In recent years, concern with the elution of exogenous endocrine disrupters from dental high polymer material has resulted in a call for dental materials that are not based on bisphenol-A. The present investigation therefore focused on natural resins as a substitute for conventional sealants and the possibility of their use as a dental material was examined.
The material used in this study was a purified form of a resinous material that is secreted by Laccifer lacca (an insect found in subtropical regions) and is a natural resin that is commonly known as shellac. The purpose of this investigation was to examine the usefulness of shellac as a sealant. Adherence to enamel and durability were observed through thermal cycling tests. In addition, marginal sealing properties and the effect of etching were also examined. The results indicated the following
1. The shellac coating formed on the enamel surface displayed resistance to thermal loads exerted by the thermal cycling test.
2. A 40% shellac concentration improved marginal sealing of voids in small pits and fissures.
3. Etching had no effect on the marginal sealing property of shellac. Although further investigation is necessary, the results of this study suggest that shellac possesses great possibility as a new type of dental material if improvements in its physical properties are made.

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With the introduction of a new fee schedule under the revised social insurance system in 1992, the term, dental caries-prone persons, came into use, and it was made possible to charge a fee for continuous management in addition to the fees for examination and treatment. It can be said however that the new fee schedule now has come short of meeting the demands of reality. With this in mind, we carried out research into the possibility teeth applied with Ag(NH₃)₂F in caries-prone children being used as restored clinical crowns. For this purpose, we analyzed the results of regular dental checkups conducted at a rural community in Niigata Prefecture. Our findings were as follows:
1. The ratio of Ag(NH₃)₂F to untreated teeth was from 34.0% to 43.4% in children 3 to 7-year-olds.
2. The largest number of teeth applied with Ag(NH₃)₂F was made up of maxillary canines, which were followed by maxillary lateral incisors and maxillary central incisors. By age, maxillary central incisors and lateral incisors accounted for the highest in 6-year-olds, and maxillary canines in 7-yearolds.
3. In the deciduous dentition, the ratio of untreated teeth to treated teeth was high. The number of incipient caries rate for teeth applied with Ag(NH₃)₂F was lower than that for untreated teeth in the anterior area.
Based on the above, we found that teeth applied with Ag(NH₃)₂F could be regarded as being no dif ferent than treated teeth, because the application of teeth applied with Ag(NH₃)₂F was more effective than crown restoration in arresting the progress of dental caries. It would therefore, be more realistic to think that in the deciduous dentition of children of 7 years or younger, maxillary as well as mandibular central incisors and canines teeth applied with Ag(NH₃)₂F should be included in the category of those teeth given crown restorations. It would also meet the needs of the times to exclude the criteria used in deciding the incidence of caries by the number of permanent teeth provided crown restora tions in children 5-7 years old.

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We report on a new and simpler method of estimating the dental anxiety of the infant. The materials of this study consisted of the ten dolls and a miniature dental office. All of the dolls and a miniature dental office for the study used in this examination were handmade. We gave the dolls to the infant, and let the infant put them in a miniature dental office as they saw fit. Sixty preschool children (ranging from three to six years old), twenty-nine boys and thirty-one girls with previous dental experience were studied. The following was obtained by this study:
1. We were able to classify them into four types based on how the dolls were arranged with respect to then chairs which installed in the miniature dental office. The types were as follow;
Type 1: The representative doll of the patient itself is put by the side of the family, and no one is put on the dental chair.
Type 2: The representative dolls expect that representing the patient are put on the dental chair.
Type 3: The representative dolls of the patient are collected and put on the line or do one place.
Type 4: The representative doll of the patient itself is put on the dental chair.
2. The increased tendency of the Type 4 was recognized, it was mane significance between Type 3and Type 4 with the increase in age.
3. A age-based fluctuation in Type 2 and Type 3 were not recognized, It seemed to be the problem in a attachment between the family and the child.

