This study was designed to clarify the relationship between the mandibular morphology and the status of the eruption of mandibular third molars. All of the subjects, male and female, were classified into three groups according to the condition of eruption of the third molars; full impaction, semi-impaction, and full eruption.
1. In males, the total length of the mandible (M), CdGn, U6-PTV, and L6-MP' proved to be significantly larger in Group C (full eruption) than in Group A (full impaction), and Facial A., and OPMP were significantly larger in Group C (full eruption) than those in Group A (full impaction).
2. In females, the total length of the mandible (M), Cd-Gn, U6-PTV, and L6-MP', were significantly larger in Group C (full eruption) than in Group A (full impaction), and the length of the mandibular corpus (C), the width of the mandibular ramus (R), Go-Me, Xi-L7, ABR-L7, and U7-PP were all significantly larger in Group C (full eruption). The Y-axis was smaller and SNA larger in Group C (full eruption) than in Group A (full impaction).
3. These results showed that in both males and females, the mandible was generally larger in subjects with fully erupted third molars, allowing ample room for the eruption of the mandibular third molar in the post region. These cases were characterized by the opening of the mandible accompanied by the elongation of the first molars.

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The purpose of the present study was to investigate the occlusal deviation frequency in the pathway of the mouth closure due to premature contacts, with reference to dentitional growth. The subjects examined were 154 children with normal occlusion and malocclusion(IIA-IIC: 38, IIIA-IIIB: 71, IIIC-IVA: 45), and was examined the occlusal deviation in the pathway of the mouth closure.
The results obtained were as followsl;
1. Occlusal deviation was found in 26 children (16.9%). In the group with occlusal deviation, the ratio of the malocclusion was significantly higher than that with the normal occlusion.
2. Occlusal deviation significantly increased(p<0.05) with the dentitional growth from IIA-IIC (0%), IIIA-IIIB (6.3%) to IIIC-IVA(17.9%) in the children with normal occlusion. However, occlusal deviation was not significant with dentitional growth from IIA-IIC (27.3%), IIIA-IIIB (47.8%) to IIIC-IVA (25.0%) in the children with the malocclusion.
3. Comparing variouslmalocclusions, occlusal deviation is the most frequent in the forced crossbites.
These findings suggested that malocclusion does lead to occlusal deviation, and the eruption of the 1st and/or 2nd permanent molars may disturb the occlusal stabilization temporarily in children.

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The purpose of this study was to understand the relationship between the morphologic patterns of the skeletal profiles of patients with anterior cross-bite in the primary dentition and the cranial base angle (NS-Ba). The patients consisted of 74 males and 65 females whose ages ranged from 2 to 7years. Lateral roentgenographic cephalograms of all of the patients were taken before treatment at the Pedodontic Clinic, Niigata University Dental Hospital, and were used for the analysis in this study. The following results were obtained; 1) Anterior cross-bite in the primary dentition seemed to be characterized primarily by maxillary retrusion when compared with the Japanese standards in the lower age group. In contrast, in the higher age group, it may be characterized by mandibular protrusion.2) Skeletal profiles of the patients ranged widely, and profiles of the children with normal occlusion in the primary dentition showed the same tendency.3) When the patients were classified into three groups according to their Cranial base angle (large group, moderate group and small group), regarding their mean profiles, it was suggested that the mesiodistal angle of the facial line from cranial base related to their mean cranial base angle.4) Multivariate analysis proved that there was almost no relationship between cranial base angle and relative position of the maxilla and the mandible. There was also almost no relationship between the cranial base angle and the age of the patients.

