The purpose of this study was to evaluate the Shore A hardness and surface roughness of two silicones for maxillofacial prosthetic treatment, under the influence of chemical disinfection and storage. Twenty-eight specimens were obtained, half of which were made of Silastic MDX 4-4210 silicone and, the other half were made of Silastic 732 RTV silicone. The specimens were divided into four groups: Silastic 732 RTV and MDX 4-4210 with disinfection 3 times a week with Efferdent tablets and the same materials without disinfection. The hardness of the materials was analyzed with a Shore A Durometer. The surface roughness was established by a digital portable roughness tester, initially and 2 months after the confection of the specimens. A variance test was applied (2-way ANOVA), followed by Tukey test (the level of significance was set at 1%). The storage time factor statistically influenced (p < 0.01) the materials' properties of hardness and roughness. MDX 4-4210 (28.59 Shore A, 0.789 Ra) presented higher values than Silastic 732 RTV (18.08 Shore A, 0.656 Ra) for both properties. Regarding the disinfection period, there was no significant difference in any of the materials tested.

Actualmente el uso de prótesis sobre implantes se incrementó gradualmente desde el descubrimiento de la oseointegración. La indicación inicial de los implantes fue para pacientes edéntulos totales extendiéndose después para pacientes parcialmente edéntulos. Las alternativas de retención de las piezas protésicas van desde las prótesis atornilladas hasta las prótesis cementadas o por preparación de los pilares de la forma convencional. Las prótesis cementadas sobre implantes se utilizan frecuentemente en los casos donde la inclinación de los implantes imposibilita la confección de prótesis atornilladas, debido a la salida de los tornillos de fijación por vestibular o entre los espacios interdentales comprometiendo la estética, y la resistencia cuando están localizados en las cúspides oclusales de los dientes posteriores. En ese sentido, la confección de "copings" en los pilares preparados, puede tornar el tratamiento en un proceso más rápido y seguro. No obstante, pueden surgir problemas en el momento de la instalación, debido a que el intermediario puede asumir diversas posiciones en relación a la posición del implante dificultando la colocación de la prótesis definitiva, principalmente en situaciones clínicas con más de dos implantes. De este modo, el objetivo de este trabajo fue mostrar una técnica del uso de una guía para posicionamiento de los pilares protésicos en prótesis fija cementada sobre implantes, por medio de la descripción de un caso clínico.

Nowadays, the use of implant-retained prostheses has been increasing progressively since the advent of the osseointegration. The basic indication was in total edentulous patients and it was also enlarged for partially edentulous patients. Alternatives of retention could be from screw-retained implant prostheses, cement-retained implant prostheses or conventional preparations. Cement-retained implant prostheses are used frequently when the implant inclination don't allow the use of screw-retained prostheses because the screw emerge in vestibular surface or the interdental space resulting in an unaesthetic appearance and when the screw emerge on the top of the posterior cuspid teeth, diminishing the resistance. The confection of the copings on the abutments, turn the treatment faster and secure. Although, some complications can appear in the placement, because the abutment can take different positions in relation to the implant modifying the set of the prosthesis, mainly in clinical situations with more than two implants support. Thus, the aim of this study was demonstrated the use of guide to positioning of cement-retained implant prostheses, by means of a clinical case.

O objetivo deste estudo foi avaliar a alteração dimensional de bases de prótese total confeccionadas com diferentes resinas após diferentes períodos de armazenagem. Para isso foram confeccionados 25 conjuntos modelo de gesso/base de resina, utilizando-se quatro resinas acrílicas: QC-20 submetida à polimerização convencional e por energia de microondas, Vip Cril submetida à polimerização convencional, Vip Wave e Onda Cryl submetida à polimerização por energia de microondas. Após a polimerização, as amostras foram seccionadas para realização de leituras de adaptação com auxílio de um microscópio comparador. As leituras foram realizadas em três pontos: crista do rebordo direito (A) e esquerdo (B), e região mediana do palato, em quatro diferentes períodos. Os resultados foram submetidos à análise de variância e ao teste de Tukey com nível de significância de 5%. A pior adaptação foi verificada na região palatina posterior da base (M) com diferença estatisticamente significante (p<0,05) para as resinas estudadas. Todas as bases de resinas apresentaram alteração dimensional e o período de armazenagem foi um fator que influenciou essa alteração.

The aim of this study was to evaluate the dimensional changes of denture bases made from different resins after different storage periods. For this purpose, 25 sets of plaster models/resin bases were prepared using 4 acrylic resins submitted to two types of polymerization: 1- QC-20 submitted to polymerization by microwave energy; 2- QC-20 submitted to polymerization by water hot bath; 3- Vipi Cril submitted to polymerization by water hot bath; 4- Vipi Wave submitted to polymerization by microwave energy; and 5- Onda Cryl submitted to polymerization by microwave energy. After polymerization, the specimens were sectioned for accuracy readings using a comparison microscope. Readings were taken at 3 points: the crests of the right (A) and left (B) ridges, and the median region of the palate, in 4 different periods. The data obtained were submitted to two-way ANOVA and Tukey's test at 5% significance level. The greatest distortions were found in the posterior palatal region of the base (M), with statistically significant difference (p<0.05) for the studied resins. All acrylic resins presented dimensional changes and the storage period influenced these alterations.