The purpose of this study was to find out the actual condition of imature permanent teeth, the care of imature permanent teeth and the establishment of oral health care during childhood. A study organaization was organized under 29 professors of the Departments of Pediatric Dentistry of dental collages and universities in Japan for this study.
The subjects,4,080 children (2,015 boys and 2,065 girls) ranging from 5 to 16 years of age, were examined transversally.
This report is concerned with results of an investigation into the degree of eruption, developmental disuturbance of tooth structure, and the pattern of occlusion.
The findings were as follows.
1) There were no differences in degree of eruption of the right and left teeth with the same name between the boys and girls in any age group. The girls showed a tendency toward more accelerated eruption compared with the boys. Among the boys and the girls as well, the teeth which showed the most accelerated eruption were the mandibular central incisors, while the mandibular teeth except the second premolars tended to show more accelerated eruption compared with the teeth with the same name in the maxilla.
2) Developmental disuturbances of the tooth structure were found most frequently in the mandibular lateral incisors among the boys and the girls as well. The frequency of enamel hypoplasia was 1% or below for any tooth. Pegged teeth and incisive blind foramen were found most frequently in the maxillary lateral incisors. Of abnormal tubercles, the Carabelli tubercle was observed most frequently. The frequency of incisive tubercles/central tubercles was 1% or below in all teeth.
3) As for malocclusion, crowding was observed most frequently and open-bite was observed most rarely. Prognathism tended to be found more frequently among the girls than the boys, and it was suggested that the frequency rises with age until around the age of 12. The frequency of either reversed occlusion or open-bite was 10% or below among the boys as well as the girls of any age group. Crowding showed a higher frequency and a tendency toward earlier development among the girls compared with the boys.

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The purpose of this study was to find out the actual condition of the imature permanent teeth, the care of imature permanent teeth and the establishment of oral health care during childhood. The subjects,4,080 children (2,015 boys and 2,065 girls) ranging from 5 to 16 years of age, were examined transversally.
This report is concerned with the results of an investigation into the state of caries prevalence, and that of restoractive treatment, in particular, based on age and degree of eruption.
The findings were as follows.
1) The prevalence rate of dental caries among the boys and girls was as follows, respectively: 19%and 20% at the age of 6; 80% and 80% at the age of 12; 89% and 93% at the age of 16. The mean number of decayed, missing or filled (DMF) teeth per child among the boys and girls was as follows, respectively: 0.4 and 0.5 at the age of 6; 3.8 and 4.1 at the age of 12; 6.6 and 8.6 at the age of 16. The rate of DMF teeth based on age was the highest,50-60%, in first molars at the age of 12, which was followed by 20-30% in second molars. The first and second molars in particular resulted in a high prevalence rate of caries,30%, even in the middle of eruption, The second molars showed a higher prevalence rate than the first molars regardless of the degree of eruption.
2) The mean number of treated teeth per child among the boys and girls was as follows, respectively: 0.2 and 0.2 at the age of 6; 2.6 and 2.9 at the age of 12; 4.6 and 6.8 at the age of 16. Filling with resin was rather frequently observed in the anterior teeth and premolars. The molars were treated more frequently by filling with resin or by repair with inlays, and the latter in particular showed an increasing tendency with age. The rate of treatment by preventive condensation on teeth after the completion of eruption was 20% for premolars,30-40% first molars and 20-30% for second molars.

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The purpose of this study was to find out the actual condition of the imature permanent teeth, the care of imature permanent teeth and the establishment of oral health care during childhood.
The subjects,4,080 children (2,015 boys and 2,065 girls) ranging from 5 to 16 years of age, were examined transversally.
This report is concerned with results of an investigation into the state of plaque adherence and that of gingivitis, in particular, based on age and degree of eruption.
The findings were as follows.
1) The rate of mexillary anterior teeth without plaque accretion (expressed as P1T 0) tended to decrease with age among the boys and the girls as well. The rate of molars with P1I 0 tended to show a lower value compared with anterior teeth and premolars among the boys as well as the girls.
2) Of all kinds of maxillary and mandibular teeth among children 16 years of age, maxillary second molars showed the lowest value for P1I 0 among the boys and the girls as well. The girls tended to show a higher value for P1I 0 compared with the boys. Teeth in the middle of eruption among the boys as well as the girls tended to show a lower value for P1I 0 compared with teeth after the completion of eruption.
3) The rate of maxillary anterior teeth with normal gingiva (expressed as GI 0) tended to rise in value with age among the boys 12-16 years of age, while the rate showed almost no variations in the girls of the same age group.
4) The rate of moderate gingivitis (expressed as GI 2) resulted in a higher value among the boys than among the girls. The rate for GI 2 was 8.66%,12.22% and 10.25% of central incisors, lateral incisors and canines, respectively, among the boys 12 years of age, while the rate was 10.64%,11.21% and 8.09%, respectively, among the boys 16 years of age. On the other hand, the rate for GI 2 was 3.61%,4.26% and 3.13% of central incisors, lateral incisors and canines, respectively, among the girls 12years of age, while the rate was 5.10%,6.07% and 5.08%, respectively, among the girls 16 years of age. In this manner, the girls showed a lower value for GI 2 in any age group.
5) There tended to be differences in value for GI 0 between canines in the middle of eruption and those after the completion of eruption among the boys as well as the girls.