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When a tooth is avulsed by trauma, some form of storage should be undertaken to prevent the drying of the periodontal ligament. Milk has been recommended as the solution for use with avulsed teeth caused by trauma. At present, solutions of two types for use as preservation solutions for extracted teeth are on the market in Japan. One was made for long term preservation of a implanted or transplanted teeth, while the other was made for short term preservation of avulsed teeth.
The purpose of this study was to compare the viability of cultured human PDL cells in the storage medium.
Three solutions including milk, preservation solution for dental implanted or transplanted tooth (Solution D), and a preservation solution for avulsed teeth (Solution N) were used as experimental solutions in this study. MEM including 10% FCS was used as the control media. The PDL cells were cultured from healthy extracted human teeth.
After the PDL cells were cultured for 8 days, they were exposed to each solution for 15 minutes at 4°C. The MTT assay was measured immediately after exposure and subsequently followed at 1,2,3,5 and 7 days after exposure. The morphological changes in the PDL cells were observed immediately and on 7 th day after exposure.
The results were as follows.
1. The growth activity: Milk and Solution N always showed superior activity. Solution D revealed poor activity from immediately after exposure to 7 days after exposure.
2. The morphological changes: Milk and Solution N caused the appearance of healthy cells with spindle-like morphology. In Solution D, at immediately after exposure, the cells had appeared a poor morphological appearance, and cells detached themselves from the plate on 7 days after exposure.
These results suggest that Solution N is as effective as same milk. and Solution D is ineffective for PDL cells.

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The purpose of this study was to compare the colorimetric values measured with the different lighting system sensors.
Colors of the central portion of the labial surface of the 16 upper central incisors of 8 adults aged from 23 years and 1 month to 34 years 9 months (average: 26 years 3 months) and 3 M Co. Silux Plus composite resin disks (shades: U, Y, DY, L, UO, YO) 1 mm in thickness were measured with the Murakami Color Research Laboratory Fast Spectro Photometer CMS-35 FS. The FSTL (trial production for semitranslucent objects) and the FS-3 (standard type) flexible sensors were used. The lighting system for the FS-TL is circumferencial illumination/diffuse transmission receiving and the lighting system for the FS-3 is the 45/0° configuration. The CIE L*a*b*color system was used for the determination of the color difference. The data was subjected to the Student t test (p<0.05).
1) Tooth Colors: The L* values of 14 teeth out of 16 teeth, the a* values of 14 teeth out of 16 teeth, and the b*, YI and C*ab values of all of the teeth measured with the FS-TL were significantly higher than those with the FS-3. The hab values of all of the teeth measured with the FS-TL were significantly lower than those with the FS-3.
2) Resin Colors: For L, UO and YO shades backed by a white plate and for all of the shades backed by a black plate, the L* values measured with the FS-TL were significantly lower than those with the FS-3. Both for resin specimens backed by a white plate or backed by a black plate, the a*, b*, YI and C*ab values of all of the shades measured with the FS-TL were significantly higher than those with the FS-3. Both for resin specimens backed by a white plate or backed by a black plate, the hab values of all of the shades measured with the FS-TL were significantly lower than those with the FS 3. The opacity % of all of the shades measured with the FS-TL were lower than those with the F-S-3.
3) Color Difference: The ΔE*ab between the values measured with the FS-TL and the FS-3 ranged from 1.05 to 16.96 for tooth colors and ranged from 28.97 (L) to 38.08 (Y) for resin colors backed by a white plate, and ranged from 23.71 (L) to 33.97 (U) for resin colors backed by a black plate.
4) Spectral Reflectance: In the comparison of the color measurement between the FS-TL and FS-3, both for tooth colors and resin colors, the spectral reflectances measured with the FS-TL showed higher reflectance in the high wave lengths (yellowish red to red color) but lower reflectance in the low wave lengths (purple blue to blue color).

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The present study is a clinical and radiographic investigation of a total of 100 cases of oral trauma involving 175 injured teeth from 94 patients aged from 5 y 0 m to 14 y 7 m who came to our hospital during the period from Dec.1987 to Aug.1994.
There were 67 boys and 33 girls. Eighty percent of the patients were 7-10 years of age. The number of teeth involved in each injury was from one to six, but the majority of the cases involved one tooth (48 cases) or two teeth (40 cases) in each injury. The maxillary central incisors were the most susceptible teeth (74%), followed by the maxillary lateral incisors (11%) and the mandibular central incisors (10%).
Prognosis of 43 cases of luxation injuries, which were able to be followed for at least 6 months, resulted in 3 cases of pulp necrosis.
Splinting was given in 46 cases, of which 5 cases showed external root resorption. There were 3cases of avulsion, one case of extrusion and one case of root fracture.
The incidence of external root resorption was examined in association with tooth mobility at the end of the splinting period. Root resorption was observed even in some cases in which the teeth had been completely fixed, while 12 cases underwent no configurational changes at all around the root surfaces, shown on radiographs, despite a remaining slight tooth mobility at the end of the splinting period and being given no further treatment.

