We conducted overall research on the prevention and progress control of caries in infants. The subjects of this research were children from 1 to 15 years of age. We conducted this research from June to October of 1999. We distributed the Cariostat®, Mucount®, dental examination forms and questionnaries among the department of pediatric dentistry at 29 colleges and universities in Japan. We also researched the content of dental examination, the caries activity test and also the questionnaire survey. Based on the result we conducted the statistic processing on the subjects, especially on those in the survey ranging from 1 to 3 years of age and we obtained the following results.
1. There was a significantly relationship individually regarding Mucount®, CSI and Cariostat®, showing that these can be used for mesuring the actual satate of the oral cavity, in other words the caries activity in the mouth.
2. With considerable eating between meals, the drinking of spot beverages, and the delay in wearing, it was shown that the risk of caries become significantly higher.
3. The caries activity nature test can be used for showing the risk of caries.

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This study was carried out on six-week-old (corresponding to schoolchild age in human beings) male wistar rats. We estimated the effect of zinc and activated vitamin D₃ (VD₃) administration on bone formation induced by endochondral ossification.
The animals were divided into 4 groups. The control group was fed a normal diet and administered olive oil orally. The experimental groups were fed the standard diet (VD₃+ group), the 50%-low-zinc diet (Zn-VD₃+ group), and 150%-high-zinc diet (Zn+VD₃+group) respectively. They were given orally administered 1α-OH-D₃(0.1μg/kg,3 times/week) which was disolved in olive oil.
1. Scanning electron microscope findings: Compared with the control group, the VD₃+ group showed expansive areas of bone resorption and formation in the matrix with active bone formation, while the Zn-VD₃+goup showed indistinct bone lacunae where irregularly scattered calcified microdepositions and distributed collagen fibrils were seen. Compared with the VD₃+ group, the Zn+VD₃+group showed that active bone formation was seen as well bone formation and resorption areas mixed.
2. Transmission electron microscopy: Compared with the control group, the VD₃+ group showed increased osteoblastes that undertaking active bone formation and that young osteocytes increased. Osteoclasts increased and the ruffled border was well developed. In the Zn-VD₃+group, inactive flat osteoblasts increased, and active osteoblasts decreased. In the Zn+VD₃+group active osteoblasts were abundant with endplasmicorgan, and young osteocytes increased. In the osteoblasts and osteocytes, endplasmicorgan was well developed, and increased Golgi, free rebosome and lysosomes. Osteoclasts increased and the ruffled border was well developed and came out as mulchdirection projections.
Form the above results, it was shown that adequate zinc intake would promote the action of 1α-OH-D₃, because the present study had revealed that bone structure was damaged by insufficiency of zinc intake_

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This study aimed at assessing the oral health effects among schoolchildren participating in a school-based oral health program for a period of 18 months. This paper uses data from a longitudinal oral health survey conducted among 708 elementary schoolchildren between six to twelve years of age. Self-administered questionnaires were used to collect information during the program. Clinical examination continued to be carried out before and after the program. At the end of the program, the parents completed a questionnaire on the changes in oral health related attitudes in their children.
The results were as follows:
1) Among those who reported brushing three times or more per day, there was a significant increase between the baseline and the end of the program.
2) Concerning their own reasons for brushing their teeth, the number of those who responded that toothbrushing was a habit significantly increased between the baseline and the end of the program.
3) Most of the respondents particular paid attention to oral hygiene for maintaining oral health during the program.
4) Most of the parent respondents pointed out a positive dental attitude relative to the changes in oral health related attitudes in their children.
5) Each age group showed a decrease in the number of DT between the baseline and a year or two later.

