3-D Finite Element Study On Maxillary Protraction Using Implant Anchorage

Abstract:Objective:1. To construct the craniofacial complex 3-D finite element model of precise biomechanical characteristic with the original DICOM data of CT; and to explore the stress change rule of suture and the interface of bone-implant against different strength and direction of protraction which provide the scientific basis for the selection of force system in clinical treatment. Methods:Acquire the original DICOM data of 2-D image craniofacial complex by high resolution CT scanning. Apply the combination of Mimics 10.0,MSC. Marc.mentat 2005 R3 and geomagic studio 10.0 software to develop 3-D finiite element models of craniofacial complex according to the original DICOM data.2. Simulate the boundary conditions of craniofacial complex protraction with MSC. Marc.Mentat software,fixed in the front area of foramen magnum and cornale.In the area of implant surface,forces of 1to ION are applied with protraction.Force direction is chosen that is inclined at 0 to 60 to Frankfort horizontal plane in the anterior and inferior directions. Forces and directions of protraction are combined into 70 different conditions.Influence to the craniofacial complex against different strength and direction of protraction is analysised.Data of principle stress,equivalent of stress,equivalent Von Mices stress of each node of each simulaton is caculated.Then the stress nephograms is protracted.Results: 1.Were constructed 3-D geometrical models of craniofacial complex are obtained.The mesh generation is precise and reasonable; the constructed model has good comparability with the morphology of reconstructed organisms' model; the constructed model has great applicability, as well as is of quite precise mechanics characteristic.2. The change rule of effectiveness of different force value of protraction in the same direction is same in different stress zone. The change rule of effectiveness of same force value of protraction in the differente direction differs in different stress zone.3.The stress of the interface of bone-implant is increased following the protraction angle's augmentation. 4.When the protraction angle is between0°-60°, it seems that the Palatal suture is experienced Tensile stress.With the protraction angle's increase, he stress value decreases. Conclutions:1.Apply the combination of Mimics10.0,MSC. Marc.mentat 2005 R3 and geomagic studio 10.0 software to develop 3-D finite element models of craniofacial complex, of which the bone suture and implant are also included.2. When the protraction angle's less than 30°, the maxillary complex will spin up.In the 30°, the maxillary complex shows the forward growth. Between 40°-50°,the growth direction is same with the protraction direction. When the protraction angle's more than 50°, the maxillary complex will spin down.3. When the protraction angle is between0°-60°, it seems that the Palatal suture are expanding. With the protraction angle's augmentation, the phenomenon of expanding weakens.4.The stress at suture and interface of bone-implant made by the normal protraction angle and protraction force are far less than the yield value of bone. and not lead to bone fracture.5. Changing the angle of implants will reduce the stress on the bone-implant interface.