实验性鼠根尖周炎组织学动态观察

Histological kinetics of experimental periapical lesions in SD rat

目的 :观察大鼠磨牙牙髓在自然暴露状态下组织学动态过程。方法 :16只SD大鼠磨牙开髓 ,分别于术后 1、2、3、4周取下颌骨组织 ;拍根尖X线片 ,图像分析系统测根尖阴影面积 ;组织经固定、脱钙后作组织切片 ,HE染色 ,进行组织学观察。结果 :从术后 1周始根尖阴影面积逐渐增大 ,第 3周达峰值(1.2 5± 0 .15 )mm2 ,4周后相对稳定 ;组织学变化表现为非特异性炎症过程 ,术后 1周根尖区即可见炎细胞浸润及轻度骨吸收 ;2周后牙髓全部坏死 ,根尖炎症加重 ;3周后根尖周出现根尖脓肿 ;4周后炎症浸润减轻 ,并可见立方状成骨细胞。结论 :开放大鼠磨牙髓腔使口腔菌丛感染后 ,可建成实验性根尖周炎模型。 1～ 3周表现为急性炎症阶段 ,根尖周破坏逐渐加重 。

Objective: To estalish a rat model system in which periapical lesions were induced by pulp exposure and infection from the oral environment. Methods: The pulps of mandibular molar of 16 SD rats were surgically exposed and kept open to be induced for infection from the oral environment. The rats were killed 1, 2, 3, 4 weeks after operation respectively. Radiographic image analysis was performed by means of computer linked to a video image digital analysis system. In addition, specimens were decalicified, sectioned, HE stained and examined under microscope. Results: Periapical lesions were readily detectable as early as 1 week after pulp exposure. A significant increase in lesion area was detected from 1 to 3 weeks in a time-dependent manner, the lesion declined a little bit in 4 weeks. Slight inflammatory cell infiltration and alveolar bone resorption were observed in the periapical tissue in the 1-week-samples, total pulp necrosis in the 2-week-samples, apical abscess and bone destruction in the 3-week-samples. Decreased infiltration and the matured osteoblasts were found on the surface of the bone in the 4-week-samples. Conclusion: Pulp exposure can induce periapical lesion in rat. A period of rapid lesion development occurs between day 7 and day 21 after pulp exposure (active phase), and a period of slower development follows thereafter (chronic phase).