A Comparison of the Accuracy of Impression Materials with Immediate and Delayed Pouring for Long Span Implant Supported Prosthesis: An Invitro study

INTRODUCTION: The use of Dental Implants to replace missing teeth in partially dentate and edentulous patients is associated with a high success rate from esthetics, functional and psychological point of view. However, biomechanical failure does occur in longspan prosthesis, which may be attributed to lack of passive fit of the Implant superstructure. Various Impression materials are used in Implant dentistry and various studies have been conducted to provide the information about accuracy of Impression materials. AIMS AND OBJECTIVES: The aim and objective of this study was to compare the accuracy of different impression materials with immediate and delayed pouring of casts by analyzing inter implant distance between the master model and casts using calibrated coordinate measuring machine. MATERIALS AND METHODS: The impression materials used in this study are Poly Ether, Monophase, Poly Vinyl siloxane, Condensation Silicone and Irreversible Hydrocolloid. Twelve impressions of each impression materials were made. Six impressions of each impression materials were poured immediately and another six impressions was poured after one hour. The cast was poured with type IV Dental stone. Inter-implant distance (1-2, 1-3, 1-4, 2-3, 2-4, 3-4) of the implant analog master model and the casts was calculated using Calibrated portable Coordinate Measuring Machine (CMM). RESULTS: Comparing the results of average inter-implant distance between impression casts and the master model, even though there is distortion but in the light of absolute values there was no statistically significant difference. CONCLUSION: On concluding from the results obtained from impression casts by immediate pouring, the Monophase impression material reproduced the master model most accurately followed by Poly Ether, Addition Silicone, Condensation Silicone and Irreversible hydrocolloid respectively. On concluding from the results obtained by delayed pouring of impression cast after one hour there was no significant difference within the impression materials used.