Impact of Chitosan and Benzalkonium Chloride as Final Irrigants on Fracture Resistance and Surface Roughness of Endodontically Treated Roots: An In Vitro Study.

BACKGROUND: Chelating agents such as ethylenediaminetetraacetic acid (EDTA) effectively remove the smear layer but may weaken dentin and lack antimicrobial activity. Chitosan (CH), which has chelating and reported antibacterial properties, and benzalkonium chloride (BAC), an antimicrobial agent used after EDTA, may serve as alternative final irrigants. This study compared the effects of CH, BAC, and EDTA, alone or combined, on dentin surface roughness (SR) and fracture resistance (FR) of endodontically treated teeth.

METHODS: Ninety-five extracted human mandibular first premolars with a single root canal were standardized to a 13 ± 1 mm root length and instrumented to ProTaper F4. For FR testing, 70 specimens were distributed into seven groups (n = 10): intact root (positive control), not-obturated (negative control), normal saline, EDTA, EDTA /CH, EDTA/ BAC, and CH alone. Roots were obturated with AH Plus sealer and gutta-percha, embedded in resin and loaded along the long axis until fracture. For SR assessment, 25 additional roots were sectioned longitudinally to obtain 50 specimens, which were then assigned to five groups based on the same final irrigation protocols used for FR (n = 10 per group). Atomic force microscopy (AFM) measured arithmetical mean SR (Ra, nm) at three midroot sites per specimen. Data analysis was performed (p = 0.05).

RESULTS: All obturated groups, including the normal saline group, showed significantly higher FR than the nonobturated group (p < 0.001). CH produced the highest FR, comparable to the intact root and significantly higher than EDTA, EDTA/CH, and normal saline groups (p < 0.05), but not significantly different from EDTA/BAC (p > 0.05). EDTA/CH and EDTA/BAC did not improve FR compared to EDTA alone (p > 0.05). Mean ± SD Ra values ranked from lowest to highest were: normal saline, CH, EDTA / BAC, EDTA / CH, and EDTA. All pairwise comparisons were statistically significant (p < 0.001).

CONCLUSION: CH demonstrated the highest FR among the tested irrigation protocols while producing mild SR. EDTA showed intermediate FR values and was associated with the highest SR. The addition of BAC after EDTA resulted in relatively favorable FR with moderate SR. Notably, CH and EDTA/BAC exhibited comparable FR values, suggesting that both protocols may help maintain dentin mechanical integrity while providing acceptable surface characteristics.