Three-dimensional Finite Element Dynamic Load Analysis Of Maxillary First Molar Implant Restoration With Different Angle Abutments

ObjectiveIn this study,a maxillary model was created based on the real jawbone morphology,and three-dimensional finite element method was used to analyze the effects of implants at different angles of abutment on bone stress and strain,implant stress and implant position shift of the single crown at the back of the upper palate first molar under the influence of dynamic load,providing certain theoretical basis for the selection of different abutment angles in clinic.In order to improve the safety and success rate of implant implantation in maxillary posterior region.MethodsIn this study,the abutment of different angles was used as variables,and the maxillary and crown models were extracted to establish the maxillary first molar implant 3D model.According to Lekholm and Zarb bone classification,theⅡosteoid model with cortical bone of 2 mm was established.The stress and strain of cortical bone and cancellous bone as well as the stress and displacement of implant were analyzed.Healthy adults without facial tumors,defects and deformities were selected as volunteers to take CBCT scans of jaw bones and teeth,and the images obtained were stored in Dicom data format.A 3D finite element Analysis model of partial maxillary bone tissue containing implants was established using Mimics21.0,Geomagic Sudio,Solidworks 2021 and Analysis Workbench R1.Seven Angle abutment implant models(0°,5°,10°,15°,20°,25°,30°)were set.Implants implanted at seven different abutment angles were simulated for a chewing cycle(0.875 s)at different time,direction,and 200 N loading force.The stress and strain of bone tissue around the implants,implant stress and displacement were observed.The data results of each group were analyzed.The masticatory cycle was divided into five stages,the first stage 0-0.13 s and the last stage 0.3-0.875 s had no force,and the middle three stages were0.13-0.15 s vertical loading of 200 N on the cheek and tongue tip,respectively.From 0.15 to 0.26 s,the bevel of the tongue of the buccal tip and the long axis of the tooth were loaded at 45°200 N;At 0.26-0.30 s,the palatine buccal inclined plane and the long axis of the tooth presented a 45°200 N load.The stress and strain of the bone interface of the implant and the stress and displacement of the implant were calculated and analyzed by software.Results1.When the abutment Angle was the same,the stress and strain of cancellous bone gradually increased with the masticatory cycle.The stress and strain of cortical bone were the highest at buccal side,followed by lingual side,and the stress and strain values of cortical bone at 0° abutment were the lowest.2.With the increase of abutment Angle,the stress and strain value of cancellous bone increased slowly.When the Angle from 5°,the stress value of cancellous bone increased slowly,and the maximum stress was 15.244 Mpa at0.3 s of 30° model,and the maximum strain was 1940 microstrain at 0.30 s of 30°model.The stress-strain of cortical bone increases with the increase of abutment Angle.The maximum stress is 55.943 Mpa when the base Angle is 30° buccal load 0.26 s,and the maximum strain is 2186.7 micro-strain when the maximum strain is 0.26 s.When the abutment Angle was from 10° to 25°,the cortical bone stress increased slowly.3.By observing the stress and strain nephogram of cortical bone,it was found that the maximum stress and strain of cortical bone were located in the neck of teeth when the abutment was stressed at different angles.4.The stress nephogram of cancellous bone was observed.When the abutment Angle was 5°,10°,15°,20°,25°,the stress concentration area of cancellous bone was evenly distributed at the bottom.For straight abutment and30° abutment,the stress concentration area of cancellous bone was mainly distributed in neck.The strain nephogram of cancellous bone showed that the maximum strain concentrated in the tooth neck.5.The stress nephogram of the implant was observed.During the same mastication period,the stress of the implant gradually increased with the increase of the Angle.When the abutment was 0°,the implant stress increased gradually with the mastication cycle.When the abutment was used at an Angle,the implant stress first increased and then decreased with the mastication cycle.The maximum stress value of the abutment at all angles was 0.26 s,and the maximum stress value was 710.73 MPa when the abutment Angle was 30°,and the maximum stress location was located at the neck of the implant.6.With the mastication cycle,the displacement values of the abutment implant models at 0° and 30° gradually increased,and the maximum values were61.465μm and 76.001μm at the lingual force of 0.30 s.With the chewing cycle of 5°,10°,15°,20°,25° and 30° abutment implant models,the maximum displacement occurred at 0.26 s buccal loading,and the maximum displacement values were52.397μm,58.707μm,59.549μm,65.35μm,71.623μm,72.364μm,respectively.In the third stage of the mastication cycle,the displacement value decreased gradually,and the minimum displacement value of 0.30 s in the 5° model was 46.909μm.ConclusionIn this experiment,by simulating the implants of different Angle abutments in Class II bone of the maxillary first molar region,it was found that the stress of cortical bone and cancellous bone was less than 60 MPa when the Angle abutments reached 30°,and the strains were all within the range of 4000 microstrain safety threshold,and the stress value and displacement of the implants were also within the safety threshold.Even if the abutment Angle was 30°,the maximum implant position was less than 100 μm,which theoretically would not affect the bone union of the implant.In view of the above bone and implant results,it is concluded that 30° Angle abutment implant can be used in maxillary first molar region Ⅱ osteoid.