The purpose of this investigation was to analyse the longitudinal change of the df teeth ratio of the deciduous teeth and to detect the relationship between the change of the df teeth ratio and the the number of diseases. According to the number of diseases, we divided the subjects into 4 groups. The 4th group were the children whose number of diseases was above 4 or with both sever phisical and mental handicaps.
The results were as followed:
1. In the first examination, there were 495 subjects. The mean age for both boys and girls were 2year old and 1 month.
2. The group with sever handicaps (the 4th group) showed the highest df teeth ratio longitudinally compared with the other 3 groups.
3. Enamel hypoplasia was recognaized in approximately 56.8% of the group with sever handicaps.
4. In the anterior and posterior teeth of the group with sever handicaps, the df teeth ratio of the enamel dysplasia group inceased longitudinally more than that of non enamel dysplasia group.
5. Concerning the space of the dentition, for both the group with sever handicaps and the 2nd group without space, the df teeth ratio was remarkable. In the group with sever handicaps the longitudinal increase of the df teeth ratio was especially more remarkable.
6. Concerning the plague index, in the first exammination the group with sever handicaps had a statistically significant variation of the distribution compared to the 2nd group.
7. The group with sever handicaps that had a high plaque index in the first examination remarkably increased the gain of the df teeth ratio to a greater extent than that had a low plaque index.
8. Concerning the longitudinal change of the df teeth ratio related to the caries activity, it was clear that the gain of the df teeth ratio of the group with sever handicaps increased much more than that of the 2nd group.
9. As for the pit and fissure sealant, the 1st group showed the highest prevalence and as the number of diseases increased, the prevalence of the pit and fissure sealant did decrease.

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The purpose of this study was to evaluate histopathologically the 4-META/MMA-TBB resin as a direct pulp capping material.
Fifty-three Class V or Class I deep cavity were prepared in four beagle dogs under general anesthesia. Without local anesthesia, cavity floors were intentionally perforated to expose the pulp. Sunmedical Co.4-META/MMA-TBB resin “Orthomite Super Bond” was directly applied to the exposed pulp (SB group). As the control, Neo Dental Chemical Products Ca(OH)₂ medicament “Calvital” was used as a direct pulp capping agent (CV group). Both in the SB groups and in the CV groups, the cavities were lined with “Orthomite Super Bond” and filled with the Kuraray Co. composite resin “Clearfil Photo Anterior” after etching and bonding. After 14 and 30 days, the histo-pathological responses of the pulp were analyzed. The number of the cases in each of the groups was: SB-14 days (17 cases), SB-30 days (14 cases), CV-14 days (13 cases) and CV-30 days (9 cases).
1 ) Inflammatory cells infiltrated into the pulp: 4 cases (23.5%) in the SB-14 day group,8 cases (57.1%) in the SB-30 day group,5 cases (38.5%) in the CV-14 day group and 2 cases (22.2%) in the CV-30 day group.
2 ) Partial necrosis of the pulp was observed in the 2 cases (14.3%) in the SB-30 day group. Complete necrosis of the pulp was observed in the 2 cases (15.4%) in the CV-14 day group and in the 2 cases (22.2%) in the CV-30 day group.
3 ) Circulatory disturbances in the remaining pulp: 10 cases (58.8%) in the SB-14 day group,6cases (42.9%) in the SB-30 day group,6 cases (46.2%) in the CV-14 day group and 4 cases (44.4%) in the CV-30 day group.
4 ) Macrophage migration aroud the interface between pulp and capping materials: 8 cases (47.1%)in the SB-14 day group,10 cases (71.4%) in the SB-30 day group,7 cases (53.8%) in the CV-14day group and 4 cases (44.4%) in the CV-30 day group.
5 ) Dentin bridge formation: 12 cases (70.6%) in the SB-14 day group, none in the SB-30 day group,1 case (7.7%) in the CV-14 day group and 3 cases (33.3%) in the CV-30 day group.
6 ) In all of the 4 groups, the SB-14 day group showed the best histo-pathological results, however, the results of the SB-30 day group was poor.

