Abstract: Objective To evaluate the treatment effects of J hook headgear and micro-screws on intrusion of upper incisor. Methods 21 adult patients with overgrown maxillary alveolar were chosen and divided into two groups: J hook headgear group (n=9), and micro-screws group (n=12), using J hook headgear and micro-screws to lower upper incisor respectively. Cephalometric analysis was performed before and after treatment, and cephalometric indicators changes and treatment time of two groups were compared. Results U1-PP of the two groups were significantly reduced (P <0.01), and the reduction of micro-screws group was greater than the J hook headgear group (P <0.01); as for U1-Sv, micro-screws group increased (P <0.01), while J hook headgear group decreased (P <0.01); in terms of U1/PP corner micro-screws group increased (P <0.01), and J hook headgear group did not change significantly (P> 0.05); U6-PP both groups have no statistically significant change (P> 0.05); as for U6-Sv, micro-screws group increased (P <0.01), while there was no statistical significant change in J hook headgear group (P> 0.05); the treatment time of micro-screws group was less than that of J hook headgear group (P <0.01). Conclusion Both J hook headgear and micro-screws have effect on the intrusion of incisors, and micro-screws is more effective than J hook headgear with less time, but it will cause anterior teeth labial inclination and increase anchorage burden.

Key words: upper incisor, intrusion, micro-screws, J hook headgear