Evaluation of the accuracy of different impression techniques in implant rehabilitation of edentulous cases

The long-term success of prosthetic treatment is related to the correct transfer of the oral environment to the laboratory. Different impression materials and techniques have been developed and continue to be developed to increase measurement accuracy. Today, with the increase in digitalization, intraoral scanners have started to be among the clinical routines in the impression taking process of implant supported prostheses, but doubts about their effectiveness in case of complete edentulism continue. In our study, it was aimed to compare the accuracy of conventional and digital impression techniques in different parameters in case of complete edentulism. Using polyvinyl siloxane impression material, 10 impressions were taken with snap-on technique, open tray splint technique and open tray splintless techniques on the model that imitates the rehabilitation of complete edentulous condition with 6 implants, and plaster models were obtained. STL data were obtained by digitizing the obtained plaster models with a laboratory scanner and scan bodies. In the digital impression technique, the main model was scanned and 10 STL format data were obtained directly. The high- precision industrial scanner reference model of the main model was obtained and the deviation amounts were determined in 2 and 3 dimensions by superimposition the STL images via reverse engineering program. As a result of the evaluation of 3-dimensional deviations, there was no significant difference between the group with open tray splint and the group open tray with out splint, but it was determined that it gave better results than snap on and digital impression. There was no significant difference between the groups in the evaluation of 2-dimensional deviations. As a result of our study, it was determined that the most sensitive measurement was obtained with the open tray splint technique, and the amount of 2-dimensional deviations increased as the distance between the implants increased. Key Words: impression techniques, digital impression, implant supported impression, accuracy, complete edentulism