Avaliação comparativa da resistência à flexão, módulo flexural e rigidez das dentinas humanas e bovinas

Abstract

Human teeth have been replaced by bovine in laboratory tests and the results questioned due differences in their mechanical properties. The purpose of this study was to investigate and compare the flexural strength (FS), flexural modulus (FM) and stiffness (ST) between species, and the influence of the investigated area and tubule orientation on the properties. Six groups (n=10) were obtained: HPA human crown dentin beams with tubules orientation parallel to the load direction; HPP human crown dentin beams with tubules orientation perpendicular to the load direction; HRO human root dentin beams with tubules orientation parallel to the load direction; BPA bovine crown dentin beams with tubules orientation parallel to the load direction; BPP bovine crown dentin beams with tubules orientation perpendicular to the load direction; BRO bovine root dentin beams with tubules orientation parallel to the load direction. FM and ST values were calculated from FS results obtained from a 3- point bending test following ISO 178 (ISO 178:2001/Amd.1:2004(E)), and submitted to Friedman and Mann Whitney statistical tests (=5%). Median values were: FR: 194,26(HPA); 152,86(HPP); 224,86(HRO); 89,84(BPA); 85,32;(BPP); 350,17(BRO). FM: 3,77(HPA); 2,53(HPP); 3,76(HRO); 2,12(BPA); 1,26(BPP); 6,38(BRO). S:3,95(HPA); 3,02(HPP); 4,30(HRO); 2,43(BPA); 1,82(BPP); 7,56(BRO).There was significant difference for HRO in comparison to HPP (HRO>HPP) in the FS only. In the 3 evaluated properties (BRO>BPA=BPP). Between species, in the 3 evaluated properties (HPA>BPA) and PP (HPP>BPP). However, bovine dentin was significantly higher than human in RO (BRO>HRO), irrespective of the evaluated property. Conclusions were that differences in mechanical properties should be considered between human and bovine dentin and that the investigated area may influence such properties. Tubules orientation seemed not to affect mechanical properties.