Edition V01N03 | Year 2011 | Editorial Original Article | Pages 34 to 40
Objective: The present study aims to evaluate the influence of root-canal irrigants in the compressive strength and surface morphological characteristics of gray MTA Angelus using scanning electron microscopy (SEM).
Methods: The MTA was mixed according to the manu instructions from manufacturer and packed incrementally into silicone cylindrical molds with an internal diameter of 2 mm and a height of 4 mm. After the initial setting, 30 samples were randomly divided into 3 groups (n=10). In Group C (control) the samples were immersed in a saline solution, in Group MC the samples were immersed in a 2.5% sodium hypochlorite solution and in Group MH the samples were immersed in a 2% chlorhexidine digluconate solution, all remaining for 1 hour. After rinsed, the compressive strength was measured in an Instron 4410 test machine with a crosshead speed of 0.5 mm / min. The surface morphological characteristics were determined by scanning electron microscopy (SEM). The statistical significance in compressive strength was evaluated by one-way analysis of variance (α=0,05).
Results: The average compressive strength values (MPa) were 69.24±7.32 (Group C), 64.74±9.21 (Group MC) e 71.15±11.54 (Group MH), with no significant difference. The results of SEM had demonstrated that the microstructures from group C and MH were crystalline, composed of cubic crystals. A granular structure, in which crystals had not formed, was observed in the Group MC.
Conclusion: The immersion in root-canal irrigants did not affect the compressive strength of MTA, with changes only in surface morphological characteristics. Further studies are needed to determine the clinical relevance of this crystal structure.