The root canals of 9 deciduous molars with periapical radiolucent areas were investigated bacteriologically. In all cases, there were no clinical symptoms such as spontaneous pain, percussion pain, fistula and swelling. X-ray observation revealed the expansion of radiolucency in the periapical areas with dislocation of the permanent tooth germ in 4 cases. The contents of the root canals were diluted, isolated and identified under anaerobic conditions.
The results were as follows:
1. Bacteria were isolated in 7 cases of 9 root canals including all of the cases in which dislocation of permanent tooth germ was observed. In these 4 cases, the number of bacteria isolated was higher(1.7×10⁵CFU-3.7×10⁶CFU per 1 ml of R. T. E) compared with other cases (1.8×10²CFU-4.2×10²CFU).
2. In the isolates, obligate anaerobes were predominant (more than 70% of the isolates in 5 cases). In the obligate anaerobes, gram-negative rods, grampositive rods and gram-positive cocci were isolated frequently. In the facultatives, the gram-positive cocci were prevalent and were isolated from all cases in the positive cultures.
3. Bacteroides, Fusobacterium, Peptostreptococcus, anaerobic Streptococcus, Eubacterium and facultative Streptococcus were predominant on the whole. In the bacterial species, non-fermentative or weak-fermentative bacteria were prevalent, however a common bacterial species was not recognized in any of the cases.
4. In the cases with dislocation of the permanent tooth germ, Bacteroides, Peptostreptococcus and Eubacterium were predominant. These results suggest that anaerobes such as Bacteroides, Peptostreptococcus and Eubacterium, just as in the case of adult periapical pathosis, may exert an important influence on the progress of periapical pathosis on deciduous teeth.

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The purpose of this paper was to investigate the dental situation of children with congenital heart disease.
The subjects were 96 children who visited the pedodontics clinic of Tohoku University Dental Hospital during the period from 1981 to 1986. The following results were abtained.
1) When children with congenital heart disease visited the hospital for the first time, they were between the ages of 0 and 14. They were especially concentrated between the ages of 4 to 6.
2) The majority of them were diagnosed as having ventricular septal defects and tetralogy of Fallot.
3) The majority of the patients asked for caries treatment before receiving heart surgery.
4) Generally, the prevalence of dental caries in the deciduous teeth of children with congenital heart disease was higher than for the healthy outpatients. The prevalence was especially significant at the age of 2 and between the ages of 5 to 8.
5) The type of the treatment for the decayed teeth was mainly restoration, followed by extraction, pulpotomy and pulpectomy in that order, and less preventive treatment.
6) Half of them have been visiting the hospital for dental examinations and care regularly.

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For the purpose of investigating the thickness of the dental structure in the mandibular first deciduous molars, the distance between the pulp cavities and the external boundaries of the teeth were measured. The materials used were 42 teeth, some without caries and some with caries localized in the enamel. The classification of the specimens and the methods of the investigation applied were similar to those applied to the maxillary molars reported previously.
The observational regions used for these measurements consisted of the occulusal aspest, the mesio-distal aspects divided on the buccal groove in the mesiodistal diameter and the bucco-lingual aspects divided on the center of the transverse ridge in the bucco-lingual diameter, adding the cross sections of the central fossa, the center of the transverse ridge and the horns of the pulp chamber.
Result:
1. The smallest measurement for the distance from the pulp horns to the occlusal surface was 2.0 mm at the disto-lingual horn in the cross section of its horn.
2. For the measurements of the distance from the bucco-lingual grooves and the lingual trigonid notch to the pulp chamber, the distance of the buccal groove was 3.0 mm, greater than the other ones.
3. The smallest measurement of the distance from the pulp horns to the buccolingual and the interproximal surfaces was 2.1 mm. This phenomenon was observed on the mesial side in the lingual aspect and type I of the lingual side in the cross section of the mesio-lingual horn.
4. The smallest measurement of the distance from the maximum bulge of the pulp chamber to the bucco-lingual and the interproximal surfaces was 1.7 mm at all regions except for the mesio-buccal angle.
5. The smallest measurement at the maximum depression of the pulp chamber and cervical regions was 1.4 mm.
6. As for the measurement of the distance from the central fossa and the center of the transverse ridge to the pulp chamber, the former was 2.4 mm, the latter 2.8 mm.
7. The mesio-lingual horn existed closest to the summit of the cusp holizontally and the disto-lingual pulp horn was at the inner most part from the summit of the cusp.
8. According to the degree of the resorption, type II was greater than the other types when measuring the distance from the pulp chamber to the occulusal surface. Appropriate attention must be given to the occasion of the cavity preparation because the thickness of the dental structure in the mandibular first molars was thin at the portions of the central fossa, distal maximum bulge of the pulp cavity and mesio-buccal horn.

