Samrit Vilas, Kharbanda Om Prakash, Duggal Ritu, Seith Ashu, Malhotra Varun
Division of Orthodontics and Dentofacial Deformities, Centre for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India.
Aust Orthod J. 2012 Nov;28(2):204-12.
The purpose of this study was to evaluate bone density in buccal inter-radicular bone between second premolars and first permanent molars and its association with the clinical stability of miniscrews used for en masse retraction of anterior teeth in extraction cases.
Thirty-eight miniscrews were placed in ten patients (8 females, 2 males: mean age, 18.9 +/- 4.12 years) to provide indirect orthodontic anchorage. Twenty miniscrews were placed in the maxilla and eighteen were inserted in the mandible. All of the miniscrews were placed in the buccal inter-radicular bone between the second premolar and the first permanent molar. Bone density at each miniscrew site was recorded by computed tomography and recorded in Hounsfield units (HU) before miniscrew placement. Nickel-titanium closed-coil springs were used to apply an orthodonticforce of 2N within one week following placement.
Cortical bone density values ranged from 506.7- 1705.6 HU (Mean, 929.27 +/- 322.12 HU) in the maxilla and 503.8 - 1544.8 HU (Mean, 1116.2 +/- 298.33 HU) in the mandible. Cancellous bone density values ranged from 185.9 - 930.8 HU (Mean, 450.09 +/- 205.66 HU) in the maxilla and 197.3 - 803.6 HU (Mean, 561.87 +/- 170.83 HU) in the mandible. There was no statistically significant difference between right and left sides. A bone density comparison between the maxilla and mandible revealed statistically significant higher values in mandibular cortical bone (p = 0.008), while no significant difference was found in cancellous bone values (p = 0.097). Clinically, the success rate of miniscrews in the maxilla was 100% but only 77.8% in the mandible. Miniscrew failures were associated with peri-implant inflammation and miniscrew proximity to dental roots. No relation was found between bone density and miniscrew stability.
The present study determined that no definitive association could be established between miniscrew success and bone density.
本研究旨在评估第二前磨牙与第一恒磨牙之间颊侧根间骨的骨密度，及其与拔牙病例中用于前牙整体后移的微螺钉临床稳定性的相关性。
在10例患者（8名女性，2名男性；平均年龄18.9±4.12岁）中植入38枚微螺钉，以提供间接正畸支抗。20枚微螺钉植入上颌，18枚植入下颌。所有微螺钉均植入第二前磨牙与第一恒磨牙之间的颊侧根间骨。在植入微螺钉前，通过计算机断层扫描记录每个微螺钉部位的骨密度，并以亨氏单位（HU）记录。在植入后一周内，使用镍钛闭合曲弹簧施加2N的正畸力。
上颌皮质骨密度值范围为506.7 - 1705.6 HU（平均929.27±322.12 HU），下颌为503.8 - 1544.8 HU（平均1116.2±298.33 HU）。上颌松质骨密度值范围为185.9 - 930.8 HU（平均450.09±205.66 HU），下颌为197.3 - 803.6 HU（平均561.87±170.83 HU）。左右两侧之间无统计学显著差异。上颌与下颌的骨密度比较显示，下颌皮质骨值在统计学上显著更高（p = 0.008），而松质骨值无显著差异（p = 0.097）。临床上，上颌微螺钉的成功率为100%，而下颌仅为77.8%。微螺钉失败与种植体周围炎症以及微螺钉靠近牙根有关。未发现骨密度与微螺钉稳定性之间存在关联。
本研究确定微螺钉的成功与骨密度之间无法建立明确的关联。