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We have previously reported that the horizontal dimensions were predominantly inherited in the murine mandible, using one model of MRL/n strain mice with large mandibles and C 57 BL/6 By mice with small mandibles in the parents, and F 1 and F 1' hybrids used as reciprocal cross.
In this study, we added two models of different inbred mice in the same manner in the previous experiment, these being were RF/J and C 57 L/6 J strains with large mandibles, and SMIJ and A/HeJ strains with small mandibles in the parents.7 (RF/J female × SM/J male) F 1 and 11 (SM/J female × RF/J male) F 1', and 22 (C 57 L/6 J female × A/HeJ male) F 1 hybrids were used. The inter-landmark distances of the right mandible were measured using an electronic digitizer. Based on the mandibular plane as the X axis, some inter-landmark distances were divided into X-components for the horizontal and Y-components for the vertical dimensions. In all of the F 1 types of these three models, the X omponent of the distance from the mental region to the mandibular angle and the distance from the-c mental region to the condylar process showed the same or higher trends as the parents with large mandibles. Since these two inter-landmark distances indicating anterior growth of the mandible significantly showed dominance in the large characteristics of the murine mandible, we suggest that these lengths of the two distances become the phenotype to elucidate the gene affecting their growth.

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The present study was conducted to investigate the relationship between the longitudinal changes of the caries activity and caries status in 468 children who participated at nine-month, eighteen-month, twenty-five-month and thirty-seven-month dental health screenings in Oku-cho, Okayama, Japan. Oral examinations and Cariostat tests of caries activity were conducted at each screening.
The following results were obtained.
1 ) In Oku-cho both the caries prevalence and mean def score was lower than the national mean values at each age.
2 ) The proportion of the subjects who had a high Cariostat score increased according to age.
3 ) Cariostat test results were significantly related to subsequent def scores.
4 ) There was a different caries status based on the transition of the Cariostat score from 9 months to 37 months.

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The enamel bonding ability of three composite resin systems including a self-etching primer was evaluated and compared in vitro. Also, enamel bonding was compared between the enamel conditioning using the conventional phosphoric acid (Scotchbond^TM Etchant/3 M) and that using the self-etching primer for each product.
The composite resin systems used for this experiment were Clearfil® Liner Bond II / Clearfil® APX (Kurare): LB, Mac Bond System/ Palfique® Light Posterior (Tokuyama): MB, and Fluorobond/Lite-fil II P (Shofu): FB. After standardized cavities were prepared on extracted human molars, the composite resins were filled according to the manufacturers' instructions except for the comparative use of phosphoric acid for the control groups. The thermal cycling test followed by the dye penetration test was performed to evaluate marginal microleakage at the enamel-composite interface.
Based on the findings in this study, the following conclusions were drawn,
1. A significantly better enamel bond was obtained by the use of phosphoric acid when compared with that using the self-etching primer for all of the experimental composite resin systems.
2. The LB and MB groups showed significantly better enamel bond than the FB group for either conditioning using phosphoric acid or a self-etching primer. Also, the MB group provided better results than the LB group.
Further improvement, therefore, is necessary for the enamel bond for the experimental systems including the self-etching primer.

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The marginal seal of composite resin restorations was compared in vitro between the preventive class II restoration (Surmont,1990) and the conventional class II restoration, and also between the 15-second etching using phosphoric acid and maleic acid. The shape of the proximal box followed that for the traditional class II amalgam restoration for either preparation and the shape and size were approximately standardized. For the preventive restoration, extension through the occlusal groove was minimized and no dove-tail retention form was applied to use the sealant for sealing the rest of the pits and fissures. All of the preparations and restorations were performed on extracted human premolars, using Scotchbond^TM Multi-Purpose system and Z-100 (3 M), except for the comparative use of phosphoric acid etchant (Scotchbond^TM Etchant). Repeated compressive stresses were applied on the isthmus area on the composite resin restoration for 10,000 cycles, or thermal stresses of 40°C and 60°C were applied alternately for 100 cycles. The dye penetration test was then performed to evaluate the microleakage at the cervical, proximal, and occlusal margins.
The results showed that no statistical difference in microleakage was found between the preventive and conventional restorations in both the maleic acid and phosphoric acid groups. However, the phosphoric acid group generally demonstrated a better marginal seal than the maleic acid group except for the cervical margins. Although no clear difference was found at the cervical margins among experimental groups, most cases prevented microleakage into the dentin.