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The aim of the present study was to evaluate the function of cementum on root resorption resulting from mechanical stress in rats, by means of the rabbit-osteoclast culture in the serum of rabbits on a low calcium diet.
Mechanical stress was created by insertion of an elastic between the first and second maxilary rat molars for two days, and tartrate resistant acid phosphatase (TRAP) positive cells in periodontal tissues were induced and appeared. However, root resorption was not observed with the mechanical stress. Cellular and acellular cementum obtained from rat molars were used for the present examinations and the following results were obtained.
1. Rabbit-osteoclasts were cultured in serum obtained from rabbits on a low calcium-diet on the root. Rabbit-osteoclasts were observed using scanning electron microscopy. As a result, the rabbitosteoclast resorbed acellular cementum on the rat root region with the mechanical stress, but it did not resorb the cellular cementum on the rat apical root region. The same resorption reaction also occurred on the cellular and acellular cementum without applying mechanical stress.
2. To examine the effect of cellular cementum on the culture of osteoclasts on a slice of calf bone in serum obtained from rabbits on a low calcium-diet, minced cellular rat cementum was added to the low calcium serum medium, and the number of osteoclast was inhibited by 70% compared to the control (p<0.01). The effect of inhibition by the cellular cementum on the culture increased with mechanical stress with respect to the rat root. These results suggest that cellular cementum could react with mechanical stress and strengthen the resistance to root resorption.

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A clinico-statistical survey was performed in 1999 involving 7,000 children had visited the pediatric dental clinic of the Tsurumi University Dental Hospital during approximately 9 years from September 1987 to July 1996, and were the subjects. Among these 7,000 child patients, children who underwent treatment for malocclusion were investigated. The targets of the investigation were those cases diagnosed as having any kind of malocclusion, the difference in gender, the incidence of malocclusion, the number of the appliances used, and the time span of the treatment.
The results were as follows:
1) The number of cases diagnosed as having any kind of malocclusion and which underwent treatment was 1,192 (17.0%), and more girls (668) were treated than boys (524).
2) The most predominant malocclusion was anterior crossbite (32.5%), followed by space shortage (17.1%), upper anterior protrusion (14.4%), and inlocking (13.1%).
3) The percentage of the cases complaining of malocclusion at the first visit was 52.3%, with the highest percentage concerning anterior crossbite (61.7%).
4) The number of appliances used was 1,740. Among these 1,740 appliances, the most frequently used appliance was chin cap (27.1%), followed by lateral expansion appliance (15.6%), biteplate (15.0%), and multi-brackets appliance (14.4%).
5) The youngest average age using the appliance was 7 y 2 m for chin cap, followed by activator, and the oldest was 12 y 1 m for multi-brackets appliance.
6) The average time span to obtain acceptable occlusion from the start of treatment was longest for biteplate (1 y 10 m). Those for chin cap and habit breaker were longer than 1 year, whereas those of the other appliances were less than 1 year.
7) Three years two months of the average treatment time span was the longest, this being for chin cap, followed by biteplate. Those of the other appliances required between 1 year and 2 years.

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In order to evaluate the effect of physical training and calcium intake on bone formation, we used thirty Wistar male rats, six weeks of age weighing around 160 g, for the present study. The animals were divided randomly into six groups as follows: group A (standard diet and no exercise), group B (standard diet, one hour training per day), group C (standard diet, two hours training per day), group D (calcium deficient diet, no special training), group E (calcium deficient diet, one hour training per day), group F (calcium deficient diet, two hours training per day). The results obtained were as follows:
1. Body weight
There were significance differences were found when group E was compared with group A, group B, group C and group D.
2. Histopathological findings
Compared to group A, the number of hypertrophy chondrocytes decreased in group B, while the calcified matrix increased and more chondroclast were seen. The endochondral ossification was more active. In the primary spongy bone, the number of osteoblasts surrounding the calcified matrix increased and the number of osteocytes increased too.
The cartilage width of group C was winder than that of group B, and there were more chondrocytes. The chondrocytes in the zone of proliferation and hypertrophy arranged regularly and closely. The intrusiveness of calcified matrix was easily seen and the endochodral ossification was active in group C.
Comparing group D to the control group, we found some changes as follows. The width of the reserve cartilage zone increased, chondrocytes in proliferation zone deformed and decreased, the calcified matrix and chondroclast decreased, accompanied by a decrease in calcified matrix absorption and delay in the trabeculae formation while the newly formed trabecular was thin.
In contrast to group D, group E showed that the number of reserve zones decreased, the chondrocytes in proliferation arranged closely, the intrusiveness of calcified matrix increased, and the trabecular formation decreased as well.
In contrast to group E, group F showed that the number of chondrocyte and chondroclased decreased, and trabecular formation was hardly seen.
These results suggested that the physical training could improve bone formation but this effect could not be seen when rats suffered from a calcium deficiency.

