An investigation into the actual condition of the first permanent molars had been carried out on the patients who came to the Tokyo Dental Clinic of Lion Foundation for Dental Health from April,1992to March,1993. Those investigated consist of 711 patients who underwent periodical recall examination at our dental clinic, and 276 new patients, both with ages ranging from 8 to 29.
The items to be investigated were distinction of vital teeth and non-vital teeth, occurrence of missing teeth, condition of dental caries, number of surfaces with caries, condition of caries on proximal surface, and rates of caries experience according to tooth surface.
The results obtained from this study were as follows:
1. In the group who underwent periodical examination, almost all of the subjects had vital teeth. On the other hand, the group consisting of new patients showed a tendency toward having non-vital teeth or missing teeth, especially in the higher age group.
2. In the periodical examination group, there was a high rate of intact teeth and most of them had been treated with pit and fissure sealant. The ratio of teeth with dental caries was 2 to 6 percent in the periodical examination group. This rate exceeds the 20 percent among new patients, and the rate reached nearly 40 percent on the mandible in the group aged 15 to 19.
3. Concerning the number of surfaces having had caries among new patients, there was a tendency for the rate of one surface to decrease and that of three, four, or five surfaces to increase with age.
4. Caries on the medial proximal surface were observed very frequently among new patients, often detected through visual and palpable inspection. In the group undergoing periodical examination, the condition of such caries was slight and generally detected through X-ray examination. As to the distal proximal surface, the rate of caries was low in the periodical examination group compared with new patient group, and not detected at all through visual and palpable inspection.
5. For each dental surface, the rate of caries experience was higher for new patients compared with those of the periodical examination group. As to the rate of caries on the maxillary buccal surface and mandibular lingual surface, the difference between the two groups became larger with increasing age.
Considering above mentioned results, it could be reasoned that periodical dental examination for the first permanent molars before their eruption, including oral examination, X-ray examination, tooth brushing and flossing instruction, prophylaxis, pit and fissure sealant, and fluoride application, was effective for the prevention of caries on the first permanent molar.

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Taking sufficient calcium in the pubescent period is very important as a preventive against osteoporosis, To our knowledge, there have been few reports about the effects of calcium intake on the bone by using the quantitative densitometry and morphological measurement. In our study, rats aged 8weeks, corresponding to adolescence in humans, were used. The effects of dietary therapy on mandibular osteoporosis produced by calcium deficiency were investigated, using computed X-ray densitometry and cephlometric radiography. The results were as follows.
1. Body weight
No significant differences were identified between the control and experimental groups.
2. Cephalometry
a. Coordinate analysis
The experimental groups exhibited significantly lower values than the control group in the coronoid process, condyle and mandibular angle (p<0.05).
b. Distance measurement
The experimental groups showed a significantly shorter condylar head and coronoid process than those of the control group (p<0.05).
c. Area measurement
The experimental groups showed significantly less area for the condyloid process than that of the control group (p<0.05).
3. Densitometry
No significant differences were found between the control and experimental groups in the bone density of the mandibular angle, condylar and coronoid processes.
From the foregoing results, dietary therapy showed a positive result for recovery of mandibular osteoporosis in pubescent rats measured by computed X-ray densitometry, but it had no significant effect on the recovery of bone morphology which was thought as a marker of bone mass based on cephalometric investigation.

