Effects of orthodontic treatment with activator appliance on patients with skeletal Class II malocclusion: a systematic review and meta-analysis

Abstract

Background: This systematic review aimed to evaluate and compare the treatment effects of activator appliances on untreated class II skeletal malocclusion patients in terms of skeletal, dental, and soft tissue changes. Methods: We searched 11 databases from January 1966 to May 2021 for randomized and clinical controlled trials that compared the treatment effects of activator appliances on untreated Class II skeletal malocclusion patients. All data were analyzed using RevMan 5.3 software. Results: According to the inclusion/exclusion criteria, 16 articles qualified for the final analysis. Thirteen outcome indicators of teeth, bone tissue, and soft tissue were compared and analyzed: SNA°, SNB°, ANB°, SN-MP°, ANS-Me, Co-Gn, Go-Me, overjet, overbite, U1-SN°, L1-MP°, UL-E, and LL-E. Five randomized controlled trials (RCTs) evaluations were of medium quality, and 11 controlled clinical trials (CCTs) evaluations were of B grade. Bone tissue changes: compared with the untreated group, the SNA and ANB decreased, and the SNB, SN-MP, ANS-Me, Co-Gn, and Go-Me increased after activator appliance treatment, and the differences were statistically significant (P<0.001). Dental changes: compared with the untreated group, the overjet, overbite and U1-SN in the treated group decreased significantly, while the L1-MP increased significantly (P<0.0001). Soft tissue changes: compared with untreated patients, the UL-E of patients treated with an activator appliance decreased significantly (P<0.0001); however, there was no significant difference in the LL-E between the two groups (P=0.09). Discussion: Since the imprecision and high level of heterogeneity of the articles, further large-sample and high-quality clinical trials are necessary to evaluate effects of orthodontic treatment with activator appliance on patients with skeletal Class II malocclusion. In addition, this study failed to explore the long-term stability of activator treatment, so long-term studies are needed to assess the stability of its effect on the skeletal, dental, and soft tissue changes.