Smoking is known to be harmful not only for smokers but also for non-smokers. It also represents the most significant enviromental risk factor for oral diseases. Many studies have been conducted about how much smoking is involved in the onsets and developments of mouth diseases and how it lowers the effectiveness of treatments. Smoking-related health problems for infants are immeasurable. With these things in consideration, in 2004, the Japanese Society of Pediatric, and the Allergy and Clinical Immunology Japan Pediatric Society made a declaration for the promotion of a smoke-free society for the benefit of children's health. Furthermore, in 2006 four dentistry-related societies, the Japanese Society for Dental Health, the Japanese Society of Oral and Maxillofacial Surgeons, the Japanese Association for Dental Science, the Japan Dental Association, and the Japan Dental Hygienists made a declaration of a smoking ban. These declarations state that dentists and dental hygenists, as medical professionals, should consider it part of their mission to prevent smoking-related problems. In this paper, we will report on the effects of smoking on infants in terms of both basic medical sciences and clinical medicine.

View full abstract

We constructed a new dental examination using standardized examination criteria and data analysis systems in order to assess the status of caries experiences of preschool children in S city. In 2007, clinical dental examinations on the new system were carried out at total of 118 nursery schools and 106 kindergartens in S city. A total of 23,222 children's data (10,432 nursery school children and 12,790 kindergarten children) was obtained, and caries prevalence and status of treatment were compared between nursery school children and kindergarten children. The following results were obtained. 1. Percentage of children with caries was 29.6% for 3-year-olds, 44.1% for 4-year-olds, 56.1% for 5- year-olds in nursery schools, whereas it was 24.3% for 3-year-olds, 39.8% for 4-year-olds, 52.0% for 5-year-olds in kindergartens. Those were significantly higher in nursery schools than in kindergartens. 2. Mean dft values per child at 3 to 5-years-old in nursery school children were also higher than those in kindergarten children. 3. Trend toward decrease in caries prevalence was showed in both nursery school children and kindergarten children, but it was 2 to 3 years behind the national trend. 4. Percentage of children with caries experience and without decayed teeth and percentage of treated teeth at each age of 3 to 5-years-old in nursery school children was significantly lower than those in kindergarten children. 5. Percentage of treated teeth for all age children in both nursery schools and kindergartens except 5- year-old children in kindergartens was far lower than the percentage of decayed teeth. These results demonstrated that both nursery school children and kindergarten children in S city still showed high caries experiences and nursery school children had higher caries prevalence and more untreated teeth than kindergarten children.

View full abstract

The aims of this retrospective study were to examine the eruption disturbances of the mandibular second premolar caused by abnormal inclination of the tooth germs and to discuss and demonstrate the recommended treatment for these cases.The subjects comprised of 11 patients (eight girls and three boys) in whom the eruption of 15 mandibular second premolars was disturbed by aberrant direction of the tooth germs. The patients were treated at the Pediatric Dental Clinic of Niigata University Medical and Dental Hospital during 28years from September 1979 to January 2008. The ages of the patients at the time of diagnosis ranged from 8 years exactly to 13 years and 11 months.The eruption disturbance occurred unilaterally in seven cases (five on the right side and two on the left) and bilaterally in four cases. In 14 of 15 affected premolars, the tooth germs exhibited distal inclinations. A strong correlation between the degree of distal inclination and the delay in formation of the tooth germ was observed (correlation coefficient : R＞0.70) ; the more significant the delay in formation of the tooth germ, the higher the degree of distal inclination.In unilateral cases, the tilting degree was very high, and the formation of the tooth germ was significantly delayed. In bilateral cases, however, both the tilting degree and delay in formation were not severe, and were almost the same on both sides. A comparison between the unilateral group and the bilateral one revealed that the degree of distal inclination was considerably higher in the unilateral group (P＜0.01).In the cases of 14 teeth among 10 patients (all but one unilateral case, in which the patient was very young), the primary second molars were removed soon after diagnosis. The cases that had serious tilting, however, showed only slight improvement of the aberrant tilting even after their predecessors were extracted early, and additional complex treatments such as bone fenestration or traction of the affected tooth were required at the developing stage of initiation or one-fourth of the tooth root formation.If a predecessor is extracted at an early stage of tooth germ formation, long-term space maintenance is required. It was concluded that in cases with a markedly severe distal inclination, eruption disturbance of the mandibular second premolar should be treated after the root formation of its tooth germ is initiated.

