Comparative Evaluation of the Smear Layer Removal Efficacy of Phytic Acid and Twin Kleen on Root Canal Dentin: An in Vitro Study

Aim: To comparatively evaluate the smear layer removal efficacy of phytic acid and Twin Kleen on root canal dentin using stereomicroscopic evaluation of longitudinally sectioned root specimens. Materials and Methods: This in vitro comparative study included 40 specimens randomly allocated into two experimental groups (n=20 each): Group I, phytic acid; and Group II, Twin Kleen. Following biomechanical preparation, the assigned chelating irrigant was used for smear-layer removal. The roots were subsequently sectioned longitudinally and evaluated using a stereomicroscope. Statistical analysis was performed using IBM SPSS Statistics for Windows, version 26.0. Normality was assessed using the Kolmogorov–Smirnov and Shapiro–Wilk tests, and intergroup comparison was performed using the Mann–Whitney U test. Statistical significance was set at p<0.05. Results: The mean smear-layer score was 2.75±0.50 in the phytic acid group and 1.50±0.40 in the Twin Kleen group. Lower scores represented less residual smear layer. The reported intergroup difference was statistically significant (p<0.05). Conclusion: Within the limitations of this in vitro model, Twin Kleen produced a lower mean smear-layer score than phytic acid. The findings should be interpreted in the context of the specific specimen preparation, irrigant exposure and stereomicroscopic assessment used in the present study.