In order to compare the incidence of 1st molar caries and incidence of secondary amalgam caries appearing on the same tooth, yearly changes of the carious incidence were obtained from the protocols made at school dental examination of 344 children at Semmaya and amalgam fillings of 579 school children at the same town were examined one year after treatment. The rate of intact teeth was decreased in constant rate as shown in the formula, logP=1.989-0.051 T, where P means remaining intact teeth rate, T means school year, and constant 0.051 may denote real incidence of the 1st molar of the given population. On the contrary, resistance against amalgam injury decreased with ageing of the children (P=1.76+32.271/T). The present findings may conclude that even if the resistance against amalgam attack may be ascribed to the known chemical and physical changes appearing after tooth eruption, but host resistance against carious attack may not be always parallel with such physical changes of the tooth. It was estimated that the cariogenecity of a population in a certain community would remain constant during fairly long period of time, and additionally, the constant incidence was obtained after similar mathematical treatment of prevalence rates surveyed from each school year class. The real incidence of another tooth was also estimable from the similar formula but involvement of more cariogenic factors would be considered. Finally incidence of the amalgam injury should be denoted by a function of ageing.

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In consideration of dental caries of deciduous teeth, it is important to examine the fact that formation of toothgerm and calcification of deciduous teeth are made in the intrauterine; and also native and acquired characters on the dental caries should be examined because of the eruption on the deciduous teeth after birth.
The present study, therefore, was performed on the elements of climate which are the outside-environment of pregnant women and dental caries of deciduous teeth, that is, on the relationship among temperature, humidity, wind velocity and discomfort index.
As the subjects of the study, 4, 992 children in Tokyo and their 93, 148 teeth were employed.
The subjects were classified into the group of age at first, and then, this group was divided into groups of the month of birth.
And comparison was made on the percentage of def experienced children, the average number of def teeth per child, the percentage of def experienced teeth, as well as the percentage of def experienced teeth classified by the kinks of teeth, the month of birth of children classified by the month of birth, and also on the monthly average values of the temperature, humidity, wind velocity, and discomfort index from the one to the five months before birth of children. The calculation was performed on the minimum and maximum zones of def from the relationship between def and elements of climate.
(1) In the def of subjected children, the percentage of def experienced children was 63.16% the average number of def teeth per child was 4.34 and percentage of def experienced teeth was 22.64 %.
(2) As for def, its highest value was observed generally in the children born in September and October in either group of age, but low values were observed in those children born in May, June and July. This tendency was most remarkable in lower age-groups.
(3) The similar tendency was observed in def classified by the kinks of teeth. Especially, it was remarkable on the teeth with high def values.
(4) As for the relationship among def of children, elements of climate and discomfort index in fetal life, the def of children classified by the month of birth in the group of age 5wes related to the temperature and discomfort index in one month before birth.
The def of children classified by the month of birth in the groups of age 4 and 5 was related to the humidity in one month before birth, and also the def of children classified by the month of birth in the group of age 2 was related to the wind velocity in one and two months before birth.
(5) In the def classified by the kinds of teeth, the def of the upper primary central and lateral incisors in the group of age 5 was related to the temperature, humidity and discomfort index in the month of birth.
The def of the upper and lower first primary molars in the group of age 5 was related to the temperature, humidity and discomfort index in two months before birth, and also the def of other teeth in the group of age 4 and 5 was related to that of one month before birth.
(6) Minimum and maximum zones of dental caries of deciduous teeth in all round-elements of climate; regarding the children of month in age groups related to def classified by the kinds of teeth and elements of climate, the minimum and maximum zones of def and the rate of appearance on maximum and minimum values were calculated in the use of the values of temperature, humidity and discomfort index on the minimum and maximum values of def.
As the result, in the minimum zone of def, the lowest was 14.5°C in the temperature, 62 % in the humidity: the highest was 12.6°C in the temperature, 73 % in the humidity; and the following equations were obtained:
log y=0.0001x+0.99
y=0.2651x²-35.958x+1224
(y: temperature, x: humidity)

