The purpose of this study was to investigate the influence of the light-irradiating times on the color changes of light-cured composite resins over specified periods of time.
Composite resin disks which were 10 mm in diameter and 1 mm in thickness, and made of the 3M Co. light-cured composite resin Silux Plus (shades: U, Y, DY, L, G, UO, YO) were made with 20,40 and 120 seconds of light exposure through a 1 mm thick glass plate. The specimens were stored in 37°C artical saliva. Colorimetric values of the specimens immediately after curing,1 day,1 month,3 months,6 months and 1 year after curing were measured without background color, backed by a white plate which was used to substitute for the lining material. The color measurements were performed with the Murakami Color Research Laboratory Fast Spectrophotometer CMS-500 and the Flexible Sensor FS-3.
1) Both in the cases of with and without background color, the ΔE*ab of many shades increased for 6 months or 1 year proportionately to the time elapsed in the 120 seconds group and compared to the ΔE*ab of immediately after curing, the 1 month ΔE*ab of many shades highly increased in the 20 and 40 second groups.
2) In the cases without background color, compared to the ΔE*ab immediately after curing, the 1 year ΔE*ab of all shades except the L-color shade showed higher values in the 40 second group than those in the 20 and 120 second groups. In the cases backed with the white plate, compared to the ΔE*ab of immediately after curing, the 1 year ΔE*ab of all shades except the L and G-color shades showed higher values in the 20 and 40 second groups than those in the 120second group.
3) The shades in which the 1 year ΔE*ab was near or over 2.5 and detectable to the naked eye were as follows: In the cases without back ground color, L and UO in the 120 second group, all shades in the 40 second group and U, Y, L, UO and YO in the 20 second group. In the cases backed with the white plate, all shades in the 20,40 and 120 second groups.
4) The color changes of light-cured composite resins over specified periods of time were influenced with the light-irradiation times. The influence of the lightirradiation time was stronger in the 20 and 40 second groups than that in the 120 second group. The influence of the light-irradiation time was obvious in the cases backed by the white plate.

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We applied MPBA modified facial masks to the skeletal reversed occlusion in the deciduous dentition and examined the effects of theappliance.
The materials consist of 22 lateral cephalograms of 11 Japanese girls, which were taken before and after the treatment and 39 lateral cephalograms of 13controls, which were observed in natural growth.
The following results were obtained:
1) Forward movements of point A, Ptm and the unerupted upper permanent incisors were statistically significant. However counter-clockwise rotation of NF and forward movement of Or and PNS were not significant.
2) Clockwise rotation of the mandible occured significantly.
3) The ratio of the movement of the four points which contributed to the improvement of the reversed occlusion was that backward movement of point B and the labial tipping of the upper deciduous incisor were about one third of the overall movements respectively and forward movement of point A and lingual movement of lower deciduous incisor were about one sixth of the overall movements respectively.
From these results, it was seen that the MPBA causes the effective changes in skeletal class III patients in deciduous dentition, namely growth acceleration on the maxilla and clockwise rotation on the mandible.

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The purpose of the study was to investigate the muscle activities of the perioral muscles during the sucking movement of infants and the differences in sucking movements during breast and bottle feedings.
Electromyographic recordings were performed on 17 healthy infants during breast feeding (9 infants, BRF group) and bottle feeding (8 infants, BOF group). Muscle activities were examined by surface electromyography from the anterior belly of the unilateral temporalis, masseter, orbicularis oris, and suprahyoid muscles. The parameters evaluated were the total feeding time (s), resting time rate (%), sucking cycle (ms), and sucking rate (times/s). The sucking force was evaluated by measuring the maximum muscle activity (μV) at the burst in 10consecutive waves of each muscle in the early, middle, and late feeding periods.
The following results were obtained:
1) In sucking movements, suprahyoid muscles (BRF,99.3: BOF 85.2 μV) and the orbicular oris muscle(BRF,75.9; BOF 54.2μV)showed a higher level of activity than the temporal muscle(BRF,27.9; BOF 34.6μV)or masseter muscles(BRF,24.1; BOF,29.2μV).
2) No significant difference was observed between the BRF and BOF groups in the total feeding time (BRF,658; BOF,610 s), the sucking cycle (BRF,607; BOF,641 ms), or the sucking rate (BRF,1.7; BOF 1.6 times/s). Howe v er, the resting time (BRF,86.7; BOF,44.4 s), resting time rate (BRF,13.7; BOF,7.3%), and the number of interruptions (BRF,18.8; BOF,10.0 times) were significantly greater in the BRF group.
3) The activities of the orbicular oris muscle of and suprahyoid muscles tended to be higher in the BRF group although the differences were not signi ficant.
The findings suggest that the orbicular oris muscles and suprahyoi d muscles may be considered to play primary roles in sucking, and greater muscle activity appeared to be needed for breast feeding than for bottle feeding.

