*2.3. Placing Specimens on the Measuring Machine (Instron Testing Machine)*

Each tooth with a post and core was subjected to a pull-out test by a universal Instron testing machine (Instron Corp.) at a crosshead speed of 0.5 mm/min. The device was calibrated before placing each sample.

To standardize the location and direction of the specimens in the machine, samples were placed in a custom-made, self-aligning device. A hook-shaped attachment was passed through the hole created in the custom post and core, which was attached to the Instron testing machine (ITM). The acrylic-resin blocks held the teeth securely during retention testing (Figure 7). Force was applied until the cemented post was removed from the prepared post space. The retention values were recorded as the amount of force required to dislodge the post and core from the prepared post space [30]. Test specimens were considered to have failed when the post and core separated from the tooth.

**Figure 6.** View of a cemented post and core.

**Figure 7.** Specimen of mounted post and core in testing assembly for retention test.
