Martins Renato Parsekian, Buschang Peter H, Gandini Luiz Gonzaga
FAEPO/UNESP, Araraquara, São Paulo, Brazil.
Am J Orthod Dentofacial Orthop. 2009 Feb;135(2):182-9. doi: 10.1016/j.ajodo.2007.02.055.
When anchorage control is critical and compliance is less than ideal, efficient treatment depends on differential tooth movements. The purpose of this study was to evaluate the distal tipping of partially retracted canines and the mesial movement of the molars.
Eleven patients had their maxillary and mandibular canines partially retracted with TMA (Ormco Corp, Orange, Calif) T-loop springs with 45 degrees gable bends distal to the loops preactivated for group A (maximum anchorage). Metallic bone markers served as references. The canines were retracted until enough space was available for alignment of the incisors without proclination. Oblique (45 degrees) radiographs were taken immediately before the initial activation and after partial retraction. The radiographs were scanned, superimposed on the bone markers, and measured digitally.
The mandibular canine crowns were retracted (4.1 +/-1.9 mm) and intruded (0.7 +/- 0.3 mm) by uncontrolled tipping. In contrast, the maxillary canine crowns were retracted (3.2 +/- 1.4 mm) by controlled tipping. The maxillary and mandibular molars crowns were protracted by similar amounts (1.0 +/- 0.6 and 1.2 +/-1.2 mm, respectively) by controlled tipping, without significant extrusion. The molars were protracted approximately 0.3 mm for every 1 mm of canine retraction.
The T-loop spring used in this investigation produced controlled tipping of the maxillary canines, but it did not produce controlled tipping of the mandibular canines or translation of the molar as expected.
当支抗控制至关重要且依从性不尽人意时,高效治疗取决于牙齿的差异移动。本研究的目的是评估部分内收尖牙的远中倾斜以及磨牙的近中移动。
11例患者使用TMA(奥美科公司,加利福尼亚州奥兰治)T形曲簧对上颌和下颌尖牙进行部分内收,A组在曲簧远中预先激活45度的山墙弯(最大支抗)。金属骨标记物作为参考。将尖牙内收,直到有足够空间排齐切牙且切牙无前倾。在初始激活前和部分内收后立即拍摄45度斜位X线片。对X线片进行扫描,叠加在骨标记物上,并进行数字测量。
下颌尖牙牙冠通过不受控制的倾斜内收(4.1±1.9mm)并压低(0.7±0.3mm)。相比之下,上颌尖牙牙冠通过控制倾斜内收(3.2±1.4mm)。上颌和下颌磨牙牙冠通过控制倾斜近中移动了相似的距离(分别为1.0±0.6mm和1.2±1.2mm),且无明显伸长。每内收1mm尖牙,磨牙近中移动约0.3mm。
本研究中使用的T形曲簧对上颌尖牙产生了控制倾斜,但未按预期对下颌尖牙产生控制倾斜或使磨牙平移。