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The aim of this study was to investigate the relationship between signs and symptoms of temporomandibular disorders (TMD) and osteoarthrosis in pubertal patients. A total of 92 patients (20 male and 72 female) with a mean age of 13.0 years (range,7-15 years) were selected from all of the patients appearing for examination and treatment of TMD at the Department of Pediatric Dentistry at Nihon University School of Dentistry at Matsudo during 5-year and 6-month period. MRI was carried out at bilateral TMJs using 0.5 T or 1.0 T MR scanner with surface or TMJ coil. Five parasagittal slices and 5 coronal slices were obtained of each TMJ with thin slice within 4.0 mm. MRI diagnosis of TMJ osteoarthrosis was defined by the presence of surface irregularities and osteophyte. An MRI diagnosis of TMJ osteoarthrosis was established in 12 of 92 patients (13 of 184 TMJs), consisting of 1 male and 11 females. One of them had the signs and symptoms of osteoarthrosis bilaterally and the others had them unilaterally on clinical and MRI diagnosis of TMJ. Regarding the distribution of TMJ osteoarthrosis established in 13 of 184 TMJs,7 and 6 were associated with an MRI diagnosis of signs of surface irregularities and osteophyte, respectively. An MRI diagnosis of TMJ internal derangement was established in all TMJs involving osteoarthrosis, whereas 2 patients (17%) were found to have a TMJ internal derangement type of disk displacement with reduction, and 10 (83%) had disk displacement without reduction. With respect to the distribution of TMJ osteoarthrosis established in 12 of 95 patients,1 (8%),8 (67%) and 3 (25%) patients were associated with an MRI diagnosis of mild, moderate and severe anterior disc displacement, respectively. MRI findings of shape of disc in TMJ involving osteoarthrosis for biconcave and biconvex were 2 (17%) and 10 (83%), respectively. An MRI diagnosis of TMJ joint effusion was established in 3 of 12 patients (25%). In conclusion, our study implied that there were significantly relationships between TMJ internal derangement and osteoarthrosis in pubertal patients (p<0.01).

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To develop a genetical diagnosis for skeletal malocclusion, we explored gene(s) regulating the anteroposterior length of the maxilla by the method of Quantitative Trait Locus (QTL) analysis using SMXA Recombinant Inbred (RI) strain mice. Anteroposterior lengths between the anterior border of the incisor pore and posterior border of the basisphenoid in the maxilla of 21 SMXA RI Strains mice at 90 days of age were measured. The maxilla of the SMXA-8 strain was the largest (11.5 mm) and that of SMXA-24 was the smallest (10.4 mm) in 21 strains. As the maxilla sizes of SMXA RI strain mice formed a continuous distribution between 11.5 mm and 10.4 mm, the data was regarded as the value of the quantitative trait. The strain distribution pattern reported in the previous study and the value of the quantitative trait were used in the QTL analysis for the whole genome using the Map-Manager QTb 28 software. Based on the result of QTL analysis, we obtained significant values on chromosome 10 and 11. Around the marker D 10 Mit 70 mapped at 57.9 cM from the centromere on chromosome 10, the LOD score showed 2.9 with a suggestive level and around the marker D 11 Mit 152 and D 11 Mit 163 mapped at 9.8 and 13.1 cM, respectively on chromosome 11, the LOD scores showed 5.8 with a significant level.
These results suggest that the major gene(s) regulating the anteroposterior length of the mouse maxilla are located on chromosomes 10 and 11.

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This study was carried out to determine the effects of recently available all-in-one-step dentinal ad hesives (Reactmer Bond, One-up Bond F, Xeno CF Bond and Prompt L-Pop) on cell viability using rat pulp cells and the amounts of fluoride released from the dentinal adhesives.
The following results were obtained.
1. The viability of cells exposed to the dentinal adhesives was greatest in the case of Reactmer Bond followed by One-up Bond F, Xeno CF Bond and Prompt L-Pop.
2. The pH value of Prompt L-Pop immersed in distilled water for 24 hours was most acidic. The pH values of all immersed in distilled water were acidic. However, the pH values of the specimens immersed in culture medium shifted to more neutral values due to the effect of the buffer. The low pH values of the dentinal adhesives and their consequent cytotoxic effects were thought to be due to re lease of acidic monomers. The pH values of Reactmer Bond and One-up Bond F immersed in distilled water were slightly acidic but became neutral in the culture medium. Cells in the culture medium to which Reactmer Bond or One-up Bond F had been added grew well.
3. The amounts of fluoride released from adhesive specimens immersed in distilled water were differ ent from those released from specimens immersed in culture medium. The specimens showed different patterns of fluoride release. The amount of fluoride released from Xeno CF Bond was initially large, then later declined gradually. Reactmer Bond released a relatively constant amount of fluoride, ranging from 17 ppm to 5 ppm, and this level was maintained throughout the study period from 24hours to 25 days. Prompt L-Pop and One-up Bond F released very small amounts of fluoride.
There were variations in both the cytotoxicities of and the amounts of fluoride released from the all-in-one-step adhesives.

