Histological kinetics of experimental periapical lesions in SD rat / 实用口腔医学杂志

ABSTRACT

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).