Influência de substâncias irrigadoras endodônticas nas propriedades mecânicas da dentina radicular

Abstract

The aim of this study was to evaluate the influence of different endodontic irrigants on the cohesive and flexural strength of the root dentin. One hundred of bovine incisor roots were selected, instrumented and randomly divided into 10 experimental groups (n = 10), according to the irrigation solution used: Control - physiological solution; N1 - sodium hypochlorite 1.0%; N5 - sodium hypochlorite 5.25%; N1EDTA - sodium hypochlorite 1.0% associate to EDTA 17%; N5EDTA - sodium hypochlorite 5.25% associate to EDTA 17%; Sclx chlorhexidine gluconate solution 2.0%; Gclx - chlorhexidine gluconate gel 2.0%; SclxEDTA - chlorhexidine gluconate solution 2.0% associate to EDTA 17%; GclxEDTA - chlorhexidine gluconate gel 2.0% associate to EDTA 17% and EDTA - EDTA 17%. The roots were axially sectioned in two halves. Half of them were used for the microtensile cohesive strength test: six 1.0mm thick slices were trimmed to produce hourglass shaped samples with a test area of 1mm2. The other halves were used in a 3-point bend flexural strength by means of dentine bars with 1X1X12 mm. Each sample remained two hours in contact with the irrigant solutions, except for EDTA, which remained for five minutes. After irrigants treatment, samples were rinsed with distilled water, and tested. Specific devices for each test were used, in a universal testing machine with a load cell of 20Kgf, and a crosshead speed of 0.5 mm/minute. Date were recorded and statistically analyzed with one-way ANOVA and Tukey test. Significant reduction in the ultimate cohesive strength and flexural strength was verified only for the groups that used sodium hypochlorite irrespective of the concentration and additional solution, differing significant from the group control. The use of chlorhexidine and EDTA separately did not cause alteration in the mechanical properties of root dentine.