View full abstract

This study was to examine changes in occlusal contacts during lateral excursion in children with mixed dentition using a computerized occlusal analysis system, T-scan II . After investigating the effects of posture on occlusion in adults, the occlusal contact relationship during lateral excursion in children with mixed dentition was observed.Subjects examined were twelve children with mixed dentition and normal occlusion, and six adult men with normal occlusion.The results showed that in both upright and supine positions, the occlusal contact area increased with time from the first occlusal contact to the intercuspal position, and the left-right balance of occlusion tended to stabilize faster in the upright position when compared to the supine position. Both occlusion time and disclusion time were significantly shorter in the children than the adults, and while lateral excursion resulted in group functioned occlusion in most subjects, it resulted in full balanced occlusion in only some subjects. In the children with mixed dentition, disclusion time was not significantly correlated to overbite or overjet, but it exhibited a significant negative correlation to load changes. The degree of changes in load and occlusal contact points on the balancing side during lateral excursion in children with mixed dentition was small during the first half of excursion and large during the second half of excursion. Also, the center of force (COF) of children with mixed dentition tended to change markedly during the second half of excursion when compared to the first half.In conclusion, it was demonstrated that the change in occlusal contacts during lateral excursion in children reflected the characteristics of occlusion with mixed dentition and the jaw movement of children, which differed from those of adults with permanent dentition.

View full abstract

It is important to habituate mentally handicapped persons to dental treatment in order to maintain good oral hygiene over the long term. The purpose of this study was to examine long-term changes of adaptability to dental treatment in such persons.The subjects were 16 profoundly mental retarded persons who had been residents for more than 20 years at "Colony Niigata Shiroiwa-no-Sato", a training institute for mentally handicapped persons in Niigata prefecture, Japan. One dentist evaluated their behavioral reactions subjectively to a routine dental treatment, divided into five situations, from being brought from the waiting space to leaving the treatment room, and classified their reactions into three ranks, as being "adaptable", "medium"and "inadaptable". We compared the current results with previous results that were gathered twice by the same procedure at the start of the initial treatment and at the end of the treatment before 20 years.The results were as follows :1.In all of the five situations, the number of subjects who were evaluated as "adaptable" increased significantly in the current results, compared to the start of the initial treatment before 20 years. The size of the long-term adaptable group (the group with acquired adaptability and the group that main tained adaptability) also increased. We considered that their adaptability was associated with acclima tization to dental treatment through their experience of repeated periodical examinations and with in creased calmness in mind and behavior as they aged.2.Long-term changes were different in each situation. During the dental treatment itself, adaptability showed remarkable improvement in a short time between the start of the initial treatment and the end of the treatment before 20 years. On the other hand, in the situation just before the treatment (from the entrance to the dental chair), adaptability showed less improvement.

View full abstract

We irradiated CO2 laser to bovine enamel at various irradiation power between 1 and 5 W and modes of CW (continuous wave irradiation), SP 1 and SP 2 (pulse irradiation). Crystallographic change in the enamel was examined by using Fourier-transform infrared absorption spectroscopy (FT-IR), X ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The laser irradiation caused a temperature rise at the enamel powder, which was dependent on the laser output and mode. The temperature rise reached about 800℃at an output of 1 W irrespective of the irradiation mode. It was visually confirmed that the enamel powder melted and agglomeration occurred above 1000℃and grain growth of the powder became remarkable with increased temperature up to 1400℃. With the laser irradiation, though the grain growth was not clear, a smooth surface was observed showing the melting of the powder. After an irradiation output of over 3 W, the enamel powder was completely melted irrespective of the irradiation modes. XRD patterns showed apatite in the enamel decomposed to α -tricalcium phosphate (TCP) and tetracalcium phosphate (TTCP) by the laser irradiation. With increasing power output of the laser, the degree of the decomposition increased in all irradiation modes. Apatite almost completely decomposed at the highest output power (5 W) in SP mode.

View full abstract

We have thus far conducted a series of experiments to clarify whether there are any differences in the way of seeking visual information from a human face among children different in personality by use of Free View, a non-contact type of eye-movement measuring apparatus. In the present study, we divided the child subjects into three groups according to personality type (dependent, standard and independent types) and three age-groups (group A : 6 years or younger ; group B : 7 to 9 ; group C : 10 to 12). Here is a summary of our findings :1.In the independent-minded group as compared with the other two personality groups, the number of eye-fixation points and saccadic eye-movement distributed in the region containing the features of the face (such as the eyes, the nose and the mouth) showed a marked tendency to increase with advancing age.2.The subjects in either age group A or B did not show any difference in the way of looking at the face which could be attributed to the difference in personality. In group C, however, there was some noticeable difference between the independent-minded subjects and the other two personality groups.3.In group C, the number of times the eyes fell on the background, appearance of the face and fixation durations in that region showed a decreasing tendency more distinctly in the independent minds than in the dependent and standard personality type children.We concluded that these findings suggested that both personality and age are factors affecting the children's way of looking at a human face, and that those children at age 10 and older need consideration just like adults (in the clinical setting).