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New patients who visited the Pediatric Dentistry clinic, Asahi University Dental Hospital during the last 15 years were surveyed to reveal the actual condition of these patients and to enable us to meet the dental requirements in our community. The results obtained were as follows:
1. The number of patients who visited our clinic newly during the period from 1983 to 1997 was 7244. While the number of patients has decreased from 1983 to 1989, after that it tended to increase, year by year.
2. The number of children with dental caries as the chief complaint has decreased during the past 15years. In contrast, the number of children who came for prevention, oral examination and orthodontic treatment has increased gradually.
3. The initial visit of patients 3-5 years old amounted to about 35%, and those 6-12 years old amounted to about 45%, while the number of patients under 2 years of age increased over the year.
4. The number of initial visits concerning of handicapped children has gradually increased.
5. Investigation the distance from the home to the clinic showed that 72% of all the outpatients came from within a 10 km area.

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The purpose of the this study was to attempt to as certain the functional and developmental changes in the microvasclar cast specimens of the fungiform papillae as a taste sensory organ on rat tongue during wearning.
Wister white rats during weaning (about 20 days old) and adult rats as the control group were used in this study.
The microvasclar cast specimens of the fungiform papillae were made with the Ojima's corrosive resin cast method, and observed and compared using the composite photomicrographs from a scantling electron microscope. The followind were results:
1. The microvasclar cast specimens of rat tongues during weaning were similar to those of the adult rat tongues.
2. The fungiform papillae were sporadicaly distributed on the antero-dorsal surface of the anterior tongue coverd an area form the top of the tongue to intermolar eminence on the rat tongue.
3. The radical structure of the fungiform papillae consisted of several ascending and descending branches and loop structure related to the capillary structure.
4. The outline of microvasclar cast specimems of fungiform papillae showed a cylincrical structure with an opening at upper and lower bottom parts. The lateral view showed the bamboo basket-line network structure made of several loop structure.
5. The fungiform papillae of rats during wearning were slightly samller than those of adult rat, but there were no other differences morphologically.
6. In the comparison of rats during weaming and adult rat, clear differences based on sex not observed in the results of this study, wtich the fungiform papillae as taste organ of rats during wearning were completely developed in terms of morphology and function.

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This study examined the relation between MRI findings and clinical symptoms in juveniles with temporomandibular joint disorder. From one hundred twelve temporomandibular joints of 56 juvenile patients (male=15, female=41, ages ranging from 9 to 16) detail information about temporomandibular joint disorder was obtained and MRI films were used.
According to the MRI findings, joints without anterior disk displacement were found in 45 cases (40.2%), those with anterior disk displacement in 54 cases (48.2%) and those with lateral disk displacement in 13 cases (11.6%).
Twenty one of the 54 joints diagnosed with anterior disk displacement indicated reduction while the remnants of 33 joints were without reduction.
Concerning the clinical finding of the anterior disk displacement group, slight displacement was recognized in 16 joints with reduction and 5 without reduction, while mild displacement was recognized in 5 joints with reduction and 27 without reduction. Severe displacement was recognized only in one joint without reduction, Thirty seven (68.5%) on the 54 joints with anterior disk displacement showed disk deformity, of which disk deformity was found in 7 (33.3%) of 21 joints with reduction and not found in 30 (90.9%) of 33 joints without reduction.
Thirty one of 112 joints showed joint effusion, and no joint was found with effusion in the displacement group without the anterior disk. In the group with reduction, three and two joints showed effusion in anterior disk displacement and the lateral disk displacement, respectively, and in the group without reduction,22 and 4 joints showed more notable effusion in the anterior disk displacement and the lateral disk displacement, respectively.
According to clinical symptoms based on MRI findings, the prevalence of pain and complaints of opening disorders were clearly present in group with anterior disk clisplacement and without reduction. Even the prevalence of the clicking sound was clearly present in the groups with anterior disk displacement, with and without reduction.

