Estudo comparativo do comportamento biomecânico de incisivos centrais superiores restaurados com núcleo metálico fundido de diferentes comprimentos submetidos a forças ortodônticas

Abstract

The Cast Metal Post (CMP) is an intraradicular retainer used in the restoration of endodontically treated teeth with little coronal remnant that alters its root biomechanical behavior. To evaluate, through the Finite Element Method, the stress distribution caused by orthodontic forces in the root of teeth restored with CMP measuring 1/2 and 2/3 of the root length. Two models of central incisors restored with CMP measuring 1/2 and 2/3 of the root length were created. After creating the finite element mesh, a buccolingual orthodontic force of 65 gf and a mesiodistal orthodontic force of 70 gf were simulated and applied parallel to the palatal plane, in the bracket slot located 4mm from the incisal edge. The maximum principal stresses and the qualitative distribution were acquired in the CMP and in the root remnant. The analysis of the stress distribution in the CMP structure revealed both force applications resulted in higher stress values in the post whose length equals 2/3 of the root length, being concentrated in the middle third of the mesial portion for the mesiodistal force (13,750 x 10 -1 MPa ) and in the middle third of the buccal portion in the buccolingual force (10,200 x 10 -1 MPa). However, the analysis of the stress distribution in the root revealed higher values in the model restored with CMP with ½ of the root length in the two force applications, being concentrated in the cervical/middle third of the mesial portion for the mesiodistal forces (3.845 x 10 - 1 Mpa) and cervical third of the buccal portion at the buccolingual force (2,800 x 10 -1 Mpa). Although there was a difference in the maximum tensions between the CMP of different lengths, the values found, as well as the difference between the tension values in the different models, are located in a safe margin for the use of the two lengths of CMP in relation to the forces used in orthodontic treatments.