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For the purpose of investigating the thickness of the dental structure in the mandibular second deciduous molars, the distance between the pulp cavities and the external boundaries of the teeth were measured. The materials used were 40 teeth, some without caries and some with caries localized to the enamel. The classification of the specimens and the methods of the investigation applied were similar to those applied to the maxillary molars reported previously.
The observational regions used for these measurements consisted of the occulusal aspect, the mesio-distal aspects divided on the buccal groove in the mesiodistal diameter and the bucco-lingual aspects divided on the central fossa in the bucco-lingual diameter, in adding the cross sections of the central fossa and horns of the pulp chamber.
Result:
1. The smallest measurement for the distance from the pulp horns to the occlusal surface was 2.4 mm at the mesio-buccal horn in the cross section of its horn.
2. As for the distance from the bucco-lingual and the disto-buccal grooves to the pulp chamber, the measurement of the distance of the lingual groove was 3.6 mm, greater than that of the other ones.
3. The smallest measurement of the distance from the pulp horns to the buccolingual and interproximal surfaces was 2.4 mm on the lingual sides in the cross section of the mesio-disto lingual horns.
4. The smallest measurement of the distance from the maximum bulge of the pulp chamber to the bucco-lingual and the interproximal surfaces was 2.0mm on the mesio-distal sides in the bucco-lingual aspects.
5. Also in the maximum depression of the pulp chamber and cervical region, the smallest distance was observed on the mesio-distal sides. It measurement was 1.9 mm at the maximum depression of the pulp chamber and 1.6 mm at the cervical region.
6. The measurement of the distance from the central fossa to the pulp chamber was 3.1 mm.
7. The distal and disto-lingual horns existed within about 1.5 mm from the summit of the each cusp, but the other horns were within 1.0 mm.
8. According to the degree of the resorption, the distances of type II of the disto-buccal horn and its surrouding regions were greater than that of the other types at the measurement of the distance from the pulp chamber to the occlusal surface. However attention must especially be given to the occasion of the cavity preparation, because the mesio-buccal horn jutted out into the occulusal surface and also the distance was the smallest.

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The purpose of this study was to investigate the eruption of the deciduous teeth by age based on months in order to establish methods of plaque control and occlusal management for infants.30 healthy children from 1 to 36 months of age were examined every 2 weeks concerning the state of the eruption of the deciduous teeth which was divided into 4 stages. We calculated the eruption time of the deciduous teeth, the time of half the eruption, and the duration of each eruption stage, then discussed the relationship between the age and the eruption stage, and between the eruption stages of each kind of teeth.
The following results were obtained:
1) The order and age of the eruption of the deciduous teeth were as follows; lower central incisors erupted at 6.5 months of age, upper central incisors 8.5months, upper lateral incisors 10.0 months, lower lateral incisors 10.9 months, upper first molars 14.6 months, upper cuspids and lower first molars 15.4months, lower cuspids 16.3 months, lower second molars 24.2 months, and upper second molars 26.7 months. No significant differences based on se x were noted. Individual distribution of the eruption time was in about 2 months except for second molars.
2) The age at the time of half the eruption of the deciduous teeth was from the earliest age of 8.5 months (lower central incisors) to the latest 29.1 months (upper second molars). It took 2.1 months to reach half the eruption on the average. Individual distribution showed value and tendency similar to that of the eruption time.
3) As for the duration of each stage of eruption, stage 1 was the shortest, stage 2 a little longer than stage 1, and stage 3 the longest on every kind of teeth.
4) For each type of teeth, the age of transition of eruption stages was found.
5) For the incisors, when the teeth which erupted previously had reached stage 2 or 3, the next one began to erupt. Cuspids and first molars were found to erupt at almost the same time when incisors had reached stage 3. Secend molars began to erupt after the others finished erupting.

