Using the deciduous dentition models of 3-year olds,4-year olds and 5-year olds, we measured the three dimensions of the palate section areas, projection areas and volumes using the semiconductor laser. We reviewed also the changes in the ages of the boys and girls in comparison.
The results were as follows;
1. The palate section areas of the width of the deciduous canines and primary first molars decreased due to gingival swelling caused by the erupting permanent incisors as age increased.
2. The palate section areas of the width of deciduous second molar and second molar distal edge increased due to the enlargement of the alveolar bone of the deciduous second molar due to the erupting permanent first molar as age increased.
3. The palate projection areas of the front and back part of the deciduous dentition increased due to the lateral expansion of the palate due to the growth of maxillary bone as age increased.
4. The palate volumes of the front and back part of the deciduous dentition increased due to the lateral and vertical expansion of the palate as age increased.
5. As for the palate section areas, projection areas and volumes, those of boys were larger than those of girls in the deciduous dentition, but there was no significant.

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Children with normal occlusion and interdental spaces in deciduous dentition were divided into two groups, of those with crowding at the stage of permanent dentition (crowding group) and those without (normal group). Differences in changes in the dental arch that accompanied growth and development were compared using study 16 models.
The results of this study were as follows:
1. Among children with normal occlusion and interdental spaces in the deciduous dentition,43.8%developed crowding at the stage of permanent dentition.
2. The crowding group showed a tendency to have fewer sites of embrasure in the deciduous dentition than the normal group.
3. The mesiodistal width of dental crowns in both deciduous teeth and permanent teeth tended to be larger in the crowding group than in the normal group.
4. The intercanine width in both the maxilla and mandible at each age and its increment from age 4to age 12 tended to be smaller in the crowding group than in the normal group.
5. No significant difference between groups was seen in dental arch length in either mean value or variation. The increment of dental arch length was smaller than that of the intercanine width in both groups.
6. Dentition that was crowded during mixed dentition mostly remained crowded in permanent dentition.
The above suggests that regarding the occurrence of crowding, attention should focus on the mesiodistal width of dental crowns, the size and increment of dental arch width, and whether there is crowding in mixed dentition, in addition to the amount of interdental spaces in deciduous dentition.

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The purpose of this study was to survey the situation and the characteristics of enamel hypoplasia found in child patients with cleft lip and palate (CLP). The authors investigated 239 children aged 3-8 with cleft lip and palate who visited Tohoku University Dental Hospital from February,2002 to January,2003.
1. 54.8% of the children with CLP had enamel hypoplasia in their deciduous and/or permanent teeth. For the deciduous dentition,55.2% of CLP children had enamel hypoplasia. As confirmed based on the type of cleft, enamel hypoplasia appeared with the following. frequency; cleft lip; 33.3%, cleft lip and jaw; 56.8%, cleft lip and palate; 77.6%, cleft palate; 23.3%. For mixed dentition,27.6% of the CLP children had enamel hypoplasia in their permanent teeth.
2. For the deciduous dentition,137 (5.2%) teeth showed enamel hypoplasia among 2,643 observed teeth- cleft lip; 2.2%, cleft lip and jaw; 5.5%, cleft lip and palate; 7.0% and cleft palate; 1.9%. For the mixed dentition 52 (7.7%) permanent teeth expressed enamel hypoplasia among 672 permanent teeth observed.
3. Among children with cleft lip, cleft lip and jaw, and cleft lip and palate, the rate of prevalence of enamel hypoplasia was higher for the anterior teeth. Among children with cleft palate, the rate of prevalence of enamel hypoplasia was high for the second deciduous molar.
4. the rate of prevalence of enamel hypoplasia at the cleft site was higher than that in the healthy site.
5. As enamel hypoplasia type of the permanent teeth, numerous white spots were observed, but in the deciduous teeth, pigmentation or enamel defects were more frequently observed than white spots.
6. There was no correlation between the appearance of enamel hypoplasia and birth weight or timing of operation for cleft lip and palate.

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We reviewed the changes in the training in basic practice in pediatric dentistry of fifth year students. Instead of basic practice which was focused mainly on cast training, we began to put more emphasis on clinical experience through a series of training consisting of 7 sections from 2003. The students became keener to learn and the new training program proved to be more effective than before. As the new teachings method sets a specific purpose, the students know exactly what should be achieve at the end of each training session and medical interviews are being conducted smoothly. In addition, we carried out a questionnaire with the students to evaluate the attained targets and the results are as follows,
1. More th an 90% of the students understood the objectives of the training very well.
2. More than 90% of the students were able to achieve the set objectives. How ever, trainer evaluation of the objectives attained differs from that of the students and we believe trainers should provide constant feedback.
3. 10% of t he students were not able to consider the state of mind of the patient during the training. In the future, more training to consider the state of mind of the patient should be included in this training program.

