A novel approach to assess surface roughness and EDX profiling of blue rotary NiTi files following dynamic immersion in various hypochlorite concentrations.

BACKGROUND

Successful root canal treatment relies on effective chemomechanical preparation. However, sodium hypochlorite (NaOCl), the standard irrigant, can corrode metals and weaken the structural integrity of nickel-titanium (NiTi) instruments. Therefore, this study aimed to evaluate the surface roughness and element composition of Fanta AF blue and E3 Azure NiTi rotary endodontic files after dynamic immersion in two different NaOCl concentrations.

METHODS

Forty-two heat-treated rotary files were divided into two groups based on the file brand, Fanta AF Blue and E3 Azure NiTi files. Each group was randomly subdivided into three subgroups (n = 7) according to irrigant exposure: Control (no exposure), 5.25% and 2.6% NaOCl. The surface morphology and elemental composition of new files and those immersed in NaOCl for 10 min were analyzed using high-resolution scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis. SEM images were analyzed with Image J 1.52 software to determine arithmetic mean roughness (Ra) and root mean square roughness (Rq). When the ANOVA test showed significance (p ≤ 0.05), pairwise comparisons were made using Bonferroni's post-hoc test.

RESULTS

Fanta files immersed in 2.6% NaOCl exhibited significantly higher mean Ra and Rq values than Azure files (p = 0.020 and 0.022, respectively). Immersing Fanta files in 2.6% NaOCl resulted in a significantly greater weight percentage (wt.%) loss of Titanium (p = 0.009) and Nickel (p = 0.021) compared to new Azure files and those immersed in 5.25% NaOCl. The carbon wt.% significantly increased in Fanta files immersed in 2.6% NaOCl (p = 0.014).

CONCLUSIONS

Within the limitations, Azure files showed lower overall surface roughness than Fanta files after dynamic immersion in 2.6% NaOCl. The undesired effects of 2.6% NaOCl on Fanta files could lead to crack propagation and decreased cyclic fatigue resistance, which requires further research.