The 1st permanent molar erupts first among the permanent teeth and is used for a long period of life. To keep this tooth healthy is an important task of Pediatric Dentistry.
This study was promoted by the Japanese Society of Pediatric Dentistry to find out the actual condition of the 1st permanent molar and to seek ways to keep this tooth healthy.
Four thousand, eight hundred and twenty-one children were selected at random from the patients in the Pedodontic Clinics of 29 university hospitals and 11 private Pedodontic Clinics and one primary school, and 18488 first permanent molars were checked. The following results were obtained.
1. During the preschool children, caries free 1st permanent molars amounted to 75 percent. After that it increased by age and in 6th grade children of primary school, it was only 20 percent.
2. The average number of caries free 1st permanent molars amounted to 2.34 in the preschool children and 0.8 in the 6th grade children of primary school.
3. Children with all four caries free 1st permanent molars amounted to approximately 54 percent among the preschool children and 11 percent among the 6th grade children.
4. In conjunction with eruption, the caries prevalence rate increased. Among the fully erupted 1st permanent molars among the preschool children,35%in the maxilla,43% in the mandible were affected.
5. Deciduous caries in 12 theeth (canines,1st and 2nd deciduous molars) were divided into two groups (1-5 dmft and 6-12 dmft). In the group with 6-12dmft, the DMFT of the 1st permanent molars was larger than in the 1-5 dmft group.
6. In the group of all four 1st permanent molars affected by caries, caries in the other permanent teeth were clearly noted.

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The purpose of this study was to investigate the color changes of light-cured composite resins over specified periods of time.
3M Co. light-cured composite resin Silux Plus(Shades: U, Y, DY, L, G, UO, YO) disks 10 mm in diameter and 1 mm thickness were prepared with 2 minutes of light exposure through a 1 mm thick glass plate. The specimens were stored in artificial saliva at 37°C. Colorimetric values of the specimens immediately after curing and every 6 months for 3 years were measured without background color, backed by a white plate which was used to substitute for the lining material with a fast spectrophotometer.
The following results were obtained.
1) For specimens without background color, theΔE*ab values of all of thc shades except the G and YO shades increased proportionately to the time elapsed. For specimens measured against a white plate, the ΔE*ab values of all of the shades increased proportionately to the time elapsed.
2) For specimens without background color, the one-yearΔE*ab values ranged between 1.59(YO)and 2.67(L), the two-yearΔE*ab values ranged between 3.28(DY)and 4.94(L)and the three-year 4E*ab values ranged between 3.82(YO)and 6.06(L).
3) For specimens measured against a white plate, the one-yearΔE*ab values ranged between 2.28(YO)and 3.23(L), the two-yearΔE*ab values ranged between 4.19(YO)and 5.70(L)and the three-yearΔE*ab values ranged between 4.91(YO)and 7.04(L).
4) For specimens measured against a white plate, the L* values for all of the shades showed a tendency to decrease proportionately to the time elapsed. However, for specimens without background color, the L* values for many shades did not show the continuous decrease proportionately to the time elapsed.
5) Both in the cases of with and without background color, the a* values of all of the shades increased proportionately to the time elapsed and the green color factor decreased, however, theb* values showed different color changes proportionately to the time elapsed among the shades.
6) For three-year specimens with and without background color, significant correlations were obtained between ΔE*ab yalues and ΔL*, Δa* and Δb*values(P<0.01).

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The purpose of this study was to analyze the tongue function in children with open bite using pressure transducers and ultrasonography.
Ten children with normal occlusion (the normal occlusion group) and 10children with open bite (the open bite group) were examined. Three pressure transducers were attached to the labial and lingual sides of the upper central incisor and central palatal area. A probe consisting of an ultrasonic apparatus was placed under the submandible to monitor the sagittal configuration of the tongue.
The following results were obtained:
1. Time courses of pressure change during swallowing of saliva on command and sipping of 5 ml of juice were classified into 7 types.
2. During swallowing of saliva on command and sipping of 5 ml of juice, the sequence of the peak positive pressure was the labial and lingual sides of the upper incisor and the central palatal area. This pressure process as time went on was needed for swallowing. However, the characteristic order was observed in the open bite group, i. e., the labial side, palatal area and lingual side.
3. During swallowing of saliva on command, there was no difference in time of pressure between the two groups, but protrusion of the tongue was observed in the open bite group. Also, during sipping of 5 ml of juice, transient large negative pressure occured in the central palatal area in the open bite group.
4. During drinking of 50 ml of juice, the positive pressure mainly occured in the central palatal area in the normal occlusion group. On the other hand, the negative pressure occured in the same area in the open bite group.
5. During eating of jelly, negative pressure occured in the central palatal area in the two groups of children.
6. In the central palatal area of the children with normal occlusion, the positive pressure occured during swallowing of juice, and the negative pressure during swallowing of jelly. Still, whether the swallowed material was juice or jelly, only the negative pressure occured during swallowing in the open bite group.
7. A real-time ultrasonic diagnosis revealed that the tongue in the rest position was highly situated in contact with the hard palate in the normal occlusion group. The tongue position was lower and the tongue moved slowly in the open bite group.
8. Simultaneous recordings of oral pressure and tongue movement were useful for the analysis of the tongue function.

