Comparison of impression techniques for a five-implant mandibular model.

Production of an accurate dental cast framework that meets the implant objective of passive fit demands an understanding of potential processing errors. Working casts fabricated from impressions using two different transfer copings, as provided by a leading implant manufacturer, were investigated for differences in accuracy. A five-implant mandibular model was used to produce seven casts by both the indirect and direct transfer coping techniques. Comparison was made by using a dental cast framework fitted to the master cast. Differences in distances measured between each group and the master cast were analyzed to establish differences between methods. For the model used, the direct technique produced more accurate working casts. A concern for potential impression distortion given the specific clinical situation underscores the method of choice.