Influence of impression techniques and impression materials, pouring time and casting materials in three-dimensional accuracy of gypsum casts

Author(s)

Aion Mangino Messias

• Document type: Doctoral Thesis
• Press: Araraquara. 2019-08-27.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2019-08-02
• Advisor: José Maurício dos Santos Nunes Reis

Abstract

This study analyzed the accuracy of total gypsum casts obtained from different casting techniques and materials, casting times and materials, taking into account the measurements of area, volume and angulation in the X, Y and Z axes of reference points specific master model (baseline), in the impression and, later, in the gypsum casts of each experimental condition. A master model was used with teeth 14, 16, 21 and 25, with punctual demarcations on its occlusal surfaces, which functioned as reference points. Three impression techniques were performed: (T1) simultaneous mixing, (T2) relining-relief with PVC film and (T3) chairside digital impression - Cerec Conect Omnicam (Sirona). For each impression technique / casting time, 8 total impression were obtained by single calibrated operator (ICC = 0.99), with metal stock tray and condensation silicone (Speedex; Coltène / Whaledent Inc.) or addition (Express XT 3M ESPE). The gypsum casts pouring process were performed with type IV conventional gypsum (GC Fuji Rock EP - GC America) and zero expansion one (Zero Stone - Dentona AG). For impressions with condensation silicone the cast was poured after 30 minutes, 3 or 7 days. For the addition silicone impressions, the gypsum casts were obtained after 2 hours, 3, 7 or 15 days. For the three-dimensional analysis, a software was used to manage threedimensional images (Rhinoceros - version 5.3.2) allowing the investigation of virtual images (three-dimensional meshes) made with an optical laboratorial digitizer (R700 - 3Shape A/S) of the impressions and gypsum casts from T1 and T2, as well as, digital images acquired from T3. It were verified the results regarding the sample number with statistically significant power, distribution of the sample data and homoscedasticity. Afterwards, statistical methods were used (ANOVA 3-way and post hoc Tukey HSD) to evaluate the influence of the independent variables of the study, with significance level of 5.0%. Overall, as for the impressions results, the majority of the comparisons from the gypsum casts results did not present statistics differences between them. It is concluded that there is no difference between the experimental and baseline groups, for the precision of the impressions and gypsum casts obtained, regardless the impression technique, pouring time and type of gypsum stone used. (AU)

• FAPESP's process: 15/12387-2 - Influence of impression materials and techniques, times and pouring materials in dimensional accuracy of total casts by contact scanner and marginal adaptation of infrastructure in Y-TZP
• Grantee: Aion Mangino Messias
• Support Opportunities: Scholarships in Brazil - Doctorate