牙周组织老龄化变化及其对正畸牙移动的影响

Periodontal remodeling with aging and effects associated with orthodontic tooth movement

牙槽骨老龄化变化表现在牙槽嵴高度降低、骨质疏松、骨密度减低,骨吸收大于骨形成。牙周膜老龄化改变体现在胶原纤维增多,牙周膜厚度变薄,牙周膜的反应性改建能力下降。牙龈老龄化变化体现在牙龈上皮角化程度降低,牙龈结缔组织中的细胞数量减少。随着牙槽嵴高度的减少,边缘龈高度也会降低。骨质疏松会加速正畸治疗过程中牙体的移动,不利于正畸移动牙体在新的位置上的重建与稳定。随着患者年龄的增长,正畸治疗会越来越费时间,牙槽骨内幼稚细胞、成骨细胞以及血管数目和骨髓腔减少,骨代谢降低,牙移动缓慢,口周肌改建适应时间延长,牙槽骨的更新、改建能力减弱。老龄化变化使牙周膜细胞活性降低,胶原形成速率减慢,受牵拉侧骨形成和受压侧骨吸收迟缓。在机械力刺激下,牙周膜细胞会反应性地增加地诺前列酮释放到龈沟液中的水平,这可能是成年患者正畸治疗速度缓慢的原因。

Remodeling of alveolar aging is expressed in the lower height of the alveolar ridge. Osteoporosis, osteoporotic fractures, and absorption of bone prevail over osteogenesis. Periodontium changes included increasing collagen fiber, thinner periodontal membrane, and declining reactivity of the periodontal ligament reconstruction. Epithelial keratinization and the number of connective tissue cells decreased with age in gingival tissue. The height of the free gingival margin reduced according to the alveolar bone. In addition, osteoporosis accelerated the rate of tooth movement, which prevented the reconstruction and stability of orthodontic tooth in a new position. Orthodontic treatment will be increasingly timeconsuming as patients age because of the decreasing alveolar immature cells, osteoblasts, blood vessels, and marrow cavity. Reduced bone metabolism and tooth movement, prolonged remodeling of perioral muscle, weakened ability of alveolar renewal and rebuilding, slowed periodontal cell activity and collagen formation rate, and pulling side formation and pressing side absorption of alveolar bone also contribute to time-consuming treatment. Under mechanical stimulus, the increase of prostaglandin in gingival crevicular fl uid may cause the reduced rate of orthodontic tooth movement in adults.