Effects Of The Mastication On The Dynamics Of The Cerebral Blood Flow

Masticatory function is one of hunman'basic functions , the beginning of the digestion and also is a complicated physiological process . Oral diseases will affect the masticatory function at first , have an direct or indirect effect on the body including the brain . At present , we didn't know the relationship between them completely .Objective: Our goal was to observe the change of cerebral blood flow before and after mastication in humans and discuss the significance of the change . method:(1) Subjects were 10 normal volunteers ( 5 men , 5 women , 22—26 years old , mean 24.44 years ) and 7 patients with edentulous jaw ( 4 men ,3 women , 50—79 years old ,mean 66.43 years ) . Each volunteer was healthy and had similar oral status , not having TMD in every team . The patients have used their full dentures for 1—3 months . (2) With the use of transcranial color Doppler analyzer the blood flow in the brain was measured before and 10 minutes after mastication in 17 subjects . The changes of the cerebral blood flow , including systolic peak flow velocity (Vs) , enddiastolic peak flow velocity (Vd) and mean peak flow velocity (Vm) of middle cerebral artery were analysed . Result : (1) Two-sample t-test results indicate that there are not significant difference of blood velocity before and after mastication between male and female .So we can combine these data together. (2) The data of the blood velocity of the MCA of all subjects before and after mastication are shown in the table 1 and 2 ( unit : cm/s ) . The mean velocity of the MCA of the normal volunteers before mastication (unit:cm/s) : Vs=91.785, Vd=39.385, Vm=55.735; The mean velocity of the MCA of the normal volunteers after mastication (unit:cm/s) : Vs=103.03, Vd=46.015, Vm=64.090; The mean velocity of the MCA of the patients with edentulous jaw before mastication (unit:cm/s): Vs=80.34, Vd=30.30, Vm=48.61; The mean velocity of the MCA of the patients with the full denture after mastication (unit:cm/s):Vs=89.54,Vd=34.51, Vm=53.70; The mean velocity of the MCA of the The patients without the full denture after mastication (unit:cm/s) : Vs=93.01, Vd=37.30, Vm=57.03. (3) The findings of Two-sample t-test for independent samples are shown in the table 3. The results indicate that there are significant difference of enddiastolic peak flow velocity (Vd) (p<0.05) , not significant difference of systolic peak flow velocity (Vs) and mean peak flow velocity (Vm) before and after mastication between the subjects with natural teeth and the patients without full denture (p>0.05) . It also indicate that there are significant difference of enddiastolic peak flow velocity (Vd) and mean peak flow velocity (Vm) (p<0.05) , not significant difference of systolic peak flow velocity (Vs) (p>.05) after mastication between the subjects with natural teeth and the patients with full denture . (4) The findings of paired t-test for dependent samples are shown in the table 4. The results indicate that there are significant difference of systolic peak flow velocity (Vs) , enddiastolic peak flow velocity (Vd) and mean peak flow velocity (Vm) between before and after mastication in all subjects (p<0.05) . It also indicate that there are significant difference of mean peak flow velocity (Vm) in the patients with edentulous jaw between using and not using full denture (p<0.05) , not significant difference of systolic peak flow velocity (Vs) and enddiastolic peak flow velocity (Vd) (p>0.05). Conclusion : Our studies indicate that : (1) Mastication can make the blood velocity of the MCA increase obviously. (2) The blood velocity of the MCA of the subjects with natural teeth increase more than that of the patients with full denture . (2) The obvious variation of the cerebral blood flow can be obtained in the patients ,who have the edentulous jaw , no matter they use full denture or not .