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With the aim of determining the influences of anti-tumor drugs used in the treatment of pediatric cancer on the teeth and periodontal tissues, vincristine sulfate (VCR) and cyclophosphamide (CPA)were injected intraperitoneally twice into rats, i. e., on the 11 th and 14 th days after birth. The following results were obtained on histopathological examination.
1. While the body weight increased in a similar manner in the VCR group and the control group, the body weight increase was less pronounced in the CPA group as compared to that in the control group.
2. There were no significant changes in the morphology of the dental corona of erupted teeth in either the VCR or the CPA group, and the morphology of this structure in the two groups was similar to that in the control group during the period of study.
3. There were no significant differences in dental root formation during the period of study between the VCR group and the control group. In the CPA group, impaired formation was first noted in the periapex area on the 19th day after birth. On the 54th day after birth, the dental root was found to be shorter in this group than in the control group, and formation of hard tissues resembling osteodentin was noted.
4. No significant differences in the periodontal tissues were noted between the VCR and the control groups. In the CPA group, inhibition of modeling of the alveolar bone was noted on the 19th day after birth, and on the 54th day after birth, disorders of expansion of the periodontal space and formation of alveolar bone were observed.
These findings indicate that while VCR has little effect on dental root formation and periodontal tissues at therapeutic concentrations, CPA inhibits the formation of the dental root and periodontal tissues in the early stages after administration, and furthermore, induces functional changes in the subsequent period.

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The LPX-250, a non-contact measurement device employing amplified light, was used to measure a plaster dentition cast in order to determine of this device efficiency and precision.
1. The scanning mode When the study cast was scanned, the plane-scanning mode (four planes) was suitable. When only the occlusal plane was scanned, the plane-scanning mode (one plane) was more suitable than the rotation-scanning mode in regard to the condition and velocity of the scanning.
2. The accuracy of size The scanning pitch of this device was 0.2 mm in both width and height for the plane-scanning mode; however, the size accuracy was installed in it or less excluding one point. This suggested that the measurement results from the interpolation were not very different from the actual size.
3. The accuracy of reproduction Neither the axes nor the projecting errors were admitted, and these errors were 0.2 mm, which was the same as the scanning pitch, or less. This suggested that the solid model was scanned with almost no distortion.

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The purpose of the present investigation was to discover the relationship among growth, dental fear and experience of dental injection in child patients. The subjects were comprised of 58 uncooperative and 121 cooperative child patients aged 5 to 12 years. They underwent regular dental examination at The Pediatric Dental Clinic of Niigata University Dental Hospital. For all of the subjects, the Dental Sub-scale of Children's Fear Survey Schedule (CFSS-DS) was conducted by mail. Inquires were then made into their experience of dental injection base on dental charts. The results were as follows.
1. The subjects were divided into 4 groups according to their age(the low-age group: from 5 to 8years or the high-age group from 9 to 12 years old) and their behavior (the uncooperative group: Frankl's scores 1,2 or the cooperative group: Frankl's scores 3,4) during dental treatment. In the low-age uncooperative and cooperative groups, the mean scores of the CFSS-DS were 31.3 and 24.8points, respectively. In the high-age uncooperative and cooperative groups, they were 32.5 and 22.8points, respectively.
2. In the cooperative groups, the mean CFSS-DS score of each item in the low-age group was less than that in the high-age group. In contrast to this, in the uncooperative groups, there was little difference between the scores of the low-age and high-age groups.
3. Distribution of the CFSS-DS scores showed a difference between the uncooperative and cooperative groups. In the uncooperative and cooperative groups, the largest number of patients were included in the CFSS-DS scores with 25 to 34 points and 15 to 24 points, respectively. There were, however, some patients who scored more than 35 in the cooperative group or less than 24 points in the uncooperative group.
4. In the high-age uncooperative group, the mean CFSS-DS score of the patients, who had not experienced of dental injection during the past year, was 39.4 points. It was statistically higher than that of the patients with such experience. In the other three groups, there were no differences between the patients with or without experiences.
The results of the present investigation show that experience of dental injection and psychological growth of child patients affect their dental fear and cooperative behavior. Therefore, to allay dental fear of patients in childhood, dentists should be aware of their patients' dental history and behavior during dental treatment in the past and take their behavior management problems into consideration.

