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A nation-wide field survey was carried out to investigate the etiology of enamel hypoplasia for permanent teeth in 286 subjects below 20 years of age with permanent dentition having enamel hypoplasia. Visual examination, photographic evaluation and questionnaire survey were used. The same questionnaire survey was also carried out in 111 subjects without hypoplastic teeth as controls. The following results were obtained. 1. The number of hypoplastic teeth ranged from 1 to 28 per subjects. 2. Upper central incisors were frequently involved, especially in subjects with few permanent teeth. Enamel hypoplasia in these teeth appeared symmetrically. 3. Only a few hypoplastic teeth seemed due to local causes. Hypoplastic teeth were not considered to be mottled teeth caused by fluoride. 4. Unbalanced diet (food liked and disliked) during pregnancy was not related to dental hypoplasia. 5. In subjects with many colored teeth, maternal diseases during embryogenesis and drugs administered for treatment were considered to be etiologically involved in the development of hypoplasia. 6. Viral infection during childhood seemed to be involved in the development of hypoplasia. 7. Many of the subjects with more than 7 hypoplastic teeth or colored teeth had contracted diseases during childhood. Moreover, the development of both viral infection and other disease was frequent. 8. The kind of teeth liable to damage, time of damage, sensitivity of individual subjects, multiple stimulation.

A nation-wide field survey was undertaken to examine clinical causes for hypoplasia of primary teeth in 141 children above 3 years of age with primary dentition having enamel hypoplasia. The survey was carried out by visual examination, photographic evaluation and questionnaire survey. The controls consisted of 120 children without enamel hypoplasia. The following results were obtained: 1. Hypoplastic teeth due to inflammation, trauma or radiation were not found. 2. Based on the configuration of the hypoplastic teeth, the place of birth and type of nursing, the teeth that developed enamel opacity could not necessarily be regarded as to mottled teeth. 3. No correlation was found between the unbalanced diet of the mothers during pregnancy and the occurrence of the hypoplastic teeth. 4. The development of enamel hypoplasia was estimated to have occurred from the neonatal to infantile stage for the primary canines and from the fetal stage to the early stage of birth or 6 months after birth for second primary molars. 5. Hypoplasia seemed to have begun from the stage of the matrix formation in many cases. 6. Among the mothers during embryogenesis, threatened abortion, severe hyperemesis gravidarum, anemia and drugs used in the treatment of these symptoms seemed to be responsible for the development of hypoplasia. Among the children, diseases occurring within one year after birth, exanthematous diseases such as exanthema submonia, common cold and pneumonia, Jaundice, intussusception and asthma seemed to be responsible. 7. The number of enamel-hypoplastic teeth per child increased, as the frequency of diseases in both mothers and children increased. 8. The kind of teeth susceptible to damage, the time of damage, the sensitivity of individuals, and the kind and severity of damage seemed to interact in the etiology of hypoplasia.

This study was designed to investigate the effect of adhesive composite resin (Clearfil SC Bond) on dental pulp and the effect of calcium hydroxide base (Dycal) on the protection of the pulp, using 66 deciduous teeth of young dogs. After forming a cavity (class 5) on the labial aspect in each tooth, the teeth were divided by the modes of plugging into 4 groups; stopping alone (Group S), stopping and capping with Dycal (Group D+S), capping with Dycal and resin (Group D+R) and capping with resin alone (Group R). After decalcification, the specimen was embedded in celloidin, sliced into thin sections and stained with hematoxylin and eosin for histopathological examination. Histological changes were examined at 3 days, 1 week, 2 weeks and 4 weeks. The following are the results obtained. 1. In Group S, slight histological changes were observed at 3 days and 1 week. However, the changes began to diminish after the 2nd week and disappeared in the 4th week. 2. In Group R, the severest histological changes persisted throughout the course of observation. The changes were not diminished even in the 4th week. Thus, the resin seemed to exert a strong and long-lasting stimulative effect against the pulp. 3. In Group D+S and D+R, the histological changes were more serve at 3 days and 1 week compared to those found in Group S, but these were diminished after the 2nd week. This seemed to suggest that the pulp was stimulated to a certain degree by Dycal but also, Dycal protected the pulp from stimulation of the resin. 4. Capping of the pulp seemed necessary in vital teeth with resin restoration.

The purpose of this study was to evaluate the influence of minor surgery conducted in the oral cavities of children. Changes in blood pressure and pulse during minor surgery were measured using a Pulse-Wave Korotokoff Sound Record Meter GP-303S (PARAMA). The subjects consisted of 28 children (15 boys and 13 girls) who underwent minor surgery at the pediatric dental clinic of Iwate Medical University. An examination of 16 of the 28 children to determine the relationship between their physique, personality, and blood pressure was made. The following results were obtained: 1) The maximum blood pressure formed a peak at the time of the impacted supernumerary teeth extraction. This was more conspicuous in boys than in girls. The pulse rose to the highest values with the infiltration of the anesthesia, the incision, and stripping. However, no significant values based on sex difference were demonstrated. 2) The maximum blood pressure changed more intensely during surgery in boys than in girls. This was distinctly observed during extraction of the impacted supernumerary tooth. 3) Both the maximum blood pressure and pulse increased with the progress of the surgery. After the surgery, it returned nearly to the presurgical level. With extraction of a supernumerary tooth and marsupialization, the return of the blood pressure to the preoperative level was more delayed in boys than in girls. 4. The changes in blood pressure and pulse seemed to be mostly induced by mental disquietude and stress such as anxiety and fear of surgery. 5. The physique and personality were related to the changes in blood pressure and pulse during minor surgery in the oral cavity.

Unlabelled: Using the X-ray films, plastic models and pathological photograph of 4824 patients seen at the Department of Pedodontics of Iwate Medical University, the patterns of ectopic eruptions of permanent incisors and first molars (restricted to these teeth in this study) were classified into 4 groups (I-IV) to investigate the conditions of its incidence, size of the teeth and dental arch, and conditions at the stage of the mixed and permanent dentitions., Results: 1. The total frequency of ectopic eruptions was 5.6%. No difference based on sex was found. 2. By classification, ectopic eruptions of the upper and lower permanent central incisors (Group I) amounted to more than half of the total frequency. The incidence of ectopic eruptions of the upper and lower permanent first molars (Group III) was very low and amounted to only 4.6% of the total frequency. 3. In Groups I and III, the incidence was higher in the maxilla than in the mandible. 4. Based on sex, the incidence was higher in boys in Group III and in girls in group II. 5. Ectopia of the permanent central incisors was frequently bilateral and those of the lower permanent lateral incisors and upper permanent first molars were frequently unilateral. 6. The mesiodistal width of the ectopically erupted permanent teeth tended to be somewhat enlarged, but showed no significant differences from Ono's mean value. 7. In ectopic eruptions at the area of the incisors, the C-C distance was narrowed with an increase in the ectopically erupted permanent teeth. 8. In patients in whom the permanent dentition was formed without occlusal guidance, the basal arch length and dental arch length were large and basal arch width and dental arch width were small. 9. In cases which were followed from the deciduous dentitions to permanent dentitions, the anterior tooth area at the stage of the mixed dentition was frequently crowded. Occlusal guidance was carried out in more than half of these cases.