This in vitro study compared the reproduction of intra-radicular surface anatomy of extracted human teeth taken by silicon, inlay casting wax and acrylic resin using an injection technique to determine which material produced fewer voids. Twenty impressions/patterns using this technique were made for each material and compared with each other on the basis of number, location and size of voids. Length of each dowel impression/ pattern was also compared. The percentage of void free surfaces using silicon, inlay casting wax and acrylic resin were 90%, 100% and 85% respectively. Most of the voids were less than 1mm in size and situated in the middle third of the impression/pattern. There was no significant difference in the length of the impression/ pattern taken by the three materials. Using the injection technique to reproduce the intra-radicular anatomy of the dowel space, all three materials will show predictably good results.