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This study was conducted on young dogs to investigate the pulpal response caused by posterior composite resin restorations using either enamel or total etching.
Histopathological changes in the pulp were examined from three to thirty five days after filling.
The findings were as follows:
1) In this experiment the remaining dentin thickness variedin thickness. There was little difference in the pulp response throughout the whole observation period regardless of the remaining dentin thickness.
2) The enamel etching and total etching groups showed slightly greater pulpal responses before seven days after filling, but the slight inflammatory changes decreased after seven days after filling in both groups. After fourteen days, the inflammatory changes disappeared and the restorative dentin formation was observed.
3) Pulpal response due to irritation by etching was slight. Also there was no great difference between enamel etching and total etching. The inflammatory changes were slight and disappeared at an early stage. The restorative dentin was formed with a minute structure. Composite resin (Clearfil-Posterior) was slightly irritative to the pulp of the primary teeth, but it was presumed that its pulpal responsewas not so severe as to cause damage to the pulp.

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The purpose of this study was to investigate the urinary catecholamine concentration in cooperative children and uncooperative children during dental treatment. The subjects were 13 healthy children aged from 3 to 8 years. They received infiltration anesthesia with Citanest-Octapressin®(without catecholamine), when local anesthesia was needed during the dental treatment. The samples for analyses were urine that was taken before dental treatment and after dental treatment. Dopamine, noradrenaline and adrenaline were isolated from the urine, and quantitative analyses were performed.
The results are summarized as follows;
1) The adrenaline concentration after dental treatment was higher than before dental treatment in most cases. The increment ratio was 98.3%.
2) The dopamine and noradrenaline concentration showed no regular relationship between before dental treatment values and those after dental treatment. The average increment ratios were lower than that of adrenaline by 7.3 % in dopamine and 6.3% in noradrenaline respectively.
3) The cooperative children showed a significant difference between before dental treatment and after dental treatment in the adrenaline concentration(p<0.05). Adrenaline after dental treatment was higher than that before dental treatment. The increment ratios were 52.2% in the adrenaline, -0.5% in the noradrenaline and 11.4 % in the dopamine.
4) The uncooperative children showed significantly higher concentrations of adrenaline (p<0.01) by 172.1% and of noradrenaline (p<0.05) by 16.9% after dental treatment than before dental treatment, whereas dopamine snowed no difference by 0.8%.
5) There was a high correlation between the increment of the adrenaline concentration and the behavior of the children during dental treatment (r=0.74).

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In the present study focusing on the crowding of the permanent lateral incisors of the upper jaw, we investigated the relationship between the arrangement of the deciduous lateral incisors and permanent lateral incisors in the upper jaw, the size of the alveolus and the angle of the tooth axis.
Drawing on serially recorded material maintained in the Department of Pediatric Dentistry, Nippon Dental University, the study used serial dental casts (upper jaw) of 26 subjects whose deciduous dentition proceeded to normal permanent dentition, and casts (upper jaw) of 7 subjects with deciduous dentition who later had inverted lateral incisor overbite due to eruption on the palatal side bilaterally in the upper jaw while proceeding to permanent dentition.
1) The arrangement of the deciduous lateral incisors was found to be type A in 46%, type E in 40%, type D in 8% and type C in 6% of the normal occlusion group, while type A was found in 22%, type C in 14% and type E in 64% of the inverted overbite occlusion group, showing differences between the two groups in the incidence of types of arrangement.
2) The inverted overbite occlusion group had both significantly smaller long and high-level diameters of the apical base of the deciduous lateral incisors than the normal occlusion group.
3) The axial angles of deciduous lateral incisors tended tobe smaller in the inverted overbite occlusion group than in the normal occlusion group.
Subjects with inverted lateral incisor overbite in their permanent dentition exhibited morphological findings in the deciduous dentition, particularly with respect to the size of the alveolus and axial angle of the deciduous lateral incisors.
These findings may provide important information for occlusal guidance during the deciduous dentition.

