Effectiveness of various irrigation methods on the removal of calcium hydroxide from root canals: A study using confocal microscopy

Aim: This study aimed to compare the effectiveness of 70% ethanol with 2.5% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), and 37% phosphoric acid used as final irrigant in the removal of calcium hydroxide (Ca(OH) 2 ) dressing from the root canal using confocal laser scanning microscopy (CLSM). Methods: This study selected 96 human incisors, extracted recently due to periodontal issues. Teeth were decoronated, and roots were prepared till F3. Ca(OH) 2 mixed with propylene glycol, and 0.1% rhodamine B dye was inserted into canals with a lentulospiral. The dressing was initially removed with saline solution and reinstrumentation with master apical file. The samples were then classified into eight groups ( n = 12) each subjected to a different irrigation protocol, with some groups employing ultrasonic activation and others using nonactivated methods: 2.5% NaOCL, 17% EDTA, 37% phosphoric acid, and 70% ethanol. The effectiveness of the cleaning was assessed by measuring the percentage of clean root canal walls and the depth of the cleaned dentinal tubules using images gathered from CLSM. Analysis of variance, along with Tukey’s post hoc test, was utilized for analysis. Results: The use of 70% ethanol for irrigation led to a greater occurrence of clean root canal walls and improved infiltration into dentinal tubules, surpassing both 2.5% NaOCL and 17% EDTA. There was no notable difference in results between passive ultrasonic irrigation and nonactivated irrigation methods. Conclusion: Within this study’s limits, 70% ethanol proved to be more effective in removing Ca(OH) 2 compared to 17% EDTA, 2.5% NaOCL, and 37% phosphoric acid, across both the irrigation methods.