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The following is the result of an investigation into the relaxation efficacy of showing video films (via ceiling mounted television) to child patients undergoing dental treatment. Patients were evaluated using four time categories and three compliance categories. The subjects were 60 1-5 year old first time patients, and 1802-5 year old patients who were undergoing treatment.
1. The level of interest among the first time patients was as follows: 30% showed a strong interest in the ceiling mounted television sets prior to entering the examination area proper. Interest grew as they approached the chair.76.7%were reported to have continued viewing during oral examination and training. This was categorized as a remarkably interested group. Of the group,66.7%continued viewing until the examination was complete. Interest faded gradually as the patients left the examination area.
2. Of the group which had been undergoing treatment,42.5% were classified as remarkably interested,50% fairly interested, and 2.5% uninterested. No significant variation was noted for age groupings. Evaluation of the state of compliance showed 92.5% acceptance or light resistance to sitting on the chair,90.7% acceptance of local anesthesia administration, and 85.8% acceptance of caries treatment.
3. Disadvantages of ceiling mounted television were noted among the 4 year old children's group.10.6% were unresponsive to the dentist's instructions, and 6.1% attempted to move the dentist's hand and face. The incidence is marked in comparison to other age groups.
4. In conclusion, since more than 90% of both first time patients and patients who were undergoing treatment exhibited a high degree of interest in video films, their use may contribute to the better management of child patient behaviour. Although the study group showed a tendency to behave better in comparison to the control group, no statistical difference was noted.

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When we examined the possibility of an apparatus for measuring the six degrees of freedom which was able to be applied to clinical easily, we obtained the following conclusions.
1. An apparatus for measuring the six degrees of freedom of the mandibular movement in which magnetism was used was developed.
2. This apparatus can display the resolving power of coordinates of the 1/10 mm value and 1/100 angle value.
3. The main unit and the sensor of this apparatus are small compared with the mandibular movement measuring assembly which can measure the other six degrees of freedom, so we might be able to measure the six degrees of freedom of the mandible movement in clinical practice.

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Proximal cavities of 25 deciduous posterior molars and 25 immature permanent posterior molars, each with C2, were restored with the use of GRAFT LC II and a clinical observation was made.
The results were as follows:
1. Both deciduous posterior molars and immature permanent posterior molars showed steps at the margin as early as one week after restoration. No abnormality in marginal adaptation one year after was seen in 23 cases (92.0%) in each group.
2. One year after, morphological changes were seen in one case each in the deciduous posterior molars and immature permanent posterior molars. The immature permanent posterior molar especially showed changes in the whole tooth.
3. Staining and discoloration were seen from one week after restoration in both deciduous posterior molars and immature permanent posterior molars. No abnormality was seen one year after in 23 cases (92.0%).
4. Marginal discoloration was seen from one week after restoration. Discoloration was not seen in 23 cases (92.0%) one year after.
5. Secondary caries were seen from three months after restoration. No abnormality was seen one year after in 23 cases (92.0%).
6. Pulp reaction at the restoration was seen in one case each in both the deciduous posterior molars and immature permanent posterior molars, but pulpal procedure was not required.
7. At the time of recall, pulpal procedure for retreatment was required for one case in the deciduous posterior molars and immature permanent posterior molars.
On the basis of the foregoing findings, it is suggested that light cured composite resin is effective for restoration of Class II cavities in deciduous posterior molars and immature permanent posterior molars.

