Application of polymer impression masses for the obtaining of dental working models for the stereolithographic 3D printing

Purpose: The aim of the work is to execute measurements of digital dental models taken by scanning prosthetic impressions using the engineering CAD software and finding dimensional differences and scale factor for precise reproduction of patient tooth dimensions. Design/methodology/approach: Tests were carried out involving the execution of 3 series of impressions for selected impression materials, which were then scanned using two types of prosthetic scanners. Gypsum models based on mentioned impressions were scanned and dimensionally compared with impression-based digital models. Benchmark impressions were also performed in order to verify the obtained results and determine the correction factor for dimensions. The dimensional differences between impression groups were calculated by using Engineering CAD software. Findings: It was found, that compared to the base model, the digital model has a smaller volume than the object being mapped, the digital models based directly on the impression should be 0.09 - 0.12% rescaled to match the dimensions of the base model. Research limitations/implications: It is necessary to perform a practical verification of the results achieved and apply the determined coefficient in practice by creating working models using precise devices such as a 3D SLA printer and verify their results with intraoral scanner based models. Practical implications: This test will allow making precise working models using a 3D printer, allowing finally to perform, for example, implant-based bridges directly from the level of implants, using the masses described in the study. Originality/value: The comparative studies of polyvinyl siloxane and alignate impression materials were carried out in order to measure dimensional differences between working models made directly from the impression and gypsum models and compared with pattern, which allowed to determine the expansion coefficient, which will allow to work in 3D printing technology with close representation of real situation in the patient's oral cavity, which is particularly important when performing full arch bridges and extensive work on implants, including direct implants. The work has practical applications for both dental engineers and dentists performing advanced prosthetic work.