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The purpose of this study was to investigate the effect on the permanent successors ofthe labio-inclinated orthodontic force on the maxillary deciduous incisors. The subjects examined in the study were 16 children (7 boys and 9 girls) with anterior crossbite who were treated for crossbite in the deciduous dentition. The mean age at the beginning of the treatment was 5 years and 2 months. Two stages of lateral cephalograms were examined, one being taken at pretreatment and the other after correction of the overbite. The new points i,1 and p were established on the cephalograms. Point i was the cutting margin, and points 1 and p were the labial and paratal cervical margins of maxillary permanent central incisor on the cephalograms. Measurement factors on the lateral cephalograms were i =SN; distance from point i to SN plane, i=Occ; distance from point i to occlusal plane, common SNA, U 1-SN; inclination of the long axis of the maxillary deciduous central incisor to the SN plane and D; inclination of the long axis as the line through point i and the middle point between point p and 1 of the maxillary permanent central incisor to the SN plane. The data was compared at pretreatment and after correction. The values of i=SN and U 1-SN after correction increased and i=Occ decreased statistcally (p<0.01) to the values of pretreatment. SNA and D did not, however, show any statistical difference. It was therefore shown that the labioinclinated orthodontic force on the maxillary deciduous incisors had no great effect on permanent successors.

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The cytotoxicity of calcium hydroxide (Ca(OH)₂) on human diploid fibroblasts (WHE-7 cells) and human gingival fibroblasts (GFB cells) was examined. The growth of WHE-7 cells and GFB-cells was not suppressed by treatment with Ca(OH)₂ at 0.003%-0.03% for 24-72h. The cytomorphological changes of both fibroblasts with Ca(OH)₂ were not microscopically observed. The concentration of calcium ion (Ca²⁺) from calcium hydroxide at 0.003%-0.03% for 72 h were increased in a dose-related manner. That of calcium ion in the cell on the other hand did not change.

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We have examined the infant and baby food texture test system by comparing the test method using infant & baby food plungers and cups with the conventional test method.
A creep meter was used in the present experiment. The food used in this test was prepared in the following manner. The thickened food developed for those with dysphagia was mixed with the distilled water and processed into three different types of test food. Three types of plungers and cups were prepared and six combinations were made.
The maximum stress, maximum energy, hardness stress and adhesiveness were evaluated with various testing methods. The results of all of these measurements increased with every increase in viscosity. The cohesive levels were measured in the tests using the three types of food of different viscosity and no consistent results were obtained. The elastic modulus was different in each test and no consistent tendency was observed. The coefficient of viscosity showed the values corresponding to the three levels of viscosity only in the test using a baby food plunger and a cup.
In this infant & baby food texture test system, we used plungers and cups developed for infants. These containers fit their oral cavities and supported their oral functions. This testing system was used to examine various physical properties of food including hardness, viscosity and adhesiveness. The results obtained in the present experiment demonstrated that this system was highly sensitive and furnished reliable objective data.

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The potential anxiety for pain which is brought forth from sharp needle tips and the actual pain when the needle is inserted are the disadvantages of local anesthesia using a syringe with needle. This certainly adds to the reluctance among pediatric patients to undergo dental treatment.
The purpose of this investigation was to evaluate the efficacy of jet injection (SYRIJET MARK II®).
The subjects were 22 adults who were dental students and 10 pediatric patients who came to the Department of Pediatric Dentistry at Nagasaki University Hospital. After the application of SYRIJET MARK II®, a questionnaire was given.
The results were as follows;
1. In the adult group, according to the questionnaire and the observation of soft tissue after pricking, the SYRIJET MARK II® does not seem to be effective in decreasing pain and anxiety.
2. In the pediatric group, according to the questionnaire, many children answered that jet injection was preferable to ordinary local anesthesia using a syringe with needle. This may indicate effectiveness for decreasing pain and anxiety.
3. The jet injection may be suitable for simple treatment such as the topical anesthesia for rubber dam placement or the extraction of primary teeth.