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The thickness of the cortical bone at the mandibular base on panoramic radiographs and the quantity of bone mineral content in the alveolar bone were measured for a total of 48 subjects selected,24 boys and 24 girls, from 6 to 8 years of age, who visited the out-patient ward, Department of Pedodontics, Attached Hospital of the hospital of Kyushu Dental College, for examination, and had normal occlusion from the clinical standpoint and were without dental caries or substantial tooth defects in the mandibular molar region.
The results were as follows:
1. The averages thickness of the cortical bone at the mandibular base for boys were 3.26±0.24 mm tor age six,3.69±0.29 mm for age seven, and 3.84±0.31mm for age eight, and for girls were 3.41±0,36 mm for age six.3.61±0.24 mm for age seven, and 3.79±0.21 mm for age eight. The averages of the bone mineral content quantity in the alveolarbone for boys were 3.33±0.21 m m Al for age six,3.49±0.17 mm Al for age seven, and 3.86±0.33 mm Al for age eight, and for girls were 3.43±0.32 mm Al for age 6,3.58±0.23 mm Al for age seven, and 3.87±0.19 mm Al for age eight.
2. T-tests on the thickness of the cortical bone at the mandibular base and bone mineral content quantity showed no significant differences between boys and girls from six to eight years old. T-tests by age on the thickness of the cortical bone at the mandibular base showed no significant differences between ages six and seven, and seven and eight. Between ages six and eight, age eight showed significantly higher values than age six. The bone mineral content quantity showed no significant differences between ages six and seven. Between ages six and eight, and seven and eight, the older ones showed signiflcantly higher values than age six. The bone mineral content quantity showed no significant differences between ages six and seven. Between ages six and eight, and seven and eight, the older ones showed significantly higher values than the younger ones.
3. The correlation coefficient between the thickness of the cortical bone at the mandibular base and the bone mineral content quantity for the 48 subjects was r=0.892. Correlation coefficients by age between the thickness of the cortical bone at the mandibular base and bone mineral content quantities were r=0.914 for age six, r=0.708 for age seven, and r=0.953 for age eight.

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The purpose of this study was to clarify the relationship between the crown size and the enamel thickness of the upper primary teeth. The materials were 59 labio (bucco) lingually nondecalcified ground specimens of the upper primary 894teeth which were extracted from Japanese children. The measurements for the size of the teeth were taken from the mesiodistal diameter, the labio (bucco) lingual diameter, and the rectangle. The measurements of the enamel thickness were taken at the maximum protrusive point of the crown, and from the thicknest diameter of the enamel on the labial (buccal) surface and lingual surface.

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It has been recognized that maleic acid produces a generalized renal tubular dysfunction in dogs and rats which closely resembles the human Fanconi syndrome. To elucidate the effects of maleic acid on the odontogenesis of rat incisors, a neutralized maleic acid (pH 7.2) was injected intraperitoneally into Fischer rats. Their incisors were sectioned and examined microscopically with the aid of a contact microradiography technique and histological staining. The results obtained were as follows;
1. The rats were divided into 3 groups according to the dose of the maleic acid injection. A layer of slight hypocalcification was present in the dental tissue in the group of rats administered with maleic acid in a dosage of 250μmol/100 g of body weight (b. w. ). In the group of 357μmol/100g b. w.,88% of the incisors had a layer of dentinal hypoplasia in which calcification was completely disrupted. Enamel hypoplasia besides the dentinal hypocalcification was also observed in these incisors. The group with 500μmol/100g b. w. showed severe dentinal hypoplasia and their survival rate was as low as 20%.
2. Significant decrease of the serum phosphorus concentration was observed for three days after the injection of maleic acid with a dosage of 375μmol/100g b. w. As to the serum calcium concentration, it was raised only on the third day after the injection.
3. Tetracycline-labelled specimens revealed that a severely affected hypocalcification layer in the dentine had been formed during the third to nineth day after the injection of maleic acid.

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The cariogenicity of Panorich and Panorich S was examined in in vitro and in vivo experiments. Mutans streptococci femented Panorich and Panorich S. Panorich and Panorich S inhibited both glucan synthesis by glucosyltransferases of mutans streptococci from sucrose and sucrose-dependent adherence of these organisms to glass surfaces. In rats infected with mutans streptococci, Panorich and Panorich S showed significantly lowered caries-inducing and plaque forming activity, when compared to sucrose. Moreover, Panorich and Panorich S significantly inhibited sucrose-induced dental caries in rats infected with S. sobrinus 6715. These results indicate that Panorich and Panorich S could serve as anti-cariogenic sweeteners.

