Infra-Zygomatic Mini Screws Compared to High Pull Headgear for Distalization And Intrusion of Maxillary Molars in Growing Patients with Class II Malocclusion: A Randomized Clinical Trial

Abstract

Objective: The aim of the present randomized clinical study was to evaluate the distalization and intrusion effect of an Infra-zygomatic mini-screws supported appliance and compare it with high pull headgear appliance in treatment of growing patients with class II malocclusion.
 Methodology: 22 growing boys aged between (10 to 12 years) with class II div 1 malocclusion randomly divided to 2 equal groups. The first group treated with high pull headgear with acrylic splint and the second one treated with an Infra-zygomatic mini-screws supported appliance. The treatment duration was 8 months for both groups. Lateral cephalometric radiographs were taken before and after the treatment for each patient to be analyzed.
 Results: The maxillary first molar distalization was 2.58±2.31 mm in head gear group and 1.53±2.83 mm in mini-screws group. There was no significant maxillary first molar intrusion in both groups. There were no significant differences between the two groups.
 Conclusions: the mini-screws supported appliance can be used as the fixed replacement of the removable high pull headgear appliance with no need for patient cooperation.

Infra zygomatic crest (IZC) and mandibular buccal shelf (MBS) bone screws: A comprehensive updated review

“…Clinically, similar differential motions can be replicated on the anterior teeth when using mechanics with extra-alveolar implants by altering the line of action of force by variations in hooks/power arm length. 6,29 When utilising short hooks, the retraction force delivered passes underneath the CR, increasing the propensity of clockwise spin of the anterior teeth, which causes torque loss and a vertical extrusion force on the incisors. Increased hook length mesial to the canine permits the force action line to approach very near the incisor's centre of resistance.…”