Calcium hydroxide removal using ultrasonic-activated acetic acid versus ultrasonic-activated sodium hypochlorite: A...

Incomplete calcium hydroxide (Ca(OH)2) removal represents a significant clinical challenge that compromises endodontic obturation quality by interfering with sealer penetration and poteatouso@unicartagena.edu.contially leading to treatment failure. Despite advances in irrigation techniques, the complete elimination of Ca(OH)2 remains difficult, particularly in anatomically complex regions. Acetic acid (AA), a weak organic acid with demonstrated antimicrobial properties, has been proposed as a cost-effective alternative to sodium hypochlorite (NaOCl) for dissolving alkaline residues due to its acidic pH and superior theoretical capacity for acid-base neutralization reactions. This study aimed to compare the calcium hydroxide removal efficacy of ultrasonic-activated 5% acetic acid versus ultrasonic-activated 5.25% sodium hypochlorite across different root canal thirds using dual microscopy evaluation.

Thirty-eight single-rooted premolars were instrumented, medicated with calcium hydroxide for 7 days, and randomly allocated to ultrasonic-activated 5% acetic acid or ultrasonic-activated 5.25% sodium hypochlorite (n=19/group). Removal capacity was evaluated using stereomicroscopy and scanning electron microscopy across coronal, middle, and apical thirds. Data were analyzed using the Mann-Whitney U test and multivariate logistic regression (=0.05).

In the middle third, ultrasonic-activated acetic acid achieved superior removal (52.7% excellent/good vs 15.8%; p=0.017; OR=6.00, 95%CI:1.40-25.85) with adequate power (1-=0.82). Multivariate regression confirmed irrigant type as an independent predictor (adjusted OR=4.23, p=0.026) with significant irrigant×third interaction (p=0.041). No differences were observed in coronal (p=0.150) or apical thirds (p=0.820).

Ultrasonic-activated acetic acid demonstrated superior calcium hydroxide removal in the middle third compared to ultrasonic-activated sodium hypochlorite. Acetic acid represents an accessible, cost-effective alternative for intracanal medicament removal.