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The purpose of this study was to evaluate the bleaching efficacy of the 10% carbamide peroxide gel Colgate Platinum® (Colgate-Palmolive Co. ).
Clinical investigation: The subjects were two females (aged 30 years 5 months and 27 years 5months) all of whose teeth were discolored by reasons unknown. A home-bleaching gel was applied to their anterior teeth from 30 minutes to 1 hour each day for 2 weeks. Color changes were observed with the naked eye and color measurement with a spectrophotometer.
In vitro investigation: Platinum® was applied on the buccal surfaces of 8 extracted premolars and one side of 8 resin composite specimens (10 mm diameter and 1 mm thick) made by Clearfil APX®(Kuraray Co. ). All of the samples were wrapped with a wrapping-film and stored in glass bottles. The samples before bleaching, and after 1,3 and 7 days of bleaching were chromatically measured and observed using a scanning electron microscope. The colorimetric values were statistically analyzed using ANOVA subsequent to Tukey-Kramer multiple range test at p<0.05.
The following results were obtained.
1) For the highly discolored case 1, significant color changes by bleaching were observed and cornpared to the values before bleaching, the ΔE*ab after two-weeks of bleaching ranged from 5.19 to 6.75. Color relapse was, however, observed after 1 month. For the mildly discolored case 2, bleaching efficacy was low and compared to the values before bleaching, the ΔE*ab after two-weeks of bleaching ranged from 2.09 to 4.67.
2) For case 1, gingival pain and tooth sensitivity were observed and for case 2, gingival redness an pain were observed. These adverse effects were transient.
3) Compared to the values before bleaching, the ΔE*ab of the extracted teeth were: one-day of bleaching (5.68), three-days of bleaching (10.47) and seven-days of bleaching (20.50).
4) Compared to the values before bleaching, the ΔE*ab of the resin composites backed by a white color and backed by a black color were: one-day of bleaching (0.94,1.00), three-days of bleaching (0.87,0.65), and seven-days of bleaching (1.96,1.98).
5) The longer the bleaching time, the clearer was the enamel surface structure of the extracted teeth.
6) Bleaching did not change the morphology of the resin composite.

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Dental anxiety and fear sometimes stem from childhood experiences. It is useful to know the stress of the patient during dental treatment to keep such anxiety and fear under control.
The aim of present study was to investigate the influence of stress cognition on the nasal skin temperature.
The subjects of this research were 82 adults (dental school students). They were a more homogeneous group and more adaptable to the experimental environment than children who show various changes in physiological and psychological response,
Procedure of this study
1. The subjects quietly reclined on the dental chair to relax themselves for 5 minutes while listening to music.
2. The music was stopped. (Control stimulus)
3. The subjects quietly reclined for 5 minutes without music.
4. The subjects were given their first verbal stimulus., (Neutral words)
5. The subjects quietly reclined for 5 minutes without music.
6. The subjects were given their second verbal stimulus. (Stressful words)
7. The subjects quietly reclined for 5 minutes without music.
This study was undertaken in 4 phases and with 3 stimuli.
The change indices (coefficient of variation and range) of the temperature changes, the start of the response, the initial speed of the response, the range of the change in response, and the response time were used as physiological indicators. From the graph of the stress and time, which expanded the time axis in the Visual Analogue Scale, the area under the curve and the length of the vertical change were calculated and used as psychological indicators,
The results were obtained as follows:
1. By using the start of the response, the initial speed of the response, and the range of the change of the response and with the nasal skin temperature as the data of the time series, processing of the data is possible.
2. With stress cognition, the nasal skin temperature changed significantly.
3. The start of the change in the nasal skin temperature had no connection with the level of stress.
4. A positive correlation was found between the stress level and the first speed of nasal skin ternperature.
5. A positive correlation was found between the stress level and the first range of the nasal skin temperature.

