Aim: The study aimed to examine the influence of NaOCl used in combination with EDTA as irrigant versus NaOCl mixed with Etidronate as irrigant on the coronal fracture resistance of endodontically treated bleached teeth.
Methodology: Twenty-four sound mandibular premolars were chosen and randomly split into two groups: control group (n= 12), NaOCl was used in combination with EDTA; in the experimental group (n=12) NaOCl mixed with etidronate was used. After obturation, internal and external bleaching were performed, and then Composite resin was used to restore teeth. The specimens were tested utilizing compressive loading by a universal testing machine.
Results: Results showed that the coronal fracture resistance of the experimental group recorded a significantly higher value in comparison to the control group. Comparing the two groups revealed a statistically significant difference. There was no significant difference in the two group's modes of failure. In the intervention group, 2 samples (16.7%) showed a favorable fracture, and 10 samples showed an unfavorable fracture (83.3%).

Conclusion: Sodium hypochlorite mixed with Etidronate has higher coronal fracture resistance than sodium hypochlorite used in combination with EDTA in endodontically treated bleached teeth.