Effects of post length on horizontal load of post-core system / 华西口腔医学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To access the effects of post length on horizontal load of cast post and core crown.</p><p><b>METHODS</b>120 simulated roots made of polymethylmethacrylate were divided into 15 groups according to different mechanical fulcrum and length of post, made the wax pattern of post-core, casted and cemented the post-core. After saline soak, loaded these specimens on the Instron-4302 by the speed of 1 mm/min and recorded the maximum force of load.</p><p><b>RESULTS</b>The means of fracture resistance Wp11 of 7.0 mm, 7.5 mm, 8.0 mm, 8.5 mm, 9.0 mm were (94.24 +/- 12.47) N, (129.76 +/- 19.89) N, (195.98 +/- 1 2.46) N, (208.88 +/- 24.37) N, (225.67 +/- 53.07) N and the means of dangerous stress (sigma degrees 11 were 65.12 N, 93.07 N, 145.84 N, 161.58 N, 181.49 N; the means of fair stress [sigma11] were 39.41 MPa, 56.34 MPa, 88.34 MPa, 97.86 MPa, 109.94 MPa. It showed that the horizontal load of post-core crown system increased gradually with the increasing of the post length. It appeared the linear regression between the length of the post and fracture resistance and physiologic load.</p><p><b>CONCLUSION</b>The increasing of the post length can increase the horizontal load of post-core crown system. During the pulp preparation of post-core system, the post length should be added as much as possible.</p>