Effect of Final Irrigation Solutions on Mechanical Properties of Root Canal Dentine Running title: Final Irrigation on Mechanical Properties.

Objectives: The final irrigation solution should have the capability of a chelation agent to remove the smear layer. The purpose of this study was to determine the effect of EDTA, novel silver citrate, and chitosan nanoparticles as a final irrigation solution on the mechanical properties of root canal dentine, namely the flexural strength and elastic modulus.

Methods: Thirty-two intact, single, and straight roots, with no caries, no cracks, and no restoration of premolars, were assigned into four groups of 8 teeth each. Group 1: irrigated with EDTA; Group 2: irrigated with novel silver citrate; Group 3: irrigated with chitosan nanoparticles; Group 4: irrigated with saline as control. Using a Universal Testing Machine, each sample was tested for flexural strength and elastic modulus with a three-point bend test. The data were analysed using one-way ANOVA and followed by the Tukey's test with a significance level of 95%.

Results: Chitosan nanoparticles generated the highest flexural strength and elastic modulus of root canal dentine (212.03 +- 1.64 and 16.40 +- 1.05, respectively) than EDTA (127.10 +- 0.90 and 7.37 +- 0.94) and novel silver citrate (177.87 +- 2.03, and 12.27 +- 1.01) (p<0.05). However, chitosan nanoparticles have similar flexural strength and elastic modulus of root canal dentine when compared to saline (213.76 +- 1.48, 17.02 +- 1.14, respectively) (p>0.05).

Conclusion: Among final irrigations used, chitosan nanoparticles produced the highest flexural strength and elastic modulus of root canal dentine compared to EDTA and novel silver citrate.