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We investigated whether the recall interval is related to the incidence of caries according to the degree of susceptibility to caries at each dentition period. Among 2797 children who first visited our pediatric dental clinic for ten years, from 1985 to 1994,1329 patients responded to periodical recall for one year or longer. These were the subjects of this research. The patients were first classified into a high risk or low risk group for dental caries according to the number or kinds of teeth with caries or restoration. Each group was then subdivided into four groups according to age at the first visit; these groups were further subdivided into those who returned at regular and irregular intervals.
The results showed that the number of newly developed caries increased markedly in the high risk group for dental caries for those who had their first visit up to three years of age at a two-mouth interval recall compared with a one-mouth interval recall. The incidence of caries decreased among children whose first visit was during the time from three to under six years, as primary dentition changed to mixed and permanent dentitions when recalls were performed for the same interval. However, such a decrease was not observed within either interval group as mixed dentition changed to permanent dentition, among children whose first visit was from the age of six to under ten. The children recalled regularly showed a greater decrease in the incidence of caries in all dentition periods, at regular interval recall compared with irregular interval recall, while those who were recalled irregularly showed a greater increase. Taken together, recall is more effective when it begins at a younger age, and the degree of caries and the time of the emergence of permanent teeth should be considered in setting the interval.

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It seems in general that the videotaping is one of the most economical and convenient media to record moving pictures, and that the recorded images are of sufficient quality to evaluate the behavior of children during dental treatment. Videotaping has a week point however: i. e. since the data format of videotapes is sequential, it takes a certain period of time to search the necessary scenes. In this study, we designed a digitized observation system of moving pictures to search the necessary scene without waiting time for evaluation of the behavior of children.
Video movies of two-year-old patient, which were taken during dental treatment in our clinic 5times, were used for the system. The movies were digitized using a Motion-Jpeg encordable card and captured by a computer as AVI files. The total volume of the digitized movie files(79 m 3 s)amounted to 2.11 GB. The quality of the movies was 16-bit-color and 640×480 pixels. The frequency of capture was 15/sec. We therefore calculated that a digitized 10 minute movie file had 9000frames. The starting frame of each treatment scene(the patient sitting on the dental chair, injection, restoration by turbine, etc. ) in the file was marked and the serial number of frames from the top of the file was taken in the database. After that, a retrieval system was made to play the digitized movies from arbitral frames in the database.
The retrieval system was then tested. The subjects were ten pediatric dentists(5 of them used the retrieval system and the others used video tapes). Both groups described the score of behavior evaluation cased on the rating scale. The results of the test were as follows.
1. The scores of behavior evaluation were not very different in both groups.
2. In the retrieval system group, not only was the time of the operation equipment short, but also both the time of observation and description was shorter than that of the group using the videotapes.

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The purpose of this study was to attempt to apply the magnetic attachment (Magfit^TMEX 400 W) as retainers for denture type spacemaintainers and orthodontic appliances in pediatric dentistry.
We studied the effect on the retention force of magnet dentures according to the direction of traction, number of anchor teeth, kinds of teeth for the anchor and the angle of the keeper to the anchor teeth using the dental study model of the mixed dentition. These data were statistically analyzed using ANOVA and subsequently Fisher's PLSD.
We moreover compared the retention force of the denture with Adamus clasps with magnetic attachments in the clinical cases. These data were statistically analyzed using the student's t-test. The results were as follows.
1)The optimum angle of the attached keeper to the tooth axis was 10°in the maxillary first and second desiduous molar and the maxillary first molar, when the retention force of the denture type appliance with a different keeper angle,0°,10°and 20° was investigated.
2) As the number of anchor teeth increased from two to four, the retentive force was increased. The comparatinely high retention force when first deciduous molar was included as an anchor tooth was also observed.
3) Concerning the relationship between retentive force and the tractive direction of denture type appliance, it tended to show a high retentive force when the anchor teeth were located near the tractive direction.
4) The retentive force of the appliance with magnetic attachment was 1.5 fold higher than that of with Adamus clasp in the clinacal cases. In all of the clinical cases, the retentive force of the appliance with magnetic attachments also showed a higher retention force than that with the Adamus clasps.
These findings suggested that the magnetic attachments can be useful as retainers for denture type appliances in pediatric dentistry.

