Stress Analysis Of Implant Crown Buccal-lingual Diameter And Implant Neck Design Under Different Bone Conditions

Purpose To evaluate the effect of different buccal-lingual diameter and implant neck design on the stress distribution of implant denture and surrounding bone under two kinds of bone conditions.Materials and methods using CBCT and intraoral scanner data,Mimics17 and UG NX7.5 software,12 3d solid models were constructed,including cortical bone,cancellar bone,implant,abutment,central screw and all-ceramic crown.Implant Straumann planting system,was used for the specification of 4.1 * 10 mm,implant types for bone implants and tissue levels implant,base stations use crown height of 5.5mm can base stations,jaw bone type for Ⅱ bone and Ⅲ bone.The buccal and lingual diameters of the implant were set as 100%,80% and 60% of the buccal and lingual diameters of the corresponding teeth(mandibular first molars)in the original CT images.Abaqus 6.13 software was used to dynamically load the model.The load size was set as300 N,and the simulated chewing period was 0.875 s.Stage 1:0.000 s to 0.130 s.Stage2:0.130 s to 0.150 s,the loading position is the tip of the cheek and the tip of the tongue.Stage 4: from 0.260 s to 0.300 s,the loading force was inclined from the tongue to the buccal side,and was loaded on the bevel of the buccal tip tongue at 45° from the long axis of the tooth.Stage 5:0.300 s to 0.875 s.In the unloading stage,the posterior mandibular teeth were separated from the conjunctive teeth and returned to the staggered position of the teeth.The maximum stress value and its distribution in each part of the 12 models were observed during the masticatory cycle.Results 1.12 the stress concentration sites of the 12 models are roughly the same in the chewing cycle,which are basically concentrated in the implant neck and surrounding bone tissues,the connection between the base and the implant,the first thread of the central screw,the screw and the connection between the nut and the screw,and the cervical margin of the crown.2.Different crowns in Ⅱ buccal tongue size classes with Ⅲ bone stress conditions in the level of statistical analysis showed that bone implant itself stress value increased obviously(p < 0.05),cancellous bone stress value significantly decreased(p < 0.05),the level of soft tissue implant itself stress value significantly decreased(p < 0.05),cancellous bone stress value change is not obvious(p > 0.05),the above two kinds of cortical bone around implant neck and the central screw stress value were significantly decreased(p < 0.05),and base stations and dental crowns stress value has not fully with buccal tongue has obvious change with the decrease of the diameter.3.Different neck design of implant in Ⅱ classes and Ⅲbone stress conditions in the statistical analysis showed that bone level stress is bigger than the value of soft tissue implant itself level stress value of implant itself(P < 0.05),while cortical bone around implant neck stress value was less than the latter(P < 0.05),other parts of the maximum stress value change is not obvious(P > 0.05).4.Different jaw bone type fully stress conditions in the statistical analysis shows that in the middle of the cortical bone around the implant and and the screw stress value comparison,Ⅱbone is Ⅲ class bone stress value significantly decreased(P < 0.05),while other parts of the fully stress value comparison,Ⅱ class between bone and bone Ⅲ class there was no significant difference(P > 0.05).Conclusion 1.In class II and class III bone,it is suggested that the soft tissue level implant crown should be reduced to eighty percent of the original crown,which can not only ensure a certain chewing function,but also reduce the stress of the implant denture.The range of crown reduction of bone level implant is smaller than that of soft tissue level implant,which reduces the risk of implant fracture.2.In class Ⅱ and class Ⅲ bone,the bone level implant is better than the soft tissue level implant in protecting the bone tissue retention and soft tissue height of the neck,but it is more likely to inducemechanical complications of the implant.3.No matter what kind of implant is designed for the neck,class Ⅱ bone is more beneficial to the success of implant repair than Class Ⅲ bone.