Biomedical subjects
Publications and source records attributed to M Yardin.
The effects of occlusal interference on masticatory cycles have been studied in twenty nine volunteers with complete natural dentition, using an electromagnetic pantograph (Sirognatograph, Siemens A.G.). After a one week recall, a decrease in speed motion was noted and the range of cycles in the horizontal plane had been altered.
The immune response is now proved to be of great importance in the control of periodontal diseases. The predominant role of T lymphocytes in the mechanisms of specific immunity is admitted and is related to the functions of effectors T cells and T-helper cells, controlling the response of macrophages and the antibody production. The relations between the evolution of the disease and the tissular T/B and T4/T8 ratio and the lymphocyte function tests are discussed.
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For some years, many authors have studied the silent periods (S.P.) in masticatory human muscles, during voluntary clenching, biting or mastication as well as during electrical or mechanical stimulation of various parts of the mouth. This S.P. appears as a flattening in the electromyograph tracing taken from masseter and temporalis anterior muscles simultaneously. After an analysis of the methods and results of previous authors, we give and discuss our result, obtained from records on masseter and temporalis anterior muscles, on right and left sides, on healthy subjects. They tapped first their teeth, then masticated pea-nuts, pieces of apple and soft bread. We obtained 571 S.P. after recording 1 745 cycles, and in contrary to the opinion of most of the authors, we were not able to obtain simultaneous S.P. in all four muscles at every cycle, except on 26 occasions. To conclude, we discuss our observations and suggest pathways for the inhibiting reflex of masticatory muscles during functions.
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Granules can be demonstrated in dental cementum which has been exposed to the oral environment as a result of gingival retraction. In the present study frozen sections of decalcified, periodontally diseased teeth were stained by the Sudan black and Schultz-Hershberger methods, which indicated that the granules contained cholesterol or steroids. The lipid content of cementum suggests that the outer layer of cementum has been penetrated by exogeneous substances of bacterial or salivary origin.
A global analysis method (the factorial analysis of correspondances) was applied to a study of oral hygiene. This first trial showed that this method of analysis is valid in this field confirming the relationship "absence of hygiene"--"periodontal disease" and the antogonism between the presence of caries and periodontal diseases in young subjects on military duty.
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The histological study of the sub-mandibular gland of the adult rabbit was followed by a study of the post-natal development until the age of 15 days. The presence at birth of acinar and intercalated granular duct cells allowed a precise study of these structures and showed a high positive differential growth of the intercalated ducts from the tenth to the fifteenth day.
A preliminary study was conducted on twenty patients to study the oro-facial behaviour when smoking a cigarette. Such a study was realized with an electromyograph, an integrator and a magnetoscope which were combined. Two types of smokers were found: "a correlated" type for whom time and degree of activity of the different muscles had a tendency to become similar; in the "dissociated" type the two preceding parameters had a tendency to move away from each other, at least for certain muscles. Each smoker presented a very stable behavioural motor pattern.
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