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Malocclusion is said to be a factor related not only to dental caries, periodontitis, a poor mastication but also to mental health. The purpose of this study was to what influences the total masticatory system, using DENTAL PRESCALE(R) with normal and malocclusion for children. The assessment of occlusions which were divided into the normal, the cross bite, the open bite, the deep overbite, the upper protrusion, the edge to edge bite and the crowding was done by measurements using DENTAL PRESCALE®50 R.
The results were as follows,
1, The occlusal contact area and force on the upper protrusion, the anterior cross bite and the open bite groups showed significantly lower values than the normal occlusion, the deep overbite, the posterior cross bite, the edge to edge bite and the crowding groups.
2, The occlusal contact area on the normal occlusion group showed a significantly lower value than the deep overbite group, and the occlusal force showed a significantly lower value than the deep overbite and the posterior cross bite groups.
3, Maximum pressure in the open bite group showed a significantly lower value than the normal occlusion and the deep overbite groups.
4, The mean pressure of occlusion in the deep overbite group showed a significantly lower value than the normal occlusion, the crowding and the upper protrusion groups, and in the normal occlusion group showed a lower value than the upper protrusion group.
As these results suggested that the upper protrusion, the anterior cross bite and the open bite groups influenced the development of total masticatory system, it is supposed that malocclusions were improved in their early stage.

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It has been reported that two changing patterns (increment or decrement) of nasal skin temperature exist when anxiety/fear is recognized. The cause of those changing patterns, however was unknown. This study was conducted to investigate the relationship between the changing patterns of nasal skin temperature during dental anesthesia, with seven factors, i. e. chronological age, social age, sex, anesthetized place, quantity of anesthesia, experience under anesthesia, and nasal temperature's coefficient of variation. The following results were obtained.
1. It was suggested that school age was a turning period from the increasing pattern, which was common in childhood, to the decreasing pattern which was common among adults.
2. Borderline for the chronological age between both increasing and decreasing patterns was nine years of age, which was significant also in the field of mental development.
3. Three factors, the social age, chronological age and experience under anesthesia, were selected as influencing the changing patterns of nasal skin temperature.
4. The social age, which was one mental developmental index, was selected as being the most effective factor in the discrimination of changing patterns.

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This study was conducted to examine the effectiveness of a recall system for 12-year-olds comparing the caries status at the initial visit to a pediatric dental clinic. The recall group was consisted of 127 children who participated in a regular oral health check up system. Six hundred and sixty five children were also enrolled as a control group. The following results were obtained:
1. The caries prevalence and df-t at the initial visit (3-5 yrs.) in the recall group were 84.3% and 6.74, and those at 3 years of age in the control group were 65.6% and 3.80, respectively.
2. The caries prevalence was 65.6% for the recall group, and 93.4% for the control group at 12 years of age.
3. There were no differences in caries prevalence and DMFT at 12 years of age in the four recall groups divided according to the caries status at the initial visit.
4. The recall group had a lower number of carious teeth (DMFT) compared with control group at 12years of age (p<0.001).
5. Over 80% of all of the subjects in the recall group achieved the WHO's goals for oral health by the year 2000 i. e. less than 3 DMFT at 12 years of age.
These results suggested that the recall system was effective for caries prevention in a pediatric dental clinic. Key words: Recall system, Caries prevention, Longitudinal study

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The purpose of this present study was to clarify the changes of fluoride concentrations in the surface enamel of immature young permanent teeth with post-eruptive maturation. The surface enamel of the lower central incisors partially erupted and completely erupted were used to determine the fluoride concentrations, acid solubilitios and Ca/P. The following results were obtained; 1. The fluoride concentrations of the surface enamel decreased from the outer surface of the enamel toward the inner parts.2. The fluoride concentrations of the surface enamel in completely erupted tooth were significantly higher than those in partially erupted at the layer depth of 1-10μm. (p<0.01-0.05)3. The mean Ca/P(w/w)values ranged from 2.01-2.10 invariably.4. The acid solubilities of the surface enamel in completely erupted teeth were significantly lower than in partially erupted teeth. Key words: Post-eruptive maturation, Fluoride concentration of the surface enamel, Immature young permanent teeth.

