Avaliação da Alteração Dimensional entre um Silicone de Polimerização por Adição e Outro por Condensação
Evaluation of dimensional changes between an addition silicone and a condensation silicone impression material
Nishioka, R.S.; Almeida, E.E.S.; Andreatta Filho, O.D.; Balducci, I.
Rev. odontol. UNESP, vol.29, n1-2, p.93-104, 2000
Resumo
O objetivo deste trabalho foi comparar as alterações dimensionais que ocorreram em modelos de gesso após 24 horas e sete dias da moldagem. Utilizamos um silicone de polimerização por reação de adição (Elite-Zhermack) pela técnica de moldagem dupla e um silicone de polimerização por reação de condensação (Optosil-Xantopren-Heraues-Kulzer) pela técnica massa/fluido. Em um modelo de resina acrílica de uso laboratorial, dois preparos protéticos foram realizados, simulando um caso de prótese parcial fixa convencional. Foram confeccionadas trinta moldeiras individuais para serem utilizadas com os diferentes materiais. Os modelos obtidos em gesso tipo IV (Durone-Dentsply) e o modelo mestre de resina foram mensurados em locais predefinidos e em diferentes áreas, utilizando uma máquina de medir por coordenadas (Societe-Genevoise) e um projetor de perfis (Jones & Lamson) no Laboratório de Metrologia Dimensional (IFI-CTA – São José dos Campos). Os valores da alteração dimensional (%) dos modelos obtidos foram submetidos ao teste ANOVA de Kruskal-Wallis em nível de significância de 5%, revelando que, nas distâncias interpilares, as mensurações obtidas no gesso foram sempre maiores do que o modelo mestre em resina, contudo, nas mensurações das caixas, todas as mensurações foram menores que o modelo original, não importando a categoria do material. Sendo assim, esses materiais possuem comportamentos demensionais diferentes, que dependem do local em que estão contidos.
Palavras-chave
materiais dentários, materiais para moldagem odontológica, propriedades, elastômeros de silicone
Abstract
Prosthesis confection depends on various steps that have to be accurately followed, in order to obtain a sucessful work. The addition silicones are impression material that allow an easy manipulation and excellent physical properties. The condensation silicones besides not being practice, continually eliminate a sub-product of its polymerization reaction, the etanol, originating molds with questionable dimensional stability. The objective of this work was to compare the dimensional changes, in models after time re-commended by the manufacturer and after seven days. We have used an addition silicone (Elite-Zhermack) by one-stage impression technique, and a condensation silicone (Optosil-Xantopren-Heraues-Kulzer) by two-stage impression technique. Two prosthetic preparations were accomplished in a laboratorial acrylic model simulating a situation of conventional partial prosthesis. It was confectioned 30 custom-made trays to be used with the diffe-rent materials. The models obtained in dental gypsum type IV (Durone-Dentsply) and the resin model, were measured at pre-determined places and in different areas using a coordinates measuring machine (Societe-Genevoise) and a projector of profiles (Jones & Lamson), in the Dimensional Metrology Laboratory (IFI-CTA – São José dos Campos). Data obtained from dimensional changes (%) of the obtained models, were submitted to ANOVA test from Kruskal-Wallis, with a level of significance of 5%, revealing that dimensional changes of interabutment distances of dental gypsum model were increased when compared with resin original model, although dimensional changes in the boxes were decresed, no matter the kind of material used. We conclude that these materials have different dimensional behaviour depen-ding on the place they are.
Keywords
Dental materials, dimensional stability, silicone condensation, silicone addition
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