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Most of the previous studies of salivary secretion in humans have been done with adult subjects. The purpose of the present study was to determine the unstimulated and stimulated salivary flow rate in response to Gum chewing, taste solution and bite force of primary teeth in children.
The results were as follows:
1. The mean unstimulated whole salivary flow rates and of saliva secreted in response to taste stimuli in children were about 79% and 72% of those in adults, respectively.
2. With the basic four taste stimuli (acid, salty, sweet and bitter stimuli), Acid was the highest flow, Fallowed by salty, sweet and bitter stimuli. There was same order of salivary volume between children and adults.
3. The mean bite forces for children were 36% of those in adults. The parotid salivary flow rates in response to the bite force stimulation increased 6 times of unstimulated flow. The mean time between initiation of stimulation and the achievement of the maximum flow rate of saliva in children was almost the same asin adults.
4. The maximum volume of parotid saliva elicited by the initiation of stimuli was 65% of that in adults. The mean time between initiation of stimulation and achievement of the maximum flow rate was almost the same as in adults.
It is suggested that the salivary flow rate in children was less than that of adult and there were no differences in the functions of the salivary flow between children and adults.

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The aim of this present study was to measure the occlusal angles of the buccal grooves in the mandibular deciduous molars and to reveal the difference of the angles between mandibular first deciduous molar and second deciduous molar. Dental casts of the deciduous dentition were obtained from children aged from three years to just under three years and one month, and caries free with hardly any attrition and with normal occlusion. The occlusal angles of the buccal grooves in the mandibular first deciduous molar and second deciduous molar were measured. The tangents were drawn at the disto-internal oblique plane of the mesio-buccal cusp and the mesio-internal oblique plane of the disto-buccal cusp. The occlusal angle of the buccal groove was defined as the interior angle which intersected these tangents.
The results were as follows.
1. The mean occlusal angle of the buccal groove of the third near the mesio central pit was 119.71° at the mandlbular first declduous molar and was 123.46°at the mandibular second deciduous molar. The mean occlusal angle of the baccal groove of the third near the buccal margin was 125.69° at the mandibular first decidaous molar and was 125.67° at the mandibular second deciduous molar.
2. The mean occlusal angles of the buccal groove of the mandibular first deciduous molar approximated that of the mandibular second deciduous molar, and indicated a tendency for the angles to stabilite from the central pit toward the buccal margin.
3. According to reseach regarding whether the buccal groove was included in the outline form of cavity on the mandibular deciduous molars, the cases of first deciduous molars which included the buccal groove accounted for 48%, and those excluding the buccal groove accounted for 52%. On the other hand, the buccal groove was included in the outline form of cavity on the second deciduous molars in all the cases.

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Genetically diabetic db/db mice showed greater neural and behavioral responses to sugar than lean contorol mice. The present study examined chorda tympani responses of db/db mice to nonsugar sweeteners and their inhibition by a sweet response inhibitor, gurmarin. We made crosses between C 57BLIKsJ-+/db, heterozygotes at the db locusa nd showing sweet taster esponsest o D-phe(ddp⁺), and BALB mice, lacking sweet responses to D-phe (dpa^-), and produced diabetic and lean mice with mixed genetic backgrounds of two inbred strains in their F 2 generations. Behavioral preferences for D-phenylalanine, sucrose and saccharin Na, mesured by a two bottle test were compared among diabetic and lean contorol F 2 mice. Diabetic and contorol mice were divided into two subgroups (dpa⁺ and dpa^-) according to their preferences for D-phe, and in total four groups, such as dpa⁺ -db/db, dpa^--db/db, dpa⁺-+/?and dpa^--+/?. The resultss howed thatr esponsest o sucrose, saccharin Na, glycine, L-alanine and D-tryptophan, but not to D-phenylalanine, were greater in db/db mice than in the control mice. The preferences for sucrose and saccharin Na of dpa^--db/db mice were significantly higher than thoseo f dpa^--+/?mice, whereas no such difbrencew as observed between dpa⁺-db/db and dpa⁺-+/?mice. The resultss uggestt hat enhanced preferencesf or sweet substanceso f db/db mice are evident in dpa^- but not dpa⁺ groups, and mixing of genetic backgrounds of BALB with C 57 may reduce differences in sweet preferences between db/db and lean contorol mice.

