Radiation therapy is performed in many cases involving malignant tumors, but at the same time some side effects are induced by this treatment. With infants and children, irradiation on the facial region causes serious disturbance of odontogenesis. Several cases of radiation-induced hypoplastic teeth and anodontia have been reported clinically and radiographically, and numerous studies have been made on the effect of irradiation on developing teeth in animals. However, little work has been done to study histopathologically the effects on the human teeth. This paper reports on the histopathologic findings of irradiated human developing teeth.
The patient was a 7-year-old boy who had been suffering from Ewing's sarcoma originating in the mandible. Irradiation with 8000 rad of Linac was performed on the mandible prior to mandibulectomy. The results of the histopathologic examination of the teeth including resected material were as follows:
1. Although the tumor tissue was not found in the resected material, complete resorption of the medullar trabecular bone with fibrosis was noted in the area between the first molar region and the mandibular ramus. Therefore it was thought that the tumor tissue had infiltrated the area between the first molar region and the mandibular ramus previously, and the first and the second premolar teeth had not been affected by tumor growth.
2. The first and the second premolar teeth were in the early stage of root formation, and conglomerates of dysplastic dentin were formed in the proliferative zones. This dysplastic dentin was surrounded by loose fibrous connective tissues. Hertwig's epithelial root sheaths disappeared.
3. The dysplastic dentin showed low mineralization, embedded irregular arrangedfibrous tissue matrix and scattered various-sized lacunae containing a few tiny and pyknotic cells.
4. Irregularly arranged odontoblasts with a pyknotic appearance were found along the tubular dentin, but diffuse fibrosis occurred in the pulpal tissues.
5. The first molar tooth had completed its root formation. Various amounts of osteodentin were formed at the secondary dentin layer. Inner-resorption of dentin and fibrosis of the pulpal tissue were also found. These changes concerning the first molar tooth were also due to the effects of irradiation.
6. The second molar tooth was resorbed by tumor infiltration, and dysplastic dentin was on the resorbed surface of the dentin.
7. The significance of dysplastic dentin and osteodentin was described, and the effect of irradiation on human odontogenesis was discussed.

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A boy,4 years and 7 months old, with a past history of plastic surgery related to cleft lip, had two supernumerary primary teeth between the maxillary right primary incisor and cuspid on the cleft side and had congenitally missing mandibular bilateral primary lateral incisors and succeeding permanent teeth.
The details were as follows:
1. One supernumerary tooth (S₁)was located between the maxillary right primary incisor and lateral incisor, and the other (S₂)between the right primary lateral incisor and cuspid.
2. The shape of S₁ was incisal and that of S₂ conical. X-ray examination showed that apexes of S₁ and S₂ were as well-developed as those of the normal primary teeth.
3. The succeeding permanent teeth to S₁ and S₂ were not observed.
4. The mandibular bilateral primary lateral incisors were congenitally missing. The succeeding permanent teeth to the lateral incisors did not exist either.

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We examined the prevalence of dental caries at five nursery schools in Kyoto: A, K, N, KY and S. The number of children who entered each school under one year of age was 70, 71, 35, 5, and 0 percent respectively.
The results obtained were as follows.
1. The Prevalence of Dental Caries The ratio of children with carious teeth in nursery schools A, K and N was less than that in nursery schools KY, S, though the difference between the two groups decreased as the children grew older.
2. Average Number of Def Teeth and Def Surfaces In nursery schools A, K and N, the average number of def teeth and def surfaces was less than that in KY and S.
3. Dental Caries Attack Pattern In nursery schools A, K and N, there were more caries-free children and fewer numbers of children who revealed severe attack patterns of dental caries compared with those in KY and S.
4. Comparison of the Prevalence of Dental Caries between Children who entered School N at less than One Year of Age and those who entered at more than One Year of Age The results sh o wed that children three, four and five years old who entered nursery school N when less than one year of age had fewer def teeth and def surfaces than those of the other groups.
5. Results of The Questionnaire Children who en tered nursery school when less than one year of age had to give up the bottle or the mother's breast, had to stop drinking sweet drinks from a bottle and had to change their food from a liquid type to a solid typeat an early age. Their intake of sweets was regularized after entering nursery school. Their mothers had an opportunity to realize that dental decay is a preven table disease.
Therefore, the earlier the regulation of nutritional intake, the smaller the possibility of the occurrence of dental caries.

