| Objective:Using the method of opening the marrow and exposing the medullary cavity,the model of the pulpitis and apical periodontitis of the mandibular first molar of the rat was established,and the PBS and 15-epi-LXA4 were used to temporarily seal the cavity.Comparative analysis the progress of inflammation in the pulp and periapical tissues.The effect of topical application of 15-epi-LXA4 on the progression of inflammation in the pulp of the first mandibular first molar and the periapical tissue of the rat was studied,thus deducing the possibility of 15-epi-LXA4 applied to the pulpitis and apical periodontitis,providing new insights into the choice of drugs for oral clinicians in the treatment of the pulpitis and apical periodontitis.Methods:1.Twenty male wistar rats were randomly divided into four groups according to the observation time(n=5):7,14,21 and 28 d,named A,B,C and D,again each group were divided into two subgroups according to different pulp capping agent(n=5):the left of the mandibular first molar as the control group(PBS pulp capping),the right of the mandibular first molar as the experimental group(15-epi-LXA4 pulp capping).Each wistar rat was prepared with a cavity on the occlusal surface of mandibular first molars on both the right and left side,and open the cavity for 7 days.PBS group applied PBS on the exposed pulp,15-epi-LXA4 group applied 15-epi-LXA4 on the exposed pulp.Rats in group A were sacrificed by intracardiac perfusion,and a rat model of pulp-root periapical disease was established.2.At 7 days after the modeling operation,when the apical period began to form,the rats in groups B,C and D were sealed with 15-epi-LXA4 saturated cotton balls at a concentration of 100 ng/ml in the right experimental group and changed once a week.The left control group was sealed with PBS cotton balls.The rats in groups B,C and D were sacrificed by intracardiac perfusion at 14d,21d and 28d after operating.The left and right mandibles were separated and the joint samples of the teeth and jaw were taken and placed in 4%formaldehyde solution.Fixed to be used.The specimens were decalcified at room temperature by EDTA,and continuous paraffin sections were prepared after routine dehydration-dipping wax-embedding.After staining with hematoxylin-eosin and immunohistochemical staining,the pathological manifestations of periapical tissues and the positive expression of NF-?Bp65 proteinthe of the rats control group and experimental group were observed and analyzed.Results:1.Successfully constructed a model of mandibular first molar pulpitis and periapical periodontitis with obvious inflammatory response,and on this basis,successfully developed the inflammation of different periods after the application of mandibular first molar pulp-root periapical inflammation.The reaction stage is precise and in line with clinical practice.2.7 days after modeling,HE staining showed partial necrosis of the pulp in crown and root canal.It was found that inflammatory cells gathered at the junction of the necrotic area and the surviving pulp,and a large number of necrotic cells coexisted with it.The root marrow showed mild inflammatory reaction,vasodilation,and a small number of inflammatory cells in the root tip area were scattered;at 14 days,the severity of inflammatory reaction in the experimental group was different from that in the control group:the necrotic area was found near the apical foramen,and a large amount of inflammation cell infiltration,accompanied by the absorption of the apical periodontal alveolar bone,the experimental group showed that the pulp necrosis reached the vicinity of the apical foramen,the inflammatory cell infiltration concentrated around the root canal,the extent of inflammatory infiltration was significantly smaller than the control group;at 21 days,the control group can be seen that the inflammation in the apical area is aggravated,necrotic foci is present,and alveolar bone absorption is obvious.In the experimental group,inflammation is limited to the vicinity of the root canal.The inflammation is lighter than the control group,and the tissue damage is less,but it is still aggravated compared with 14 days;at 28 days,the degree of inflammation was not aggravated,and the destruction of the periapical tissue did not continue to increase,but the degree of inflammation in the experimental group was lighter than that in the control group.Immunohistochemical staining showed that there was a small amount of NF-?Bp65 positive staining cells at 7 days,and the expression increased at 14 days.The number of NF-KBp65-positive cells reached the highest at 14 days,decreased slightly at 21 days,and reached the lowest at 28 days.The expression levels of the groups at each time point were lower than those of the control group except the 28d group.Under the local application of 15-epi-LXA4,the inflammation and inflammatory cell infiltration in the pulp and apical tissues of the experimental group were lower than those in the control group,the positive expression of NF-?Bp65 was lower than that in the control group in the period of acute inflammation.Conclusions:1.The rat model of periapical periodontitis established after exposure to the oral environment can reflect the occurrence and development of pulpitis and periapical periodontitis,which is a kind of clinical simulation.2.The local application of 15-epi-LXA4 during periapical periodontitis is related to the progression of inflammation of the pulp and periapical tissues,the degree of inflammatory cell infiltration and the expression of NF-?Bp65,suggesting that the local application of 15-epi-LXA4 may inhibite the inflammatory response in the periapical region. |
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