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According to recent reports, atopic diseases in children have increased, and the number of visits to dental hospitals has also increased. The aim of this study was to examine the statements of children in kindergarten with atopic diseases who attended the kindergarten in the vicinity of Meikai University Hospital. The questionnaires were on the condition and allergens concerning atopic diseases and the past and family histories were collected.
The order of frequency of atopic disease was Atopic Dermatitis, bronchial asthma, allergic rhinitis, food allergy and allergic conjuctivitis. About half of all of the children had one atopic disease, and one third of children had more than two diseases. The order of the frequency of allergens was house dust, pollen, food and mite and one half of the food identified as food allergy was eggs and milk. An allergic procession reported previously was observed as the effects of aging on the frequency, and the high frequency with atopic diseases were also observed in families which have allergic children. These results reconfirmed that atopic children need careful examination and close contoct with medical personnel.

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The purpose of this study was to evaluate the stomatognathic function in children with the jaw movement data in 6 degrees of freedom. Seventeen healthy subjects with normal occlusion were divided into two age groups: the early mixed dentition group(2 boys,5 girls), and the permanent dentition group(2 men,8 women). Border jaw movements and excursions were measured with 2 devices for tracking 6 degrees of freedom jaw movement. The jaw movement of the children was examined using the diagnostic parameters of the stomatognathic function in comparison with adults.
The results obtained were as follows:
1. The longest distance of the condylar path was significantly smaller in children than in adults. The distance of the condylar path in the most protrusive occlusal position was significantly larger in children than in adults. The distance of the working condylar path in the most lateral occlusal position was significantly larger in children than in adults.
2. The sagittal angle of the incisal path during protrusive excursion was significantly smaller in children than in adults. The sagittal and frontal angle of the incisal path during lataral excursion was significantly smaller in children than in adults.
3. Other diagnostic parameters did not show any significant difference between children and adults.
These results suggest that during protrusive and lateral excursion the condylar movement has high mobility in children and jaw movement of the whole mandible is more horizontal in children than in adults.

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The purpose of this study was to evaluate the effectivenes of various agents on hard tissue formation (dentin bridge and hard tissue deposited on the root canal wall i. e., reparative dentin) and to evaluate the pH changes of these materials. Rat molars were used. The groups were as follows: no agent (control), calcium hydroxide, Life®c, a lcium carbonate, magnesium hydroxide, aluminium hydroxide, calcium phosphate cement, calcium phosphate cement containing 10% fluoride,0.1% tetraethylammonium hydroxide sol. applied for 15 min., alkaline sol. for 15 min., alkaline sol. for 15 min.4 times every 12 hours and acidic sol. for 15 min. After 28 days, histopathological changes of the pulp and evidence of hard tissue formation were examined. All pulpotomy agents were applied to the dorsal subcutaneous tissue of rats and the pH values were measured.
The results were as follows:
1) Hard tissue formation in descending order was: calcium hydroxide > Life®> alkaline sol. applied 4 times > tetraethylammonium hydroxide sol. > calcium phosphate cement containing fluoride >others (p<0.0001).
2) The sterility of the agents, high alkalinity, and presence of Ca²⁺ and OH^- were external factors influencing hard tissue formation (p<0.001).
These findings suggest that the factors influencing hard tissue formation are multiple. Calcium hydroxide having sterility, high alkalinity, and presence of Ca²⁺ and OH^- was shown in this study as being an ideal agent for hard tissue formation.

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To find a more biologically acceptable and effective alternative to gentle hemostatic techniques and pharmacologic agents in difficult cases of stopping bleeding from amputated dental pulp in vital pulpotomy, we examined the fibrin material Bolheal® that has biological affinity. Thepurpose of this study was to evaluate the hemostatic effect of the fibrin material Bolheal® on dental pulp tissue in the case of vital pulpotomy and to observe the healing process of the remaining pulpal tissue histopathologically and immunohistologically. We divided the permanent teeth of 15 young mongrel dogs into 3 groups (control group A: the placement of Ca(OH)₂ after cotton pellets hemostating, experimental group B: the placement of Ca(OH)₂, after Bolheal® hemostating, experimental group C: no placement of Ca(OH)₂, Bolheal® used only). All groups were sealed with a ZOE base.193 teeth were obtained for this study. The period of observation was 3,7,14,30,60 days after the operation. The results were as follows.
1) The hemostatic effect was higher using Bolheal® than using cotton pellets(p<0.01). Bleeding after the placement of Ca(OH)₂ was less with Bolheal® hemostating than with cotton pellets(p<0.01).
2) With the histopathological analysis, we found a slight delay of the dentin bridge formation in group B. We did not however notice an obvious difference between group A and group B with respect to dentin formation. The mean distance from the pulpal stump to the starting position of the dentin bridge formation was as follows; groupA: 721.3 μm, group B: 260.9 μm, group C: 23.0μm. There was a significant difference among all of the groups(p<0.01). Especially in group B, we considered that Bolheal® weakened the alkaline stimulus of Calvital® and decreased the width of the necrotic layer, and consequently the starting position of dentin bridge formation rose. As for histopathological marks, there was a significant difference between group B and group C at 3 days (p <0.05), and in addition, between group A and group C(p<0.01), group B and group C(p<0.01) at each of the periods after 7 days. The group C showed the lowest marks at all observation periods.
3) PCNA positive cells were observed around the amputated pulp surface until 14 days in group A and group B by immunohistostaining. Otherwise, in group C, they were observed at 3 days only. There was no significant difference between group A and group B proliferative activity and differentiation of pulp cells.
These findings suggested that Bolheal® had a very quick and certain hemostatic effect on dental pulp tissue and no harmful effects on the pulp tissue. This technique can be useful in vital pulpotomy.