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Many authors have developed laser based diagnosis systams for dental caries.
In Recent years, DIAGNOdent® was reported as having reproducibility in permanent tooth caries, but in caries of the primary teeth this was not clear.
The aim of this study was to evaluate the relationship between the laser-based caries diagnosis system DIAGNOdent® and the digital radiographic methods for the primary teeth.
Seventeen primary teeth and fourteen permanent teeth with caries were prepared for the examination. The approximal surface of each tooth was examined using DIAGNOdent® and subsequently digital radiography of the teeth was taken for the radiographic diagnosis of each surface. The radiography was analyzed with 256 gray scales using a computer system and the depth of the caries regions was measured by comparison of the density of the caries surface healthy regions of the tooth.
The values of under thirty were 0.06±0.04cm and 0.08±0.01cm of caries depth, the maximum values as 99 were 0.18±0.04cm and 0.23±0.03cm of caries depth for the primary and the permanent teeth.
The correlation coefficients between the radiographic analysis of the caries depth and the DIAGNOdent® analysis were r_s=0.800(p<0.01)for the primary teeth and r_s=0.692(p<0.01)for the permanent teeth.
These results show a high correlation between the results with laser diagnosis systems and those with the digital radiograph methods.
In conclusion, this laser diagnosis system is a useful method for dental caries diagnosis.

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We developed a three-dimensional magnetic head sway measuring device to measure and analyze head sway for use in assessing shifts in the occlusion.
We evaluated the precision of this device and the reproducibility of measurements using this system on adult subjects, and obtained the following results:
1. This device can measure head sway when set up 50 cm in front of subjects with an apparent margin of error of under 0.3 mm.
2. When we measured the head sway of adults subjects in a static position using this system, the results gave convincing evidence of individual variation when standing but no convincing evidence of individual variation when sitting, from day to day or by time of day.

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We investigated the relationship between past dental treatment experiences and dental fears which patients feel at present using a questionnaire and Visual Analog Scale (VAS). The subjects were eighty-seven students in the school of dentistry. The following conclusions were drawn.
All of the subjects had at least one experience of dental treatment.51.7% experienced some agony with dental treatment.35.7% had not experienced any agony.12.6% could not remember any agony.9% had experienced restraining during dental treatment.
In the valuation of dental fears based on VAS, the minimum value was 0 mm and the maximum was 88 mm, the average was 35.8 mm. Firstly, we looked at the relationship between agony and VAS, the score of that with experience was 42.1 mm, the score of those without experience was 26.4mm. There was a significant difference between the score as those with experience and those without.
Secondly, when we looked at the relationship between restraining and VAS, the score of those with expeience was 53.0 mm, the score of those without experience was 33.3 mm. According to the statistics, the scores of those with experience and without experience of this experienced and the inexperienced showed a significant difference.
The result of this investigation clearly shows that those who had experienced some agony and restraining during dental treatments were affected by this and now experience fear during dental treatment.

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We experienced a very rare case of a patient with three impacted supernumerary teeth in the midline region of the maxilla. The patient, a boy, was 9 yrs 8 months old when he was first seen. His chief complaint was mid-line diastema. His past medical history showed nothing of significance. Family history showed nothing of significance; his parents and younger sister showed no abnormality in the number of teeth. The intraoral findings were as follows: The patient was at the III A stage. The maxillary central incisors were 5.6 mm apart. The bilateral lateral incisors were erupting on the lingual side and showed a cross-bite with the mandible. X-ray examination revealed no abnormalities in the number of teeth other than the three supernumerary teeth in the maxillary mid-line region. One supernumerary tooth was found on the mesiolingual side of the right central incisor in the normal direction. The second supernumerary tooth was inverted and extended from the neck of the left central incisor to the palate, and the third supernumerary tooth was located somewhat right of the midline, lying horizontally with the apex directed toward the labial side and with the crown directed toward the palate. At the apex of each erupted maxillary central incisor, there was stenosis narrowing at one third of the area of the root apex due to the supernumerary teeth. The three supernumerary teeth were extracted from the palate under local anesthesia.
The extracted supernumerary tooth that had been in a normal direction was 15.38 mm long,5.85mm wide, of the incisor type, and with the apex unclosed. The extracted supernumerary tooth that had been inverted was 14.15 mm long 6.10 mm wide, of the canine type, and with the apex closed. There was resorption in the apex of this tooth, which had presumably been in contact with the horizontal supernumerary tooth. The extracted supernumerary tooth that had been horizontal was 14.84mm long 6.20 mm wide, of the canine type, and with the apex closed. The distal third of the apex of this tooth was curved toward the labial side. During the past 64 years, there have only been 15 reported in Japan of the cases of three supernumerary teeth without any systemic disease, including the present case. This abnormality is extremely rare. One month after extraction, occlusal guidance to improve the malocclusion was begun to obtain a better outcome.

