Análise microscópica da superfície de moldes obtidos com diferentes hidrocolóides irreversíveis submetidos à três técnicas de manipulação

Abstract

One of the causes of increased imprecision of moldings is the formation of bubbles on their surfaces during impression taking, different handling methods and compositions of the impression material may influence this unwanted phenomenon. Objective - To analyze defects (bubbles) in molds produced from three distinct manipulation techniques using two different alginate formulations. Methods - For the test the selected alginate formulations were Hydrogum® and HydrogunFive®. The techniques used were the conventional handling of Skinner & Pomes, the handling by Shelley and Alsup plastic bag technique and the vacuum handling technique. Samples were obtained in triplicate. The upper arch of a mobile dental mannequin was used as a matrix. The number of bubbles was counted using a 16-fold magnifying MC-M12ERGO® microscope, each bubble was counted within the previously delimited area in the anterior palate regardless of its size. Data were subjected to statistical analysis where a test was performed to verify normal distribution of results (Komolgorov-Smirnoff test - n> 50). After confirming the normal distribution of data, the analysis of variance (ANOVA), multiple comparisons, Student's t-test and post-Tukey tests were applied, all with a significance level of 5% using the SPSS version 19.0 software. Results - There are differences between the averages of bubbles formed by the Conventional Skinner & Pomes, Shelley and Alsup plastic bag and vacuum techniques. The vacuum technique obtained fewer bubbles and irregularities on its surface, however these differences are not statistically significant (p = 0.062). The number of bubbles formed with Hydrogum® alginate is smaller than the number of bubbles formed by Hydrogum Five® by the three spatulation techniques, but this difference is not statistically significant (p=0.491). Conclusions - The vacuum spatulation technique obtained smaller number of bubbles and irregularities in its surface being the most precise technique. The technique that most formed bubbles on the surface of the molds was the conventional technique of Skinner and Pomes. Among the six groups studied, the one that obtained the best results was the group that used Hydrogum® alginate and the vacuum manipulation technique (HT3), producing fewer surface bubbles.