The aim of this study was to evaluate the influence of overtorque on integrity, strength and stress on external hexagonal implants (EH), with two different grades (N=10): conventional (C), grade 4; and modified (M), grade 4 with thermal treatment. The dimensions of EH were 3.75 × 13 mm; the specimens were fixed and submitted to SEM analysis and image acquisition. The abutment was then retained with 70 N/cm, re-analyzed by SEM, and a second image was obtained. The images were analyzed by Image J software (1.44o- NIH, USA) for dimensional variations measurement on surface of the hexagonal area. The finite element method was applied with a similar compliance to calculate the resultant stress (MPa) during the torque. Results were statistically analyzed with t-student test (5 %). The dimensional accuracy of M (0.22 mm2 ) was statistically significant (p<0.05). Minimum principal stress and von-Mises stress of C (-19.95 MPa, -19.94 MPa), were lower than M values (-55.83 MPa, -55.96 MPa), respectively. However, the M group showed lower deformation than C group. Therefore, more rigid titanium alloy is a promising alternative to avoid plastic deformation of prosthetic connections even concentrating higher stress magnitude on its structure.
KEY WORDS: dental implants, finite element analysis, dental alloys.
How to cite this article
SILVA, A. M.; MATOS, J. D. M.; TRIBST, J. P. M.; LOPES, G. R. S.; MARTINELLI, C. S. M.; BORGES, A. L. S., KIMPARA, E. T.; NOGUEIRA JR, L.; DE MELO, R. M. & BOTTINO, M. A. Effect of titanium hardness on the integrity and stress concentration of external hexagon dental implants. Int. J. Odontostomat., 15(4):1053-1059, 2021.