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The purpose of our study was to investigate the development of the masticatory function of the infants. To do this we examined the methods of feeding baby foods every two weeks.
The subjects totaled 28 healthy nursery school children,15 boys and 13girls, who were from 4 to 23 months old. They were fed on the same foods.
Regarding the deciduous central and lateral incisor and the 1st deciduous molar we classified the types of eruption into 6 types each, considering the degree of the eruption. Based on the types of eruption we examined the changes of the feeding methods classified them into 14 ways.
The results were as follows.
1) As for the types of eruption of the deciduous central incisor, the changes of the feeding methods were shown very clearly with type A4, in which the ways “to thrust the tongue frequently” and “to be hard to swallow the solid foods”decreased markedly, while the way “to let the mouth move holding the foods mainly at the region of the anterior” increased.
2) As for the types of eruption of the deciduous lateral incisor, definitive changes were not shown.
3) As for the types of eruption of the 1st deciduous molar, the changes were shown very clearly with type D6, in which the way “to let the mouth move holding the foods at the region of the molar” became 100%.

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Fissure sealant is used for the prevention of pit and fissure caries. Fluoride (F)-releasing sealant (F-sealant) was developed to supply the F to the enamel adjacent to the sealant. In this in vitro experiment, we studied both the amount of F released from sealant and the uptake of F by the hydroxyapatite and the human enamel.
We found that a very small amount of F was released from the F-sealant at least for a 4 month period. The amount of F released decreased gradually with time.
In the case of the hydroxyapatite, the F was incorporated into its surface during first 2 weeks. Thereafter, the F was incorporated into the much deeper layer of the hydroxyapatite.
The amount of F in the enamel of human tooth sealed with F-sealant was shown to be significantly larger than that of the control. The amount of F incorporated into the enamel was two time larger at 4 weeks than that at 2 weeks. Similarly to the hydroxyapatite, the F was incorporated into the much deeper layer of the enamel with the lapse of time.
Our data suggest that F-sealant can contribute the increase in the acidresistance and remineralization of the enamel.

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In an effort to elcucidate the functional difference of the masticatory muscles during the transition from primary to permanent dentition between mormal occlusion and crowding, I examined, by using cross-sectional the cephalometric rentgenograms, the dental arch models, the number of interocclusal points and the electromyographs of 40 subjects with normal occlusion and 40 subjects with crowding dentition during the II A, III A, III C and IV A stage of Hellman's dental age.
1) The crowding group possesed the following characteristic craniofacial morphology: the length of each maxilla and mandible was smaller and shorter in comparison with the control group. Also the dental arch perimeter was shorter, as well.
2) The number of interocclusal points was smaller in the crowding group than in the control group. In particular, significant difference was found in stage III C and IV A.
3) As a result of analysis using integrated method for electromyographs, in the control group, it was found that the total electric potentials in TA tended to decrease in proportion to the advancement of the dental stages, while the ratio of M was shown to have a tendency of increasing. In the crowding group, however, the decrease of the TA percentage and the increase of the M percentage were smaller in comparison with the control group.
4) By electromyographic analysis of the lateral mastication, both of the two groups were considered to have a common tendency in that the masseter muscle worked mainly on the working side in the permanent dentition.
5) On comparising the gum chewing patterns (duration, interval, cycle) recorded from the masseter muscle, I found that the patterns were more stable in the control group than in the crowding groups except for the III A stage.
6) In the crowding group, the frequency of occurance of the silent period was low and in regard to the duration of the silent period, it was shorter than in the control group.
7) The cause of the characteristic ratio of TA and M to the total electric potential in the crowding groups was considered to be the small number of interocclusal points in comparison with the control group.