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The present investigation was undertaken to examine how the masticatory function is affected by an acute nasal obstruction. The nasal obstruction was administered by pinching the nose of each subject with a nose clip. We measured the chewing time and number of strokes, as well as the water content of the food bolus during the mastication of peanuts. In addition, the masticatory efficiency was also calculated using the mesh separation method. Under conditions of nasal obstruction, the chewing time lengthened significantly and the number of chewing strokes also increased compared to the control. In contrast to this, there were no significant differences between the water contents of the food bolus and the masticatory efficiency in the normal condition and the condition of nasal obstruction. When the chewing time was limited to that under the normal condition, all of the above mentioned parameters, such as the number of chewing strokes, the water content of food bolus and the masticatory efficiency, decreased significantly compared to those under the control condition. These results suggest that the prolonged chewing time under a condition of nasal obstruction may possibly be attributed to a compensatory action for getting an equivalent water content of the food bolus as under the normal conditions.

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We evaluated statistically 375 handicapped patients who underwent intensive dental treatment under general anesthesia during a seventeen-year period at our hospital (1981-1997).
The results were obtained as follows:
1.375 patients consisted of 235 males and 140 females; the average age of the cases being ten years and six months.
2. Patients from the outskirts of Kagoshima City accounted for about 69% of the total.
3. In classifying the types of handicap we found that mental retardation showed the highest frequency of all of the cases, followed by autism, cerebral palsy and other handicaps.
4. About 80% of the premedication involved a combination of scopolamine and pentazocine. The greater majority of the general anesthesia administrated was inhalation anesthesia by slow induction/nasotracheal intubation.
5. The average number of treated teeth per patient was 13.6, and the average time of treatment was 159 minutes. The treatments involved composite resin filling, extraction and dental pulp treatment in the order.
6. The average age of the patients increased year by year. The results suggested the necessity for making a new care system for patients of advanced age under general anesthesia.

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To examine the bone mineral changes on the human mandibular condyle during development of the child,100 human dry skulls classified according to Hellman's dental age were selected from the collection held by the Department of Pediatric Dentistry of Meikai University, School of Dentistry. In order to evaluate the bone mineral density of the cortical and trabecular bone, frontal and lateral Xray images were obtained from the mandibular condyle, attaching an aluminum step-wedge to the film to give a reference image. Optical bone mineral density was scanned at the point of constriction of the condylar neck using a microdensitometer PDS-15 (Konishiroku Photo Ind Co., Ltd) The effective slit width was 10μm, with an aperture of 50×500μm²; the specimens were traversed at a speed of 0.2 mm/sec. The bone mineral density of the cortical bone was measured from the true profile plot by conversion the thickness of aluminum expressed as mm Al eqs. The mineral density of the trabecular bone was obtained from a power spectrum profile and it was then calculated to square centimeters.
The cortical and trabecular bone of the condylar neck showed different patterns of mineral density. Cortical bone resembled the Scammon growth curve for general somatic tissues during two period of increase; initial (IA-II A) and final (IVA-VA), with a middle period of small increases (IIC-III C). The bone matrix showed the highest period of increase during the initial stages (IA-IIA), followed a period of small increases.
This study indicates th at the trabecular bone tends to show changes in mineralization much earlier than the cortical bone. Supporting trabecular patterns need to be adapted to transmit and distribute mastication loading, while, the cortical bone mineralization is principally influenced by general growth.

