Total mesialization of the mandibular dentition using a mini-implant-supported device : A finite element analysis.

PURPOSE: Total mandibular arch mesialization using mini-implants is challenging due to anatomic limitations. The aim of this study was to introduce a mini-implant-supported device for total mesialization of the mandibular dentition and to analyze the biomechanical properties of the device.

METHODS

Finite element models were constructed to explore the effect of friction and force direction on the force transmission efficiency of the device. In addition, the three-dimensional displacement of each tooth was evaluated with two force application points (2 or 8 mm hooks) under three force conditions (symmetric: 150 g of force on both sides, or asymmetric: 100 and 200 g of force on each side).

RESULTS

The force transmission efficiency was 66.7% under a friction coefficient of 0.15 and parallel pushing and pulling forces. The force transmission efficiency was 65.90 and 66.63% when the pushing force was 15° away from the pulling force on the sagittal and horizontal planes, respectively. The mandibular dentition moved mesially with a greater tendency for incisor labial crown tipping, mesial molar rotation and buccal second molar crown tipping when using the 8 mm hook compared to that when using the 2 mm hook. Rigid archwires resulted in more consistent tooth mesialization than stainless steel archwires. Asymmetric forces resulted in asymmetric dental arch mesialization.

CONCLUSION

The forces transmitted by the presented mini-implant-supported device varied depending on the friction level and force direction. The device should be able to achieve symmetric or asymmetric total mesialization of the mandibular dentition.