Effect of bite force on orthodontic mini-implants in the molar region: Finite element analysis / 대한치과교정학회지

ABSTRACT

OBJECTIVE: To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. METHODS: Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of 45degrees and 90degrees to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were 0degrees, 5degrees, and 10degrees to the long axis of the tooth. RESULTS: With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at 90degrees. The maximum Von Mises stress increased with the inclination of the loading direction. CONCLUSIONS: These results suggest that placement of OMIs between the second premolar and first molar at 45degrees to the cortical bone reduces the effect of bite force on OMIs.