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Subctaneous injection of suspension of odoriferous pus collected from the lesion of experimental Vincent's disease induced on a guinea pig was made in depilated back of another guinea pig weighing from 250 to 350 grams. The water solutions of Flagyl were injected subctaneously to the other portion on the back of the guinea pig, 10, 5 and 2.5mgs a day for 7 days respectively. The Flagyl group had a less production of pus and did not remain spirochaete or odour in the pus.
Clinical trial:
Clinical examination was made in 50 adults who were pointed out halitosis by means of double blind method. They were given 400mgs of either Flagyl or placebo tablets once a day for 5 days. Unexpectancy, disappearance of halitosis was not experienced only in the Flagyl group. The consideration of these results was discussed.

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It has already been pointed out that dental calculus is one of major factors in periodontal disease. Recent finding by fluorescent antibody technique is suggesting the immunologic response in the inflamed gingiva.
It leads to the hypothesis that calculus may play an important role in periodontal tissues as antigen.
Rabbits were immunized with calculus, heat-immobilized calculus or lyophilized organic substance of calculus as antigens. Using immune sera of treated rabbits, antigen-antibody reactions were performed by PCA-method (Passive Cutaneous Anaphylaxis) and Agar Gel Double Diffusion (Immuno-diffusion) for the analysis of the antigenicity of calculus, calculus extract, dental plaque, saliva, serum protein and experimental calculus in vitro.
The results were as follows:
1. PCA-reaction in guinea pigs with calculus extract antigen was evidently positive, : suggesting the existence of some allergens provoking cutaneous anaphylaxis.
In Agar Gel Double Diffusion experiments,
2. Natural calculus formed four precipitin bands against immune serum of rabbit immunized with human calculus. It indicated that calculus contained at least four saline soluble antigens.
3. Calculus extract semi-purified by physical and chemical procedures composed of two groups, of which the saline soluble fraction produced two precipitin bands. The other salineinsoluble fraction gave only one band.
4. When the rabbits antisera reacted with the filtrates of EDTA-demineralized calculus obtained through Membrane filter or Ultra-fine filter, the appearance of precipitin bands changed according to the pore size of filters. This suggested the possible separation of several antigenic substances by the choice of filters.
5. Dental plaque yielded two bands against antiserum.
6. The concentrated whole saliva gave three bands, while concentrated parotid saliva gave only one detectable band.
7. Gamma globulin and albumin in human serum formed respectively one clear-cut band.
8. Several bands were observed between antisera and experimental calculus in vitro which was formed from incubated saliva and mineral salts.
9. The findings mentioned above indicate the close serological relationship between calculus antigens and oral proteins such as dental plaque, saliva, serum protein and oral microbes.

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The effect of fluoride on purified enolase and the supernatant of mouse muscle homogenate, was studied in vitro and the change of enolase activity in mouse muscle was determined after feeding fluoride water of graded concentration for a week. The crude enolase in homogenate supernatant was more strongly inhibited than purified enolase, particularly when the activity was assayed by the sample mixed with fluoride in advance, namely as high as 50% inhibition in 0.5mM F. The author introduced a new hypothesis of incomplete inhibition (reversible) and complete inhibition (irreversible). In the latter case, it required the third factor, i. e. homogenate factor (H-factor), to be fully demonstrated. It was contained in the homogenate and probably comosed of phosphate, magnesium or other divalent metal and special protein. With the H-factor, the enolase became very sensitive to fluoride and was strongly and irreversibly inhibited. The inhibition went on to the greater extent with time.
In vivo experiment, the slight inhibition of enolase activity was only observed at 100 and 400 ppm F feeding. The level was, however, so high that other enzyme systems might also be disturbed and the result might not be attributed solely to the effect of fluoride.

