大鼠实验性牙髓炎痛敏模型的建立及检验

Establishment and verification of rat experimental hyperalgesic pulpitis

目的:验证牙髓暴露法建立大鼠实验性牙髓炎痛敏模型的可行性。方法:取健康雄性SD大鼠36只,随机分为2组;对照组(n=10)麻醉后不作任何处理,牙髓炎模型组(n=26)麻醉后于左侧上颌第一磨牙穿髓并使之暴露于口腔。然后,每组中各随机抽取6只分别检测其术前及术后1、3、7、14 d的擦面行为。对照组所余4只于术后2 h取延髓及牙髓,牙髓炎组所余20只分别于术后2 h取延髓,1、3、7、14 d取牙髓;用免疫荧光染色检测延髓中c-Fos蛋白及牙髓中TNF-α的表达,HE染色观察牙髓炎症情况。结果:1牙髓炎组在建模术后1 d时的擦面总时间最高,其次为术后3 d组,两者分别与组内其他各时间相比,以及与同一时间点的对照组相比差异均有统计学意义(P<0.05);2HE染色显示,牙髓暴露1 d时即可见明显炎症,术后1、3、7、14 d,其坏死组织的边缘分别位于髓角和根上、中、下1/3处;3牙髓炎组在术后1、3、7、14 d各时间点的TNF-α表达强度的平均光密度值均明显高于对照组(P<0.05);4术后2 h牙髓炎组和对照组延髓背角的c-Fos阳性细胞数为176.8±14.82和18.2±4.08(P<0.05)。结论:牙髓暴露法能有效模拟临床牙髓炎及其痛敏过程。

AIM： To establish and verify rat experimental hyperalgesic pulpitis. METHODS： 36 male SD rats were randomly divided into 2 groups. The rats in control group（ n = 10） received no treatment after anesthesia,while the left maxillary first molar pulp of the rats in the pulpitis group（ n = 26） were exposed after anesthesia. 6 rats of each group were randomly selected for face grooming test before and after 1,3,7 and 14 d of surgery respectively. The medulla oblongatas and pulps of the remaining 4 rats in the control group were taken after 2 h of surgery. The remaining 20 rats in the pulpitis group were randomly divided into 5 groups（ n = 4）,the pulps were taken after 1,3,7 and 14 d of surgery respectively. HE staining,TNF-α and c-Fos immunofluorescence staining were conducted to measure the changes of pulp and bulbus medullae. RESULTS： The face Grooming after 1 d or 3 d of surgery in pulpitis groups were longer than that in the control group（ P 0. 05）. In the pulpitis groups longest face grooming was observed 1d followed by 3 d（ P 0. 05） after surgery. HE staining revealed that 1,3,7 and 14 d after surgery,inflammation and necrotic tissues appeared at the pulp horn,cervical-third,middle-third and apical-third of the root respectively. The mean optical density of TNF-α at various time points of pulpitis group were significantly higher than that of control group（ P 0. 05）. In pulpitis group highest TNF-α level was observed 1d followed by 3 and 7 d after surgery（ P 0. 05）,the lowest at 14 d after surgery（ P 0. 05）. c-Fos immunostaining results showed that c-Fos-positive cells were significantly increased in medullary dorsal horn after 2 h of pulp exposure. CONCLUON： Pulp exposure method can effectively establish rat experimental hyperalgesic pulpitis madel,which simulates the process of clinical pulpitis and hyperalgesia.