Statement of problem – Most of implant impression techniques, such as, pick-up, and transfer techniques and splint and non splint techniques, have been introduced, in search of the most accurate technique. In certain clinical situation, some of the factor such as the angulations or depth of implants, may affect the accuracy of the implant impressions. Purpose -Purpose of this review was to compare the various impression techniques for dental implant restorations published in the literature and followed by statistical evaluation. Material and methods - Electronic searches were performed in July 2014 from PubMed, and Google database with combinations, databases with the key words dental implants, impression technique, and impressions. The study which investigated the accuracy of implant impression techniques and are published in an English peer-reviewed journal are included for the review. After completing the search strategies 62 articles were chosen which will included in the review process. Results: All of the selected articles were in vitro studies. Of the 14 studies that compared the accuracy between the splint and non splint techniques, 10 were in favour of the splint technique, 1 advocated the non splint technique, and 3 reported no difference. 11 studies compared the accuracy of transfer impression and pick-up impression techniques in which 5 showed more accurate impression with the pick-up techniques, 4 with the transfer technique, and 2 showed no difference. The number of implants affected the comparison of the pick-up and splint techniques.13 articles were analysed for checking affect of implant materials in which 6 articles showed polyether is better, while 2 articles supported addition silicone impression material, 3 studies supported activated polysilioxane whereas 1 article supported vinylsilioxane.10 articles was analysed for comparing conventional and digital impression techniques in which 1 article suggested cad cam was better than conventional,3 articles suggested accuracy as comparable to conventional and suggested that the accuracy is lower as compared to conventional. While 5 article suggested digital better than conventional techniques. Conclusions: The review of abutment level or implant level internal connection implants showed that the splint technique have greater accuracy as compared to the non splint technique. It was seen that there was not much difference between the pick-up and transfer techniques when there were 3 or fewer implants, whereas studies showed superior results with the pick-up technique when more than 4 implants were used. In materials Polyether and VPS gave more accurate results for the implant impressions. In digital and conventional method, the digital impression technique was more efficient and overall time consumption was also less.