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In order to obtain an adequate cavity morphology suitable for the application of adhesive composite resin, the present study was undertaken on 50 healthy extracted upper first primary molars. Two composite resins, i. e., Single Bond® (3 M Co. ) and Liner Bond II® (Kuraray Co. ) were used. The cavity forms studied were the bowl-type and box-type. On the occlusal surface of each tooth, a class 1 cavity was formed.
The cavity marginal configuration was either a regular round bevel (a) or a more gently-sloping round bevel (b). Based on the combination of cavity forms and adhesive composite resin systems, the cavities studied were classified into 4 groups. Group I was a combination of a Single Bond® and a bowl-type cavity with a bevel (a). Group II was a combination of a Single Bond® and a bowl-type cavity with a bevel (b). Group II Iwas a combination of a Liner Bond II® and a bowl-type cavity with a bevel (b). Group IV was a combination of a Liner Bond II® and a box-type cavity with a bevel (a). After filling, each tooth was exposed to 10,000 thermal cycles. After soaking in a 0.2% basic fuchsin staining solution, the samples were embedded in a resin and 500 μm sections were prepared. Each section was examined for detection of microleakage from the cavity margin and for measurement of the thickness of the layer of bonding material. The results were as follows.
No microleakage whatsoever was detected in some cavities of group I and II. Particularly in those of group II,73.3% did not show any microleakage. The areas of microleakage were confined to the margin and floor of the cavity. In contrast, microleakage was detected in all of the cavities of groups III and IV. Furthrmore, the leakage sometimes reached the tooth pulp in these groups.
In groups I and II, the bonding material was absent near the margin of the cavity, but was found in the dentin and in the corner and floor of the cavity. The thickness of the bonding material layer was about 20 μm. In groups III and IV, bonding material was found in the margin of the cavity. In group IV, the thickness of the layer of bonding material was a little less than twice the thickness of the layer of the bonding material in the corresponding areas of group Ell.
The bowl-type cavity with a gently-sloping marginal configuration was therefore adequate for the application of adhesive composite material to primary molars. Furthermore, it is conceivable that acid etching combined with the use of more fluid bonding material can reduce microleakage from the cavity margin.

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The aim of this study was to determine the variation in mineral ion contents (Ca, P, F) in dental plaque from different areas of the dentition in order to help explain the site-specificity of caries formation.4-day plaque samples were collected from 8 different sites of 15 male subjects living in Hokkaido (average age 25.2 yr. ) upper-anterior-buccal (UAB) and lingual (UAL), upper-posterior-buccal (UPB) and lingual (UPL), lower-anterior-buceal (LAB) and lingual (LAL), lower-posterior-buccal (LPB) and lingual (LPL). Plaque samples were weighed, freeze-dried, and subjected to acid extraction, using a mixed-acid digestion procedure that was described by Margolis and Moreno (1992). The acid extracts were analyzed for Ca using atomic absorption, P using colorimetry and F using the F ion electrode.
For the plaque wet and dry weights, the highest site was the UPB(mean±S. D.: 17.96±8.75mg wet weight,3.26±1.36 mg dry weight) whereas the lowest site was the UAL(2.62±259 mg wet weight,0.71±0.51 mg dry weight). However the water content of plaque samples were similar at all sites (around 80%), with the possible exception of the UAL site.
Statistical differences were seen in the Ca and P tested using two-way ANOVA (p<0.0001), and in F (p<0.05). Plaque associated with the LAL, which is very prone to saliva and less prone to caries, had significantly highest levels of Ca and P using Scheffe's test. It was concluded that sitespecific plaque mineral contents may reflect the differences in exposure to saliva, resulting in differences in local cariostatic challenge.

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We performed dental examinations on kindergarten children in Shanghai, China. Using upper and lower dental casts obtained from the children, we anatomically observed the morphology of the deciduous molar crowns. We evaluated the results compared to those in past reports and obtained the following conclusions.
1. Among the deciduous molar teeth observed, there were no differences between Japanese and Chinese children in the crown occlusal surface patterns.
2. The incidence of the protoconule, metaconule, and crista obliqua in the upper deciduous molars of children in Shanghai was lower than that in Shijiazhuang.
3. The incidence of the moon-shaped ridge on the upper molar buccal surface and the cingulum in maxillary deciduous first molars of children in Shanghai was higher than that in Shijiazhuang.
4. There were no differences in the incidence of the mesial tubercle, the 6 th and 7 th cusps in mandibular deciduous second molars, and the cingulum in mandibular deciduous first molars observed between the Chinese children in Shanghai and Shijiazhuang.
5. It could not be determined whether there were differences in the proportions of the anterior occlusal measurement with respect to the posterior one in mandibular deciduous first molars between the Chinese children in Shanghai and Shijiazhuang.