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The aim of this study was to estimate the relationship of the presence of the bilaminar zone and temporomandibular joint (TMJ) structures on the MR images in juveniles using multivariate analysis. Four hundred eighteen TMJ MR imaging films taken from 209 juvenile subjects (71 male and 138 female, with ages ranging from 6 to 16) were used in this study. We appraised the presence of bilaminar zone, joint effusion, disk displacement, disk configuration, disk reduction of the maximum opening position, lateral disk displacement, condylar bony deformation and articular eminence configuration on the MR imaging.
The results in dicated that the upper stratum of the bilaminar zone could be identified in all of the 418 TMJs (100%), while the lower stratum of the bilaminar zone was identified in 107 TMJs (25.6%). Among 82 (75.9%) subjects, the lower stratum of the bilaminar zone was identified bilaterally, while it was unilaterally identified in 25 (23.4%) subjects. Based on score by category, it was found that the lower stratum of the bilaminar zone tended not to be identified in joint eminence configuration, moderate and severe anterior disc displacement, interior anterior disc displacement, disk displacement without reduction and condylar bony deformation on the MR image. In addition, the determining variable of scores according to showed that disk configuration, joint eminence configuration, joint with anterior disk displacement, disk displacement with or without reduction were some of the etiological factors for the lower stratum of the bilaminar zone.
In conclusion, our study implied that the presence of the lower stratum of the bilaminar zone on the MR imaging was one of the indication of the etiological factors of the TMJ internal derangement in juvenile subjects.

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To elucidate the association children in between the interdental space and the occlusal status of the primary dentition, we divided 39 Hellman dental age stage II A (17 boys,22 girls, mean age: 4 years 7 months) with individual normal occlusion into an early primary dentition period group who were under 4 years 6 months of age and a late primary dentition period group who were 4 years 6 months of age and over, and then divided each of them into an interdental space group, which had an total upper interdental space of 3.0 mm or more and a total lower interdental space of 2.0 mm or more, and a closed group, which had a total upper interdental space less than 3.0 mm and a total lower interdental space less than 2.0 mm. We then analyzed the relationships between interdental space size and morphology of dentition, occlusal wear of the primary canines, occlusal force, and occlusal contact surface area, and obtained the following results:
1. In the closed group, the upper interdental spaces in the early primary dentition period were larger than in the late primary dentition period, and in the interdental space group, were the reverse opposite.
2. The crown mesiodistal width in both the upper and lower primary incisor area was greater in the closed group than in the interdental space group, but no difference between the groups was found in the primary molar area.
3. The overbite and overjet were larger in the closed group than in the interdental space group.
4. The occlusal wear of the primary canine teeth was less in the closed group than in the interdental space group.
5. The total occlusal force and total occlusal contact area were smaller in the closed group than in the interdental space group.
6. The occlusal force and occlusal contact area at primary canines and primary molar were higher in the interdental space group than in the closed group, but at the primary incisor were higher in the closed group, especialy in the early primary dentition period.
7. In the interdental space group, the distribution of occlusal force and the distribution of occlusal contact area in the primary anterior tooth area were higher in the late primary dentition period than in the early primary dentition period, but in the primary molar area they were higher in the early primary dentition period than in the late primary dentition period.
8. In the closed group, the distribution of occlusal force and distribution of occlusal contact surface in the primary anterior tooth area were higher in the early primary dentition period than in the late primary dentition period, but in the primary molar area they were higher in the late primary dentition period than in the early primary dentition period.

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To evaluate the usefulness of new hydroxyapatite(HAP), HAP+CaCO₃andHAP+β-TCP as a pulp capping agent, comparisons with a calcium hydroxide agent (calvital®) and formocresol, which are generally used for pulpotomy, were performed. After pulpotomy in rat molars using each material, the degree of the formation of dentin-like hard tissue and inflammatory changes in the pulp tissue were examined micro CT radiographically and histopathology. It was found that the hard tissue formation beneath the sectioned pulp surface was most marked in the calvital group, and the hard tissue for the formation was marked only HAP + CaCO₃ in the HAP group. However, the HAP group developed no necrotic layers, and inflammation improved at an earlier stage. Our experiments suggested that HAP can be a good pulp capping agent, since pulp irritation was lower with HAP than with calvital® and formocresol. Moremore, HAP +CaCO₃ which developed as hard tissue formation beneath the sectioned pulp surface was marked somewhat.

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The use of the MUH Shield, which is a functional orthodontic appliance used to improve muscular balance, is the one first selected to treat cases of anterior cross bite during the primary dentition period. However, since improvement in the overlap is not obtained in some cases, it is necessary to evaluate the criteria for judging indications for functional orthodontic appliances. In this study, using lateral X-ray cephalograms before treatment in 10 pediatric patients in whom anterior cross bite in the primary dentition improved using the MUH Shield alone (single use group), and in 10 pediatric patients in whom it improved by the combined use of the MUH Shield and other appliances (combined use group), maxillo-facial morphological measurement items including the position of the hyoid bone were compared between the 2 groups.
As a result, the combined use group showed significant differences in ANB, AO-BO, overjet, and Kix-index, which are maxillo-facial measurement items, in comparison with the single use group.
It is suggested that these items could be used as the criteria for judging indications for functional orthodontic appliances, before starting treatment for cases of anterior cross bite in the primary dentition period.

