evaluation of stress generation on the cortical bone and the palatal micro-implant complex during the implant-supported en masse retraction in lingual orthodontic technique using the fem: original research

Background. this study aimed to evaluate and analyze the distribution of stresses on the palatal micro-implants and the cortical bone at the micro-implant site with optimal orthodontic retraction force in lingual orthodontics. methods. ansys 12.1 software was used to construct the finite element model of the maxillary bone, teeth and the perio-dontal ligament along with the lingual bracket set-up with wire and the micro-implant. six- and 8-mm micro-implants were constructed. the final model consisted of 99190 nodes and 324364 elements. a 200-gram of retraction force was applied from the micro-implant to the anterior retraction hook. the micro-implant was embedded between the second premolar and the first molar. hyper-view software was used to get the results in x-y-z dimensions. results. the maximum von mises stresses detected were 52.543 mpa for 6-mm micro-implant and 54.489 mpa for 8-mm micro-implant. maximum stress was at the neck of the micro-implant. the 8-mm implant model showed 6×10^-3 mm of lingual displacement. the least displacement of 1×10^-3 mm was noticed for both the implant models in the apico-occlusal direction. the maximum von mises stresses in the cortical bone at the micro-implant site was 18.875 mpa for 6-mm micro-implant and 21.551 mpa for 8-mm micro-implant. conclusion. six-mm micro-implant can be the choice for the implant-supported lingual orthodontic retraction as it produced minimal stresses on the cortical bone, and the initial stress displacements produced on the micro-implant were also minimal.