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The purpose of this study was to evaluate the validity of three kinds of caries activity tests for caries prediction. The caries activity tests used in this study were Cariostat (Cariostat^TM: Sankin), Resazurin Disk test (RD test®: Showa) and MSB broth (Mucount®: Showa). Caries activity tests and dental examinations at one year interval were performed on 71 patients ranging in the Hellman Dental Age II A to IV A as the first caries activity tests and continued for 5 to 9 years. The patients had all been seen for regular recall treatments at the Pediatric Dental Clinic of Nagasaki University School of Dentistry. The intervals of the recall visit of the patients were 3 to 6 months. All of the dental examinations, caries activity tests and recall treatments were performed by one of the authors. Results at one year intervals of the dental examination and caries activity tests were classified according to the dental age. The correlation between the scores on the caries activity tests and caries incidence 1 year after each of the caries activity tested periods were analyzed. Spearman's rank correlation coefficients (p<0.05)were used to calculatet he correlationb etween the scores on the caries activityt estes and the following 3 items. These were the total number of the C₀ (enamel white spot or incipient caries without enamel defect)increased for 1 year, the total number of the decayed teeth (d+D)except for C₀ increased for one year, and Caries Severity Index (CSI) 1 year after each of the caries activity tested periods. According to the scores on the caries activity tests, the chi-square test for statistical significance (p<0.05) was attempted between the presence and absence of the C₀, the presence and absence of the d+D for every 1 year interval, and between the CSI 1 year after each of the caries activity tested periods was over 8 and less than 8.
The following results were obtained.
1) For all of the caries activity tests, in comparing of the correlation between the caries activity score and the one-year total number of the C₀, the one-year total number of the d+D and the CSI after one year from each of the caries activity tested periods, no significant correlation was obtained in Dental Age II A.
2) The Dental Ages that showed a significant correlation in the plural number items were the II C, IIIB and IIIC.
3) The caries activity test that showed the significant correlation in the highest number items was the Cariostat 48 hour scores.
4) The item that related to caries incidence and most often showed a significant correlation was the CSI and then the d+D.
These results suggested that the Cariostat 48 hours scores at the time of permanent tooth eruption may be useful for caries prediction.

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The present study aimed at studying the effect of dietary calcium and protein on the development and growth of the mandible in weanling rats. In the current study, forty 3-week-old male Wister rats, corresponding to the weanling period in humans, were used. They were divided randomly into four groups. The control group was fed on a standard diet for fourteen weeks, and the experimental groups were fed on calcium deficient diet, low calcium diet and high protein diet, respectively. After four weeks, all of them were fed on a standard diet for ten weeks. The effects of diet on the mandibular with respect to morphology and density in weanling rats were investigated, using computed X-ray densitometry and cephlometry. The results were as follows.
1. Weight
There is no significant difference among four groups.
2. Cephalometry
The calcium deficient group showed a significantly smaller mandibular form than the control group (p<0.05).
3. Densitometry
A significant difference was only found between the control and the calcium deficient group with respect to bone density (p<0.05).

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We carried out structure analysis by using the three dimensional finite element method for the mandibular primary anterior teeth and mandibule of children in order to research the damage mode during trauma. The results were as follws;
1. For the load of the labial on mandibular primary central and lateral incisor, the tendency in which the tooth causes the luxation, mobility and shedding by the external force is strong, but the tendency which causes the fracture of tooth is weak.
2. For the load of the labial on mandibular primary canine, the tendency in which the tooth causes the luxation, mobility and shedding by the external force is weak, and the tendency which causes the fracture of tooth also is weak. The tendency of the opposite side of neck of the mandibule and the opposite side of head of the temporomandibular joint to cause bone fracture is strong.
3. For the load of the bone surface on chin, the tendency in which the neck of mandibule and the head of temporomandibular joint causes bone fracture is strong, but the tendency in which the chin causes bone fracture is weak.
4. For the load of the bone surface on mandibular first and second primary molar, the tendency in which the distal of the second primary molar, the oppsite side of the neck of mandibule and the oppsite side of the head of temporomandibular joint causes bone fracture is strong.
5. For the load of the bone surface on mandibular first molar, the tendency in which the neck of mandibule and the head of temporomandibular joint causes bone fracture is weak, but the tendency in which the lower first molar portion causes bone fracture is strong.
6. For the load of the bone surface on the angle of the mandibule, the tendency in which the angle of mandibule, the same side of the neck of mandibule and the same side of the head of temporomandibular joint to cause bone fracture is strong.
We believe which this structure analysis is useful for the clinical research of the trauma of lower primary anterior teeth and mandibule in childhood.

