Evaluating the effectiveness of different irrigant solutions in removing the smear layer and opening the dentinal canals: A scanning electron microscopic study

Abstract

Abstract Aim: The study aims to evaluate the effectiveness of different irrigant solutions in removing the smear layer and opening the dentinal canals using a scanning electron microscope (SEM). Materials and Methods: A total of 50 mandibular premolars (N = 50) were decoronated at the cementoenamel junction and the samples were standardized to 17 mm. Using a #10 k file (Mani, Utsunomiya, Tochigi, Japan), the initial patency was established up to the working length (WL). The ProFit S3 file system (Profit Dental, India) was used for cleaning and shaping. The samples were randomly divided into six groups: GROUP I: 2.5% sodium hypochlorite (NaOCl) solution and 2% chlorhexidine (CHX; n = 10) were used to irrigate the samples, GROUP II: 2.5% NaOCl solution followed by 5% sodium thiosulfate (Na2S2O3) and 2% CHX (n = 10) were used to irrigate the samples, GROUP III: 2.5% Calcium hypochlorite [Ca(OCl)2] solution and 2% CHX (n = 10) were used to irrigate the samples, GROUP IV: 2.5% Ca(OCl)2 solution, 5% Na2S2O3 solution, and 2% CHX solution were used to irrigate the samples (n = 10), GROUP V (control): 2.5% Ca(OCl)2 solution (n = 5) was used to irrigate the samples, GROUP VI (control): 2.5% NaOCl solution (n = 5) was used to irrigate the samples. SEM was applied to the samples at various levels to eliminate the smear layer. Results: There was a statistically significant difference in the effectiveness of different irrigant solutions in removing the smear layer and opening the dentinal tubules (P < 0.05) as compared with the control, and, between groups in apical third, middle third, and coronal third (P < 0.05). Conclusions: When 2.5% Ca(OCl)2 and 2% CHX were used separately or in combination with Na2S2O3, the results showed that the former had the greatest number of opened dentinal tubules and the least amount of smear layer formation.