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The major morphologic characteristic of dentin is its fluid-filled tubular structure connecting the pulp to the enamel-dentinal junction. The movement of the fluid within tubules has been called transdentinal permeability. It is responsible for dentin sensitivity and the constant wetness of the exposed dentin surface due to the outward fluid movement from the pulp. Penetration of adhesive resin monomers into the intertubular dentin or peritubular dentin is also a subset of transdentinal permeability. Our previous study showed that the type I collagen was able to inhibit the permeation of dentinal fluid under simulated pulpal pressure. The aim of this study was to evaluate the effects of collagen application times on dentin permeability, the ability to infiltrate the resin monomer into the dentin treated with the collagen solution and the effects of collagen treatment on the shear bond strengths of resin to the dentin.
The collagen solutions used in this study were prepared in the same manner as in the previous study. The permeability of the dentin treated with collagen solution at 37°C for 30,50,180 and 300sec. was evaluated under a simulated pulpal pressure of about 25 mmHg. The data was statistically analyzed using ANOVA and subsequently Scheffe's F test. The cross section of the resin-dentin interfaces applied with All Bond 2® or Super Bond D-liner H® were observed, and the thickness of the hybrid layer was measured with SEM. To compare them with or without collagen treatment, collagen was applied to one half of the dentin surface and the other half side was not treated with collagen as a control. The shear bond strengths of resin to dentin treated with or without collagen were measured for All Bond 2® and Super Bond D-liner H®. Data was statistically analyzed using student's t-test. As for the results, the following findings were obtained.
1. To achieve sufficient of inhibition of the dentin permeability with the collagen treatment, application times of more than 60 seconds were needed, but extension of the treatment times over the 60 seconds did not indeed result in a significant decrease of dentin permeability.
2. The thickness of the hybrid layer significantly increased in the area treated with collagen than in the control area for both adhesive systems.
3. The bond strengths of resin to dentin did not show a significant difference between the control and experimental groups for both adhesive systems.
Our results suggested that collagen treatment for dentin for 60 sec. was enough to inhibit the permeation of the dentinal fluid, and the resin monomer infiltration into the dentin and the shear bond strengths of resin to the dentin were not interrupted by the collagen treatment.

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To examine the effects fused deciduous teeth have on successional permanent teeth and teeth alignments, we carried out an investigation of such sites based on a study of the intraoral status of 80 children with fused deciduous teeth, and the use of study casts from 37 people in Hellman Dental ages of stage II A.
1) We observed a total of 107 cases with fused deciduous teeth, and of these,18 cases were maxillary, and 89 cases were mandibular. The greatest number,46 cases, was observed for mandibular AB fused teeth, followed by 5 cases of mandibular BC fused teeth.
2) Bilateral cases of fused deciduous teeth were observed in 22 out of the 80 cases, with most of these cases possessing fused teeth in locations with left-right symmetry,
3) Successional permanent teeth deficiencies were observed in 9 out of the 15 cases of fused maxillary AB teeth. Of the 46 cases of mandibular AB fused teeth, successional permanent teeth deficiencies were also observed in 9 cases, while fusion of successional permanent teeth were observed in 4cases. Of the 43 cases of mandibular BC fused teeth, successional permanent teeth deficiencies were observed in 29 cases, and fusion of successional permanent teeth was observed in 7 cases.
4) Concerning the terminal planes, we were unable to observe any major differences between sides with fused teeth, and sides without. Tooth alignments where maxillary and mandibular AB were fused teeth, were of the vertical types, but the mesial types were more numerous in tooth alignments with BC fused teeth on one side of the mandibular. Concerning deciduous canine occlusion relationships, there was a tendency for there to be an increase in type 3 on the fused side of the tooth alignments with AB fused teeth on one side of the mandibular.
5) There was also a tendency for there to be a narrowing of the lower dental arch width in cases where fused teeth were found to exist in the mandibular, and this trend was particularly conspicuous for tooth alignments where BC were fused teeth. A strong tendency towards a shortening of the lower dental arch length was also observed when fused teeth existed on both the left and right sides.

