Uprighting of mesial inclined second molar with different anchorage methods- an evaluation by finite element analysis

In our study, stress distribution which occurs in the second molar, anchorage units and the bone were examined by finite element analysis with different second molar uprighting methods. Besides, the displacements occurring in the teeth when the force is applied were evaluated by finite element analysis. In our study, three different anchorage structures used for the second molar uprighting were evaluated by creating three study model. In the first study model all the teeth in the arch were anchoraged. In the second model, the bracket abutment mini screw ancorage which placed in the first molar space, perpendicular to the mandibular plane; in the third model, dental implant anchorage which placed in the first molar space, perpendicular to the mandibular plane were used. We assumed that the implant we used is not yet osteointegrated. In all models, Ni- Ti open coil, which applies 150 gr force placed on stainless steel wire, was used for uprighting. At the end of analysis, similar stress intensity occurred in the second molar roots in all study models. The stresses occured in second molars crown were followed the most when mini screw anchor was used, then the implant anchor was used, and the least anchorage of the teeth was used. In all study models, when the uprighting force was applied, extrusion, distolingual rotation and linguale bending were observed as side effects. While the extrusion was observed less when the mini screw and implant anchorage were used, rotation and bending to the linguale were occured less when using anchorage of the teeth. In the first model, some side effects have occurred in the teeth used as an anchor during uprighting. When using mini screws and implant anchors, stress is mostly concentrated on the neck area on both structures. It was observed that the stress in the mini screw was higher than the implant. Since the bracket slot on the mini screw is thinner than the bracket slot in the implant, more stress has occurred in the second molar and cortical bone in the second model. As a result, it has been seen that all the treatment methods for mandibular molar erection are clinically feasible.