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The growth of the trabecular pattern was evaluated using bite-wing dental x-ray films which were taken during a regular dental check up.
The results were as follows:
1. It was revealed that the correlation value of the trabecular pattern decreased to about 60 per cent by 9 years of age, after 10 to 14 years of age, the trabecular pattern increased to about 90 per cent.
2. The modulation transfer function was confirmed in the area of low frequency in 6 to 9 year olds, but it moved to the area of high frequency with aging. These suggested the matrix area of the trabecular pattern increased and another vacant area decreased with aging.

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Although salivary clearance rates in different parts of the mouth are known to vary, there is little information about salivary clearance on the occlusal surface of teeth. The aim of this study was to compare the clearance rates of the occlusal surface with those of different surface ares in the mouth.
The diffusant was 1 mol/l KCl in a 1.0% agarose matrix, placed in small acrylic devices which could be attached to the teeth with a resin plate. Four different sites in the mouth were chosen for taking measurements. The occlusal surface of the tooth applied to the distal area of the permanent second molars. The diffusion chambers were taken from the mouth after 10 minutes and the gels transferred quantitatively to flasks containing 100 ml of 100 ppm NaCl. The fluid was agitated intermittently for 1 h and analyzed for pottassium using atomic absorption spectrophotometry.
For 5 subjects, the clearance rates of potassium chloride from the gel were lowest in the upper anterior buccal regions and were highest in the lower anterior lingual regions statistically. The clearance rate for the lower occlusal surfaces were higher than those of the upper occlusal surfaces. The location of the parotid duct opening seemed to affect the clearance rates in the upper posterior occlusal region. In the lower posterior occlusal region, the flow of saliva from the submandibular and sublingual saliva affect the clearance in the posterior occlusal region.

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Dental treatment before liver transplantation was administered to a five-year, three-month-old girl and a four-year, three-month-old boy. In the literature it was difficult to find a suitable course of treatment for dental caries before the operation. We therefore present a protocol for dentists facing similar cases.
Infection from the teeth is the most important complication to be avoided. In consultation with endodontists and anesthesiologists, we decided to extract carious teeth with pulp exposure and to give antibiotics for one day.
1) In the first case, amalgam alloy restorations were placed in_??__??__??_under a rubber dam, and _??__??__??_ were extracted under 40% N2O in the two months prior to the operation. To insure hemostasis, we used sutures and a surgical splint with a periodontal pack for a week.
2) Amalgam alloy restorations were placed in_??__??__??_in case 2. We advised the patient's mother to get in touch with us immediately if much bleeding, colic, gray feces, fever, or jaundice appeared. After being subjected to the foregoing dental treatment, our patients received liver transplantations, maintained effective oral hygiene procedures, and are doing fine.

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Regional odontodysplasia is a rare developmental anomaly of hard tissues in which enamel and dentin are involved. It most commonly affects the maxillary anterior teeth of both the permanent and primary dentition. This paper describes the case of 7 year and 9 month old boy with regional odontodysplasia in the maxillary left anterior teeth. The findings were as follows.
1. The maxillary left incisors and canine were affected with regional odontodysplasia, since both enamel and dentin were hypoplastic and hypocalcificated. Dental radiographs showed the typical appearance of ghost teeth and there was a lack of contrast between the enamel and dentin.
2. Amorphous calcified materials were found on the surface of the enamel, particularly in the cervical area in which the formation and calcification of the enamel were irregular.
3. The formation and calcification of the dentin were poor and interglobular dentin was found everywhere, although the odontoblasts appeared to be normal in form.

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The Ellis-van Creveld syndrome is a rare herediatry disorder accompanied by chondrodysplasia, polydactly of the hand, ectodermal dysplasia, and congenital heart malformations. A 6-year-5 month old male was first examined at the Pedodontic Clinic of Kobe Children's Hospital because o-f aesthetic problems.
The skeltal anomalies, ectodermal dysplasia, polydactly of the hands and congenital heart disease were observed. The dental anomalies were congenital missing teeth, malformed teeth, occulusal anomalies, an oral vestibulum anomaly, and a superior-inferiorlabial frenumanomaly. The mesio-distal width of the deciduous teeth and the width of the dental arch were smaller than the standard average. Analysis using cephalometric radiography revealed a relatively flattened genial angle. Upper and lower anterior acrylic partial dentures were constructed to maintain space, and to improve mastication.

