New solutions are needed to overcome the disadvantages of irrigation solutions that are frequently used to remove the inorganic part of the smear layer. The goal of the current study was to compare the effect of 5%-, 10%-, and 17% GA, 9% HEBP, 17% EDTA, and 10% CA on the fracture strength of endodontically treated premolars. Eighty-eight mandibular premolar teeth were selected. Eleven intact specimens were preserved as negative controls. After root canal preparation, specimens were divided into 8 groups for final irrigation procedure: Positive control (distilled water), 17 % EDTA, 10% CA, 9% HEBP, 5% GA, 10% GA, 17% GA (n = 11). After the final irrigation procedure, root canals were obturated. Access cavities were filled with composite resin. A universal testing machine was used to measure the force required to fracture the specimen. Data was statistically analyzed. The negative control group showed higher fracture strength than all other groups except the positive control group (P < 0.05). There was no statistically significant difference among EDTA, CA, HEBP and GA groups (P > 0.05). Within the limitations of this study, 1 min use of 17% EDTA, 10% CA, 9% HEBP, 5% GA, 10% GA, and 17% GA as final irrigation solution, in combination with NaOCl, have no effect on the fracture resistance of premolar teeth.
Keywords: Endodontically treated teeth, etidronic acid, fracture strength, glycolic acid.