View full abstract

Ectopic eruption of the maxillary first permanent molar is one of the abnormalities sometimes encountered in clinical pediatric dentistry. In some cases, treatments are finished by a very local approach, but in other cases are finished by a comprehensive approach under the long-term perspective.The basic treatment is distal movement of the maxillary first permanent molar locked by the maxillary second deciduous molar. But even if this treatment is successful in treating the early stages, the following problems may occur ; the second deciduous molar may fall out, retention of the maxillary first permanent molar may be necessary, or some maxillary second premolars may erupt from the lingual side. Moreover, more attentive care should also be paid to the second molar's biting relationship. Whenever a problem happens in the process of the treatment, it is very difficult for parents and guardians to imagine the treatment goal. A flow chart is designed as a tool for understanding this abnormality. This flow chart becomes our medical guideline. It is also available for parents and guardians to understand the treatment process correctly.In this article, the flow chart is introduced and five typical cases treated along the flow chart are presented. Furthermore, we report consideration from the literatures about ectopic eruption of the maxillary first permanent molar.

View full abstract

Opercula of the first molars delay in eruption were investigated histologically to detect the cause of eruption failure. The material was comprised of operation specimens from the exposure of 4 nonerupted first molars in Ichinose Pediatric Dental Office. There were no lesions in oral inspection and x-ray examination such as odontogenic tumor, odontoma and ectopic eruption. But location of tooth germ, development of root and comparison with another first molar presented delayed eruption.All specimens contained hamartomatous lesions with an odontogenic epithelial island. All of them stopped eruption when teeth germs were fresh from alveolar bone. I performed fenestration and after the surgery, three of them presented a tendency to erupt. There was no tendency to erupt in one case,so I opted traction. The eruption process was successfully completed.When the cases revealed delayed development of the first molar, we should keep these cases under observation without any intervention. But we should treat permanent first molars delayed in eruption as soon as we can for occlusal development.

View full abstract

A case of a palatal tumorous lesion was found in a 2 years and 3 months old Japanese boy. Histopathologically, it was diagnosed as the odontogenic hamartomatous lesion of the palate. It occurs very rarely in the oral region.The findings were as follows ;Intraoral examination showed a gingival-colored mass with a smooth surface, measuring 8×4×3 mm on the palatal mucosa adjacent to the left upper central primary incisor.Radiographic examination revealed a small calcified mass in the left upper central primary incisor region, which was almost the same place as the base of the palatal tumorous lesion. Impacted supernumerary tooth was found between the upper central primary incisor regions.Histopathologically, the myxoid mesenchymal tissue was increasing in the tumor-like lesion area and it included cord-like or a little of an odontgenic epithelium component. Furthermore, the enamel matrix component and the dysplastic dentin were found.Also, the small calcified mass in the tumorous lesion had enamel, dentin, cementium and pulp tissue, so that it was thought to be derived from the dental hard tissue. It had probably developed as same as the impacted supernumerary tooth.We concluded that this tumorous lesion was an odontogenic hamartomatous lesion and it was made because of the existance of the small calcified mass, but that the impacted supernumerary tooth was not related to the tumorous lesion.The tumorous lesion including the calcified mass was completely removed under general anesthesia, and the impacted supernumerary tooth was extracted. Postoperative course was good, and there was no recurrence after 9 months follow-up.

View full abstract

Oral-facial-digital syndrome (OFD syndrome) is a hereditary syndrome. The main signs are oral cavity abnormality (ligule, a fraenum in the oral cavity, and tooth socket irregularity), and perodactylia (brachydactyly, syndactylism, and many fingers).This is a case report of a female of biovular twins, 4 years and 5 months old at the time diagnosis with OFD syndrome that was brought to our hospital to have her oral cavity cleaned and receive guidance on chewing and deglutition. X-rays were taken of her body from head to foot. Abnormality of the lips and cheeks fraenum and hypoplasia of the teeth was seen in the x-ray images. Also, the oral cavity views showed a native lack of the side incisive tooth.Patients of OFD syndrome have oral cavity abnormalities, so it is necessary for them to take close care of their dental health over the long term. Otherwise there is the possibility of problems in articulation functions, feeding functions, and/or deglutition.

View full abstract