Background <p>This study aimed to evaluate the effect of different temporary filling (TF) materials and pre-endodontic build-up on upper premolar teeth fracture resistance (FR).</p> Methods <p>90 premolar teeth were selected. Except for 5 randomly selected teeth in the negative control group (group 1, intact teeth), mesio-occluso-distal cavities were prepared for the remaining teeth. The canals were shaped with OneCurve (#25/0.6) files. Irrigation was performed with sodium hypochlorite and ethylenediaminetetraacetic acid. Then calcium hydroxide was placed into the canals. Five teeth were selected as the positive control group (group 2, Temporary filling material not applied). The remaining 80 teeth were then randomly divided into 4 groups. TF was performed with Cavit G in group 3 and Voco Clip F in group 5. In groups 4 and 6, cavities were built up with composite, and TF was performed with Cavit G in group 4 and Voco Clip F in group 6. A Universal testing machine was used for FR testing. A two-way ANOVA test was performed for statistical analysis.</p> Results <p>The FR of the group 1 was higher than the other groups (<i>p</i> &lt; 0.05). The FR of groups 4 and 6 was significantly higher than groups 3 and 5 (<i>p</i> &lt; 0.05). Group 2 has the lowest FR (<i>p</i> &lt; 0.05). The most common type of fractures were restorable fractures. There is a significant difference between the experimental groups (<i>p</i> &lt; 0.05).</p> Conclusion <p>During endodontic treatment, placing TF materials after pre-endodontic build-up until the permanent restoration is completed increases the FR of the teeth.</p>