The application of radioactive tracers gives a powerful tool in opening a new reseach field in dental science. However, in almost all experiments with radioactive tracers, it is not very easy to interpret the results obtained accurately because of the lack of definite chemical form of radioactive materials used.
The present authors have engaged in the study of preparations, syntheses and assignments of radioactive materials which might be useful for radioactive tracer works both in fundamental and clinical dental researches. In the present paper the preparation of dental cement liquids labelled with radioactive phosphorus (³²P) is described with some studies on their chemical and radiochemical purities.
Dental cements, i. e. zinc phosphate cement, silicate cement and others, are frequently used in routine dental practice, as a very important material in operative and prosthetic dentistry. ZANDER et al. [1], GLASS and ZANDER [2] had reported that the successful use of radioactive phosphorus for investigations in the properties of dental cements. But these reports contained only a bare mention of the procedure for ³²P-labelling and the chemical form of the resulted labelled cement liquids. This is the reason why the present authors have undertaked the study on the preparation of ³²P-labelled dental cement liquids. The chemical forms of the labelled cement liquids are determined by means of paper chromatography.

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The purpose of this paper is to gain some perspective on the future setting in which we and our immediate successors will practice and to study some of the forces which are operative in this field.
A paper of this length can do no more than outline what is going on in our profession and give some of the evidence we have so far found concerning the factors which are deciding the future.
We need to do some hard thinking on this subject of dentistry in the Soviet Union and ideas behind the revolutionary changes there and our response to them, whether we like it or not, because one of the new factors which dominates and controls dental practice in nearly half of the whole human family is the Soviet system. of training, practice and philosophy.
There is a story told of a hen-run which was situated near to a Rugby field. On one occasion the Rugby ball was kicked over the wire into the hen-run. When the cock saw the Rugby ball lying there, he walked round it and then he called all the hens together and he said, “Now girls, I don't want to complain, but just take a look at what some other firms are producing.”
Any responsible attempt to look into the future will of necessity include a study of the Soviet system and the dynamic idea which gives it such momentum.
There are three major features about the Soviet which we wish to deal with, arising from the above, and we wish to deal quite briefly with each.
First-the creation of a new framework for the dental profession.
Second-the fact that the dentist is faced with a continuing choice of loyalty.
Third-the intense programme of indoctrination in Marxist-Leninist ideology.

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As a result of serial observations of models collected of grade school children at an interval of 8 years with twice a year in which efforts were made to determine the incidence period of deep overbites and factors involved in their formation, the following findings are noteworthy.
1. No matter what causes are involved in the process, the majority of deep overbites occur when the patients are comparatively young, around 7 to 11 years.
2. It is found that the destruction and loss of deciduous molar crowns have much bearings upon the incidence of deep overbite and in the scope of the present study, nearly 80 % of cases are attributable to this cause.
3. The majority of deep overbite cases were found to suffer from the destruction and loss of deciduous molar crown both on their upper and lower jaws. When only one jaw is concerned, there is a strong tendency that deep overbite, when it exists, is due to the destruction and loss of molar crowns and is found on the lower jaw.
4. It may be considered that a strong tendency of deep overbite exists when there is found the destruction and loss of deciduous molar crowns bilaterally rather than unilaterally.

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Early enamel caries had been electron microscopically examined and the following findings have been brought to light.
1. Abundant streptococci, bacillary, and filamentous bacteria cover the carious enamel surface in a diffuse manner. However, no bacteria at all are found in the interior of the enamel portion under the bacterial layer during the early stage of caries.
2. The earliest structural alterations in caries, as visible in the bacteria-free modified enamel portion, are a result of mineral loss. As a manifestation of the mineral loss, fine defects innumerably distribute in a diffuse manner in the altered enamel. However, the defects often tend to appear as if they abound especially within the rods, while relatively a few of them being detected in interrod areas and rod sheaths. In keeping pace with the advancement of caries, these fine defects gradually increase in number in the bacteria-free altered enamel zone, particularly most remarkably within the limits of the rods. This tendency corresponds to the different quantities of mineral materials in the enamel structures, and indicates that in the progress of caries, carious destruction of the interrod substance and rod sheath take place less heavily than that of the rod due to mineral loss.
3. In accordance with the increase of carious defects the orientation of crystals in enamel gradually becomes unclear, and finally completely obscure in the bacteria-free altered enamel portion.

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