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Depending on the economical standpoint of the public health administration, the screening method for the dental health of a population was extremely simplified by means of that unit of examination was fixed on each mouth, consisting of 4 examination items, tooth, gingiva, occlusion and changing dentition. Each items did not evaluate by counting score, but classified into three categories, healthy, questionable, necessary for treatment.
Results of each items could not added, but the worst category of any one of items represented the final evaluation of the mouth. Every examinee was classified into either excellent (healthy), fair (treated), satisfactory (questionable) or unsatisfactory (necessary for treatment). After examination, an examinee received the advice of either more presize examination in the case of satisfactory result or prompt treatment against unsatisfactory result.
The present screening method was applied on a business population which did not provide with dental room during three years since 1966. The effect was estimated in comparison of another two similar business population providing with the dental room. The differences of rates of excellent and fair persons in the total examinees between experimental and control groups were statistically significant. The time consumed for the screening was shortest at the experimental group.

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A stainless steel marker possessing known size was surgically implanted in the alveolar bone between lower M₁ and the fourth decidous tooth of each mandibular of 7 popies, of one month age. The growth of the M₁ was radiographycally followed during four months. The obtained radiogram was traced on a piece of paper on which every measurements were carried and then actual values were corrected by aid of the marker. The length of the developing tooth and the thickness of the mandibula locating at inferior part from the apex of the M₁ increased according to the progress of time. The growth rate of them were well correlated until 2nd month, but the length of the tooth elongated rapidly in respect of its radicular growth there after, independ from the mandibular growth rate. Distance between apex and the marker was constant, in spite of the growth of their portion. The facts obtained would indicated the evidences that growth of tooth generated at the top of the root did not go into mandibular body but directed to eruption and developing agent worked differently on tooth and mandibular body.

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Antibacterial action of human saliva has been reported by numerous investigators. Among the antibacterial factors in human saliva, lysozyme, inhibine, and anti-lactobacillus factor are the most familiar and with the most extensive studies. Recently, the nature of the antilactobacillus factor which required thiocyanate for its activity has extensively clarified to be a salivary peroxidase. The salivary peroxidase antibacterial system consists of three components, peroxidase, hydrogen peroxide and thiocyanate.
Concerning the salivary antibacterial factor and its relation to dental caries, Hill found an anti-lactobacillus casei factor to be present in the whole saliva of caries resistant individuals. Green, Dodd and Inverso also reported a non-dialyzable, heat labile factor in the saliva of caries immune individuals which inhibited the growth of lactobacilli and streptococci. This substance was found lacking in the saliva of caries susceptible individuals. Matsumura, Morioka and Onishi reported an inverse proportion between the activity of salivary antibacterial factor (S.A. Factor) and DMF teeth rate. No experimental work, however, exists describing the salivary antibacterial factor (s) against cariogenic lactobacilli.
The purpose of this experiment is to determine the antibacterial and bactericidal action of the salivary peroxidase antibacterial system on cariogenic Lactobacillus casei ATCC 4646 (Rosen, Lenney and O'Malley, 1968).
As the results, growth of cariogenic Lactobacillus casei was apparently inhibited in SL broth (pH5.4) by the human salivary peroxidase antibacterial system. This antibacterial activity was quantitatively determined in the culture medium. The cariogenic lactobacillus was markedly killed by the antibacterial system in human saliva at pH5.8.
This experiment is important in that it helps to clarify the physiological significance of the salivary peroxidase antibacterial system in oral cavity with the direct evidence of the bactericidal action on the cariogenic lactobacillus.

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Three different dentifrices, two of which contained either Na-monofluorophosphate (M) or stannous fluoride (S) and one removed fluoride compound from M, were compared in respect of rate of cavities appeared during experimental period of one year on the susceptible sites, remaining actually healthy at the time of preliminary examination. Experiment was carried onto total 1101 school children, aged from 5 to 12 years, divided into three similar experimental groups. M prohibited cavitation at smooth surface in rate of 40.5% and at pit and fissure in rate of 16.1% against the control dentifrice while S showed only 19.4% reduction at pit and fissure if the dentifrice with absent fluoride would be acceptable as a control to S in respect of containing F. These reductions were proved to be significant by means of χ²-test. It was stressed in the present paper that use of actual susceptible site increased the rate of yearly cavitation of each groups, applying χ²-test on the results was absolutely necessary, and fluoride was effective for the caries appearing not only on the smooth surface but also on the pit and fissure.

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