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In order to know the relationship between milk and dental caries, the effect of milk rinse on plaque fluid was investigated. Plaque samples were collected from 13 Japanese male dental students. Prior to the plaque collection, all of the subjects refrained from oral hygiene for 48 hr. Supragingival plaque samples were collected from one-half of the mouth of the subjects. Supragingival plaque samples were then collected from the other half of the same mouth following a rinse with milk. Plaque fluid was then isolated by centrifugation and analyzed for calcium, phosphate, magnesium, sodium, anmmonium, potassium, chlorine and pH. The degree of saturation of the plaque fluid samples was calculated using the data, and the effect of the milk rinse on the degree of saturation was studied.
The pH of the plaque fluid decreased significantly with the milk rinse. If the effect of the milk rinse was only on the pH, the degree of saturation with respect to the enamel of the plaque fluid should have decreased and the enamel should have been liable to decalcification. The calcium ion concentration in the plaque fluid increased, however, significantly with the rinse with milk. It consequently prevented the decrease of the degree of saturation with respect to enamel in the plaque fluid, and acted to offset the demineralizing effect by the decrease of pH.

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Previous studies have shown that the bite force of children can be measured using a pressure-sensitive sheet known as “Dental Prescale” (Fuji Photo Film Co. ). A common method for measuring the bite force using “Dental Prescale” has however not yet been established.
The first aim of this study was to compare the accuracy of two types of pressure-sensitive sheets, “Dental Prescale 30 H” and “Dental Prescale 50 H” (Fuji Photo Film Co. ). Twelve children with normal occlusions; 8 boys and 4 girls (avg.8.4 years) were selected. The maximum bite force was recorded by using “Dental Prescale 30 H, type R (pressure measurement range,3-13 MPa)” and “Dental Prescale 50 H, type R (5-120 MPa)”. The proportion of bite tests from the subjects which fell within the pressure measurement range of the two types of “Dental Prescale” was 82.4% for 30 H, and 98.1% for 50 H. “Dental Prescale 50 H” should therefore be used for measuring the bite force of children because 30 H could not measure the 17.6% of the bite force test results which were greater than its maximum pressure measurement level.
The second aim of this study was to determine the best length of time that clenching should be maintained when measuring maximum clenching in children using “Dental Prescale”. Sixteen children with normal occlusions; 8 boys and 8 girls (avg.9.3 years) were selected. The maximum bite force which was exerted 0 sec.,1 sec.,2 sec. and 3 sec. after maximum clenching was achieved was recorded using “Dental Prescale 50 H”.
The results showed that the longer that clenching was maintained, the larger the maximum bite force tended to be. The maximum bite force, however, was nearly the same for 2 sec. and 3 sec. furthermore, the variation coefficient at 0 sec. was larger than for 1 sec.,2 sec. and 3 sec.. It is therefore reasonable to suggest that the length of time for which maximum clenching should be measured is 2sec. or 3 sec.

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It is important to screen infants with a high risk of dental caries and give them appropriate oral health instruction. In this study, relationships between the dental caries status and their life style were investigated longitudinally in infants from 18 to 24 months old. The subjects were 1641 children who participated in dental health screening both at 18 months and 24 months of age. Oral examinations, caries activity tests (the Cariostat) and dental health questionnaires were used out in each screening. The subjects were divided into three groups according to their status of dental caries at 18 months of age; the caries-free group (Group 1), the initial carious group (Group 2) and the dental carious group (Group 3). The results are as follow:
1. Group 2 showed a worse caries status at 24 months of age than Group 1.
2. According to the Cariostat test, Group 2 presented lower caries activity than Group 3.
3. Group 2 reported different responses to life style questions compared with Group 1 and 3. These results suggested that initial caries could be utilized as one of the screening methods for infants.

