Abstract:

Objective To explore the effect of treatment with 17% EDTA gel and solution for different periods of time on the microstructure of root surfaces and compare the effect between 17% EDTA gel and solution and 24% EDTA solution. Methods Thirty freshly extracted teeth from patients with periodontitis were treated with scaling and root planing (SRP), and dentin fragments and cementum fragments were prepared. These fragments were randomly assigned to the A group treated with saline solution for 3 min, the B group treated with 24% EDTA solution for 3 min, the C group treated with 17% EDTA gel for 3 min, the D group treated with 17% EDTA gel for 5 min, the E group treated with 17% EDTA solution for 3 min, and the F group treated with 17% EDTA solution for 5 min. Scanning electron microscopy was used to observe the microstructure of root surfaces. Results ①The dentin on root surfaces: There were no exposed dentin tubules on the surface of dentin in the A group. The number of open dentin tubules in the B group was the largest and the exposure was the clearest, followed by the D group and F group. The C group and E group had the fewest open dentin tubules, where many blocked tubules existed. ②The cementum on root surfaces: Root surfaces in all groups were clean and the smear layer was removed except the A group. The cementum demineralization in group B was presented significantly and collagen fibers were exposed clearly. The D and F groups showed partial cementum demineralization and collagen fibers on the surface of cementum were lumpish with no significant spatial conformation. The cementum demineralization in the C and E groups was not significant with no exposure of collagen fibers. Conclusion There is no significant difference in the treatment of root surfaces with 17% EDTA gel and solution. When extending the treatment time from 3 min to 5 min, the effect of 17% EDTA becomes better, but is still inferior to 24% EDTA solution.

Key words: root conditioning, ethylenediaminetetraacetic acid, smear layer, dentin tubule；scanning electron microscopy