The effect of vibrational force on neighboring teeth: a finite element analysis.

OBJECTIVES: To determine force distribution on the maxillary dentition under a vibrational force (VF) with two frequencies on the left canine (L-CA) using a finite element model (FEM) to quantify effects on targeted and neighboring teeth and to understand effects of different orthodontic appliances on distribution of VF. MATERIALS AND METHODS: Three-dimensional FEMs of a human maxilla were created. Models included teeth, periodontal ligament, alveolar bone, brackets, archwire, and mouthpiece. Brackets with nine different types of archwires were tested. A VF (0.3 N) with two frequencies was applied to the L-CA. Force distributions on teeth corresponding to the archwires were calculated. FEM was validated experimentally. RESULTS: Peak load (PL) distribution on teeth was bell shaped with maximum force on the L-CA. The L-CA received the most external force (50-82%); the left lateral incisor (L-LI) and first premolar (L-1PM) received between 7% and 18% each, and the left central incisor (L-CI) and second premolar (L-2PM) received only 1-6% each. Increasing wire stiffness caused decrease of force on the L-CA and increase on neighboring teeth. Rectangular wire was stiffer than round wire. The 0.022 × 0.028-in archwire decreased force on the L-CA to 50% and increased force on the L-LI and L-1PM to 15% each. Both magnitudes and distributions of PL corresponding to the two frequencies were similar. CONCLUSIONS: External force is primarily withstood by the L-CA and has significantly reduced impact on neighboring teeth. Archwire stiffness reduction increases the proportion of the force on the L-CA, which is desired to ensure the stimulation effect is localized.