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With an eye to casting light on the visual perception on of the dental clinicians, a photographic image of a dental unit(the unit) reproduced on the screen was shown to dentist. While the subject dentists were looking at the image of the unit, which is, of course, familiar to them, we measured their eye movements using a Visicon Eye-camera. The data thus obtained were scientifically analyzed. The following is a summary of our findings.
1. The component of the unit where the initial points of fixation were found, the scanning of the eyes before resting on the initial fixation points, the frequency of rests and the duration of fixation -all these considered, it appeared that there was a tendency for the subjects to encode what they saw in the structure of the unit, and reconstruct its image, suggesting they had looked at the unit in its entirety.
2. The distribution of all of the fixation points also suggested that the subjects had perceived the size of the object correctly using their own stature as a yardstick for judgment.
3. The saccadic movements from one fixation point to another were small, when the subjects were running their eyes over the unit. On the other hand, the movements were large, when they were looking beyond the unit.
4. In many subjects, when they scanned the unit, their eyes moved following a certain fixed path.
5. With the eyes of the operators turned downward, it would not be difficult to collect a much information about items on the working table and the patient's face and body on the chair.

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A photographic image of a dental unit(the unit) was shown to child subjects, who knew little about the unit, and the way they looked at it was carefully observed. With the aid of a Visicon Eyecamera, their eye movements were measured and the data thus obtained were analyzed. Our findings were as follows.
1. A check of the records of which part of the unit they fixed their eyes on first and foremost, the movement of their eyes before getting to the initial fixation points, and the frequency and duration of pauses in the eye movement suggested that they had not perceived the unit as a whole but had recognized the table, light and chair constituting part of the whole as being separate things.
2. The distribution of all the fixation points of the eyes showed the possibility that they saw each component of the unit a little larger than what it really is. This is probably because they sized up the object on the basis of their small build.
3. Their eyes jumped back and forth from the table to the lighting and the chair in a small saccadic movement. In a large saccadic movement of eyes, they looked at the unit and its background.
4. A very few of the child subjects scanned their eyes in any particular order. Most of them darted their eyes at random.
5. There was a strong tendency for the children to look up, probably because it a habitual reaction. It would be difficult for us to gather much information from their eyes as their field of vision was often blocked in depth.

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The present report was conducted to study the antibacterial activity of the containing fluoride sealants on Streptococcus mutans NCTC 10449, Streptococcus sanguis ATCC 10557 and Lactobacillus casei ATCC 7469. We examined four samples used for the light cured fissure sealants: two sealants containing fluoride(B and C), a sealant with no-fluoride in its (A) and a glassionomer cement (D). We investigated the productivities of the inhibition zone on the agar plates and the effect of viable cell counts in the broth. In addition we measured the concentration of the fluoride ion and the pH from the samples.
The results were as follows;
1. The sample A, B and C showed antibacterial activity only toward S. mutans in the aerobic condition.
2. The sample D showed antibacterial activity toward all of the strains tested.
3. The sample D showed the highest fluoride release.
4. The sample D showed the highest pH.
In conclution with the use of the fissure sealants, it is possible to inhibit the growth of S. mutans. The property of these materials might have the advantage of the clinical effectiveness of fissure sealants.

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The incidence of dental caries is still high especially in susceptible areas such as the occlusal and buccal pits.The purpose of this study was to clarify the shape of the buccal pits in the first permanent mandibular molars.Twenty unerupted first mandibular molars were investigated.After SEM observation, the specimens were embedded in epoxy resin.Finally, in order to measure the different aspects in the buccal pits, ground sections were made and observed by optical microscope.
The following results were obtained:
1.13 out of 20 teeth examined showed the presence of buccal pits, representing 65% of the sample. Some teeth had more than one pit resulting in a total of 18 pits observed.The prevalence of the buccal pits in the left and the right molars was symmetric in the same individual.
2. The average length of the buccal groove was 2.5 mm.The pit was always located in the lower third of the groove.
3. Regarding the shape of the entrance of the pit,12 pits out of the 18 pits observed showed an oval shape, representing 66.7% of the sample.
4. The entrance of the pit showed an average length of 553 μm and a width of 189 pm.The average depth of the pit was 867μm and its enamel thickness at the bottom was 658 pm on the average.
5.There was a positive correlation between the length of the pit at the entrance and depth of the pit, as well as between the width and length of the pit at the entrance of the pit (p< 0.01).
6. Regarding the shape of the pit, the DV shape was the most common, representing 38.90% from the sample.
Based on these findings, it is possible to conclude that the preventive measures applied to occlusal pits should also be considered in the case of buccal pits.

