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Abstract
The aim of this study was to evaluate the effect of the three types irrigating solutions namely:
2.5% Sodium hypochlorite
2% Chlorhexidine gluconate
17% EDTA
On:
1. Microhardness of root dentin
2. Fracture resistance of root dentin
For the microhardness; forty freshly extracted single rooted teeth were selected, decapped and mechanically prepared to exact working length using K-type files. The roots were sectioned longitudinally into two segments, separated into buccal and lingual segments making a total of 80 segments. These segments were divided into four groups of 20 segments each. Then the segments were horizontally embedded in self cure acrylic resin held in a plastic rings, exposed their dentin. The exposed root dentin were treated with irrigating solutions as: Segments of the first group treated with 5 ml saline solution as control for 15 min... Segments of second group treated with 5 ml. of 2% chlorhexidine gluconate solution for 15 min. Segments of third group treated with 5 ml. of 2.5% NaOCl solution for 15 min and the last group treated with 5ml of 17% EDTA solution for 15 min. Then these segments were used to determine the microhardness of root dentin using of a microhardness tester HV-1000.
The second aim of this study was to evaluate the effect of each tested irrigating solutions on the fracture resistance of root canal dentin. Forty extracted teeth were used, decapped and mechanically prepared also using K-type files, and then divided into four groups of 10 roots each. Roots of first group irrigated with 5 ml of saline solution as control, roots of second group irrigated with 5 ml of 2.0 % chlorhexidine gluconate, roots of third group irrigated with 5 ml. of 2.5% NaOCl solution and roots of the last group irrigated with 5ml 17% EDTA solution. Then the roots were mounted vertically in acrylic resin blocks at level l.0 ml apical to cemento enamel junction, then the mounted rooted treated with tested irrigating solutions such classified groups for 15min. These roots were used to determine the fracture resistance of root dentin using the Loyed Universal testing machine.
The results of the first part of this study revealed that, the 2.5% NaOCl and the 17% EDTA solutions were decreased the microhardness of root dentin compared with saline solution as control. But chlorhexidine gluconate solution not affected the microhardness of root dentin when used in this experiment.