Abstract: PURPOSE: To compare and analyze the orthodontic effects of micro-implant screw support and flat guide plate on excessive deep overbite of lower anterior teeth. METHODS: Eighty-two patients with excessive deep overbite of the lower anterior teeth who were treated from January to December 2022 were selected and randomly divided into two groups (41 in each group) by random number table method. Both groups were treated with straight wire arch orthodontic technology, and the anterior teeth were supported by micro-implant screws (micro-implant screw group) and flat guide plates (flat guide plate group), respectively. The effect of upper anterior tooth compression, changes in occlusal plane, and apical absorption were compared between the two groups. SPSS 25.0 software package was used for statistical analysis. RESULTS: There were no significant changes in SNA angle, SNB angle, ANB angle, U1-PP, U6-PP, and L6-MP before and after treatment between the two groups (P>0.05). L1-MP significantly increased in both groups after treatment than before treatment(P<0.05). There was no significant difference in bite opening, Spee curve depth, U1 depression, L1 depression, U6 elongation, L6 elongation and occlusal opening time between the two groups before and after treatment(P>0.05). The root apex absorption of the mandibular central incisors and lateral incisors in the micro-implant screw group was significantly lower than that in the flat guide plate group(P<0.05), while there was no significant difference in root apex absorption between the two groups of canines(P>0.05). CONCLUSIONS: Both micro-implant screw support and flat guide plate can effectively lower the mandibular anterior teeth in the treatment of deep overbite in adults, with good orthodontic effects. However, the latter can lead to increased root resorption.

Key words: Deep overbite, Micro-implant screw support, Flat guide plate, Straight wire arch treatment, Root resorption