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We investigated the frequency of abnormalities of the primary and permanent teeth in the maxillary anterior region for the children with cleft lip and palate.
The subjects were 116 patients (57 males and 59 females) with cleft lip, alveolus and/or palate who had visited and recieved oral management at the Pediatric Dentistry Clinic of Showa University Dental Hospital.
The results were as follows;
1. With the type of cleft, children with cleft lip, alveolus and palate were occupied a large number of the subjects, followed by cleft lip and alveolus, isolated cleft palate and cleft lip.
2. With the position of alveolar cleft, A∇BC type was found 55.4% of the subjectsw ith alveolar cleft, followed by AB∇C type 24.5% and A∇C type 19.1%.
3. Abnormalities of the teeth were more observed in the permanent teeth than in the primary teeth. With abnormality of tooth number, supernumerary teeth were observed in 20.7 % of the subjects with primary dentition and congenitally missing 57.8% with mixed dentition.
Abnormalities of tooth number and tooth position of permanent teeth were found more frequently in the children with alveolar cleft.
4. Abnormalities of the teeth were observed more frequently at the cleft side than the non-cleft side. The primary and permanent lateral incisors were affected in the highest frequency.
5. With the relation between abnormalities of primary teeth and those of permanent teeth, the cases which no abnormalities were observed in the primary dentition but abnormalities observed in the mixed dentition were seen frequently.

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The purpose of this study was to verify whether the Dental Prescale system regarding portable 1 ch electromyographic unit as a monitor was effective for children. Ten children (five boys, five girls)were employed in the study. Moreover we compared the method using just a Dental Prescale (single method) with the method using the portable 1 ch electromyographic unit as visual monitor (mixed method).
The results were as follows:
1. The occlusal contact area and the occlusal force recorded with the “mixed method” were significantly larger than those recorded with the “single method”.
2. The reproducibility of the “mixed method” was superior to that of the “single method”.
3. It is suggested for children that the level-ramps of the portable 1 ch electromyographic unit were useful for increasing the occlusal force.
4. We consequently decided that the “mixed method” was more effective for children than the “single method”.

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This study was aimed at clarification of the advantages of the use of electromyograms recording multiple muscles with different functions in evaluation of muscle activity during sleep at night. We, there-fore, investigated the durations of the activity and the ratios of the magnitudes of the activity of the temporal muscles and the masseters during sleep at night.
The subjects were 5 healthy adults. Electromyograms recording the temporal muscles and masseters of the subjects during sleep at night were made using a simplified electromyograph, and the muscle activity durations and magnitude ratios were determined from the records.
In three subjects the activity of the temporal muscles lasted longer than that of the masseters, whereas in the other two subjects that of the masseters lasted longer than that of the temporal muscles. The temporal muscle was activated more strongly than the masseter muscle in three subjects and in the other two subjects it was activated more strongly than a masseter muscle.
The masticatory muscle activities during sleep at night, thus, showed two different features: temporal muscle dominance and masseter dominance.
The above results suggest that analysis of electromyograms recording multiple muscles is necessary in investigation of masticatory muscle activity during sleep at night, since they can reveal differences in muscle activities.

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It is important to know that the process of development of the dental arch without early loss of deciduous or permanent teeth is considered one of the causes of malocclusion, based on pediatric observations. The authors therefore, investigated 86 children (male: 39, female: 47). These children were arriving at the permanent dentition without early loss of deciduous or permanent teeth. The subjects had impressions taken and longitudinal casts made every two months from 3 to 28 years of age.
As for the maxillary, there were 45 cases (52.3%) with normal dental arches, there were 29 cases (33.7%) with crowded dental arches, there were 12 cases (14.0%) with spaced dental arches. In the mandible, there were 44 cases (51.2%) with normal dental arches, there were 32 cases (37.2%) with crowded dental arches, and there were 10 cases (11.6%) with spaced dental arches.
So, normal occlusion, therefore occurred in 30 cases (34.9%), and malocclusion occurred in 56cases (65.1%). In these malocclusions, crowded dental arches amounted to 23 cases (26.7%), spaced dental arches to 12 cases (14.0%), spaced and crowded dental arches to 2 cases (2.3%), deep overbites to 6 cases (7.0%), maxillary protrusions to 3 cases (3.5%), reserved occlusions to 2 cases (2.3%), and total scissors bites to 8 cases (9.3%). There were no cases of open bite.
The cases with the distal step type of the terminal plane in the deciduous occlusion tend to malocclusion of Angle II.
The results presented here suggest that normal occlusion occurred in about 1/3 of the cases of the permanent dental arches where there was no early loss of deciduous or permanent teeth, while malocclusion occurred in about 2/3 of the cases.
Malocclusion is dependent on several factors. Of prime importance among these factors are hereditary factors such as tooth size and the size of the basal bone of the jaw accommodating the teeth, growth difference from maxillary and mandible jaws.

