Dental caries and periodontitis, two major conditions encountered in the field of dentistry, are regarded as infectious diseases caused by specific oral bacterial species. These species are known to not only show pathogenicity in the oral cavity, but can also invade the bloodstream as a result of invasive treatments, such as tooth extraction. Although bacteremia is generally transient in healthy individuals,a complex composed of platelets, fibrin, and bacteria on the endothelium of the heart can lead to the onset of infective endocarditis in individuals with certain kinds of heart disorders. In addition, the bacteremia is considered to be frequently caused by daily oral hygiene procedures in addition to invasive treatments, which led us to consider that an oral bacterial invasion of the bloodstream occurs more often than expected. If such invasion occurs frequently, it is reasonable to speculate that oral bacteria are able to migrate to other tissues and organs via the bloodstream, and cause a variety of systemic diseases. The association of periodontitis with various kinds of systemic diseases is known.We have conducted numerous analyses of the virulence of various strains of Streptococcus mutans for bacteremia, and their effects on cardiovascular and cerebrovascular tissues. Those studies have provided abundant information and knowledge of bacterial features, which we intend to apply to future studies of other species. For example, our results have shown that strains with alterations of cell surface antigens are highly virulent. Based on our findings, additional investigations of a variety of different oral bacterial species are now being performed.

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The purpose of pediatric dentistry is to develop a healthy oral function. In the field of pediatric dentistry, dental caries and periodontal disease prevention, coronal restoration, root canal and surgical treatment, and occlusal guidance including space maintenance are clinically performed based on the philosophy of pediatric dentistry, aiming to achieve a healthy oral function. Requests for dentition and occlusal examinations have increased with recent changes in disease structure in pediatric patients visiting dental clinics, and morphological and functional anomalies are actually noted in many cases. A normal oral function from the deciduous dentition period leads to the development of an ideal morphology and occlusal condition, and is mainly achieved by the functional learning of mastication and swallowing during the process of ideal maxillo-facial growth. Therefore, morphology and function work in close cooperation with each other in biological tissue. Occlusal guidance, which will be a major treatment in pediatric dentistry in the future, should be performed with a consideration of oral functional development.

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Aggregatibacter actinomycetemcomitans (A. a) is frequently associated with aggressive periodontitis in children and adolescence. Although, it is well understood that lipopolysaccharide (LPS) derived from A. a stimulates host-immune system and induces osteocrastic differentiation, the effect of LPS on bone formation and cell to cell communication via gap junction in osteoblast is still unknown.In the present study, we revealed the expressions of mRNA of differentiation markers (alkaline phosphatase, osteocalcin, and bone sialoprotein) and cell-cell communication via gap junction in mouse osteoblast MC3T3-E1 were inhibited remarkably with LPS derived from A. a.

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Congenitally missing permanent teeth (CMPT) is one of the most frequent anomalies in dentistry. CMPT affects not only the occlusal relationships within the maxilla and mandible, but also the total occlusion. In addition CMPT can lead to future skeletal and facial problems. The purpose of this study was to estimate the nation-wide frequency of (CMPT) in Japanese children. Prior to beginning this epidemiological study, the authors obtained permission for the investigation from the ethics committee of Kagoshima University Graduate School of Medical and Dental Sciences (June 25^th, 2007).Seven pediatric clinics at dental colleges or universities and several private pediatric clinics participated in this study. The sample consisted of 15,544 pediatric dental patients (7,502 males and 7,502 females). Data were collected from longitudinal dental X-rays, orthopantomograms, and some dental models to determine CMPT (excluding 3^rd molars) within 6 months. All patients were judged to be over 7 years of age if they had all their permanent teeth in the dental films. In cases where it was difficult to judge the kind of tooth or its location, the committee members from all 7 colleges/universities reached a consensus on the number of missing teeth and their locations on a case by case basis.A total of 1,568 subjects (10.09%) were diagnosed with CMPT. Of these, 685 were males (9.13%),and 883 were females (10.98%). Differences between the maxilla and the mandible were seen in 4.37% of males and 7.58% of females. Differences between the right and left sides were seen in 0.11% of males and 0.14% of females. The most common missing tooth was the lower second premolar ; missing in 2.96% of adolescents, 2.64% of males (1.32% both sides) and 3.31% of females (1.72% on the right side and 1.59% on the left side). In descending order the next most common missing teeth were the mandibular lateral incisors, the maxillary second premolars, and the upper lateral incisors.