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2 p trisomy is a syndrome due to a recombination of chromosomes whereby a small amount of chromatin is attached onto the short arm of chromosome 2. It is said that the life expectancy of a patient suffering with this syndrome depends upon problems with the respiratory and circulation systems.
We attempted orthodontic treatment for a young girl with 2 p trsisomy syndrome whose chief complaint was difficulty in tooth brushing due to molar inclination. We designed a plan of treatment in two steps. For the first step we planned to fit a bite plate for uprighting the lower first molars and to assess the adaptability of the patient and her mother to orthodontic treatment. For the socend step we applied a 3D lingual arch for uprighting the lower first molars and spreading the lower dental arch. The result was comparatively satisfactory with respect to the upper and lower dental arch and tooth brushing. Upper bilateral incisors, however, erupted in a twisted fashion and dental caries were found to appear in some teeth.

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Children with supernumerary teeth are not rare. Although there are a number of reports concerning two supernumerary teeth, reports on eruption of more than three supernumerary teeth on the same site are rare. The incidence rates of permanent fused teeth are lower than those of deciduous fused teeth, estimated at 0.05 to 0.35%. The rates are approximately one tenth as low as the rates of deciduous fused teeth. A fused normal maxillary central incisor among the supernumerary teeth is in particular extremely rare in Japan.
We had an opportunity to treat a 9 years 4 months boy who visited our Department of Pediatric Dentistry, Suidobashi Hospital of Tokyo Dental College, complaining of supernumerary teeth. On the first examination, he appeared to have developed two supernumerary teeth on the median maxilla and a fused tooth consisting of another supernumerary tooth and the right maxillary central incisor to form twin teeth.
The general condition of the patient showed no abnormalities. A simple corn type of a supernumerary tooth had erupted in the left maxillary central incisor region, and another supernumerary tooth had erupted on the palate site of the right maxillary central incisor with only its caput erupting. The shape of the right central incisor appeared as fused tooth consisting of a supernumerary tooth and a labial portion of the incisor. Dental X-rays found that the simple corn shaped fused tooth had only one tooth root and that the left maxillary central incisor had not erupted. The right maxillary central incisor had a simple corn or double corn shaped appearance, indicating that the twin teeth were formed by the supernumerary tooth and the incisor. The X-rays also revealed that the twin teeth had a branched dental pulp on its crown with a common pulp on its root.

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We reported a case of Cleidocranial dysostosis which had been observed in our pediatric clinic for 6 years. The patient, who was a 13-year-old boy, visited our clinic with a complaint of the delayed eruption of upper front permanent teeth. Small stature with partial hypoplasia of the clavicle, and a bellshaped thorax and underdevelopment of sinus frontalis were found as general clinical findings. Persistence of 7 deciduous teeth, delayed eruption of 13 permanent teeth and 6 supernumerary teeth were also found as aspects of the oral status. All of the deciduous teeth and impacted supernumerary teeth were extracted. Marsupialization treatment was applied for 6 impacted permanent teeth. Traction treatment was applied for 3 impacted teeth which had not been exposed after the observation period of 12 months. Eleven impacted permanent teeth were exposed after 6 year 3 months from the initial visit.

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The patient, a eight years old boy, was refered to the Dental Hospital of Meikai University School of Dentistry for a detailed dental examination of delayed eruption of the upper left central incisor. His medical history and oral findings showed no demonstrable abnomalities at the site of the upper left central incisor except for delayed eruption. The radiographical examinations revealed that the root of the upper left central incisor had been almost completed, and the cusp of the tooth was still impacted at the level of the cervical area of the right central incisor. According to the analysis of the dental study model, the arch length discrepancy showed shortage of 3 mm.
The 3 D-Quard Herix appliance was applied at the upper dentition for expansion of the upper dentition and then the impacted tooth was guided in its eruption by fenestration and traction procedures. The tooth was finally aligned with the normal dental arch using the direct-bonding system.

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