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We experienced a case of idiopathic hypoparathyroidism in a 2-year,3 month old girl. She had hypocalcemia immediately after birth, and was diagnosed as having idiopathic hypoparathyroidism at the age of 3 months.
Vitamin D supplements and low phosphorus level milk were prescribed to correct the low serum calcium and high serum phosphorus concentrations. Severe growth failure persisted despite correction of her biochemical abnormalities. Slight mental retardation, sensorineural deafness, small hands and feet, and a depressed nasal bridge were found.
The eruption of the deciduous teeth was slightly delayed. Enamel hypoplasia was found in all of the deciduous teeth. Judged from the extent and specific placement of the enamel defects, enamel hypoplasia seemed to represent the result of a severe hypocalcemia episode occurring after birth. Radiographic examination revealed that there was no evidence of blunting of the root apexes nor thickening of the lamina dura while calcification patterns of the permanent teeth germs were within normal limits. Study model analysis revealed that the mesio-distal diameters of the deciduous teeth were small and the widths of the deciduous dental arch were also small.

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A 12-year-old girl with a tumor in her left cheek was referred to Chiba Children's Hospital. At the initial examination, a hard, localized movable tumor in the left cheek 3 cm in diameter was found. There was no inflammatory local and systemic symptoms, including the blood data tested. A benign tumor of the cheek was suspected and surgical excision was planned to be performed in three months.
After one month, the patient came to us because of a reddish changing of the skin on the tumor. As the lesion had apparently undergone abscess formation, a small incision was made for pus drainage. Roentgenograph showed a small apical radiolucency caused by periodontitis in the mandibular left first molar, which seemed likely to be the cause of the abscess or external dental fistula. This was confirmed from endodontic treatment, with which the periapical lesion soon disappeared and the skin lesion healed with no residual scarring.
Although no physical or hematological evidences of inflammation were found, we should pay attention to even small periapical lesion or radicular cysts which may cause an external fistula of the cheek. When apical lesions involving the fistula are smaller, conservative modalities such as endodontic therapy of the pertinent tooth or awaiting of the favorable disappearance of the fistulous tract are recommended. Use of surgery does not seem to be too late even after these considerations.

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Foreign bodies in the nose are commonly found in children. Boredom, curiosity, habit, fun-making and mental retardation have all been mentioned as causes of foreign bodies in the nose. This report describes an undetected nasal foreign body in a child which was discovered in a dental radiograph and also the subsequent removal of the body.-A five-year-old boy was brought by his mother to the Pedodontic Department of Meikai University for a regular dental check up. His medical history and oral findings showed nothing particular to report. The orthopantomogram revealed an unusual radiopaque-appearing body in the right nasal cavity of the patient. The mother stated there were no subjective symptoms which would have indicated its presence. The patient was referred to the Department of Otorhinolaryngology in this University Hospital for evaluation and removal of the foreign nasal body. The examination of the patient revealed that the radio-opaque and round shape object was located in the anterior portion of the right nasal passage. The object was removed from the nose by grasping forceps and suction pipe immediately without local anesthesia. Gross examination of the object revealed a plastic toy bullet of slightly rugged appearance. The patient did not complain of symptons after the removal of the object.-Many of the foreign bodies in the nose are found to be associated with some irritative disease, but in this case, the subject had no such symptons. If left for long periods of time, these objects may lead to inflammation or infection of the nasal mucous membrane. This case was presented to show that dentists may possibly be the first to discover foreign bodies in the nose.

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