Flexible and rigid guidance in skeletally-anchored maxillary molar distalization: The miniscrew-supported pendulum vs the Beneslider

Introduction

This study aimed to demonstrate the effects of flexible and rigid appliance designs on maxillary molar distalization.

Methods

Thirty-six patients with bilateral Class II molar relationships and fully erupted maxillary second molars were included in this study. Half of the patients were treated with the miniscrew-supported pendulum appliance (group 1; aged 16.5 ± 2.1 years) and the other half with the Beneslider appliance (group 2; aged 15.6 ± 1.5 years). Lateral cephalometric radiographs and digital dental models were used to study the dentoalveolar and skeletal changes.

Results

Distalization time was significantly shorter in group 1 (P = 0.006); however, the first molars in this group displayed considerably more distal tipping (P = 0.030), with lower distalization values (P = 0.022) and rates measured at the crown (P = 0.248), trifurcation (P = 0.410), and root apex levels (P = 0.048). Distalization at the apex level occured only in the Beneslider group, with a root-to-crown distalization ratio of 33.5%. SNB angle decreased (P = 0.010), and ANB (P = 0.010) and SN-GoGn angles (P = 0.010) increased significantly in group 1, all of which were negligible in group 2. Distobuccal rotation of the first molars was significantly higher in group 1 (P = 0.004). The amount of distalization, distal tipping of the maxillary second molars, and appliance success rates were comparable between the groups.

Conclusions

The Beneslider appliance provided faster maxillary molar distalization with substantially less distal tipping and distobuccal rotation. In contrast, the miniscrew-supported pendulum appliance led to the posterior rotation of the mandible, worsened the sagittal and vertical parameters, and failed to provide distalization at the apex. In summary, our findings indicated that a rigid design for maxillary molar distalization yields more favorable outcomes.