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This case involves a male,1 year and 1 month after birth, who had been receiving artificial respiration since he was one month old, due to right pulmonary hypoplasia under nasal intubation. With the eruption of the lower deciduous central incisor, the tip of the tooth touched the lower surface of the tongue tip, forming an oval ulcer, and sometimes bleeding was noted (Riga-Fede's disease). In such a case, the sharp edge of the incisor is shaved, or the tooth is extracted, but in this case as the period of eruption was normal and the bony implantation was firm, we prepared the splint pack used to keep the wound at rest for a child with hemophilia or after extraction of many teeth, to cure the ulcer occurring at the some time.

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A case of ameloblastic fibroma appearing in the lower right second primary molor area is discribed. This case was the youngest child in Japan so far as reports on females are concerned.
On May 23, 1980, the patient, a 3-year-old girl, was submitted for treatment of retarded eruption of the lower right second primary molar.
On September 7, 1981, the tumor was removed under local anesthesia and the lower right second primary molar was erupting. Seven months later no reccurrence was observed.

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At present it is almost impossible to conduct a precise dental examination without X-ray films, especially in pedodontics. However, children obviously face more risks from radiation than adults, because their tissues which have much metabolic activity are much more sensitive to radial rays than adults. Therefore it is necessary to protect the child's immature organs from these rays, particularly the thyroid gland, the eyes (crystalline lens), gonad etc.
Recently the influence of exposure doses for long p eriods of time has been attracting much attention also in the field of the study of dosimetrics in dental radiation. Therefore we are compelled to study its influence, especially on children who are by nature relatively more sensitive to radiat on.
For this investigation the author employed the stabi l i zed TLD and measured the effect of doses on several organs (of children) using water and Mix-D phantom. Based upon this data, the author developed an exposure cone (of children) which was thought to be the best concrete method for reduction of absorbed doses for children who are most frequentry X-rayed and therefore most likely to reduced absorbed doses in a considerable amount. The major findings have been obtained concerning this cone compared with the standard cone as follows.
1. The full mouth 6-film examination showed the largest of the absorbed doses to be on skin, eyes and the thyroid gland.
2. For example, the dose on thyroid gland with a full mouth 6-film examination was 0.734R.
3. The dose on the gonad was less than 0.001R with every technique.
4. Using the developed exposure cone for children we have succeeded in reducing the amount of doses on these organs. In addition the image quality im proved due to the reduction of scattered X-rays.
5. Using the developed exposure cone (for children) the risk of thyroid cancer can be reduced a level of 10^-6 to a level of 10^-7 as compared with the sta n dard exposure cone.
6. Supposing that it is over the crystalline lens limits of dose-equivalent in a year at several times with full mouth 6-film examinations can be estimated wh ich with standard cone was about three times, developed cone was about e i ghtyeight times in a year.

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The purpose of this study was to estimate the hemostasis effects of TDZ jelly on children without hemostasis disorders who visited the department of Pedodontics of Osaka Dental University Hospital.
Classification of minor bleeding on oral soft tissue was due to (1) a reduction of the subgingival tooth structure, (2) removal of the rubber dam, and (3) extraction of primary teeth. Hemostatic effects of TDZ jelly showed 100% in case of (1)and (2) and 77.8 per cent in case of (3).
The results of this study indicate that minor bleeding is easily and safely controlled by using TDZ jelly.

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Cleidocranial dysostosis is generally characterized by hypoplasia of the clavicle and the cranium.
This case concerned a nineteen year old male patient diagnosed as having cleidocranial dysostosis.
The patient showed mental retardation, pseudoautism, prolonged retention of the deciduous teeth and delayed eruption of the permanent teeth.
From the clinical point of view, we are planning to follow up the present general status and to pay close attention to the oral conditions.

