Acurácia dos métodos convencionais e digitais para obtenção de moldagem dentária e impressões 3D

Abstract

This work aimed to evaluate and compare the accuracy of digital models generated by two intraoral scanners and to evaluate and compare the accuracy of conventional models and 3D printed models. In Chapter 1 of this study, 25 models were made and divided into digital models, 3D printed models and conventional gypsum models. To obtain the samples, a reference model was used that had the teeth 16 and 14 prepared to receive a fixed partial prosthesis. In this way, the digital models were constructed from an experienced operator who used two different intra-oral scanning systems (Cerec Omnicam and Trios 3 Shape) to scan the reference model. These digital models were saved in the "surface tessellation language" (STL) format and sent to a 3D printer (Zenith D) for manufacturing. The conventional gypsum models were manufactured by impression with elastomeric material of the reference model. In order to analyze the accuracy (trueness and precision) of the models, a software (Geomagic Control 2015) was used. Therefore, all physical models, including the reference model, were scanned by an extra oral scanner whose accuracy is 5m (D2000, 3 Shape) and saved in the STL format. The trueness analysis was performed for all groups considering the complete arch, partial arch and only the tooth preparation area, while the precision analysis was performed considering the complete arch. To measure the trueness, the models were compared with the reference model and to measure the precision the models were compared to each other. Data distribution and equality of variances were analyzed by the Shapiro-Wilk and Levene tests, respectively. One-way ANOVA test was applied to the comparisons of the precision of the scanners, and the two-way ANOVA test for the trueness evaluation, followed by the Tukey test to identify where there were differences between the groups. All tests were performed with a significance level of 5%. No significant intergroup differences in trueness and precision were observed for the two intra oral scanners. 3D printed casts had the lowest trueness when complete arch was analyzed and differs statistically from the stone cast. On the other hand, for complete arch precision, stone cast presented better results, however statistically different only from the Cerec Omnicam.Thus, the two intraoral scanner systems had similar accuracy. Stone casts had higher trueness than 3D printed casts for complete arch, but similar results for partial arch and teeth prepared area. For complete arch precision, 3D printed cast may present similar results to the stone cast.