Preventing J-Hook Orthodontic Injury.

Injuries are reported in the patients who use J-type head gears. This article describes a simple chair side practical method to avoid J-hook injuries

Directional forces using skeletal anchorage for treatment of skeletal Class II div.1 malocclusion / 대한치과교정학회지

Tweed-Merrifield directional force technology is a very useful concept, especially for the treatment of Class II malocclusion. It has contributed to creating a favorable counter-clockwise skeletal change and balanced face, while head gear force using high pull J-hook (HPJH) in an appropriate direction is also essential to influence such results. Clinicians have encountered some problems concerning patients' compliance; however skeletal anchorage has been used widely of late because it does not necessitate patients' compliance, yet produces absolute anchorage. In this case, a good facial balance was obtained by Tweed-Merrifield directional force technology using HPJH together with skeletal anchorage, which provided anchorage control in the maxillary posterior area, torque control in the maxillary anterior area, and mandibular response. This indicates that skeletal anchorage can be used to reinforce sagittal and vertical anchorage in the maxillary posterior area during the retraction of anterior teeth. The author used HPJH for torque control, intrusion, and the bodily movement of maxillary anterior teeth during en masse movement. However, it is thought that such a result may also be achieved by substituting mini- or microscrews for HPJH. Consequently, Tweed-Merrifield directional force technology using skeletal anchorage for the treatment of Class II malocclusion not only maximizes the result of treatment but can also minimize patients' compliance.

A cephalometric evaluation of anterior J hook headgear traction to the maxilla / 대한치과교정학회지

This study was aimed to observe the effect of Anterior J hook headgear on the craniofacial structures in mixed dentition with Class II malocclusion. The laterial c-phalograms of 20' children treated by Anterior J hook headgear were traced, digitized and statistically analyzed. The results were as follows 1. Forward growth of maxilla was inhibited. 2. Rotational effect of maxilla was not observed. 3. There was distal movement of maxillary dentition. 4. Maxillary_.dentoalveolar growth changes were more effective in anterior portion than posterior portion. &.Mandible maintained a normal growth and mandibular plane angle- was maintained during treatment period. 6. The ratio of anterior facial height to posterior facial height was almostly not changed.

A photoelastic study on the stress distribution of the upper anterior teeth when retract with high pull J-hook headgear / 대한치과교정학회지

This study was designed to inveatigate the stress intensity and distribution produced by 1mm activation of retraction archwire with 0degrees, 7degrees, 14degrees torque and application of high pull J-hook headgear during retraction of four maxillary incisors using the photoelatic stress analysis. The photoelastic model was made with a PL-3 type epoxy resin which was substituted by alveolar bone portion. Each retraction archwire was fagricated from .020" x .025" stainless steel wire which had vertical loops in 7mm height and hook for high pull J-hook headgear between central and lateral incisors. The high pull J-hook headgear was applied 35 degree backward and upward to occlusal plane with 200mg per each side. The findings of study as follows : 1. In case of 0degrees torque, the stress was distributed from cervical 1/3 to apex of root of central and lateral incisors which were the froms of arc mode. When the high pull J-hook headgear was applied, the stress disrtrbuted by following by arc mode was presented from cervical 1/2 to apex of roots of central and lateral incisors. And the stress distributed by following the root surface was presented from alveolar crest to cervical 1/2 of central and lateral incisors. The stress between apecies of central and lateral incisors was presented also. 2. In case of 7degrees torque, the stress distributed by arc mode was presented from cervical 1/2 to apex of roots of central and lateral incisors. And the stress distributed by following the root surface was presented from alveolar crest to cervical 1/2 of roots of central and lateral incisors. When the hight pull J-hook headgear was applied, the stress distributed by following the root surface was presented more apically than without headgear. The stress between apecies of central and lateral incisors was presented also. 3. In case of 14degrees torque, the stress distributed by following the root surface was presented from alveolar crest to apex of roots of central and lateral incisors. When the high pull J-hook headgear was applied, the stress distributed by following the root surface was presented stronger than without headgear. The stress between apecies of central and lateral incisors was presented also.