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The purpose of the present investigation was to ascertain the virtical mandibular maximal opening capacity, measuring the incisal edge to edge distance of both jaws and to establish a norm or average range of values in children. The subjects were 2207 children (1114 boys and 1093 girls) ranged 3 to 15 years old.
The results obtained were as follows;
1. The mean value of the maximal opening capacity increased with age, and the values were greater in boys than in girls.
2. The amount of increase throughout the period of from 3 to 15 years of age was 16.7 mm in boys and 12.1 mm in girls.
3. The minimal values of the mandibular opening were 32.7 mm for 3 to 5 year olds,33.8 mm for 6 to 8 year olds,37.5 mm for 9 to 11 year olds and 35.8 mm for 12 to 15 year olds.

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Biting force measurements and Ricketts' comprehensive descriptive analysis of frontal and lateral cephalograms were made in 60 5-year-old subjects at Hellman's dental stage of IIA in order to study the relationship between the biting force and maxillofacial morphology in children.
The following results were obtained:
1. Mean values of the biting force were 25.8±4.2 for males and 23.5±3.8 kg for females, with a difference between the genders. Mean averages of height and body weight were 110.3±4.1 cm and 18.9±2.0 kg, respectively, with no difference between males and females. No correlation was observed between height and biting force or between body weight and biting force.
2. Significant differences in biting force were noted between the brachyfacial, mesofacial and dolichofacial types. The mean biting force became smaller with a more retruded position of the chin in this order of facial types.
3. Positive correlations were observed between the biting force and the condylar length and between the biting force and the mandibular arc. Positive correlations were also found between the biting force and the ramus height.
4. There existed a negative correlation between the biting force and the amount of mandibular incisor protrusion and a positive correlation between the biting force and the occlusal plane inclination. Furthermore, a negative correlation was observed between the biting force and the amount of space available posterior to the terminal primary molar for the permanent molars. These results indicated that the biting force in the decidous dention was related to the maxillofacial morphology, the mandible, the mandibular position to the craniofacial complex and the dentition.

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This study was made in order to find out the relationships between the cranial morphology and craniofacial complex in their growth processes, by means of roentgenocephalometry using 138 dry skulls of Indian children which were classified by the cephalic index as dolicocephaly, mesocephaly and brachycephaly, and by Hellman's dental age as IIA, TIC, IIIA and IIIB, individually.
The results of the measurements in the length and multiple regression analysis were as follows:
1) Dolicocephaly was longer in the depth of the anterior and posterior cranium, and shorter in the cranial width than brachycephaly. Dolicocephaly was slightly longer in the height and depth of the anterior facial portions than brachycephaly, and showed a long oval face on the whole.
2) It was demonstrated that the head form depended largely upon the growth in depth of the posterior cranial portion (CL 3). This was done by multiple regression analysis using the cephalic index as criterion variables and the other measurements in length as explanatory variables.
3) By multiple regression analysis using the posterior cranial portion (CL 3) as criterion variables and the other measurements in length as explanatory variables, the following was shown.
In the dolicocephaly 6 variables were selected. The multiple correlation coefficient was 0.673, and the contribution rate was 45.2%, and CL 3 was strongly influenced by the growth in the height of face.
In the mesocephaly 7 variables were selected. The multiple correlation coefficient was 0.740, the contribution rate was 54.7%, and CL 3 was strongly influenced by the growth in the height of the face and the width of the face and cranium.
In the brachycephaly 4 variables were selected. The multiple correlation coefficient was 0.570, the contribution rate was 32.5%, and CL 3 was strongly influenced by the growth in the width of the face and cranium.

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Cases of impacted permanent teeth have been often observed. However, cases of impacted deciduous teeth are rare. An 8-year 8-month old girl (Case 1)and a 7-year 5-month old girl (Case 2) visited the Department of Oral and Maxillofacial Surgery at Kagawa Medical school complaining that the lower right second deciduous molars had not erupted.
Clinical examination and x-rays showed, the grems of the lower right second deciduous molars were impacted in the mandibule in both cases too, but it was not noted that these axes were inclined. Also these germs of the lower first molars of the affected site were inclined to the mesial site and they were deficiented in the eruptional space of lower second deciduous teeth. Further the germ of the lower second premolar which was a succedaneous permanent tooth, was located in the distal region of the impacted tooth, in Case 2. In both of these cases, the history of present illnesses and family histories, even in a general sense, showed absence of abnormal findings. We therefore considered that impactions of E occured due to by special causes.
We extracted the impacted E and marsupialized 5 in these two cases. For regaining of the eruptional spaces of 5, in case 1, the space was regained using in active plate, sectional arch and cross elastic system. In case 2, the space was regained by a direct-bonding system with power chains.

