| Objective:To use three-dimensional(3D)finite element method to analyze the effects of abutment angulation changes and bone quality changes on the biomechanical aspects of the maxillary anterior teeth area after implant restoration,and observe the effect of implant length change on bone.It provides a certain theoretical reference of using angled abutments for clinical in different bone qualitiesMethods:The CBCT images provided by a volunteer were imported into Mimics to obtain the anterior maxillary bone model and crown model.With reference to the parameters of the Noble implant system,the implants and angle abutments models were drawn using Catia.The processing of each part model was optimized by Geomagic Wrap Finally,the overall model was accurately assembled in Catia.The obtained models were calculated and analyzed in ANSYS.The equivalent stress and equivalent strain distribution of the bone tissue were observed,and the maximum equivalent stress(von-Mises peak stress,σvM)and the maximum equivalent peak elastic strain(εmax)of cortical bone and cancellous bone were compared and analyzedResults:1.32 groups of 3D finite element analysis models were established according to the abutment angulation,bone qualities and implant length.2.Under the same bone quality,the σvM of cortical bone and cancellous bone both increased,and the σvM of cortical bone was significantly higher than that of cancellous bone.Cortical bone and cancellous bone εmax also increased with increasing angle.3.Under the same angle,as the bone quality changes from D1 to D4,the σvM of the cortical bone around the implant increases and the σvM of the cancellous bone gradually decreases.The trend is the same in different angles of the abutment.Around the implant cortical bone and cancellous boneεmax increased,and the trend was the same in different angled abutments.The 0°abutment in all four types of bone had εmax below the bone threshold of 4000 μstrain.At 10°abutment,the bone tissue εmax exceeded the bone threshold from D3.The cortical bone εmax of the 20° abutment approached the bone threshold in D2,and the bone tissueεmax appeared beyond bone threshold from D3.The cortical bone εmax and cancellous bone εmax of the 30°abutment approached the bone threshold in D1 and D2,and the bone tissue εmax appeared beyond bone threshold from D3.4.Compared with the L1(13mm)implant,the implant with a length of L2(15mm)has a significantly lower σvM in the four types of cortical bone in 10°and 20°abutments,however,changes of boneσvM show not obvious in 0°and 30°abutments.The cancellous bone σvM does not decrease significantly in any bone qualities and any abutments.The cortical bone εmax of the four types of bone has decreased in the 10°and 20°abutment,but the changes of cancellous bone were not obvious.In addition,in D3 and D4 bones,abutments of 20°and above cannot be completely lowered away from the bone threshold even with L2 length implants.Conclusions:1.According to the results of this 3D finite element analysis,an increase in angulation of the abutment will increase the stress concentration and elastic deformation of the bone tissue around the implant.As the angle increases,there is a risk of exceeding the bone threshold.Therefore,in clinical practice,choosing an angled abutment that is more consistent with the long axis of the implant for repair and reduce the risk of bone resorption.2.In different bone qualities,as the bone quality from Ⅰ to Ⅳ,the adverse effects of the resistance angled abutments on the bone tissue become weaker and weaker.In the worse bone quality,the use of angled abutment is not recommended The increase in the length of the implant can offset the adverse effects of some angled abutments on the bone tissue. |
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