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Since mastication is one of the most important mandibular functions, much attention has been paid to this. Numerous reports, which analyzed this function from the viewpoint of the mandibular movement, have been published on this subject, and the dividing of this masticatory movement into its component cycle has been mandatory in such studies. Although the method to divide these movements greatly influenced the results, less attention has been paid, especially with respect to children with primary dentition. In this study an appropriate method to divide the masticatory movement into component cycles was sought in order to apply this to children.
The subject group for children with primary dentition consisted of 9 girls ranging in age from 4 to 6 years. They were instructed to chew gum. The mandibular movement at the lower incisal point was recorded and analyzed to find the best method for dividing of the chewing movement. First, the best frame for the terminal position of each component cycle was looked for, using two conditions, namely the method to smooth the mandibular movement and a cycle duration. Next, it was examined whether the maximum opening positions, which existed between the terminal positions, would be appropriate. The number of cycles divided from the masticatory movements using these two steps compared with the number of cycles visually recognized as a cycle. In addition,27 women, ranging in age from 16 to 27 years, also participated in this study. Comparison between children with primary dentition and adults with permanent dentition was carried out.
1) More than 99% of the terminal positions were able to be recognized automatically by the smoothing method and minimum cycle duration in children.
2) The same method was applicable to adults with permanent dentition, though the minimum cycle duration was not the same in case of children with primary dentition.
3) Movements, which were not considered as an active chewing cycle could be excludable from the masticatory movement using the condition both of the terminal position and the vertical position of the lower incisal point.

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Records of children treated under general anesthesia for comprehensive dental treatment at the Department of Pediatric Dentistry, Matsumoto Dental University Hospital between January 1990 and May 2000 were reviewed in a clinical-statistical survey.
The results were as follows:
1. A total of 176 children(101 boys,75 girls) were treated. The ages of the children ranged from 1year 9 months to 7 years 2 months, with a median age of 3 years 9 months.
2. The most frequent reason a general anesthetic was given for comprehensive dental treatment was gross caries.
3. The number of teeth treated per child was 15.6 on average. The treatment involved restoration with composite resin filling in 8.1 teeth, metal crowns in 3.8 teeth, composite resin crown in 2.8 teeth, extraction in 0.6 teeth and treatment with fissure sealants in 0.3 teeth, along with 6.1 teeth with pulp treatment.
4. The average duration of the anesthesia was 212.6 minutes. In the great majority of cases, inhalation anesthesia was administered by slow induction/nasal intubation.
5. All of these children were admitted to the hospital for 3 days. There were no serious postoperative complications.

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This study was carried out to design an ideal cavity for restoration of primary molars with adhesive composite resin. The materials used in this study were extracted primary molars from children, and class 1 cavities on the occlusal surface were prepared. An ideal cavity design was considered as being a bowl-shaped, flat floor cavity at an angle of 75°with the occlusal surface to the buccal and lingual walls. A box-shaped cavity was prepared for the control group.
The materials used in this study were Single Bond® as a bonding agent and AP-X® or Z-100® as a restoration material for the cavities. We determined the presence of microleakage in the cavity margin, the thickness of bonding agent, and the remaining monomer after the polymerized composite resin. After a thermal shock tester was used, the two kinds of cavity designs were compared for their adaptability. As a result, the following conclusions were obtained:
1. In the bowl-shaped cavity with a flat floor, teeth without microleakage amounted to 86.4% and this was more pronounced compared with the box-shaped cavity. When the areas of microleakage were found, they reached the cavity floor in both types of cavities.
2. In the bowl-shaped cavity with a flat floor, a thick layer of bonding agent was found in the corner and floor of the cavity after filling with AP-X®, and it was found also in the vertical wall of the dentin after Z 100® filling. Furthermore, in box-shaped cavity after AP-X® filling, the bonding agent layer was also found at the enamel wall. There was no difference between the two filling materials, concerning the thickness of bonding agent in the bowl-shaped cavity with a flat floor. There was, however, a tendency for the bonding agent to accumulate in the cavity corner in the box-shaped cavity with Z 100®.
3. Regardless of the cavity designs, the content of the remaining monomer after the cured composite resins was at a higher level in the walls of the cavity than on the center of the cavity. The level of the monomer on the wall of cavity was higher in the box-shaped cavity than in the bowl-shaped cavity with a flat floor. From these results, the bowl-shaped cavity with a flat floor appears to be an ideal cavity design for applying adhesive composite resin to primary molars.

