A Comparative Study To The Displacement Of Natural Tooth And Tooth Implant Under Dynamic Loads

ObjectiveTwo three-dimensional finite element models of a human mandibular second premolar and an implant of full crown restoration under equal conditions and the supporting tissues have been established to compare the displacement differences between natural teeth and implants,so as to provide theoretical references to the tooth-implant-supported fixed denture.MethodsA normal human mandible was used as an anatomy foundation to establish a three-dimensional finite element model with CT scanning aided model building, AutoCAD software and ANSYS software.Finite element analysis was performed on the tooth model and the implant of full crown restoration and the supporting tissues model under vertical and oblique dynamic loads in a circle of mastication.The amount and directions of displacement of these 2 models were obtained and compared.Results1 Two three-dimensional finite element models were constructed successfully with great resemblance in geometry and mechanics.2 When dynamic loads were applied,there was statistical difference in the displacement of the natural tooth and of the implant.In 0.15～0.26s and 0.30～0.875s, the difference between the natural tooth and the implant was found in the cervical and the root.In 0.26～0.30s,the difference was found in the root.3 The artificial crown of the implant and implant abutment had large difference in the amount of displacement,where relative movement appeared. 4 Except the dental crown,under the oblique loads,the maximum amount of displacement of the natural tooth was 36.759μm,and the maximum amount of displacement of the implant was 26.377μm.The maximum amount of displacement at the cervical of the natural tooth could be 2.98 times more than that of the implant at the same point of time.5 By the influence of the periodontal membrane,there was a significant variance in the amount of displacement at the root and the root apical of natural tooth with time. But the variance of implant changed slowly.6 There was difference between the natural tooth and the implant in the directions of displacement.Conclusions1 A complicated biological tissue model with good geometry and mechanics resemblance can be established by applying the finite element method.2 The maximum amount of displacement at the artificial crown of tooth implant can be 163.8 times more than the implant abutment.There is large relative movement between the implant abutment and the artificial crown of the implant.3 Except the crown,in 0.134～0.30s,each point of natural tooth has larger amount of displacement than the implant,especially under the oblique loads.4 At the same point of time,the difference between the amount of displacement of natural tooth and implant is small.5 The natural tooth revolves following by the different loading directions.The rotation center of the natural tooth locates at lingual cervical or 1/2 buccal root of tooth.When the artificial crown of the implant revolves,the implant right along maintains a stable direction of displacement.