[Establishment of dental pulp hyperemia in an animal experiment model]

To establish an animal model of dental pulp hyperemia, 96 molars in 12 Wistar rats were studied. In each rat, the four right molars, including the right upper and lower first and second molars, were assigned as the experimental group. The four left corresponding molars in each rat were included in the control group. The animals were anesthetized and a 3% silver nitrate solution was applied to the exposed dentin at the cusp tip of the molars for one minute. After 2, 5, and 24 hours, four animals in each subgroup were sacrificed. The upper and lower jaws in conjunction with the dentition were removed and fixed in a 10% neutral formalin solution for 24 hours. The first and second molars and the surrounding alveolar bone in en bloc were trimmed off, fixed for another 24 hours, and processed according to routine histological procedures. The histopathologic changes in the dental pulp were examined by light microscopy. For convenience of interpretation, the intensity of the pulp tissue reaction was graded as follows: grade O: normal pulp tissue; grade I: vessel dilatation and congestion, as well as stromal edema; grade II: focal pulp hemorhage and plasma extravasation; grade III: pulp tissue destruction including pyknotic change in the odontoblastic nuclei; and grade IV: abscess formation in the pulp tissue.(ABSTRACT TRUNCATED AT 250 WORDS)