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We conducted a cross-sectional study on the palatal morphology in Chinese female twins. The materials consisted of dental study models taken from 59 twin pairs from 6 year-olds to 11 year-olds, and were classified into three groups(III A-1, IIIA-2 and III B) according to their dental ages. We examined the three-dimensional growth pattern of the palate with the non-contact three-dimensional measurement device, and estimated the degree of genetic factors on the pattern using the twin method.
The results were as follows:
1. There were no significant differences among the three groups at all the measurement regions both for the palatal widths and lengths.
2. For the palatal depths, there were significant differences both at the deciduous canine region(between III A-2 and III B) and the deciduous molars regions (between III A-1 and III B).
3. For the palatal volumes, there was a significant difference only at the post-first molar region (between IIIA-1 and III A-2, between III A-1 and III B).
4. The estimation of the heritability showed that both the widths and the volumes had many genetically stable regions, while both the lengths and the depths had a few genetically stable regions.
5. For the palatal widths, the regions that were genetically stable moved distally as the dental age advanced
6. The palatal volumes were genetically stable as a whole in all the three groups. There was, however, a tendency except in the III B group that the more distally the region after the deciduous canine moved, the higher was the heritability.
7. It is suggested that as a whole the palatal morphogenesis at the mixed dentition period is genetically stable, but that the degree of the stability at the posterior regions is higher than the anterior regions and both the lengths and the depths were relatively variable under the stable widths.

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The Air-abrasion system is thought to be a useful method especially for the pediatric dental field. This system has however, very high cutting efficacy, so that it may cause accidental or inapparent pulp exposure and need direct pulp capping before crown restoration.
The present study was undertaken in order to observe the influence of direct pulp capping with the adhesive resin on the exposed pulp caused by the air-abrasion. Class V cavities were prepared in 159intact permanent teeth of 10 young mongrel dogs, and the pulps were intentionally exposed by airabrasion. The experimental teeth were divided into the experimental groups and control groups. After chemical surgery, in the experimental groups, cavities were capped and sealed with adhesive resin system “Liner Bond II ®”(K uraray) and resin composite “Clearfil AP-X®”( Kuraray), while in the control groups, cavities were capped with calcium hydroxide medicament “Calvital®”(Neo medicine manufacture). At 7,14,30,60 and 90 days after operation, histo-pathological observations of the pulp were undertaken using light microscope and transfer electron microscope (TEM).
1) As a result of light microscope observation, no remarkable inflammatory changes were seen in both for the experimental groups and control groups. Compared with the control groups, a slight delay of the dentin bridge formation was observed in cases of the groups after the 7 day and 14 day of the experimental groups. However, for dentin bridge formation, a clear difference between the experimental groups and the control groups was not observed after the 60 day and 90 day groups.
2) As a result of transfer electron microscope observation and X-ray microanalysis, no remarkable inflammatory cells into the pulp were observed around the Al₂O₃, particles in the 30 day experimental groups. In the 60 day experimental groups, growth of the endoplasmic reticulum of fibroblast was observed and pulpal cells were activated.
These findings suggested a slight influence of Al₂O₃, particles on the pulp remained but “Liner Bond II ®”(Kuraray; adhesive resin system) is useful for direct pulp capping and sealing to pulp exposed by the air-abrasion.

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An approach was taken to treat a mesial proximal carious lesion in a freshly erupted first molar in contact with a second primary molar. Caries were observed in 107 first molars of patients examined in the Pediatric Dental Clinic of Hokkaido University Dental Hospital from December 1998 to Feburary 2000. The second primary molars were extracted when the succedaneous teeth were about to erupt, thus opening up a sufficiently large space in the mesial proximal surface of the first molar to enable exact observation and easy treatment. (In each case, a rubber dam was fitted to the first molar following extraction of the second primary molar. ) Cleaning of the mesial proximal surface with an ultrasonic instrument revealed a surprising degree of decalcification. Of the 107 teeth examined in children aged 8 to 15 years, normal enamel surface was detected in only 8.4% of the teeth. Discoloration enamel but not affected by the ultrasonic instrument showed 10.3%. Decalcified enamel or enamel caries amounted to 66.4% in which caries would have advanced to dentin caries. Decalcified dentin or dentin caries amounted to 15.0%. The results were very surprising. More than 80% of the mesial surface of the first molars was initially decalcified and originated from the contact point between the second primary molars and freshly erupted first molars. This means an increase in risk of caries progression.
This study demonstrated the importance of detecting caries at the earliest possible stage in order to minimize the amount of sound tooth structure that must be removed.

