Abstract: Objective To study comparatively the impact of invisalign and fixed appliance on the periodontal health of the orthodontic patients through their changes of the periodontal indexes in the orthodontic process. Methods 20 adult patients who were treated with fixed and invisible orthodontic treatment from March 2013 to April 2015 were selected from the Affiliated Hospital of Wenzhou Medical University. Patients periodontal indexes(including GI, SBI, PLI, SPD) were examined respectively before the treatment, one month after accepting treatment, six months after accepting treatment, when completing the treatment, and three months after the treatment. Results At two time points, namely before the treatment and three months after the treatment, there was no obvious difference in the periodontal indexes between the two patient groups. During the whole process of the orthodontic treatment, the periodontal indexes of the invisalign group had a downward trend whereas those of the fixed appliance group had increased significantly. Besides, the sulcus probing depth did not differ between the two groups. Conclusion The use of traditional fixed appliance might cause deterioration of oral conditions, while the invisaligh can well protect the periodontal tissues.

Key words: invisalign, periodontal health, orthodontic, gingival index