The purpose of this study was to investigate the relationship between past dental treatment and present dental fear, and to clarify factors influencing the formation of the present dental fear in adults.
The subjects were 113 adults, ranging from twenty to thirty-nine years of age, who were randomly selected from a list of client companies.
The investigation was performed using a questionnaire that checked on how a person associates himself to dental treatment (present image), degree of dental fear and past dental experiences. The subjects were asked to describe freely about their present images. They were also asked to mark the degree of dental fear using a Visual Analog Scale (VAS). The following conclusions were drawn.
The average degree of dental fear of all of the subjects was 51.3mm, for females 52.6mm, and for the males 46.6 mm. There were no significant differences between females and males. The present images for dental treatment was able to be classified into four groups according to the description.
The first group described only the purposes of seeking dental treatment (treatment purpose group). The second group described pain, fear or negative feelings related to dental treatment (pain/fear group). The third group described about negative feelings towards dental environment such as dislike of certain members of the dental staff or certain smells (negative group). The fourth group is showed a positive towards dental treatment or the environment (positive group). Comparing the four groups to VAS, the positive group had a lower VAS than that of any other group. In relation to the experience of pain during past dental treatment and the degree of present dental fear, the VAS of the experienced group was marked higher than that of the non-experienced group.
In relation to the experience of restraining during past dental treatment and the degree of present dental fear, VAS of the experienced group was markedly higher than that of the non-experienced group.
The results of this study suggest that the degree of present dental fear is related to the present images a person has toward dental treatment. Furthermore, the experience of pain or restraining during past dental treatment influences the formation of present dental fear.

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This study was conducted to investigate the validity of the Cariostat test using the mailing method for screening of dental caries. The subjects were two hundred forty-five children who participated in all dental health screenings at one and a half years of age,2 years of age and 3 years of age in Okayama Prefecture, Japan. Oral examinations and the Cariostat test were carried out at each screening. The dental plaque sample, which was taken from buccal surfaces with a cotton swab and put into a plastic bag, was mailed to the institution having cultivating equipment, and then was put into the Cariostat medium and incubated at 37°C centigrade for 48 hours. The results shown that this Cariostat method had a statistically high positive correlation with present caries status. It was also found that high-risk group at one and a half years of age and 2 years of age showed a higher caries prevalence and a larger number of caries at 3 years of age compared with the low-risk group. Based on these results, we conclude that the Cariostat test by mailing method possesses adequate predictive value and should be considered as an effective caries activity test.

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In the previous questionnaire, we discovered that the children who had been born as extremely low birthweight infants (ELBIs) had significantly more problems with the sucking and masticatory function than the children who had been born as full term infants (FTIs). The purpose of the present study was further to investigate the difference in the nutritive sucking patterns between ELBIs and FTIs and to examine the change in those sucking patterns with maturation after birth.
We measured the sucking wave pattern of both 8 ELBIs aged between 25 weeks and 34 weeks (mean gestational age was 28.4 weeks at birth and mean birthweight was 1015.3 g) and 7 FTIs aged between 2 and 7 days (mean gestational age was 39.1 weeks at birth and mean birthweight was 3296g). Four of the ELBIs and 7 of the FTIs were continued to measure for 10 months to investigate the change in the sucking wave patterns.
While there was no significant difference in the positive phase of the sucking wave, there was a significant difference in the negative phase (p<0.01) between the ELBIs and the FTIs, eventually the sucking cycle time (the positive phase and the negative phase) was significantly shorter in the ELBIs. The intensity of the sucking pressure in the ELBIs was significantly smaller than that in the FTIs (p<0.01). There was significant correlation between the actual age or the modified age and the sucking pressure (r=0.699 or r=0.708) in both ELBIs and FTIs.
Sucking cycle time, however, did not vary with maturation. Shorter time in the negative phase of sucking and smaller intensity of sucking pressure in the ELBIs meant smaller amounts of milk intake at each sucking and shorter time for swallowing. These results might be caused by the weakness of the muscular function and immaturity of the sucking function itself in ELBIs. These results, furthermore, indicated that lower sucking pressure in ELBIs might last for a longer period, which might cause a deficit in the development of the oral muscular function and the training for sucking and swallowing. Finally, those deficits could bring about the possibility of the deficiency of masticatory function in ELBIs.