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This paper describes the delayed eruption of permanent first molars, which included 56 cases in the maxilla,19 cases in the mandible and 1 case in the maxillary and mandibular first molar. Based on radiographic examination, the cause of the disturbed eruption in most of cases of the maxilla could not be clarified. The radiographic findings of arrested eruption in most of the cases of the mandible showed an enlarged follicular space and radiopaque masses around the teeth. Ectopic eruption was present in 13 cases of the maxilla and in 5 cases of the mandible. When we found pathological entities and abnormal position of the teeth, we performed surgical removal of the impediment or exposure of the crown. After the surgery, if there was no tendency to erupt, we opted for a second exposure or traction, and it that point most of the cases had the eruption process successfully completed. When there were no pathological entities or ectopic position of the tooth, we examined the tooth development based on their panoramic radiographs. Most of the cases revealed delayed development of the first molar in conjunction with an adjacent second molar. After periodic observation, we found that they had erupted spontaneously at ages 8 to 11, and this fact made us believe that we should keep these cases under observation without any intervention on our part.

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The concentrations of strontium (Sr), aluminum (Al), and Manganese (Mn) in the enamel and dentine of 350 human deciduous teeth were determined in order to examine the relationship between these 3 trace elements and dental caries. Deciduous teeth were collected at dental offices in the city of Kitakyushu and classified into three groups consisting of the sound tooth group (caries-free teeth), the carious tooth group (without restoration), and the filled tooth group. The concentrations of Sr, Al, and Mn were measured using flameless atomic absorption spectrophotometry.
In both the enamel and dentine of the sound tooth group, no difference was observed in the concentrations of the 3 elements between males and females. Tooth type (incisor and canine) affected the Al and Mn concentrations in the sound enamel and dentine. The Sr and Mn concentrations of the sound tooth group were similar to those of the carious tooth and filled tooth groups, in both the enamel and dentine. The Al concentration in the sound tooth group was 1.6-fold and 1.4-fold higher than those in the carious tooth group and the filled tooth group in the enamel, and was 1.6-fold and 2.5-fold higher than those in the carious tooth group and the filled tooth group in the dentin, respectively. Even with the incisor alone, the Al concentrations were significantly higher in the sound tooth group than those in the carious tooth group and the filled teeth group, in both the enamel and dentine.
These findings suggested that Al acts as a cariostatic agent by itself, but Sr and Mn in the enamel and dentine have no relation to caries.

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This study is an investigation of the state of dental restorations in 1750 primary molars among 239children aged between one and five. The study also analyzes the data comparing three groups. Group 1 was composed of children whose first visit to a dentist in his/her life was at the age of one or two; Group 2 was composed of children who visited a dentist for the first time when they were three years old; Group 3 was composed of children who visited a dentist for the first time when they were four or five years old.
1. The percentages of usable restorations in the primary molars of the children were 92.8% after half a year,77.0% after a year,55.1% after two years,45.9% after two and a half years. The number decreased to less than 50% between two and two and a half years.
2. The lower the age of a child who went to see a dentist for the first time in his/her life, the shorter the life of the restorations.
3. The average time of dental treatment to place a restoration in a primary molar was 2.19. The average times of dental treatment to restore a tooth was 2.67 in Group 1,2.28 in Group 2, and 1.76 in Group 3. The younger a child who visits a dentist for the first time is, the more times he has dental restorations. (ANOVA p<0.01)
4. The average duration of the first restorations in primary molars was 2.78 years. The number of the year is 2.51 in Group 1,2.64 in Group 2, and 3.09 in Group 3. The younger a child who visits a dentist is, the shorter the duration of the restorations is. (ANOVA p<0.05)
Results of the restorations in primary molar is of very short durability, so we should pay more attention to prevention the secondary caries of the restorations as well as new dental caries by a recall system at the dental clinic.