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We investigated the relationship between mastication and respiration during acute nasal obstruction in infants.
Methods: The subjects were 16 healthy infants (Hellman dental age II A- II C). Electromyograms (EMG) were obtained from the masseter muscle using a surface electrode technique. The respiratory curve was obtained with a mechanoelectrical transducer for respiration. The EMG and respiratory curve were recorded simultaneously. We analyzed the respiratory rate, respiratory cycle time, relative tidal volume, masticatory rate and masticatory cycle time. The condition of nasal obstruction was simulated by pinching the nose.
Results: 1. At rest, the respiratory cycle time tended to be prolonged under acute nasal obstruction with mastication of gum, there were significant differences in the prologation (p<0.001).
2. As for the respiratory rate, at rest, this decreased during the acute nasal obstruction with mastication of gum, there were significant differences in decrease during acute nasal obstruction (p<0.05).
3. As for the relative tidal volume, at rest and mastication of chewing gum, there was an increase during acute nasal obstruction.
4. As for the masticatory cycle time, this showed a similar time both non-obstructed and nasal obstructed.
5. As for the masticatory rate, this decreased during acute nasal obstruction.
Conclusions: These results, indicated that nasal obstruction of infants affects respiration, but that nasal obstruction of infants did not show any affect on mastication.

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Fibrous lesions such as fibroma, fibrous hyperplasia, fibrous epulis, denture fibroma are not so rare in the oral cavity. There are, however, few reports about them in children. We experienced 22 cases of oral fibrous lesions at the Pedodontic Clinic of Niigata University Dental Hospital during a period of 19 years from 1979 to 1998 and investigated them clinically and histopathologically.
The results were as follows:
1. The patients consisted of 9 males and 13 females. Their ages ranged from 8 months to 11 years and 4 months. Three patients were under 1 year old.
2. Sixteen cases were located on the gingiva,4 on the palate and 2 on the buccal mucosa. They were pathologically diagnosed as fibrous epulides in 16 cases and fibrous hyperplasia or fibroepithelial hyperplasia in 6 cases.
3. As for the 16 cases of fibrous epulides,10 cases occurred in the maxilla and 6 in the mandible. Fifteen cases were in the incisor region. All of the epulides were smaller than 1 cm in diameter. Microscopically, they were shown to be composed of numerous fibroblasts and proliferating collagen fibers.
4. As for the 6 cases of fibrous hyperplasia, four cases occurred on the palate and two on the buccal mucosa. Three of the four cases of palatal fibrous hyperplasia were similarly located near the incisor foramen. They were hemispherical or elliptical in shape,3-7 mm in diameter, and pedunculated or sessile and elastic-hard. Buccal lesions were clinically well-defined masses with smooth, normalcolored surfaces and broad bases. They were clinically suspected of mucocele. Microscopically, the lesions were shown to be composed of proliferating collagen fibers.
5. All of the fibrous lesions were excised surgically and no recurrence was found.
6. Most of the oral fibrous lesions in children may be fibrous epulides. Histological examination of the excised specimens is needed to confirm the diagnosis.

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The histiocytosis X representing eosinophilic granuloma, the Letterer-Siwe disease, and the Hand-Schuler-Christian syndrom that may cause bone or intraoral lesions is now called the Langerhans-Cell-histocytosis (LCH).
The patient with LCH was a 14-year-1 month old girl, who visited us primarily for dental treatment. The findings observed were; bone loss in the skull, severe bone resorption in the maxilla and mandibula, loosening and exfoliation of the teeth, intensive gingivitis, malaligment, and malocclusion of the primary dentition.
As for the dental treatment, composite resin filling and extraction were performed under local or general anesthesia, and after extraction of 15 Permanent teeth, anterior acrylic partial dentures were constructed to maintain space.
Periodical examinations including oral hygiene advice will have to be provided.