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The purpose of this study was to investigate the relationship between the occlusocervical convexity of the tooth crown and the cervical line of primary teeth by using the three-dimensional measuring system with microcomputer analysis.
The materials were 25 lower right second primary molars ofJapanese children. Three-dimensional data was obtained, and the averages and radius vectors (the radius vector is the distance from the center point to each measuring point) were calculated. The difference in the values of Z and the radius vector, and the correlation coefficient on each measuring point between the occlusocervical convexity of the tooth crown and the cervical line were then found. The data was observed from a direction of the occlusal surface and the horizontal direction of the occlusal surface.
The results obtained were considered as follows.
1) Observed from the direction of the occlusal surface, there was a positive correlation between the occlusocervical convexity of the tooth crown and the cervical line on the whole part. Especially on the part from the distal center area to the distolingual area, the correlation coefficients were large, and on the mesiolingual area, were small.
2) On the part from the distal center area to the distolingual angle area, the standard deviations of the radius vectors and those of the difference in the values about the radius vectors were small, and there was a high correlation. It was therefore considered that this part about the occlusocervical convexity of the tooth crown and the cervical line, from which the direction of the occlusal surface was observed, was stabilized.
3) Observed from the horizontal direction of occlusal surface, there was a positive correlation between the height of contour and the cervical line on the part from mesiobuccal angle to the distobuccal. Especially on the part of distobuccal cusp surface, the correlation coefficients were large. While on the mesiobuccal angle and the distobuccal angle, those were small.
4) On the part from the distobuccal cusp surface to the distobuccal groove, the difference in the values about the z value and the standard deviations were small, and there was a high correlation. It was therefore considered that this part was stabilized about the occlusocervical convexity ofthe tooth crown and the cervical line that was observed from the horizontal direction of the occlusal surface.

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We measured the biting pressure and masticatory efficiency using A. T. P. particles for 80 children, their ages ranging from 3 to 5 years, and who visited the Department of Pedodontics Kyushu Dental College Hospital.
The results were as follows:
1. The mean of the biting pressure for a 3 year old boy was 14.00 Kg, for a 4 year old boy 15.64 Kg, and for a 5 year old boy 21.33 Kg. For a 3 year old girl it was 13.70 Kg, for a 4 year old girl 15.21 Kg, and for a 5 year old girl a 20.40 Kg.
2. Masticatory efficiency was measured by spectrophotometer and the mean of the masticatory efficiency for a 3 year old boy it was 0.096 Abs, for a 4 year old boy 0.113 Abs, and for a 5 year old boy 0.127 Abs. Fora 3 year old girl was 0.092 Abs, for a 4 year old girl 0.111 Abs, for a 5 year old girl 0.117 Abs. We made a calibration curve and changed the percentage froman expression of the regressive line, Y=0.726 X. The result was that the mean of the percentage from a 3 year old boy was 7.00%, from a 4 year old boy 8.20%, for a 5 year old boy was 8.47%. For 3 year old girl was 6.69%, for 4 year old girl 8.05%, and for 5 year old girl 8.49%.
3. The coefficient of the correlation of the biting pressure and the masticatory efficiency for 3 year old children was 0.613, the coefficiency of the correlation for 4 year old children was 0.332, and the coefficient of the correlation for 5year old children was 0.530. Thc whole is 0.635. (p<0.01)

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Immature permanent teeth of young adult dogs were displaced by placing forces of 50 g and 200 g and the changes in the structure of the cells on the compression and tension areas were investigated by a transmission electron microscope.
The results obtained were as follows:
1. Structural changes in the cells of the compression area. Three days after the operation, fibroblasts and osteoblasts had degenerated. In the degenerated cells, mitochondria of which the structure had been changed and dense bodies like lysosome were observed. Necrosis of the osteocytes was observed. Formation of a ruffled border was observed in the osteoclasts by the treatment. Figures of macrophage-like cells were detected near the ruffled border. The number of degenerated cells after treatment for two weeks was smaller than that after the treatment forthree days, suggesting repairment of the cells.
2. Structural Changes in the cells of the tension area. Three days and two weeks after the operation, development of some kind of organelles was observed in the fibroblasts and osteoblasts. In the organelles, the development of rough surfaced endoplasmic reticulum and Golgi apparatus was predominant. Osteocytes, which were located on the surface of alveolar bone, were similar to the osteoblasts in structure, but the osteocytes in the alveolar bone had fewer organelles than those located on its surface. A month after the operation, the decreases in the number ofmitochondrion and the rough surfaced endoplasmic reticulum in the fibroblasts, osteocytes and cementoblasts were observed, accompanying the formationof dental root.
3. Changes of collagen fibers. The periodicity of the stria of the collagen fibers did not change by the treatment on the compression area and the arrangement of them onthe tension area became slightly scarcer than those on the compression area without affecting the periodicity.

