Abstract
Objective: The objective of this study was to observe the effect that 3% Sodium Hypochlorite and 17% Ethylenediamine Tetraacetic Acid (EDTA) with water in between, used sequentially and individually had in the disinfection of dentin blocks that were contaminated with Enterococcus faecalis. Materials and Methods: Thirty apical and coronal dentin block samples were divided into five groups (n=5): All samples were inoculated with Enterococcus faecalis Group 1: Samples were submerged in 3% NaOCl then in 17% EDTA. Group 2: Samples were submerged first in 17% EDTA and then in 3% NaOCl. Group 3: Samples were immersed in 3% NaOCl only. Group 4: Samples were submerged in 17% EDTA only. Group 5 (positive control group): Samples were only submerged in distilled water. All samples were submerged in distilled water after each irrigation cycle. The irrigation protocol was repeated in all groups until all dentin samples were exposed to 24ml of the irrigating solutions. CFU units were counted and classified in an ordinal scale and compared with the linear-by-linear association test. Results: A significant linear trend in the reduction of CFU was observed when NaOCl and EDTA were combined (independently of the sequence used) when compared to groups 3 and 4 where the irrigants were used individually both in coronal (p=9.45 x 10-21), and apical slices (p=2.33 x 10-20). NaOCl was significantly more effective than EDTA in both coronal and apical slices (p ≥ 0.000001) when used alone. Conclusion: 3% Sodium Hypochlorite was more effective than 17% EDTA. However, alternating 3% NaOCl with 17% EDTA resulted in better dentinal disinfection. Clinical Relevance: Establishing an irrigation protocol that is effective in eradicating bacteria entrenched in dentinal tubules can lead to a more successful outcome in endodontically treated teeth.