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There are case reports of gingival recession due to improper tooth brushing.
The first case was a 2.2 year old girl whose chief complaint was gingival recession, swelling, bleeding and redness at the buccal gingiva of the 54-64. The mother had to brush the girl's teeth because of the girl's refuser to brush her teeth. As the cause of her gingival recession was thought to be excessive brushing pressure, the mother was instructed to brush her daughter's teeth gently with gauze for a while. After 6 weeks, the gingival inflammation came to disappear and then the gingival recession gradually recovered.
The second case was a 3.5 year old girl whose chief complaint was gingival recession at the buccal gingiva of the 61-64. She had been brushing her teeth habitually, especially at the region with gingival recession. She and her mother were also instructed to brush her teeth and gingiva with gauze gently for a while. After one month, the gingival inflammation disappeared and the gingival recession gradually recovered.
In conclusion, it is suggested that the improper tooth brushing caused the gingival recession, so it is important to give instraction on the correct way of brushing to both children and parents.

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A case of an 11-year-old girl with intensive gingival swelling due to a raducular-gingival groove was presented. Gingival swelling was localized at the distal gingiva of the mandibular lateral incisor. Roentogenographic examination revealed a vertical radiolucent line from the cingulum to the apex of the affected tooth. Irrigation and general and local prescription of antibiotics made the lesion noninflammatory. The intensive swelling, however, was persistent, and the affected gingiva was excised under infiltration anesthesia. The histopathological appearance exhibited a great deal of neutorophils and plasma cells, which were diagnosed as epulis granulomatosa. After the wound healed, examinationing by probe on the surface of the root of affected tooth indicated the presence of developmental groove. CT image, moreover, exhibited a groove-like structure at the middle of the root at the affected tooth. Taken together, these clinical symptoms and examinations, and the presence of radiculargingival groove of the mandibular left lateral incisor caused intensive gingival swelling.

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We experienced a rare case of multiple impacted teeth and inversion of the upper right second deciduous molar and upper right second premolar in a 13 year 8 month, old boy.
1) Radiographs showed impaction of the upper right canine, occurrence of supernumerary teeth between the lower first and second premolars and at the distal region of the upper right second premolar and inversion of the upper right second deciduous molar and the upper right second premolar.
2) It was judged histologically and morphologically that the upper right second deciduous molar was situated at the right maxillary sinus region and the upper right second premolar was situated at the distal site between the upper right first premolar and the upper right first molar.
3) We considered that the impacted upper right second premolar was disturbed in the formation of the tooth crown by the supernumerary tooth and inversion of the upper right second deciduous molar and the upper right second premolar was caused by the remaining second premolar above the second deciduous molar at the initiation of tooth development

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Supernumerary teeth are frequently found in the maxillary anterior region. It is reported that the frequency was 0.5 to 2.5 percent, and children with supernumerary teeth are not rare.
We reported a rare case of a supernumerary tooth with reoccurred at the same site after extraction of The impacted supernumerary tooth in The upper incisor region of a 9 year 4 month old boy with a chief complaint of delayed eruption of the right maxillary central incisor.
1) An impacted supernumerary tooth was found in the maxillary anterior region and caused a delayed eruption of the right maxillary central incisor.
2) We found an impacted supernumerary tooth reoccurring at the same site 3 years and 2 months after extraction of the supernumerary tooth.

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A rare case of highly advanced alveolar bone loss caused by a foreign body in a 3-year-old girl is reported.
The patient came to the Pedodontic Clinic of Health Sciences University of Hokkaido with swelling at the cervical area of the mandibular primary central incisor.
She had a strong dental phobia, and a habit of biting things made of nylon, along with finger sucking and onychophagia. The diseased gingival showed redness, swelling, highly developed alveolar bone loss and tooth mobility (+ +).
When a scaling was done as standard periodontal treatment, a transparent tube appeared out up the periodontal pocket. It was conjectured that the foreign body was a straw with a soft drink based on its form.
The prognosis after removing of foreign body was good in this case. In order to prevent the occurrence such as this case, the following is suggested:
1. During the oral examination, the dentist should pay attention to the possible existence of a foreign body in the oral cavity.
2. Behavior in which the child might put something into its oral cavity, can possibly cause dental injury.
3. It is necessary to inform the community that safety education is a very important factor.

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