Relationship Study Between Oral Physiological Characteristics,Salivary Rheological Properties And Chewing Ability

Oral cavity is one of the most important parts in human body for taste and flavor perception.Age,gender,ethnicity and health status will pose impacts on oral physiology,which ultimately alters the texture,aroma and taste perception of individuals of the same consumed food.In this study,a total of 104 healthy subjects(aged from 22 to 89 years)were recruited,then divided into young adult,middle-aged and elderly groups based on age differences.Oral physiological character-ristics and salivary rheological properties were evaluated,and accord-ingly the influence of age on oral physiological function was studied.The relationship between oral physiological function and chewing ability was investigated with cluster analysis.The main research contents and conclusions of this study are as follows:(1)The effect of age on oral physiology was studied based on a thorough investigation of subject's maximum biting force,tongue pressure,oral volume and salivary flow rate,in addition to the corresponding dental status and hand gripping force.Results showed that there is a significant difference in body mass index distribution across the three age groups,and the percentages of overweight subjects in the middle-aged and elderly group are higher than that in the young adult group.With the increase of age,a decline was observed for the subjects' dental status and muscle strength(biting force,tongue pressure and hand gripping force).No significant difference was found in the oral physiological characteristics between the young and the middle-aged group.The biting force,oral volume and hand gripping force of male subjects were significantly higher than in the female subjects.(2)Saliva was collected via both unstimulated(US)and stimulated(SS)approaches.The flow rate,surface tension,shear viscosity and extension-al viscosity of collected saliva were evaluated.The effect of age,gender,stimulation difference on salivary rheological properties was studied.Results showed that there was a significant difference between US and SS for the salivary flow rate,surface tension,shear viscosity and extensi-onal viscosity.Shear viscosity of US in young adults was significantly higher than that of the middle-aged and the elderly group,but no significant difference was observed between the middle-aged and the elderly.Shear viscosity of SS in the middle-aged group was significantly lower than that in the young and elderly groups,while no significant difference between the young and elderly.The young adult group has the smallest percentage of saliva with low extensional viscosity(type ?),while no significant difference between the middle-aged and elderly groups.Gender exerted very little impact on the shear and extensional viscosity of collected saliva samples.(3)Subjects were divided into good,median and weak groups based on a cluster analysis of their oral physiological characteristics.A total of 10 subjects from 'good' and 'median' groups were selected for chewing efficiency and chewing performance determination.No significant differ-ence in chewing efficiency was found between these two clusters of subjects;however,a discrepancy was observed in the breakage function and selection function between the two clusters of subjects,indicating there may be other factors affecting chewing efficiency.