Table 2.

Comparison of the hook vertical height and retraction conditions relative to Z-axis displacement

Positive figures mean tooth intrusion and negative figures mean extrusion. Condition 1, The lingual anterior retraction hooks (LARHs) were placed between the upper central incisors and lateral incisors 6^° of toe in angle. Condition 2, The LARHs were placed between the lateral incisors and canines with 15^°of toe in angle. Condition 3, The LARHs were placed between the upper central incisors and lateral incisors after second premolar extraction. Condition 4, The LARHs were placed between the lateral incisors and canines with 15^°of toe in angle after second premolar extraction.