Dynamic And Static Comparative Study Of The Displacement Of Dental Implant And The Stress Distribution In The Supporting Bone

ObjectiveThis study used the finite element method(FEM) to simulate stress and displacement induced in the bone surrounding a dental implant in the mandible under dynamic and static loads, so as to provide theoretical references of biomechanics for clinical application of implantation.MethodsThree dimensional finite element model was created of a second pre-molar section of the mandible with single tooth implant-supported all-ceramic crown.Dynamic loads were applied in a circle of mastication.The stress distribution of the surpporting bone and the displacement of the implant were analyzed to study the biomechanical behavior of the implant,compared with the static analysis.Result1 The three-dimensional finite element model was good in geometry,which could serve for the needs of the three-dimensional stress analysis.2 The distribution rules of the implant's displacement under dynamic loading were similar to those under static loading.The displacement was concentrated on the cervical of the implant, especially in the lingual and buccal sides,and decreased towards the root.Its direction was the same as the loads'.Under static loading,the maximum displacement values of the implant were arranged in order:oblique loads from lingua to bucca(8.967μm)＞oblique loads from bucca to lingua(7.019μm)＞vertical loads(3.777μm),while in a dynamic loading circle,the maximum displacement values of the implant were arranged in order:the stage of oblique loads from lingua to bucca(25.559μm)＞that of oblique loads from bucca to lingua(14.619μm)＞that of vertical loads(8.884μm).In a dynamic loading circle,the maximum value was 2.9 times that under static loading.3 The distribution rules of the supporting bone's stress under dynamic loading were similar to those under static loading.The stress was concentrated on the cortical bone,especially in the lingual and buccal sides,and decreased round the cortical bone,while there was less stress in the cancellous bone but it was more even distributed.Under static loading,the maximum Von Mises vulues of the supporting bone were arranged in order:oblique loads from lingua to bucca (126.540MPa)＞oblique loads from bucca to lingua(90.196MPa)＞vertical loads (38.676MPa),while in a dynamic loading circle,the maximum Von Mises vulues of the supporting bone were arranged in order:the stage of oblique loads from lingua to bucca (360.238MPa)＞that of oblique loads from bucca to lingua(184.356MPa)＞that of vertical loads(89.037MPa).In a dynamic loading circle,the maximum stress was manifested as tension stress,and was 2.9 times that under static loading.4 There was statistical difference between the values under static loading and those under dynamic loading,refering to the displacement of the implant and the stress of the supporting bone,values under dynamic loading were greater.Thanks to the acceleration,the maximum displacement of the implant and the maximum Von Mises value of the bone under dynamic loading were 2.85 times those under static loading,and kept increasing by 30%as the loading continued.After unloading,there were still displacement in the implant,and residual stress in the supporting bone.Conclusions1 CT scanning aided finite element model building,used with AutoCAD software and ANSYS software,is a convenient and credible method.2 The maximum displacement of the implant and the maximum Von Mises value of the supporting bone under oblique loads are greater than those under vertical loads.3 The distribution rules of the implant's displacement under dynamic loading are similar to those under static loading,but the values of the former are greater than those of the latter. Compared to the root,there are greater displacement in the cervical of the implant.Its direction is the same as the loads'.4 The distribution rules of the supporting bone's stress under dynamic loading are similar to those under static loading,but the values of the former are greater than those of the latter.The stress is concentrated on lingual and buccal sides of the cortical bone,there is less stress in the cancellous bone.5 In a dynamic loading circle,acceleration and the continuous loading lead to the increasing of the maximum displacement of the implant and the maximum Von Mises value of the supporting bone.After unloading,there are still displacement in the implant,and residual stress in the supporting bone.