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Vibrissae are geometrically-arranged tactile hairs, and are represented in each station of the somatosensory pathway. Vibrissa-related central representation in the brainstem trigeminal nucleus is referred to as barrelettes. It has been explained that glutamate transporter GLT1 is transiently localized on growing axons before establishing astrocytic expression. In the present study, we examined the expression switch of GLT1 in correlation with barrelette formation and development. At fetal stages, GLT1 was localized on growing axons tranversing the trigeminal nucleus. At birth, GLT1 was localized both on axons and astrocytes. On postnatal day 7, expression of GLT1 was only detected in the reticular processes of the astrocytes that enwrapped the somatosensory synapses. Simultaneously with the expression switch, barrelettes as revealed by cytochrome oxidase histochemistry emerged in the trigeminal nucleus. It is therefore concluded that the expression switch of GLT1 from growing axons to astrocytes occurred in correlation with barrelette formation.

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There are many occasions in which children are injured in the face and jaw while engaged in sports. About 10% of the injuries to the face and jaw occur while engaged in sports. Injury to the maxillar anterior teeth and mandibular fracture are among the most numerous unjuries. We noticed injury to the mandibular teeth and the mandibular bone during sport activities. We analyzed the status of the injury when the mouth guard is attached to the teeth using the finite element method.
The results were as follows;
1. It was considered that the effect of the external force on the mandibular teeth decreased when the mouth guard was attached.
2. As the thickness of the mouth guard material increased, the effect of the external force on the mandibular teeth decreased, but the effect on the mandibular process increased.
3. Concerning in the load of the mouth guard mesal position, the effect of the external force on the mandibular process decreased.
4. Concerning in the load of the mouth guard lateral position, the effect of the external force on the mandibular process increased.
We concluded that injury to the mandibular teeth was prevented when the mouth guard was attached but that consideration should be given to the effect on the mandible.

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The number of Mutans Streptococci was assessed using the Dentocult-SM®s trip mutans among 114 caries-free children. The age range was from 3-5 years old. A questionnaire was used to evaluate the daily habits of the children. Hayashi's Quantifying Theory was used to analyze the relationship between the number of Mutans Streptococcus and daily habits. Results:
1. Dentocult-SM strip Mutans test
(1)69.3% (79/114 children) had a Class 0 result
(2)21.9% (25/114 children) had a Class 1 result
(3)8.8% (10/114 children) had a Class 2 result
(4)Nobody had a Class 3 result
2. Factors showing a highly significant correlation with regard to the number of Mutans Streptococci are as follows
(1)Children with irregular eating habits (chi-square test p<0.01)
(2)Children who eat 3 times or more a day (chi-square test p<0.01)
(3)Excessive intake of sweet drinks (chi-square test p<0.05)
(4)Children with many guardians have more caries (chi-square test p<0.05)
(5)Not brushing teeth after snak (chi-square test p<0.05)
Based on these factors, we can see that a high possibility for the number of Mutans Streptococci.

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The craniofacial growth of 12 untreated children with skeletal Class II malocclusions was evaluated from two sets of serial lateral cephalometric radiographs. The mean age of the first films (D 1) was 7years 10 months, and the second (D 2) was 11 years. The mean values of 13 linear and 10 angular cephalometric parameters were compared to a series of Class I control data. The characteristics of the skeletal Class II growth pattern included:
1. An anteriorly displaced maxilla at D 1.
2. A retrognathic and retrusive mandible at D 2.
3. Relatively small amount of maxillary and mandibular growth between D 1 and D 2.
These results suggested that the main factors of the skeletal Class II growth pattern were different between the growth phases. We concluded that the skeletal Class II growth pattern was started by an anteriorly displaced maxilla, and the following retrognathic mandible could be produced by this jaw relationship.

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The purpose of this study was to assess the gingival health and oral hygiene status in junior high school students and to compare the effectiveness of periodontal education. A two-year longitudinal survey was conducted for 116 school students from 1998 to 2000 in Hiroshima, Japan. The Oral Rating Index (ORI) was used for assessing periodontal status and his/her result was given to each student. A brochure has been provided since 1995, following completion of the first survey. The mean ORI score of females was significantly higher than that of males at each grade level, except the third grade in 2000. The mean ORI score of males from 1998 to 2000 significantly increased (p<0.05). There were no significant differences in the mean ORI score of females from 1998 to 1999 significantly increased (p<0.01).
In conclusion, the results of the present study indicate that an informational brochure on periodontal diseases could be helpful to improve the periodontal condition of junior high school students.