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There are many benefits of marsupialization of large dental cysts. In our case, the embedded tooth, which existed horizontally in the bottom of a dentigerous cyst, was induced to erupt by means of marsupialization.
An 11-year-old girl was referred to The Oral Surgery of Chiba University on June 6,1988, complaining of a labial swelling of the lower left alveolus.
Radiographic findings revealed an oval radiolucency in the mandible with an embedded left lower canine lying horizontally towards the distal direction. The lesion involved the area from the right lower central incisor to the left lower first premolar. A diagnosis of the dentigerous cyst was made and the marsupialization was performed with a window at the lower labial alveolus. In order to maintain the surgical opening, an acrylic obturator employed, which had a plug with a penetrating hole from the cyst side to the oral vestibule.
Five months after surgery, the impacted canine had rotated 90 degrees and moved to the natural position. The canine erupted about 2/3 of the crown in 1year 2 months, and thoroughly in 1 year and 8 months after the surgery. After the cyst had completely disappeared, unfortunately a recurring cyst developed in 1 year and 3 months. It was then completely removed with a Partsch II operation.
After that, the cyst cavity was filled with the new bone tissue.
It became clear that even the noticeably rotated and impacted tooth, causing a dentigerous cyst, stands a good chance of eruption in the normal dentition by means of marsupialization.

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We found rootless teeth in the entire dentition of 9-year-old girl whose main complaint at the initial visit to our clinic was severe movability in the lower incisors. The follow-up changes in her dental tissues were studied until she was 20years old.
The clinical and histopathological findings were as follows:
1)At the initial visit, her upper and lower central incisors were reverse and traumatic occlusion and showed severe movability. The crowns of both the deciduous and permanent teeth were nearly normal in shape and color, but they were somewhat small in size, especially the permanent first molars.
2)Roentogenographic examination revealed that all of the anterior teeth had extremely short, blunted roots. Each molar had a single root which was also short and conical. The lower central incisors had periapical radiolucencies, although they were free from caries.
3)Although pulpal obliterations were not found in the anterior teeth, the molars exhibited longitudinally crushed, flat pulp chambers with steep pulp horns. At first, therefore, the present case seemed to belong to dentin dysplasia type I (Shields' classification).
4)The follow-up examinations revealed that all of the newly erupted teeth had also the same short roots. However, the shapes of the pulp chambers stayed unchanged in all of the teeth, and none of the teeth had a distinct sign of pulpal obliteration.
5)Ground sections of the exfoliated or extracted teeth demonstrated nearly normal enamel and coronal dentin. In the roots, however, the dentin showed an abnormal structure, and the dentinal tubules were irregular in direction. The change in dentin structure occured abruptly near the cervical region. A few denticles were found in pulp chambers of the molars, although no sign of pulpal obliteration was recognized
.6)Ground sections were further examined microradiographically and immunohistochemically. The data suggested that morphogenesis and dentinogenesis of the teeth might occur normally until the formation of the irregular dentin starts in the root portion.
7)At the last vist, neither distinct pulpal obliteration nor decrease in the x-ray contrast in root dentin was observed in any of the teeth. Therefore, it seems that this case dose not belong to dentin dysplasia type I, but to a new type of abnormal dentinogenesis.

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A 4 year and 6 months old girl who complained of temporomandibular joint sound on both sides, was referred to the clinic of Pediatric Dentistry, Asahi Univ. Hospital. The functional examination of the patient disclosed that reciprocal clicking sounds at the opening and closing phases of the jaw were heard. The clicking sound was audible and intensified at the jaw closing. Oral findings showed that the lower right first primary molar was amalgam filled, the lower left first primary molar was restored with preformed primary crown and the bilateral lower 2nd primary crowns were inlay restored. There was no sign of occlusal interferences caused by those restorations. However, the midline of the mandibule deviated lateraly to the right, as the patient had a sucking habit of index and middle finger.
The treatment was focused on giving instructions as to how to stop the habit and an occlusal adjustment was performed as well. With these treatments, the clicking sounds were greatly diminished but not entirely. An occlusal adjustment, therefore, through renewed restorative work was accomplished, and the entire diminishing of the clicking sounds was apparent.

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