M G Barrett1, W G de Rijk, J O Burgess. 1. Department of Restorative Dentistry, University of Texas Health Science Center San Antonio 78284-7912.
Abstract
PURPOSE: Six impression techniques were evaluated using tapered and square impression copings. MATERIALS AND METHODS: The absolute distortion was measured using a cast metal impression tray with fiduciary reference points external to the impression material. Measurements of the x, y, z coordinates on the master cast and the impressions were directly made with a travelling digitizing microscope. The difference between the coordinates of each of six sites in the impression and the corresponding reference site were compared. RESULTS: There was no significant difference between the techniques for the square copings but that there was a significant loss of accuracy in the z-axis with the tapered copings. CONCLUSIONS: No significant differences were noted.
PURPOSE: Six impression techniques were evaluated using tapered and square impression copings. MATERIALS AND METHODS: The absolute distortion was measured using a cast metal impression tray with fiduciary reference points external to the impression material. Measurements of the x, y, z coordinates on the master cast and the impressions were directly made with a travelling digitizing microscope. The difference between the coordinates of each of six sites in the impression and the corresponding reference site were compared. RESULTS: There was no significant difference between the techniques for the square copings but that there was a significant loss of accuracy in the z-axis with the tapered copings. CONCLUSIONS: No significant differences were noted.