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We conducted dental examinations on kindergarten children in Tianjin, China. Using upper and lower dental casts obtained from the children, we anatomically observed the morphology of the deciduous molar crowns. The results were compared to those in previous studies.
1. Among the deciduous molar teeth observed, there were no differences between Japanese and Chinese children in the crown occlusal surface patterns.
2. There were no differences in the incidence of the cingulum in maxillary and mandibular deciduous first molars, the moon-shaped ridge on the upper second molar buccal surface, the Carabelli's tubercle in maxillary deciduous first molars, and the 6 th cusps in mandibular deciduous second molars between Japanese and Chinese children.
3. There were no differences in the incidence of the mesial tubercle in maxillary deciduous molars between the Chinese children in Tianjin and Shanghai or Shijiazhuang.
4. There was a correlation between the incidence of the Carabelli's tubercle in the maxillary deciduous first molars and that in the maxillary deciduous second molars in the same dental arch.
5. There was a correlation between the incidence of the Carabelli's tubercle and that of the protoconule in the same maxillary deciduous second molar.
6. The incidences of the 7 th cusp and protostylid in the mandibular deciduous second molars were high in the Japanese and Chinese children.

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The purpose of our study was to elucidate the influence of the lateral mandibular deviation (LMD)on the mastication in children with deciduous dentition by evaluating the difference of the jaw muscle activities between the side of deviated mandibles and that of the other side.
The subjects were 9 children with deciduous dentition. The side of The LMD was measured on posteroanterior plain skull radiographs.
All through this study, the subjects were instructed to perform three jaw motor tasks, tooth clenching, tooth tapping and gum-chewing on both impaired and intact side. Temporal (TA) and Masseter (M) muscles electromyograms were recorded on the bilateral sides to observe the jaw muscle activities.
The balance of the mastication muscle activity during clenching tasks was assessed using the Asymmetry Index (A. I. ). The activity of the TA proved more dominant on the deviated side, while that of the M tended to be more remarkable on the contalateral side.
In the gum-chewing on the contralateral side, both the activities of M and TA showed more significant increase than during the tooth tapping task (p<0.05). In this case, however, no significant difference was observed between the chewing task and tooth tapping task on the deviated side of TA (p>0.05).
Conclusion: in spite of marked muscle activity during the clenching task, dysfunction of TA on the deviated side during gum-chewing was suggested to occur, probably due to influence of mandibular deviation which leads to an impaired feedback system of oral sensation.

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Er: YAG laser pulpotomy was used to treat 14 primary molars in 8 patients. Following the procedure, none of the teeth showed abunormal clinical or radiographic findings, except for one whict demonstrated internal root resorption one year after the procedure, the cell components of pulp tissuc had disappeared which was revealed in histo-pathological examination examination. Further, there waino hard tissue formation or root obliteration observed in any of the patients. These results suggest tha an Er: YAG laser pulpotomy procedure leads to the good clinical results, though the pulp may som etimes be necrosed. Additional advantages include a quick cessation of bleeding, shortened treatment time, and absence of post-operative pain. Therefore this type of laser pulpotomy may be acceptable for clinical uses after further consideration of the output power required in order to prevent the pulp necrosis.

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We encountered a girl patient with von Recklinghausen disease who consulted our department with a chief complaint of dental caries. Dental findings and the summary of treatment results were as follows:
1. Extensive cafe-au-lait spots in the cervical region were observed, and the postero-cervical region was bulged.
2. A tumor was noted in the vertebral canals of the cervical vertebrae, and deformation of the second, third, and fourth cervical vertebrae showing a _??_-shaped posterior curvature due to the subluxation of the atlas was noted.
3. The paients was in Hellman's occlusal developmental stage was II A in the patient, and marked destruction of the molars due to caries, and deep overbite in the anterior tooth region were found.
4. Ossification stage of the carpal bones closely corresponded with the age of the patient, in which the number of bone nuclei was 4.
5. Lateral roentgenographic cephalometric analysis showed no abnormal findings.
6. Since patient cooperation during dental treatment was poor, and it was impossible to stabilize the head position, intensive dental treatment was performed under general anesthesia.

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