Comportamento dimensional de gessos dos tipos IV e V na confecção de modelos obtidos de moldes em duas diferentes temperaturas: 22 e 35 °C

Abstract

The experiments It was conceived with the objective of to compare the procedures of reheating moldings with the leaking of cooled molds with types IV and V gypsum.The materials used were Adsil Vigodent, Express e Impregum 3M Espe, Zeta Plus and Oranwash Zhermack. The molds passed without exception, from a temperature of 35ºC where they were obtained, to 22ºC, where they were stored. The delimitation of all experiments followed the division of the following groups as of the thermic treating: Some groups received gypsum type IV and V leaking after the reheating of the molds to 35ºC, whilst others received the same gypsums at 22ºC temperature. The selected molding technique for the first experiment was of a double-mix. The used elastomers were Impregum 3M Espe, Express 3M Espe and Adsil Vigodent, and the impressions materials were the gypsum Vel-Mix Kerrande Exadur Polidental. The statistical analysis showed a significance in the cooled impressions and leaked with type V gypsum, and that the reheating of the impressions produced adequate models when these are leaked whth type IV gypsum. On the second experiment, the used molding technique was the double molding.The molding materials were Zeta Plus and Oranwash Zhermak, Adsil Vigodent and Express 3M Espe this technique is known as double molding. The model materials were the same used in the first experiment, as well as the thermal treatment used before. Considering this technique was used in two different molding times, a relief was needed between the two steps of the procedure, calibrated to create a leap of 2mm in the interior of the dense material at the first operatory step. On this experiment, the elastomeric materials did not influence on the result, therefore being statistically equivalent. We can conclude that the variation of temperature, i.e. the reheating of the molds of the models material, substitution of the gypsum type IV for type V, were statistically significant. On the third evaluation the influence of the molding techniques against the thermal variation on the two silicones, Adsil and Express, that according to the manufacturer may be used on both double-mix and double-molding techniques, there was a notable difference on the results, where the double-mix technique had a more uniform and adequate behavior.