Three Dimensional Finite Element Analysis Of Implant-bone Interface Of Orthodontic Anchorage

Implant anchorage is an important concept in orthodontics. It is especially important for those adult patients who lack intro-oral dental anchorage because of the loss of teeth without appropriate anchorage under the condition that does not affect the appearance. Patients are unwilling to accept extra-oral anchorage for the reason of aesthetics. With the development of oral implantology, implant anchorage has been introduced into orthodontics and applied in clinics. Previous studies were focused on the stress distribution of implant-bone interface used for denture restoration. Considering the difference of implant shape, indication, load distribution and function between these two kinds of implants.The purposes of this study were to: (1) establish the 3-dimention finite element model of anchorage implant in mandibular teeth-deprived areas; (2) choose appropriate implant used for anchorage; (3) investigate the stress distribution of implant-bone interface of different value, direction, and form of force; (4) investigate the stress distribution of implant-bone interface of different thickness of the compact bone. Results: 1. Firstly, three-dimensional finite element model of human mandibular teeth-deprived areas was established by computer plane stretch imitation technique. Then, the model of mandibular anchorage implant was established by implanting implants of different shapes and sizes into mandibular. The compact bone was supposed to be anisotropic material and the cancellated bone was supposed to be isotropic material. The mechanical parameters of fresh human mandible for the tensile test were used as the mechanical parameters of the compact bone, so the real physiological condition was imitated accurately. The standard model was established by put the length of the knife-edged threaded implant as 10mm 4 diameter in 3.75mm, angle of screw in 600 , abutment 7mm in height and the compact bone 1mm in thicknes at the neck level of implant. 2. The stress at implant-bone interface was analyzed by implant three cylinder implant (knife-edged threaded, square threaded and smooth type implants) into teeth-deprived areas of mandible. The Von-Mises stresses at neck level of the implant-bone interface were 0.533 MPa, 1.160 MPa, and 0.890 MPa, respectively. 3. Orthodontic load was exerted on knife-edged threaded implants with different screw angle (60~ 750 , and 1200 ). The Von-Mises stress at neck level of the implant-bone interface reached minimum value when the angle was 600 These three implants have the same law of stress distribution. The difference of displacement among these three implant-bone interfaces is very small and they have nearly the same law of displacement. The results show that angle of screw does not affect displacement of implant-bone interface. 4. Orthodontic load were exerted on implants of different length (7mm, 10mm, and 15mm). The Von-Mises stresses of the implant-bone interfaces were 0.545 MPa, 0.533 MPa and 0.532 MPa, respectively. The displacements were 0.169 i?m, 0.163 p m, and 0.161 1?m, respectively. Orthodontic load were exerted on implants with different diameters (3 mm, 3.75 mm, and 5 mm). The Von-Mises stresses of the implant-bone interfaces were 0.807 MPa, 0.533 MPa and 1.080 MPa, respectively. The displacements were 0.232 i~t m, 0.16311 m and 0.111 1?m, respectively.