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Prevalence of caries was examined in 327 Japanese children, ranging in age from 0.6 to 16.5 with a mean age of 6.3, and expressed as DT%, DFT%, DS%, and DFS%, irrespective of the dentition. Mutans streptococci were also isolated from the saliva of the subjects and examined with respect to their serotypes, the ability of the sucrose dependent adherence, and extracellular glucosyltransferase activities. In twelve children, mutans streptococci were not found. The percentage of children who had S. mutans (serotype c/e/f), S. sobrinus (serotype d/g), or both of them were 75.9%,15.7%, and 8.4%, respectively. Salivary mutans streptococci were found to be significantly correlated to the prevalence of caries. Children with both S. mutans and S. sobrinus not only had higher salivary counts of mutans streptococci but also a higher caries prevalence than children with S. mutans or S. sobrinus alone. Also the correlation between caries prevalence and sucrose dependent adherence in children who had S. sobrinus was higher than that in children who had S. mutans. These results indicate that there may be some differences in the caries inducing mechanism between S. mutans and S. sobrinus in humans.

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The actual state of nutrition and dental caries in young patients from 3 to 5 years of age at a dental clinic employing a nutritionist, in Ohmiya, a mediumsized city close to Tokyo, was investigated. The main materials used for analysis in this study were the diet records of what each patients had eaten over a three day period.
Of the 96 patients (male: 46, female: 50) investigated during the course of this study from April 1984 to March 1986,90 had dental caries. This constituted 93.8% of the total. Using the ministry of Health's criteria which indicates the degree of severity of dental caries,78 patients,81.3% of the total were placed in the severe category of class B and C. Compared to the average recomended intake of variouls types of food suggested by KAGAWA, it was found that the general balance and variety of food in meals in all of the cases was poor as eight out of 11 types of food were taken in an insufficient quantity and two types of food including sugar exceeded the suggested level. The intake quantity of sugar increased according to the severity of dental caries from class O to C. In class C, especially, the general balance, quantity and variation of food was extremely poor, with only one out of the 11 types of food on KAGAWA's list being taken in a sufficient quantity. Compared to the guidelines on nutrition issued by the ministry of Health in 1984, it was found that the general balance of nutrition in the patient's diet in our total was comparatively poor with the result that while the quantity of calcium and vitamins was large, energy, iron and protein were insufficient. The quantity of iron decreased corresponding to the severity of dental caries, although this was not conormed statistically. On average they took 20.3different kinds of food a day. It decreased slightly corresponding to the severity of dental caries. There was no significant relationship between the severity of dental caries and other categories: the energy pattern among protein, fat and carbohydrate, the ration of animal protein to vegetable protein, the number of smacks for a day, and the ratio of smacks to main meals in quantity.

