The Reaction Of Dental Pulp After Different Times Exposure, A Preliminary Study In Dog's Mature Permanent Teeth

Objective: To establish experimental pulpitis models in Beagle dogs,then screen the potential indicators of cytokines in early progress of pulpal inflammation for further vital pulp therapy research.Methods: Nine 10-month-old Beagle dog's premolars from bilateral maxillary 2,3 premolar and mandibular 2,3,4 premolar teeth were chose for this experiment. Totally 54 premolars were randomly assigned in to 4 groups respectively(that is after 0 hours, 24 hours, 48 hours, and 72 hours). The pulpitis were induced by exposed the pulp champer to oral environment with different times as mentioned before, then:(1) Each group selected three experimental teeth, using Spongel and MTA for direct pulp capping therapy respectively. Then the access cavities were sealed with glass ionomer cement and composite resin. Radiographs were taken to observed the periapical radiolucent after 1 month. According to the prognosis of different exposure time pulpitis groups, the pulpitis models, was evaluated whether it is reversible or irreversible pulpitis.(2) Pulps were obtained from four groups of teeth, pulpal tissues were collected, prepared, and analyzed for TNF-?,IFN-?,IL-2,IL-6,IL-8,IL-10 concentration by using Milliplex MAP Canine kits. The data were statistically analyzed using nonparametric Kruskal-Wallis test, significance was computed at the 5% level.Results:(1) Spongel and MTA were not effective in arresting severe inflammatory alteration of dental pulp when exposed after 24, 48 and 72 h. In 24 h and 48 h group, one tooth capping by Spongel in 24 h group and another one capping by MTA in 48 h group occurs a submucosal abscess. All of teeth in 24 h, 48 h, 72 h group, can observed apical lesion and tooth discoloration like the pulp necrosis tooth. But there were no discoloration or apical lesions appeared in control group teeth.(2) Nonparametric Kruskal-Wallis test revealed no significant differences between IL-8 concentration in 4 groups(P>0.05) but shows significant differences TNF-?,IFN-?,IL-2,IL-6,IL-10 concentration in pulp samples between the four exposing time group(P<0.05). Between 24 h and 48 h, there were an increasing expression of TNF-? and IL-2, then following a decreasing expression of TNF-?, IFN –?, IL-2, IL-6, IL-10 between 48 h and 72h(P<0.05).Conclusion:(1)The 10-month-old Beagle dogs premolar, when exposed the pulp champer to oral environment 24 h, 48 h and 72 h, the pulp tissue can not be preserved by vital pulp therapy.(2) TNF-?, IL-2 can be potential diagnostic markers of the early progress of pulpal inflammation.