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This study was conducted to investigate the relationship of the Cariostat test and salivary buffer test to caries status in 344 junior high school students. The effectiveness of combination both tests was also investigated.
The following results were obtained;
1. The caries prevalence and mean DF-tooth of the subjects were 91.0%,5.02, respectively.
2. The Cariostat test and salivary buffer test showed a highly significant correlation with the DF-tooth (p<0.001).
3. The Cariostat test score did not correlate to the salivary buffer test.
4. When the Cariostat score was divided into three groups (low risk / middle risk / high risk), the mean DF-tooth showed a significant difference among the three groups (ANOVA p<0.001).
5. When the salivary buffer score was divided into three groups (low risk / middle risk / high risk), the mean DF-tooth showed a significant difference among the three groups (ANOVA p<0.001).
6. When the Cariostat score and the Salivary buffer score were combined, the low-low risk group showed the lowest mean DF-tooth. On the other hand, the high-high risk group showed a highest mean DF-tooth.
From these results, it is suggested that the Cariostat test and the salivary buffer test is useful for clinical application. Futhermore, when the Cariostat test and the salivary buffer test were combined, a higher correlation was shown with the carious status of junior high school students.

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Although saliva has an important role enabling food to be chewed smoothly, there are few studies of the effect of the saliva flow rate on the chewing food. The aim of this study was to evaluate the saliva volume secreted and the change of the water contents of the food bolus when food is chewed.
The water content of the food bolus at time of 1/3,2/3,1 and 4/3 from the chewing start to swallowing was examined in 8 adults. The foods selected were biscuit(water content: 3%), sponge cake (26.9%), hot cake (40%), rice (60%), corn (70%), apple (85.8%).
The percent of the water content of the food bolus in the same subjectsshowed a constant value with a low standard deviation. The mean salivary volume secreted by one mouthful of food was highest with biscuit, and this was inversely related to the initial water content of the food. The increasing rate of the water content of the food bolus was highest at time of 1/3 from the chewing start to swallow, and after then this rate showed fixed changes.
These results suggests that the initial water content of food is an important factor regarding the salivary flow and having the food bolus swallowed in chewing.

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The purpose of this study was to investigate the long-term effects of recombinant human basic fibroblast growth factor (rhbFGF) in the infant human alveolar process of the maxilla-derived osteoblastic cells(HAB).
The results were as follows,
1. bFGF (2.5ng/ml) significantly increased the DNA content of the HAB.
2. bFGF significantly decreased the alkaline phosphatase activity (ALP) of the HAB.
3. While bFGF inhibited the expression of ALP mRNA, and stimulated the expression of osteocalcin mRNA in HAB, it did not markedly effect the expression of type I collagen mRNA in HAB.
4. bFGF markedly inhibited the mineralized nodule formation and calcium incorporation.
These findings indicate that long-term treatment with rhbFGF stimulates cell growth, but its effect on the differentiation varies depending on each differentiation parameter in the infant human alveolar process of the maxilla-derived osteoblastic cells (HAB).

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Although there are many reports searching for an ideal method for imaging and measurements of swallowing, there is little information about methods applicable to children. In addition, despite the key roles played during the oral phase of swallowing, little is known about the relationship between tongue movements and the structure of the hard palate. The purpose of this study was to design a standardized method of tongue surface imaging for children by applying a helmet-type transducer holder, and to clarify the influence on the hard palate structure to tongue surface movement.
Fifteen normal children (age 3 y 8 m to 6 y 5 m) with full deciduous dentition were studied using the ultrasound of a coronal scanning view of tongue surfaces while swallowing apple juice (2 cc) and yogurt (2 g). The results were as follows:
1. The tongue grooving depth when swallowing yogurt increased significantly compared to juice.
2. The grooving duration was significantly longer than groove disappearance duration.
3. Grooving speed when swallowing yogurt was significantly faster compared to juice. Groove disappearance speed was significantly faster than grooving speed in both foods.
4. There was a significant correlation between palate depth and grooving depth while swallowing yogurt. (r=0.51)
5. There was a significant correlation between palate volume and grooving duration while swallowing juice. (r=0.54)
Our new method using the helmet-type transducer holder made it easier to measure the grooving depth, width, time and speed of the tongue at a certain scanning plane. We conclude that tongue surface movements are mutually related to palate volume and palate depth. It is essential that we examine the palate structure and take it into consideration when examining children, especially those with cerebral palsy or cleft palate who have abnormal palates affecting swallowing skills.

