Abstract: Objective: To investigate the distribution of periodontal stress and the risk area of root resorption in the maxillary whole dentition with different loading modes by using three-dimensional finite element technique. Methods: Three dimensional finite element models including maxilla, upper dentition, and periodontal membrane were established. The periodontal stress of each tooth in the maxillary dentition was recorded and analyzed by controlling different traction directions (a total of 12 groups). Results: The traction hook height was 0 mm, implant position located between lateral incisors and canines or between canines and first premolars, and the micro-implant length was 0 mm or 7 mm were relatively uniform in the 12 groups. The periodontal stress of each tooth was within a moderate range, and the efficiency of the dentition moving in the sagittal direction was high. Conclusion: When the traction force is parallel to the arch wire (23-0-0, 34-0-0), the force system is relatively uniform, the periodontal membrane of each tooth is subjected to a moderate range of stress, and the efficiency of the dentition moving in the sagittal direction is high. The molars area is not prone to excessive pressure, while the anterior teeth area is prone to excessive pressure, which may be related to the anatomy and location. The tooth near the hook is a risk area for root resorption. It is not recommended to use the high micro-implant and high traction hook together, and pay attention to the vertical force on the lateral incisors and canines.

Key words: three dimensional finite element, micro-implant, periodontal membrane stress, root absorption