[Exploration on the sliding mechanism of implant anchorage assisted self-ligating appliance].

Purpose: To investigate non-extraction treatment of borderline cases through analysis of cases treated by maxillary implant anchorage assisted self-ligating appliance.

Methods: Twenty adult patients with moderate-crowding malocclusion were reviewed. The patients were divided into 2 groups. G1 group comprised 10 patients, 6 males, 4 females, aged 18-26 years(mean: 22 years old), treated by implant anchorage assisted self-ligating appliance; G2 group comprised 10 patients, 5 males, 5 females, aged 19-25 years(mean: 23 years old), treated by self-ligating appliance. Dental casts and lateral cephalometric radiographs were measured before and after orthodontic treatment (or after leveling and alignment). SAS8.02 software package was used for statistical analysis.

Results: Significant increase in inter-premolar arch width and inter-molar arch width were noted after orthodontic treatment or first treatment phase in both groups, with no significant difference between the G1 and G2 groups. No significant difference was observed in molar inclination within the treatment process in both groups. UI-SN and UI-NA increased significantly after orthodontic treatment or first treatment phase in two groups with statistical difference between the G1 and G2 groups, indicating that implant-anchorage contributed better control of the upper incisor. G1 also showed a statistically greater molar distal movement than G2.

Conclusions: During the non-extraction treatment of borderline cases, maxillary implant-anchorage assisted self-ligating appliance can entirely retract the upper dental arch, expand the arch width and show better control of the upper incisor, so the fine naso-labial relationship, upper lip protrusion and soft-tissue profile can be maintained. Compared with headgear and pendulum, implant anchorage assisted self-ligating appliance is a better way to handle borderline cases with non-extraction approach.