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It has been known that zinc is a very important essential trace element. In the present study, forty 5-week-old male Wistar rats were divided randomly into four groups as the control (34.4 ppm) group, zinc deficient diet (0%: 3.7 ppm) group, low zinc diet (50%: 14.7 ppm) group and high zinc diet (150% 51.4 ppm) group. We aimed at observing the effect of zinc on the ultrastructure alteration of enchondral ossification in the mandibular condyle of growing rats. We obtained the following results.
1) There were more osteoblasts found in the high zinc diet group than that in the low zinc diet group. The number of active osteoblast decreased in the zinc deficient diet group, and it increased in the order of the low zinc diet group, high zinc diet group and control group. In the zinc deficient diet group, the numbers of osteoblast and osteoclast decreased clearly.
2) In contrast to the control group, osteocytes in the zinc deficient diet group were surrounded by many collagen fibrils and the inactive osteoblast were often noted which showed the bone formation was inactive. Compared to the zinc deficient diet group, the bone formation and the differentiation from osteoblast to osteocyte were more active in low zinc diet group. In the high zinc diet group, the active osteoblast showed active bone formation.
These findings suggested that zinc plays an important role in the morphologic feature in the enchondral ossifacation in the mandibular condyle of growing rats.

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The X-linked hypophosphatemic (Hyp) mouse is a model of human X-linked hypophosphatemic rickets(XLH) and is characterized by hypophosphatemia, growth retardation, and osteomalacia. A histological examination of Hyp mouse incisors revealed evidence of poor dentin mineralization such as interglobular dentin, widened predentin, and irregular dentinal tubules. Bone and dentin disorders in Hypmice are considered to be induced by low serum phosphate levels caused by impaired renal phosphate reabsorption. The purpose of this study was to examine the distribution of osteocalcin (OC), which is the major non-collagenous protein in dentin, in Hyp mice using an immunohistochemical method. In the labial region, which corresponds to the crown region in the molar, we found OC-like immunoreactivity (-LI) in dentin and predentin of wild type mice. On the other hand, the dentin and predentin of Hyp mice lacked OC-LI. In the palatal region, which corresponds to the root of the molar, OC-LI was observed in the dentin and cementum of wild type mice, whereas it was observed in the cementum, but not in the dentin of Hyp mice. These findings suggest that odontoblasts in Hypmice may have a defect in the secretion of OC, and that the hypominerarization of dentin seen in Hyp mice may not be caused by only hypophosphatemia but also by this defect.

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The purpose of this study was to investigate the movement of mandibular first molars and second molars after enucleation.
The subjects were 20 patients (aged 8-15 years,10 males,10 females) who underwent bilateral enucleation of the mandibular third molars. None of the subjects were treated with the multibracket system after enucleation. The control group consisted of 20 patients with the third molars (aged 10-16years,4 males,16 females).
We compared angular and linear measurements on 45° oblique roentgenographic cephalograms classified into before and after enucleation with similar measurements from the control group.
The results were as follows;
1. The mean age at which the third molar germ enucleation was performed was 10 years 9 months. The most frequent age was 10 (32.5%), followed by 9 (22.5%).
2. The axial inclination of the lower first molars to the mandibular plane was increased by a mean of 2.4°, and 2.8° at the lower second molars.
3. The axial inclinations of the lower first molars and second molars to the occlusal plane both increased by a mean of O.5°.
4. In the linear measurement, the position of the lower first molars and second molars was more mesial by a mean of 2.5 mm and 2.9 mm in the control group than that of the enucleation group, respectively.