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This study showed the photocatalytic effect of the semiconductor, Titanium Dioxide (TiO₂) with solar battery, in inhibiting the adhesive properties of S. mutans.
The inhibition of adhesion was compared among these three groups, TiO₂ without electrode, TiO₂and TiO₂ with solar battery. S. mutans that adhered to hydoroxyapatite pellets were then picked out using Erythrocin and each area of adhesion was investigated. The following results were obtained.
1. A 100% adhesion rate was observed in the TiO₂ group without electrode, while the TiO₂ group and TiO₂ group with solar battery had a 65.6% and 26.6% adhesion rate, respectively. It was observed that the photocatalytic reaction of TiO₂ was effective in inhibiting the adhesive properties of S. mutans
2. The TiO₂ group with solar battery showed a stronger effect compared to the TiO₂ group. It was demonstrated that the photocatalytic effect of TiO₂ was enhanced by use of the solar battery.

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The aim of this study was to identify the change in the manipulation of chopsticks to pick up food products which involved the feeding function using chopsticks in childhood. The subjects were 37young children ranging from 3 to 5 years of age; they were categorized into the 3 year-old group,4year-old group and 5 year-old group. The subjects were tasked to pick up the globate imitation food with chopsticks. The results showed that the 5 year-old group showed significantly higher percentage when they controlled the further chopstick than the closer chopstick. Furthermore, regarding to the direction in which subjects moved the chopsticks, no one moved the closer chopstick distally, and little tendency was indicated about the further chopstick in the 5 year-old group. The measurement of the number of executions to pick up the imitation food showed that the number of attempts decreased significantly the older the subjects were. Consequently, it was suggested that manipulation of the closer chopstick becomes stable earlier than the further chopstick; the function to pick up a food product matures as the child increases in age in childhood.

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In clinical pedodontics, it is necessary to implement early treatment as the impacted teeth impede the growth of the dentition and the bite relationship. An appropriate diagnosis is however necessary. It is difficult to pronounce exact diagnosis of an inverse impacted maxillary central incisors based on X-ray examination.
We report on the three-dimensional images of the an inverse impacted maxillary central incisor using 3 DX Multi-Image Micro CT (3 DX^TM, Morita Co., Japan) images for diagnosis, and we were able to begin marsupialization and traction at once.
The patient was a 7-year-old girl. The chief complaint of patient and her guardian was delayed eruption of the maxillary central incisors, with the need for aesthetic improvement. General factors and local factors which could cause an inverse impacted maxillary central incisor were not evident based on previous medical history.
First of all, the mesial side of the maxillary left central incisors and the midline were made to match by using a lingual arch. Three months after the beginning of treatment, we began marsupialization and traction at the same time. Also, it was possible to touch the edge of the impacted right central incisors, and in five months, the eruption of crown 2/3 was noted. Nine months after the beginning of traction, we were able to complete to induction of the impacted right central incisor for the inside of the dentition, and shortly after that the frontal teeth were disposed. Treatment was completed in 18 months. In the meantime, diagnosis was carried out using the 3 DX^TM. The patient is now using a Hawley retainer.
For the future, the necessity of regular long term monitoring using 3 DX^TM images is suggested to observe absorption of dental root and changes in the periodontium

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Treatment of condylar process fractures in children is especially important due to the risk of a mandibular growth center in the cartilage of the condylar head. Functional treatment using a removable orthodontic appliance (activator) is usually given for conservative treatment at pediatric dental clinic in our hospital. The concept of using the activator is to promote normal mandibular growth in the disrupted anatomy of the soft and hard tissue of mandible. In addition, a chin cap is effective to have younger children keep the activator at the suitable position.
To evaluate the healing process of the damaged tissue and the effectiveness of the functional treatment using the activator, we provided functional treatment for a condylar process fracture in a 5-yearold boy and observed the remodeling process using images with three-dimensional computedtomography (3 DCT).
He was injur ed in a traffic accident when riding bicycle.3 DCT images confirmed displacement and dislocation fracture of the left condylar process at pretreatment. Functional treatment was given with the activator and chin cap for 17 days. Remodeling of the condylar process was observed with CT examination after 1,4,7 and 15 months with agreement of the parents of the patient.3 DCT images suggested conspicuous bone resorption of the fracture fragments and rapid formation of a new condyler head with additional bone after 4 months. After 7 months, the regenerated condylar head was observed to be nearly completely remodeled with morphology in mandibular fossa. After 15months, the condylar head was healed completely. Clinical outcome of this case was successful with normal occlusion, pain-and-noise-free TMJ, normal jaw opening and symmetry at follow-up 2 year and 4 months later.
These obser vations indicated that the functional treatment using activator is a very effective conservative management for condylar process fractures in children.

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[in Japanese]

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[in Japanese]

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