Alteração dimensional modelos de gesso tipo IV e V obtidos a partir de moldagem com polissulfeto, com duas espessuras
The aim of this study was to test the hypothesis of that the type of gypsum andthe thickness of the impression material influence in the dimensional alterationof prosthetic models. Master-Model of mandibular arch was confectioned, usingtwo extracted human teeth: an inferior first molar, first premolar and absence ofinferior second premolar, completed with acrylic resin teeth. The human teethhad received prepares for metal-ceramic full crown, six reference points hadbeen established in each tooth, resulting in seven measurements: mesiodistal,buccopalatine and occlusal-cervico for both, and teeth interpillars distance. Theprepared teeth had been molded by the shell technique in acrylic resin withrelief in 2 thicknesses: 0,8mm and 1,5mm, using regular polysulfide (n= 30).The moulds had been poured with three types of special plaster: natural type IV(Vel-mix), artificial (Tuff-Rock) and type V (Exadur). Three examiners measuredthe master-die and the samples in microscope of measurement with precision of1mm. The data had been analyzed statistically by means of ANOVA and test ofTukey (a=0,05), demonstrating that it did not have difference statistics infunction of the thickness of the impression material. However, significantvariation in the distance interpillars was verified on the types of gypsum andbetween these and the master-die, when dental stone type IV demonstratedmore steady behavior. The gypsums (Exadur, Vel-mix e Tuff-rock) showedvertical behavior dimensionality stable in 61% of the measures (horizontal andvertical) and significances statistics differences in 39%, representing expansion,17% to Exadur, 14% to Vel-mix and 11% to Tuff-rock.
Advisor:Alfredo Júlio Fernandes Neto; Adérito Soares da Mota; Carlos José Soares; Marcos Dias Lanza
School:Universidade Federal de Uberlândia
Source Type:Master's Thesis
Date of Publication:08/22/2006