J Korean Acad Conserv Dent.  2006 May;31(3):169-178. 10.5395/JKACD.2006.31.3.169.

Time-dependent effects of EDTA application on removal of smear layer in the root canal system

• Lee JK
• Park SH
• Choi GW

• KMID: 2175816
• DOI: http://doi.org/10.5395/JKACD.2006.31.3.169

Abstract

This study was to verify that the combined application of NaOCl and EDTA was more effective in removal of smear layer than the application of NaOCl alone. Furthermore it was aimed to find out the optimal time for the application of EDTA. Thirty five single rooted teeth were cleaned and shaped. NaOCl solution was used as an irrigant during instrumentation. After instrumentation, root canals of the control group were irrigated with 5 ml of NaOCl for 2 minutes. 30 sec, 1 min, and 2 min group were irrigated with 5 ml of 17% EDTA for 30 sec, 1 min, and 2 min respectively. Then the roots were examined with scanning electron microscopy for evaluating removal of smear layer and erosion of dentinal tubule. The results were as follows; 1. The control group: The smear layer was not removed at all. 2. The other groups: 1) Middle(1/3): All groups showed almost no smear layer. And the erosion occurred more frequently as increasing irrigation time. 2) Apical(1/3): The cleaning effect of 2 min group was better than the others. The results suggest that 2 min application of 17% EDTA should be adequate to remove smear layer on both apical(1/3) and middle(1/3).

Keyword

NaOCl; EDTA; Smear layer; Irrigation; Root canals; Cleaning

MeSH Terms

Dental Pulp Cavity*
Dentin
Edetic Acid*
Microscopy, Electron, Scanning
Smear Layer*
Tooth
Edetic Acid

Figure

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  Figure 1 Representative photograph of the control group at apical⅓ (× 2000); score 0, surface completely covered with smear layer, no tubules visible.

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  Figure 2 Representative photograph of the control group at middle⅓ (× 2000); score 0, surface completely covered with smear layer, no tubules visible.

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  Figure 3 Representative photograph of the 30 sec group at apical⅓ (× 2000); score 1, surface covered with thin smear layer but orifices of tubules visible; occasional tubules open.

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  Figure 4 Representative photograph of the 30 sec group at middle⅓ (× 2000); score 4, smear layer completely removed; peritubular dentin removed, resulting in increased size of tubular orifices.

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  Figure 5 Representative photograph of the 1 min group at apical⅓ (× 2000); score 2, smear layer partly removed; orifices of most tubules open or partially open.

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  Figure 6 Representative photograph of the 1 min group at middle⅓ (× 2000); score 4, smear layer completely removed; peritubular dentin removed, resulting in increased size of tubular orifices.

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  Figure 7 Representative photograph of the 2 min group at apical⅓ (× 2000); score 3, smear layer mainly removed, most tubules completely open.

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  Figure 8 Representative photograph of the 2 min group at middle⅓ (× 2000); score 4, smear layer completely removed; peritubular dentin removed, resulting in increased size of tubular orifices Erosion exists.

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