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The clinical application of ampicillin suppository (KS-R1) was studied. This antibiotic drug has been used for prophylactic and therapeutic purposes with handicapped children. As far as the absorption of ABPC is concerned, rectal use of KS-R1 was compared with oral and parenteral administrations. In addition, the irritabilities of KS-R1 on the rectum was observed clinically. The results were as follows:
1. Blood levels of ampicillin (ABPC) were measured from 10 patients with heart diseases and acute leukemia after the rectal administration of 250 mg of KSR1. The average blood level of ABPC at 15,105 and 240 minutes after the administration of KS-R1 were 7.75,0.76 and 0.36μ9/ml respectively.
2. Five patients received 250 mg of ABPC orally. The average level of ABPC at 15,105 and 240 minutes after oral administration of ABPC were 0.82,2.56 and 0.91μg/ml respcctively.
3. KS-R1 is a useful drug as an antibiotic for children who are not able to take oral administration of medication due to oral malfunction and inability, and so forth.
4. No infectious diseases were seen clinically in all of patients after the administration of KS-R1.5. As far as rectal irritabilities are concerned after rectal administration of 250mg KS-R1, no complaints were observed clinically. KS-R1 is, therefore, very useful rectal antibiotic suppository for children as a prophylactic treatment in the pedodontic clinic.

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This paper reports on a case of focal enamel hypoplasia of the lower second molar tooth associated with a dentigerous cyst. Macroscopically, enamel hypoplasia extended from the central groove to the lingual surface. Un-decalcified ground section revealed that a complete defect of all the layers of the enamel, and no significant pathological changes were seen in the dentin and pulp. The observation of the present case study and review of the literature suggest the possibility that there may be two types of dentigerous cysts, perhaps with different causes and arising at different stages of tooth development. One would start to develop after the crown has fully formed and arise by separation within the cells of the reduced enamel epithelium due to accumulation of tissue fluid. The other type would commence at an early stage of tooth development and is likely to be associated with enamel hypoplasia; this type of cyst begins with degeneration of the stellate reticulum of the enamel organ.

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From 1983 to 1985,5195 restorations were performed on the primary teeth of 780 children at the Nagasaki University Dental Clinic of Pediatric Dentistry. Results and conclusions.
1. The average number of the restorations per patient was 6.7 and the highest number shown was 8.5 at three years of age.
2. In a total of 5195 restorations 2025 (39%) were composite-resin restorations,1627 (31.3%) were steel crowns,793 (15.3%) were metal inlays,415 (8%)were amalgam restorations, and 311 (6%) were composite-resin crowns.
3. Primary anterior teeth were restored with the following materials; compositeresin (77.8%), composite-resin crowns (18.2%), steel crowns (2.8%).
4. Primary molars were restored with the following materials; steel crowns (45.3%), metal inlays (22.7%), composite-resin (20%), and amalgam (11.5%).
5. In primary molars 955 restorations included proximal surfaces, and 76.8%of the restorations were metal inlays,15.3% were composite-resin restorations, and 7.4% were amalgam restorations.
6. The rate of the restorations was compared with ages of the patients. Composite-resin restorations were used preferentially for patients under 3years of age and metal inlays and steel crowns were used preferentially for patients over 6 years of age.
7. In the primary teeth which were afflicted with caries extending only to the enamel, composite-resin was used for 98.8% of primary anterior teeth and 74.8% of primary molars.
8. In primary teeth in which caries extended only into the dentin,89.6% were restored with composite-resin in the primary anterior teeth and 35.9% were restored with inlays,27.5% were restored with composite-resin,19.3% were restored with amalgam and 17.3% were restored with steel crowns in the primary molars.
9. In the primary teeth in which caries extended to the pulp,51.2% were restored with composite-resin crowns, and 42.7% were restored with composite-resin in primary anterior teeth, and 92.2% of primary molars were restored with steel crowns.

