The efficacy of acetic acid and citric acid on calcium silicate based cement removal from root canals and their effect on dentine structure – an in vitro study

Objectives: This study evaluated the effectiveness of acids on calcium silicate cement surface hardness, perforation, and their impact on root dentine microstructure. Materials and methods: Root dentine discs were exposed to hydrochloric, acetic, and citric acids. Fourier transform infrared spectroscopy (FTIR) assessed dentine microstructure after exposure to these acids. Sixty discs of Biodentine and NeoPUTTY (n = 30 each) were treated with 2% acetic acid, 5% citric acid, or saline (control), then tested for surface microhardness (Vickers hardness number, VHN). Another 60 dentine discs filled with these cements were exposed to the acids or saline and mechanically perforated with a Peeso reamer; perforation time was recorded. Scanning electron microscopy (SEM) examined dentine and cement surfaces. Results: FTIR revealed that hydrochloric acid caused severe demineralization of dentine microstructure, whereas 2% acetic and 5% citric acids had no significant effect on dentine microstructure. Both acids (acetic and citric) significantly reduced VHN compared to controls (p < 0.001). Acid-treated groups were perforated faster, with citric acid showing the greatest time reduction (p < 0.001). NeoPUTTY required less perforation time than Biodentine (p < 0.001). SEM revealed surface cracks in Biodentine and round-shaped defects in NeoPUTTY after acid exposure; citric acid opened dentinal tubules more distinctly than acetic acid. Conclusions: Acetic and citric acids significantly reduced microhardness and facilitated mechanical perforation of calcium silicate cements, with citric acid exerting greater effect.