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Antineoplastic agents used in the treatment of acute leukemia in children may harm growth and development, when used in childhood, due to their strong side effects, even if they have excellent therapeutic effects. The present study was conducted to clarify the effect of intraperitoneal injection of an antineoplastic agent on the whole body and craniofacial region; namely, vincristine (VCR) or cyclophosphamide (CPA), which has been widely used in clinical practice, was intraperitoneally injected in rats during the growth period, and then changes in the humerus and craniofacial bones were morphologically and histopathologically observed and compared. The results obtained were as follows:
1. The VCR-treated group showed body weight gains comparable to those of the control group, while the CPA-treated group had lower weight gains.
2. Craniofacial growth was identical between the VCR-treated and control groups. In the CPA-treated group, the growth of the anterior craniofacial width was delayed at 22 days after birth, and measurement were decreased in all sites examined at 54 days after birth.
3. The length of the humerus at 54 days after birth did not differ between the VCR-treated and control groups, but was shorter in the CPA-treated group, compared with the other 2 groups. Osteogenesis in the VCR-treated group did not differ from that seen in the control group. In the CPA-treated group, osteogenesis with normal modeling was inhibited at 22 days after birth, but was restored to the normal level at 54 days after birth.
Based on these results, it was confirmed that CPA inhibits bone modeling in an earlier growth period, compared with VCR, causing the delay of growth and development of the whole body as well as of the craniofacial region in rats.

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The purpose of the present study was to standardize the criterion of dental fear in young Japanese adults and to clarify the relationship between patient's impression of dental treatment and amount of the dental fear. The subjects of this study were 231 Liberal Arts students of Niigata University (117males and 114 females).
The mean age of the subjects was 19.5 years. The Dental Fear Survey (DFS)was translated into Japanese and then distributed to the subjects. The mean total score of the DFS was 45.15. The score agreed with the DFS scores in other countries of previous studies. The mean total scores of the females and males were 46.24 and 44.09 respectively. The score of the females was higher than that of the males, and this finding was also shown in the previous studies. In Item 18 (fear of dental drilling), there was a significant difference between the mean scores of the males and females (p<0.05). The results suggested that the DFS of the Japanese version would be a self-report measurement of the dental fear in adolescents and young adults for screening.
The impressions of the subjects toward dental treatment were categorized into three types; positive, negative and neutral impression. The mean total scores of subjects with positive impression (17subjects), with negative impression (114 subjects) and with neutral impression (100 subjects) were 33.9,54.6 and 36.3 respectively. The score with negative impression was significantly higher than those of the others (p<0.01).
As the results of factor analysis,20 items of the DFS were clearly categorized into four factors; fear of proximate dental treatment, fear of actual dental treatment, felt physiological responses and avoidance of dentistry. This finding indicated that the dental fears in the subjects were comprised of the four factors of fear. These four factors of dental fear will enable us to distinguish the characteristics of dental fear of patients clinically.

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Down's syndrome is a chromosome abnormality with a high frequency. It is possible that different dental materials have different toxicities, but there is no basic data on which to choose between them. We, therefore, examined the cytotoxicity of five commercial dental cement liquids on fibroblast-like Down's syndrome cells (Detroit 539). We compared the IC 50 values of the Detroit 539 and fibroblast-like normal human cells (HUC-F). Cytotoxicity was evaluated using the MTT test. As for the Detroit 539 cells, the cytotoxicity of four kinds of luching cement liquids were lower than the HUC-F cells. The IC 50 of Detroit 539 cells in particular declined at the a resin modified glassionomer cement. Futher testing with defferent kinds of dental materials is required.

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Application of the pit and fissure sealant has been widely used as a caries preventive measure, particularly in pediatric dental practice. Two types of the sealant, Fluorosealant® and Clearseal-F®, the subjects in this study, have fluoride releasing ability and contain no Bis-GMA, while the conventionally used sealants contain Bis-GMA as the main component.
These sealants were applied to the pits and fissures diagnosed respectively as intact, CO or Cl, of 41 permanent molars in two groups of children who visited our Pediatric Dental Clinic, and were evaluated in regard to the retention rates as well as caries prevention rates of the sealants.
The retention rate of Fluorosealant® was 51.2% and that of Clearseal-F® was 87.8%, whereas no carious lesions were detected in the sealant applied molar teeth in both groups.
From these findings, it was considered that these materials were equally effective for caries prevention as well as disturbing the caries progress in pits and fissures of the permanent molars of children, although the retention rate was superior in case of Clearseal-F®.

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A dental clinic attached to a maternity hospital was opened in 1993 to provide oral health care for mothers and children. In this research,211 of the children who participated in the one year, one year six months and two years old dental health screening at the maternity hospital from April 1996 to October 2001 were investigated to assess the influence of the prolonged breast-feeding on the oral statue and habits.
The following results were obtained.
1. The children with prolonged breast-feeding had a higher Cariostat value at one year and six months of age than children with termination of weaning at one year and six months of age.
2. The children with prolonged breast-feeding had a higher caries prevalence and df-index at two years of age than children with end of weaning at one year and six months of age.
3. The children with prolonged breast-feeding had a more frequent consumption of snacks than the children with termination of weaning at one year and six months of age.

