Investigation On Insertion Torque And Osseointegration Failure Of Dental Implant

Long-term lacking of teeth would not only affect the chewing function,but also have negative effects on health.The implant-denture has become the best choice for patients as it high success rate and excellent esthetics.The success of it depends on the long-trem stability and osseointegration of implant.Studies have shown that the initial stability of implant is positively correlated with insertion torque,the geometry of implant and the surgical method.The stress distribution brought by insertion torque and function load leads to the process of bone remodeling.In this process,the osseointegration would be occurrence,which is crucial to achieve secondary stability of implant.Therefore,the analysis of insertion torque and osseointegration are essential to implantation success.This paper focuses on the calculation insertion torque,the rational selection of insertion torque and the osseointegration of implant.The main works are as follows:(1)The preoperative prediction of insertion torque was presented through the establishmen of calculation model for insertion torque.First,the mechanical model of insertion torque was established.The effects of bone quality,the geometry of implant and the surgical method on insertion torque were explained by this mechanical model.Then,the parameters of cutting and forming process were obtained by insertion experiments and the proposed model was verified.Finally,the material model of specimen was obtained by establishing two three-dimension microstructural solid models.And the insertion torque of dental implant was further obtained by a series of numerical simulations.The following conclusions was obtained in this section:1)The effects on insertion torque were brought by implant geometry,including implant diameter,length,thread pitch and tooth shape,surgical plan,including implantation speed and size of implant hole,bone quality on dental implants.2)The insertion torque is positively correlated with the bone density,and the fluctuation is related to fabric tensor.The more obvious the anisotropy are,the greater the fluctuation.(2)Secondly,the selection of dental implants and insertion torque for Ⅱ,Ⅲ,Ⅳbone were shown.Firstly,the mathematical model was established to describe the wolff law in bone remodeling process.Then,the displacement(<0.1mm)of the bone contact surface and the secondary contact rate(>40%)were chosen as the criteria,and taking DIO,IS and ITI implants as examples,the reasonable selection of implants and insertion torque were analyzed.Finally,combined with the microscopic solid model,the reasonable selection of implants and insertion torque for Ⅱ,Ⅲ and IV bone were proposed.The results showed that the rational implantation torque of type Ⅱ bone was the largest whiel the type IV bone the smallest.(3)Finally,the failure of osseointegration under three load states and different load conditions was discussed by establishing the finite element model of osseointegration failure.First,the finite element model of osseointegration was established and the failure of osseointegration under different load conditions was discussed.Then the osseointegration failure under the alternate load was further analyzed.Finally,the osseointegration failure under cyclic loading under conventional load is analyzed.It have shown that bone resorption occurs immediately under static load and early load,there is no bone resorption under the single alternating load,,there is micromove>100 μm under 10~8 cycles of loading and osseointegration failure.