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We studied 17 clinically diagnosed as “jaw cysts” cases from five years and one month to twelve years and four months.
Because of most cases did not involve pain, they were discovered by obvious facial swelling or during recall. All of the cases were found with swelling of the buccal plates of the bone in the areas of the cysts. Based on the clinical and radiographic findings, it was found that the cysts involved the roots of the primary predecessors and the permanent successors. In the roentgengram, the width of the pericoronal space with the definite lining showed over 3.0 mm. Yellowish fluid was obtained in the cysts in the most of the cases. Pulpotomy was performed on the primary predecessors of six cases and root canal treatment, on three cases. In six other cases, the primary predecessors were affected and non vital. These cysts occurred most frequently in the lower second premolars, and the periapical regions of the primary predecessors and next in the upper anterior teeth regions in five cases. Based on the clinical and histopathological findings, it was thought that the cause of the cysts was that they originated as periapical regions of the primary predecessors. Most of cases were treated by the extraction of the primary teeth and the marsupialization.
The result was that the cysts became smaller and the unerupted successors were successfully arranged in the regular positions.

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We encountered four cases (father, son, and two daughters) diagnosed as partial anodontia without congenital ectodermal dysplasia.
The results were as follows.
1) Case 1: A l3.9 year-old female with_??_which were congenitally absent.
Case 2: An 18.3 year-o1d male with_??_which also.
Case 3: A 10.9 year-o1d female with_??_which also.
Case 4: A 45.8 year-old male with_??_which also.
2) The upper lateral incisor of the children showed signs of having a rudimentary form and also smaller mesiodistal diameters of the crown. In Case 1 a large number of teeth were missing, and the permanent teeth erupted were sm a ller than in the other cases. Especially, the upper lateral incisors showed signs of having conical shaped teeth and the upper 1st molars showed also s igns of the upper 3rd molars.
3) In Case 1, the underdeveloped growth of the maxilla resulted in the formation of mandibular prognathism and cross bite. Thus for improvement of them, expansion of the maxilla was performed, and chin cap for mandibulla was applied. Dentures were placed in the missing regions of Case 3, and the m asticatory functional rate was recovered.
4) From the observations on the phenotypic level, it was considered that the cause of the partial anodontia is from the presence of a dominant gene. In Case 1, it was also considered that the poor condition of mother's womb during pregnancy had hastened the congenital absence of teeth.

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Progressive muscular dystrophy is a muscular disease characterized by progressive atrophy and weakness of the skeletal muscles.
Several authors have described the effects of this disease on the occlusion of the patient. Some of the oral manifestations which they observed included open bite, macroglosia and expanded dental arches.
We encountered the case of a 5 year 4 month-old boy first diagnosed as having progressive muscular dystrophy at the age of 3, and we have followed up it for about 5 years. We measured the arch width on dental casts taken every 6 months.
The results are summarized as follows.
1) At the first oral examination the patient did not show any functional disorders of the body. Also the value of his maxillary arch width was within th e range of the standard deviation but the mandibular dental arch width was greater than the average value in children of the same age.
2) The increase in the mandibular arch width had started earlier than in the maxillary. With the progress of the functional disorders, the arch width in creased markedly in the maxilla.
3) The increase in the arch width was greater in the maxilla than in the mandibule after 8 years and 6 months of age.
4) The increase in the distance between deciduous canines was within the standard deviation in both maxilla and mandibule.
5) The rate of increase of the arch width was the greatest between the permanent first molars, and followed by the distance between the deciduous seco nd molars and the deciduous canines.