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Neonatal mammals initiate suckling after birth and transiently change their feeding behavior from suckling to mastication along with the eruption of molars. The transition of food ingestive behavior during the developmental period is thought to be governed by the maturation of feeding center in the brain. In the present experiment, feeding-associated activation of neurons in the medulla oblongata was examined in both developing and adult rats, using the c-fos gene-encoded protein (Fos) as a marker. Neonates were isolated from mothers for 12 h during the dark phase of the 12: 12 light-dark cycle on postnatal days 3,7 and 14. After lights on, they were either breast-fed intensively or further isolated for another 3 h, and then sacrificed. Adult rats fasted for 24 hours by depriving them of solid food and water, and were either given food and water before sacrifice or sacrificed without food intake. In the breast-fed pups, Fos-immunoreactive (FI) neurons were predominantly localized in the nucleus of the solitary tract (NST) and in the dorsal medullary reticular formation (dRF). Satiated adult rats with food showed similar patterns of Fos expression in both NST and dRF, although the FI cells were less prominent than those found in the neonates. In contrast, many fewer Fl cells were observed in the NST and dRF in the pups and adults which had fasted. The distinct localization of Fos in both fed pups and adults indicates the functional significance of the NST and dRF in the feeding behavior.

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We reported on the oral findings and the dental treatment for a patient with osteogenesis imperfecta type IVB between the ages of 11 and 17.
1. At the age of 11, the patient exhibited Skeletal Class III tendency malocclusion. The upper teeth and lower teeth were in contact only at the central incisors and right first molars.
2. All of the permanent teeth were translucent and brown. The teeth that had surfaces in contact were accompanied with exfoliation of the enamel following dentin exposure and wear.
3. Increased constrictions at the coronal-radicular junction and thinner roots were observed in all of the permanent teeth.
4. A resin splint was fitted on the lower dentition for the purpose of improving mastication and preventing attrition.
5. The patient has been using the resin splint successfully. We consider that the application of the resin splint is an effective treatment for patients with osteogenesis imperfecta.

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At the age of ten years and two months a female was referred to the out-patient ward of the Pediatric Clinic, Tokyo Dental College Chiba Hospital with the chief complaint of delayed eruption of the right first mandibular molar.
An orthopantomogram and dental radiograph presented a mesially tilted mandibular first molar. This patient had an unerupted mandibular molar and surroundingd there was a radiolucent lesion. This lesion had a distinct border with a thin line of radiodensity at the periphery. This was the dentigerous cyst, which is another type of odontogenic cyst and occurs due to the cystic degeneration of the tooth follicle after the formation of the enamel. Dentigerous cysts always surround the crown of an unerupted tooth. In addition, we performed a punctured fluid test. The case was diagnosed as an impacted mandibular right first permanent molar caused by a dentigerous cyst.
The impacted molar was guided in its eruption by fenestration and traction procedures. After two years of traction the tooth was guided to the occlusal plane.

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Fused teeth are more frequent in the deciduous dentition than among permanent teeth. Generally fused deciduous teeth appear in the mandibular anterior region, and fusion of the maxillary deciduous central and lateral incisors is rare. In addition, bilateral dental fusion in the deciduous dentition is a rare dental anomaly.
Many cases with maxillary ab-type fused teeth may cause aesthetic problems and functional disorders in the anterior region of the maxilla.
We treated case of maxillary ab-type bilateral fused teeth over a long period of time.
Case 1 with maxillary ab-type fused teeth bilaterally involved congenitally missing of permanent successors in the same region.
Case 2 with maxillary ab-type fused teeth bilaterally involved the presence of permanent successors, but the growth of maxillary lateral incisors was very delayed.
Cases with deciduous fused teeth therefore need long-term clinical care. The long-term clinical care was especially of great importance in cases with maxillary ab-type fused teeth bilaterally.

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Ectodermal dysplasia is a hereditary disease characterized by the abnormal development of the ectodermal tissues associated with abnormal tooth eruption (congenital defects of the teeth, delayed tooth eruption, etc), decrease in the density of sweat glands, thin hair, etc. The syndrome is inherited by the sex-linked recessive mode, which accounts for the 90% incidence in males. We encountered a 4-year 5-month-old boy with complete anodontia associated with anhidrotic ectodermal dysplasia, and periodically monitored the changes in the biting strength and the apical base over a period of approximately 6 years. The following observations were made.
1. Cosmetic recovery of the face and improvement in masticatory function were achieved through complete change of the denture corresponding to the tooth arrangement according to age.
2. The temporomandibular position was stabilized following the change of denture, suggesting that the motion of the center of gravity was probably reduced.
3. The biting strength improved with age after the complete denture change.
4. New dentures must be prepared during the growth and development stage because the apical base increased in size with age even in the complete anodontia.

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