[The level of PPTA mRNA and its proteins expression in trigeminal ganglia in rats with occlusal recovery].

PURPOSE: To study the level of substance P(SP) and preprotachykinin A(PPTA) mRNA in trigeminal ganglia(TG)in rats with occlusal recoveryìand to discuss the mechanism of temporomandibular disorders. METHODS: 48 Wistar male rats were randomly divided into 3 experimental groups and 3 control groupsì8 rats in each group. The right maxillary and mandibular molars in the experimental groups were ground to the gingival level without occlusal contact. The occlusal contact was recovered by stoping grinding the molars gradually. The section of trigeminal ganglia were used for immunohistological and in situ hybridization study. Light microscope and microscoic photo analytic software were employed to detect the percentage of SP and PPTA mRNA positive neurons in the frozen section of TGs in 48 rats. SPSS10.0 software package were used for statistical analysis. RESULTS: The percentage of SP positive neurons in TG with unilateral chew experimental group decreased significantly compared to the control group (P<0.01,P<0.05).The decreased extent in the non-chewing side was much higher than that in the chewing side(P<0.05).The percentage of PPTA mRNA positive neurons was significantly higher in both of the chewing and non-chewing sides of the unilateral chew experimental group than that in the control group (P<0.05,P<0.01)ì and that non-chewing side was significantly higher than that in the chewing side(P<0.01).There was no significant difference in the percentage of SP and PPTA mRNA positive neurons between the early occlusal reconstruction the experimental group and the control group(P>0.05), and there was no significant difference of those between the non-chewing side and the chewing side(P>0.05). The results of later occlusal recovery in the experimental group was same to that of the unilateral chew experimental group. CONCLUSIONS: The expressions of SP and PPTA mRNA in TG can recover normal in the early occlusal recovery but can not in the later occlusal recovery. SP and PPTA mRNA might participate in the histopathologic mechanism of temporomandibular disorders.

[Changes of masticatory muscles after occlusal recovery in rats with unilateral chew].

PURPOSE: To study the effect of occlusal recovery on masticatory muscles in rats with unilateral chew. METHODS: 40 white rats were divided into two experimental groups and two control groups. The right upper and lower posterior teeth of all the rats were ground to the gingival level without occlusal contact. The rats of the first experimental and control group were killed 10 weeks late,those of the second groups were killed 16 weeks late. The pathological changes of masticatory muscles were studied. SPSS 10.0 software package was used for statistical analysis. RESULTS: There was significant correlation between the first experimental group and control group in the damage of masticatory muscles (Chi(2)=40, P<0.01). However,there was no significant correlation between the second experimental group and control group in the damage of masticatory muscles (Chi(2)=3.66, P>0.05). CONCLUSION: Early occlusal recovery can rehabilitate the damage of masticatory muscles in rats with unilateral chew.