The aim of the present research study is to estimate the maximum permissible intrusive force mathematically with one-dimensional finite element method and to achieve the safe intrusion of a canine tooth without any damage to periodontal ligament (PDL). For this purpose, one-dimensional finite element (FE) model of a canine tooth was developed consisting of tooth (crown and root) and PDL structure. The maximum permissible intrusive force was computed mathematically. For this purpose, the maximum permissible stress was considered as `E-PDL/1.5', where `E-PDL' is the Young's Modulus of PDL and factor of safety (FOS) is 1.5. The maximum permissible intrusive force was computed to be approximately 10 g-force (gf). For verification of this computed force value, finite element analysis was carried out on 3-dimensional canine tooth, PDL and bone structures for better verification and it is proved that 10 g force (gf) value is safe without any damage to PDL tissues. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 1st International Conference on Computations in Materials and Applied Engineering - 2021.