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From 1983 to 1985,1415 restorations were performed on the permanent teeth of 371 children at the Nagasaki University Dental Clinic of Pediatric Dentistry. Results and conclusions.
1. The average number of restorations per patient was 3.8 and the higher the age of the patients, the more the number of the restorations.
2. In a total of 1415 restorations,728 (51.4%) were composite-resin restorations,309 (21.8%) were metal inlays,285 (20.1%) were amalgam restorations,26(1.8%) were steel crowns,23 (1.6%) were composite-resin crowns, and 19(1.3%) were metal onlays.
3. Of the anterior teeth 85.8% were restored with composite-resin.
4. Molars and premolars were restored with following materials; compositeresin (44.2%), metal inlays (26.4%), and amalgam (23.8%).
5. Of the molars and premolars 193 restorations included proximal surfaces, and 71% of the restorations were metal inlays,15% were composite-resin restorations,8.3% were metal onlays, and 5.7% were amalgam restorations.
6. For the teeth which were afflicted with caries extending only to the enamel, composite-resin was used for 100% of anterior teeth and 92.7% of molars and premolars.
7. For the teeth in which caries extended only into the dentin,90.1%, of anterior teeth were restored with composite-resin and 37.3% were restored with compositeresin,30.4% were restored with amalgam, and 30% were restored with metal inlays in molars and premolars.
8. For the teeth in which caries extended to the pulp,60.7% were restored with composite-resin, and 35.7% were restored with composite-resin crowns in the anterior teeth and 34.7% were restored with metal inlays,20.4% were restored with composite-resin in the molars and premolars.
9. For the teeth in which most of the tooth crown was destroyed by caries,66.7%of the anterior teeth were restored with pivot crowns and all the molars and premolars were restored with steel crowns.

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We conducted a radiographic follow up and discussion concerning 100 primary teeth (42 boys and 37 girls), which were random samplings from all primary teeth which had been treated by vital pulp amputation with calcium hydroxide paste (CALVITAL) during the period from January 1980 to December 1985 at Pediatric Dentistry clinic of the School of Dentistry, Hiroshima University. For the follow up examination, we used only the radiograms which were radiographically available.
The results obtained were as follows:
1) At the time of final follow up examinaiton for each treated tooth, the teeth judged as being successful were 74 (74.0%) and 26 (26.0%) as being unsuccessful. We observed many teeth judged as being unsuccessfull, during the period from 24 months to 30 months after treatment.
2) In this investigation, we observed all the radiograms which had been taken at the recall after treatment, and therefore the number of cases examined was 197. According to the results at the time of each follow up examination, unsuccessful cases were few up to 24 months after treatment, but they were numerous during the period from 24 to 30 months.
3) According to the location of the treated teeth and the age at the time of treatment, abnormal findings appeared in the majority of the unsuccessful cases within 30 months after treatment. Unsuccessful cases were more numerous for the lower second deciduous molars and less for the anterior teeth. Unsuccessful cases of patients aged 4 and 5 years, when vital pulp amputation had been performed, were more numerous.
4) Of 26 teeth judged as being unsuccessful,16 showed internal root resorption,9 abnormal root resorption,18 obliteration of lamina dura and 16 alveolar bone resorption in the periapical and/or furcation areas.
5) The formation of the dentin bridge were radiographically observed 2 months later after treatment, and the number of the teeth and root canals where it was recognized, was 33 and 41, respectively.

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The author experienced a case of a completely impacted right maxillary second primary molar in a 4-year and 7-month-old child and performed surgical exposure and orthodontic guidance.
The present case presented anterior crossbite accompanying poor maxillary growth, whith the bone age being about 2 years behind the chronological age. Neither local and general findings nor anamnesis suggestive of the relationship with the impaction was recognized.
An orthodontic bracket and inray fitted with hooks, an elastic thread ligature and uprighting spring, as well as a lingual arch were applied as maintenance devices, with an orthodontic guidance force and fixing source, respectively, for orthodontic guidance. In about 12 months, the second primary molar was able to be guided in the set of teeth.
Orthopantomography after orthodontic guidance confirmed the existence of a tooth germ of the second premolar, i. e. permanent tooth in succession to the second primary molar, but with a transposed picture of the tooth germ.
Although about 2 year-time lag was found in the eruptionperiod of the permanent tooth, no discomfort has been complained of except for caries. The case is still under observation.

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[in Japanese]

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