onda-Cryl, short cycle – 500W/3 min, long – 90W/13 min + 500W/90 sec, and manufacturing microwave cycle - 320W/ 3 min + 0W/3 min + 720W/3 min); T (Clássico, water bath cycle – 74°C/9h) and Q (Jet, press chamber cycle – 50°C/15 min at 2 bar). Ten specimens (65 x 10 x 3.3mm) were prepared for each cycle. The flexural strength of the five groups was measured using a three-point bending test at a cross-head speed of 5 mm/min. Flexural strength values were analyzed by one-way ANOVA and the Tukey's test was performed to identify the groups that were significantly different at 5% level. The microwave-polymerized groups showed the highest means (p<0.05) for flexural strength (MPa) (A = 106.97 ± 5.31; B = 107.57 ± 3.99; C = 109.63 ± 5.19), and there were no significant differences among them. The heat-polymerized group (T) showed the lowest flexural strength means (84.40 ± 1.68), and differ significantly from all groups. The specimens of a microwavable denture base resin could be polymerized by different microwave cycles without risk of decreasing the flexural strength.

The purpose of this study was to evaluate the relationship between Candida and denture wear during the night. Twenty-four edentulous volunteers were randomly divided into two groups. Group I (GI, n = 11) was composed of volunteers who wore their complete dentures day and night and Group II (GII, n = 13) was composed of volunteers who wore their complete dentures only during the day. Three examination periods were performed for both groups. In GI, the first examination (A) was carried out after overnight denture wearing. Subsequent examinations were conducted after one (B) and seven nights (C) without denture use during sleep. In GII, the first (A) was done without previous use during sleep, and the following were carried out after one (B) and seven nights (C) of overnight denture wearing. Total unstimulated saliva was collected in a sterile container and cultured in duplicate inside Petri dishes. The values of colony forming units (CFU mL(-1) +/- s.d.) were obtained: GI A - 10.1 x 10(3) +/- 1.2 x 10(4), B - 2.0 x 10(3) +/- 2.6 x 10(3), and C - 2.6 x 10(3) +/- 5.9 x 10(3) and GII: A - 0.4 x 10(3) +/- 0.6 x 10(3), B - 9.4 x 10(3) +/- 17.7 x 10(3) and C - 6.3 x 10(3) +/- 15.3 x 10(3). The mean counts for Candida sp. were expressed as log (CFU + 1) mL(-1) and statistical significance of differences among groups was tested by anova (alpha = 0.05). Multiple comparisons were performed according to Bonferroni test and indicated significant differences between A-B and A-C, but not between B and C for both groups. It was concluded that there is a significant relationship between continuous denture wear and Candida sp.

Complete denture wearing and fractures among edentulous patients treated in university clinicsObjective: The prevalence of wearing and fracture of complete dentures was evaluated among edentulous patients treated in two dental schools in Brazil. Background: Acceptance and wearing of complete dentures are related to adaptive behaviour of edentulous patients. However, one reason that could interfere with the wearing dentures is their potential to fracture, which is still a common complication in denture rehabilitation practice. Results: Almost 26% of the patients did not wear their dentures, and among the remainder, the majority wore the maxillary denture. About 30% of the dentures were fractured, with higher prevalence in the maxillary arch (p = 0.003). Conclusions: Discontinuation of wearing dentures was quite high, especially considering the treatment which was carried out in university clinics. Prevalence of fractures was also high, greater for the maxillary denture, and was one of the main reasons for non-wearing of complete dentures.

These findings may contribute to the development of oral care products containing tyrosol and farnesol to combat oral infections caused by Candida species.

No abstract

AgNPs associated or not to calcium glycerophosphate produced by a 'green' process may be a promising novel antimicrobial agent against oral microorganisms.

After complete denture insertion, edentulous patients usually present transitory difficulties. This is one of the most critical stages of prosthetic treatment and it is strongly related to the prostheses acceptance. The aim of this study was to evaluate potential changes in the mandibular movement pattern related to insertion of the complete denture during the functional adaptation period. The kinesiograph instrument K6-I (Myotronics Research Inc., Seattle, WA) was used to evaluate eight edentulous patients that received conventional complete denture treatment. Recordings of opening and closure movement limits, movement velocity, postural rest position, chewing cycle and limits of eccentric movements were performed. Each patient was evaluated in four different stages: with the old dentures, immediately after insertion of the new dentures, and 30 days and 6 months after insertion of the dentures. The results showed that there were no remarkable changes in the mandibular motion patterns after insertion of the new dentures. It was suggested that the problems related to the process of utilization of new dentures are not strictly associated to the mandibular movement. Therefore, functional adaptation after denture insertion is not directly related to functional changes, but to the quality of the dentures and to individual features.

Fraturas em bases de resina acrílica representam um problema nas reabilitações com próteses totais. Várias pesquisas vêm sendo desenvolvidas buscando-se melhorar a resistência das resinas acrílicas, utilizando, para isso, novos métodos de processamento. O objetivo desse trabalho foi avaliar a influência de dois ciclos de polimerização por microondas sobre a resistência à flexão de um tipo de resina acrílica. Para isso, três grupos foram avaliados (A, B e C), utilizando-se para todos eles a resina acrílica termopolimerizável convencional Clássico. Em dois grupos polimerizou-se a resina acrílica em forno de microondas (Continental AW-30) nos seguintes ciclos: Grupo A) 3 minutos a 500W e Grupo B) pré-polimerização com a mufla posicionada verticalmente por 13 minutos a 90W e polimerização final por 90 segundos a 500W com a mufla na horizontal. O Grupo C foi polimerizado em banho de água quente por 9 horas a 74ºC e utilizado como controle nessa pesquisa. Os corpos-de-prova (n= 9 por grupo) foram submetidos ao ensio de flexão de três pontos na máquina para ensaios mecânicos MTS-810. As médias de resistência flexural (MPa) para os grupos A, B e C foram 101,27 (±12,31),90,66 (±7,56) e 85,06 (±17,50), respectivamente. A análise de variância mostrou diferença significativa entre os grupos avaliados, sendo esta evidenciada entre os grupos A e C através do teste de Tuckey (p<0,05). Concluiuse, dessa forma, que a resina acrílica termopolimerizável convencional Clássico pôde ser polimerizada pela energia de microondas, sem prejuízo à propriedade mecânica avaliada.