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A 9 year-7 months-old girl was referred to the pediatric dental clinic, Tsurumi University Dental Hospital with a chief complaint of delayed eruption of the lower left first permanent molar.
Radiographic findings at the first visit revealed an impacted and mesially tilted lower left first permanent molar with round radiolucency of approximately 4 mm in diameter in the mesio-buccal coronal dentin. The outline of the crown seemed normal.
First, the lower left second premolar was extracted for creating the space for eruption of the lower left first permanent molar. Secondly the coronal part of the first permanent molar was surgically exposed. The mesially tilted first and second molars were then guided for their eruption by using a crown distal-shoe space maintainer set on the adjacent canine and first premolar, and the multibrackets appliance was used for the final alignment of the first and second permanent molars, which were uprighted and reached the occlusal plane.
On the enamel surface of the erupted first permanent molar corresponding to the dentin resorption site, there was no defect or discoloration, and any uncomfortable symptoms to the teeth were not noticed clinically. The periodic radiographic examinations revealed no change of size and site of the dentin resorption, nor abnormal periodontal tissue, indicating the dentin resorption unlikely being a progressive lesion.

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In clinical pediatric dentistry, there are numerous cases encountered of impacted supernumerary teeth. Reports of erupted front of maxillary supernumerary tooth in the maxillary sinus are however rare. A case is presented here in which a supernumerary tooth erupted into the maxillary sinus.
An eleven-year, two-month old girl was brought to the out-patient ward of dentistry for children, Tokyo Dental College Chiba Hospital for caries prevention and a treatments of an impacted supernumerary tooth. Radiographic examination which included a panoramic radiograph revealed a supernumerary tooth in near the root of the lateral incisor and canine. The patient has been followed up and no clinical abnormalities have been observed.
Two years later, at the age of 13 year,2 month, a supernumerary tooth seemed to be erupted into the maxillary sinus by a panoramic radiograph. CT scanning revealed one-third of the crown of a supernumerary tooth erupted in the maxillary sinus. The maxillary sinus did not however reveal sinusitis or a cyst, and clinical examination of the nose and oral did not reveal any abnormality. We intend to following regular radiographic examination and observation.
CT scanning was effective in reveal the relation between the supernumerary tooth and maxillary sinus.

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We encountered four patients in whom hematologic disease was found through the symptom of oral bleeding.
Case 1: A 14-year-old boy suffered from gingival bleeding. He had been given a diagnosis of gingivitis by a dentist. The patient had a marked bleeding tendency and severe general fatigue at the time of his first medical examination. Compression with a dental splint was applied to the local gingival bleeding, which resulted in successful local hemostasis. He was diagnosed as having acute myelocytic leukemia with disseminated intravascular coagulation.
Case 2: A five-year-old girl was admitted to the Chiba Children's Hospital because of severe gingival hemonhage. The blood platelet count was 0.7*104/μl at at the time of her first medical examination. As a result of several examinations, she was suspected of having idiopathic thrombocytopenic purpura. Compression with a dental splint was applied immediately and γ-globulin was administered once daily for four days. After that, the blood platelet count gradually increased and the severe gingival bleeding was arrested.
Case 3: A one-year-old boy fell down very hard and bit his tongue. The boy was seen at the Chiba Children's Hospital because of persistent mucosal bleeding from the tongue. As a result of several hematologic examinations, he was diagnosed with hemophilia A. The tongue was sutured and VIII factor was administered.
Case 4: An eight-year-old boy was referred to the Chiba Children's Hospital for the treatment of recurring mucosal bleeding. The patient had been treated surgically for alveolar abscess at a dental clinic. By compression with a dental splint, we were able to arrest the bleeding. The patient was diagnosed as having hemophilia B.
Diagnosing hematologic disease merely through the symptom of oral bleeding is difficult. However, attention must be paid to the fact that some patients with oral bleeding have hematologic disease. It is possible that these patients have recurring, severe, or broad mucosal bleeding, or general symptoms such as fever and fatigue.

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[in Japanese]

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