Randomized clinical trial of the influence of impression technique on the fabrication of cast metal posts

Statement of problem. Direct and indirect techniques are used for intracanal impression and fabrication of cast metal posts. However, whether those techniques affect the accuracy of cast metal posts is unknown. Purpose. The purpose of this randomized clinical trial was to evaluate the accuracy of cast metal posts depending on tooth position and impression technique. Material and methods. Endodontically treated teeth (anterior or posterior) planned to receive cast metal posts and complete crowns were randomized according to impression technique (direct or indirect). Impressions were made by 2 operators, and time for the impression was recorded. All impressions and cast metal posts were photographed to assess any possible differences between techniques in length of the cast metal post. Results. All cast metal posts were shorter than the impressions. The mean reduction for the metal posts was 2.3% for direct in anterior teeth, 5.7% for direct in posterior teeth, 6.3% for indirect in anterior teeth, and 7.2% for indirect in posterior teeth (all P<.05). Statistically significant differences were found between time of technique and tooth position (P=.031), with the direct technique more time consuming than the indirect technique (P<.001) for both tooth positions. For the indirect technique, the impression times for both tooth groups were similar (P=.459). Conclusions. Both of the intracanal impression techniques resulted in cast posts that were shorter than the impressed post space. The discrepancy was greatest for the indirect technique. Nevertheless, all posts were considered clinically acceptable and were cemented.