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An eight year old boy was referred to the Kyushu University Dental Hospital complaining of delayed eruption of the upper left central incisor. Based on his medical history impaction of permanent successor was suspected due to traumatic injury of the primary tooth at three years old. Radiographical findings revealed that the impacted tooth crown inclined by 90 degrees to the palatal side and crown-root angulation was 45 degrees. The purpose of the treatment was to draw the impacted upper central incisor into the oral cavity, and lead it to its connect position in the upper dental arch. However, the case presented special difficulty as a result of the very severe, and rare palatal inclination and shape of the impacted tooth. A unique traction appliance was applied to draw the impacted tooth to the labial side with a suitable elevation-speed. Two months later, the tooth crown erupted into the oral cavity. The tooth was finally successfully aligned in the upper dental arch by, use of the lingual arch appliance and the sectional arch wire without causing any uncomfortable symptoms to the tooth and any alteration to the dental pulp.

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Transposition of teeth has been observed and reported in the past.
In most of these cases, the treatment of transposition of the teeth begins at Hellman's dental stage III B.
In this case, we found them at Hellman's dental stage III A and conducted for a long term investigation.
Causes of transposition of the teeth seemed to be the malposition and the wrong direction of the canine and the first premolor.
The following had to be considered in the treatment of this case.
1. At, the early stage of Hellman's dental stage III A, we recognized transposition of the teeth and put this under observation for a long period of time. We then made best choice of starting the treatment.
2. We needed to maintain the eruption space in order to promote the natural eruption of the transposition of the teeth.
3. We needed to know the root formation, position, direction and existance of impediment factors (such as odontoma) to diagnosis the natural eruption of the transposition of the teeth, so using 3 DCT was very useful.
4. At Hellman's dental stage III B, we decided the order of tooth arrangement, and it was then possible to shorten the treatment period.

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The objective of this study was to clarify the effect of CO₂ laser irradiation on the soft tissues during oral surgery in children. The CO₂ lasers were used for 35 subjects, aged between 1 and 14, having main indications for frenectomy from 1994 to 1999 in the pedodontic clinic of Tokyo Medical Dental University. The CO₂ laser was used in a 2-watt or a 3-watt continuous mode in all of the clinical cases.
The advantages of CO₂ laser as an instrument in surgical procedures for children were as follows.
1. Soft tissue cutting was efficient with minimal bleeding, giving a clear operative field during operation. There was no need for the use of sutures as application of CO₂ resulted in controlled bleeding both during the operation and after the operation.
2. The process of the operation was simple and less time was required.
3. There was no need to give analgesics as post-surgical pain was eliminated.
4. The contraction and scarring of the wound was decreased or was eliminated. As a result, the appearance of the healed tissue was nearly that of the normal tissues.
Considering above mentioned advantages, the use of CO₂ laser proved to be very safe and effective for soft tissue surgery in children. We conclude that using CO₂ laser might well be an effective mode of treatment in oral surgery for children.

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A case of partial anodontia affecting numerous teeth in both the primary dentition and permanent dentition in which occlusal guidance was carried out for about ten years, is reported.
At the initial examination, a 3-year-1 month-old girl showed four congenitally missing teeth at _??_, conical tooth at __??_, retarded eruption at __??_.
According to the cephalometric analysis, the maxilla was underdeveloped. The maxillary dental arch was expanded using a removable appliance with a screw to correct cross bite as she grew. Difficulties in mastication and esthetic problems were treated using a space maintainer. There were also psychological effects.
At the present time satisfactory occlusion of the premanent dental arch has been obtained with the space maintainer. A long-term oral management with orthodontic, prosthetic treatments and dental implantation will be needed in the future.

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