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The purpose of this study was to clarify the factors influencing the adaptability of the child to the first visit to dental clinic. The subjects encompased a total of 306 persons consisting of 102 children ranging from 3 to 12 years of age and 204 parents who had visited the dental clinic of the Department of Pedodontics, School of Dentistry, Aichi-Gakuin University. A total of 39 items were evaluated by means of psychological tests (child-personality test and parents-upbringing test), and questionnaires recorded in dental charts.
Children were classified into two groupsthe adaptation group and the maladaptation group according to their attitude shown at the first visit. The personality of the child and the manner of the parents in bringing up the child were analized in the two groups.
The results are summarized as follows:
1. The subjects were able to be divided into two groups 63 children in the adaptation group (61.8%) and 39 children in the maladaptation group (38.2% )according to the adaptability to the first visit.
2. Among the psychological factors influencing adaptability to the first visit to the dental clinic, were found significant differences between the two groups in the following points.
1) The manner of the father in upbringing in the “positive disapproval pattern” category.
2) The manner of the mother in upbringing in the “anxiety pattern”, “dotage pattern” and “blinde obedience pattern” categories.
3) The personality of the child “aggressive movement pattern”, “sociality pattern” and “social stability pattern” categories.
4) The age of the child in the questionnaire survey.

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The anti-bacterial efficacy of 78 tooth pastes collected from 16 countries was studied in vitro against the following representative strains of oral dental plaqueforming microorganisms:Streptococcus mutans, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mitis, Actinomyces viscosus and Actinomyces naeslundii.The results obtained by the disk method revealed that the supernates of 71 (93%)pastes had some anti-bacterial efficacy against the above strains. Minimum inhibitory concentrations (MIC) were also measured in the ten most highly effective pastes.S. mutans, A. viscocus and A. naeslundii were found to be more sensitive against these pastes than other species.
All of the highly anti-bacteria l pastes were found to contain Sodium N-lauroyl salcocinate (SLS). The effect of SLS, however, was found not to be sufficient enough to account for the total anti-bacterial efficacy of each paste. The value of pH and the amount of F^- of the paste solution were not related to the anti-bacterial efficacy.
The sediment of each paste showed no effect.
The value of MIC was found to increase with exposure time to the air.

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Two methods have been used in applying fluoride containing compounds as agents to prevent caries in humans. One is to use few applications at high concentrations, and the other is to use multiple applications at low concentrations.
In this experiment, the effectiveness of preventing caries and restraining the progress of caries of (NH₄)₂MoO₂F₄ and SrTiF₆, both which were developed as fluoride containing compounds and can be utilized according to a previous investigator's method, was tested using rat experiments. APF and Ag(NH₃)₂F were tested for comparison.
The results showed that both (NH₄)₂MoO₂F₄ and SrTiF₆ were as effective as APF in preventing caries. Furthermore, it was found that both agents checked the progress of caries to the same extent as 38% Ag(NH₃)₂F.

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There are many case reports of supernumerary teeth, but rarely in the primary dentition. We found a supernumerary tooth in the mandibular left deciduous incisal region and a geminated tooth in the mandibular right deciduous incisal region in a 3 year 7 month old girl.
The findings were as follows. Oral condition
1) Her dentition was that of Hellman's stage IIA. The number and the size of the deciduous teeth were normal except for the mandibular incisors.
2) In the mandibular incisor region, five deciduous incisor were recognized. A supernumerary tooth was found in the region of the left deciduous central incisor. It was similar to the normal deciduous left incisor with resp ect to color, shape, and size.
3) The mandibular right deciduous central incisor appeared as the geminated tooth and was larger in size. The fused line was recognized in its crown. X-ray findings
1) The number and the development of the permanent teeth were normal except for the mandibular incisor region.
2) The mandibular deciduous incisors including the supernumerary tooth and the geminated tooth showed normal root formation, and were associated with the permanent successor.3) The permanent incisors showed normal development except that the median one was displaced to the labial side. On the basis of these findings we arrived at the following conclusions.
1) The deciduous incisor in the mandibular median region is the supernumerary tooth associated with the permanent successor.
2) The mandibular right deciduous central incisor had joined with another supernumerary deciduous incisor to form a single large crown and then showed a fused line in it.

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