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We have especially considered and studied the host susceptibility to dental caries on genetic grounds using several kinds of inbred mice.
In this paper, we investigated not only the inheritance patterns of the host susceptibility but also the participate H-2 haplotypes, wards allelic combinations of the major histocompatibility complex (MHC) to dental caries.
9 C57BL/6NJcl inbred mice, H-2 haplotype b and 13 AKR/JSlc inbred mice, H-2 haplotype k as parent mice, and 38 F² [(F¹(C57BL/6NJcl×AKR/JSlc) male ×F¹ (c57BL/6NJcl×AKR/JSlc) female)] mice and 24 N2 [(F¹(c57BL/NJcl×AKR/JSlc) male×AKR/JSlc female)] mice were used as the experiment animals.
All of the mice were weaned on the 21th day after birth, and were infected with S. mutans JC-2 (serotype c) which was resistant to streptomycin for 7 days, and were fed with Diet 2000 containing 56% sucrose. The number of S. mutans was counted and the caries score was calculated when the mice were sacrificed on the 90th day after birth. The following results were obtained in this study.
1. The mean and standard error of the caries scores for C57BL/6NJcl and AKR/JSlc were 111.0±9.9 and 12.2±2.2, respectively. It was reaffirmed that C57BL/6NJcl was a caries susceptible mouse and AKR/JSlc was a caries resistant mouse. Based on these two caries scores, F² and N2 mice were divided into two groups; the caries susceptible and caries resistant groups.
2. The caries scores for the caries susceptible and caries resistant groups among F² mice were 117.4±12.3 and 27.4±3.5, respectively. The number of caries susceptible mice and caries resistant mice was 27 and 11, in which 3: 1 ratio belonged (x²=0.16 df=1 P=0.68).
3. The caries scores for caries susceptible and caries resistant groups among N2mice were 82.4±10.8 and 27.5±2.6, respectively. The number of carics susceptible mice and caries resistant mice was 12 and 12, in which belonged 1: 1ratio (x²=0.00 df=1 P=1.00).
From the results mentioned above, it is suggested that the genetic factor including H-2 genes plays a role in the development of dentalcaries in mice.

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The clinical retention and efficacy of light cured pit andfissure resin sealant (Teethmate-A) were evaluated in this study.
The sealant was applied to 81 first permanent molars of thechildren (mean age: 7y5m) who visited the Pediatric Clinic of Tohoku University Dental Hospital. All of the teeth to which the sealant had been applied wereexamined periodically by clinical inspection and exploration for the sealant retention and the occurence of caries on each pit and fissure.
The results were as follows.
1) In the observation carried out after 12 months, the rates of complete retention of the sealant was about 90% on the occlusal surfaces of the upper first molars, while it was 100% on the occlusal surfaces of the lower ones. In the observation carried out after 36 months, however, the rates of complete retention of the sealant were about 60% on both upper and lower first molars.
2) In the observation of the sealant on the smooth surfacesof the first molars carried out after 12 months, the rates of complete retention of the sealant was about 70% on both the lingual groove of upper molars andthe buccal groove of lower ones. In the observation carried out after 36 months, however, they decreased to 30% on both the lingual groove and buccal groove.
3) On the occlusal surfaces of both the upper and lower first molars, the retention rate of the sealant on the mesial pit was lower than that of the sealant on the distal pit.
4) There was no relationship between the status (intact or initial caries) of the teeth at the time of applying the sealant and the retentionof the sealant.
5) The ratio cases keeping up good progress of the sealant during the period from 12 months to 36 months amounted to about 60% on the occlusal surfaces in both the upper and lower first molars. On the other hand, the ratio of cases keeping up good progress of the sealant amounted to about 30% on the smooth surfaces of both upper and lower first molars.

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Many investigations have described that trauma of the temporomandibular joint (TMJ) in early childhood might cause TMJ-ankylosis, micrognathia and other facial deformities, unless proper treatment was done at initial stage. Along within recent increase of traffic accidents, it is assumed that the number of patients with traumatic TMJ-dysfunction has increased.
Recently, the authors experienced a boy who suffered the dislocation of the jaw to the left side with trauma of the TMJ and was obtained good result with the use of orthodontic techniques. We present the clinical evaluation and discuss a few points about the role of orthodontic techniques to treat such dislocation of the jaw in this paper.

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We investigated the case of 8 year-old-girl with odontoma.
1) The odontoma was located in the apical area of the maxillary right primary central incisor.
2) The palatal side of the root of primary central incisor showed an abnormal process in which anomalies of the root development were as also present.
3) The odontoma was examined for pathological diagnosis anddiagnosed as compound odontoma.

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A nine year and six month old boy with the Hallermann-Streiff syndrome was examined morphologically and functionally from a dentalpoint of view, and the following findings were obtained.
1) Microdontia of all of the deciduous teeth and persistence of many of the deciduous teeth were noted. Congenital missing of many of the permanent teeth was also seen.
2) The occlusal relationship indicated unstable and open bite.
3) According to X-ray cephalometric analysis, the mandible rotated clockwise and the length was short.
4) According to X-ray cephalometric and CT analysis, bilateral missing of the mandibular condyle and bilateral hypoplasty of the tuberculum articulare were found.
5) The mandibular kinesiograph revealed that the route and convergence were not stable during the mandibular border movement, and that the convergence and rhythm during the tapping movement were also unstable.
6) According to the electromyography of the masseter and temporal muscles, (a) the amplitudes and durations were not stable, and the durations of the silent periods were unclear during the tapping movement (b)the muscular activities were simultaneous and regular during mastication.

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