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Trigeminal mesencephalic nucleus neurons transmit oral sensation. The soma of these neurons contain GABA(A) receptors. Our objective is to quantify the gene expression corresponding to subunits of the GABA(A) receptor in trigeminal neurons in the mesencephalic nucleus, particularly those that project to muscle spindles of the masseter muscle. In order to accomplish this objective, we have developed a protocol in which we identify the target soma using retrograde fluorescence staining, resect and collect them with a laser-microdissection system, and quantify the expression of the genes coding for subunits of the GABA(A) receptor using PCR. We have tested this protocol with the following results :1.The retrograde fluorescence-staining technique using dextran-rhodamine B efficiently identifies the target soma to be resected with the laser-microdissection system.2.Resection with a laser-microdissection system is an efficient means to collect micro-structural tissue samples.3.Consistent with the report of Ishii et al, we detected the mRNA of each of the subunits of the GABA(A) receptor in soma resected and collected using the laser-microdissection system.

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A forecast of demineralization and remineralization on teeth in the oral cavity is important to prevent and treatment of the occurrence and progression of caries. The automatic pH-cycling system developed by Mastuda et al. can simulate daily changes in pH that occur in the oral cavity. In the previous study, permanent teeth were used to evaluate the caries progression and inhibition. However,there was no study that used deciduous teeth. Therefore, the aim of this study was to compare and evaluate the demineralization on deciduous and permanent tooth enamel using the automatic pHcycling system.A 150-μm thick single-section specimen was prepared from a human extracted deciduous molar and permanent third molar and polished surface was coated with Sticky Wax. The experimented condition was 9 pH cycles/day for four weeks, and a demineralizing solution (lactic acid solution, pH 4.5) and remineralizing solution (HEPES solution, pH 7.0) were used to reproduce the same pH changes that typically occur in the oral cavity. During the interval, the specimen was left in the remineralization solution. The Transverse Microradiography(TMR) images of each specimen were examined to evaluate the progression of artificial caries with respect to integrated mineral loss(IML) and lesion depth(Ld) at week 1, week 2, week 3 and week 4.Integrated mineral loss of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Lesion depth of the deciduous teeth was significantly higher than that of the permanent teeth at all weeks. Especially, integrated mineral loss and lesion depth of the deciduous tooth at week 4 was higher than that at other weeks.The results suggested that the occurrence and progression of demineralization of the deciduous tooth is higher than the permanent tooth, and we concluded that the automatic pH-cycling system was qualified as a system that evaluated demineralization of the deciduous tooth and the permanent tooth. It could be beneficially employed to clarify the difference of the deciduous tooth and the permanent toothinoralcavity.

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In order to investigate the actual status of the dental treatment for disabled patients in private practice, we conducted questionnaire surveys and got answers from 450 specialists out of 1404 specialists in private practice that provided pediatric dentistry (a response rate of 32.1%).About half of the respondents (48.7%) had 26−30 years of clinical experience. A ratio of the number of disabled children to all patients in most private practices was 1−5%. A small number of respondents (13.3%) separated the time for the treatment between normal and disabled children. And most of the reasons for visiting the private practice were consisted of the patient's or their parent's own motive. These results indicated that expert specialists in each area had been performing comprehensive and high-quality treatment for disabled children as well as the normal patients, regardless of the patient's age. And it seemed that the specialists in private practice played a role as primary care dentists for the patients. On the other hand, there was great variability related to the age of the respondents in these questionnaire surveys. Therefore, it seemed to be necessary for specialists over generations to share the information for technology and knowledge associated with the dental treatment for disabled children.

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In order to investigate the actual status of the dental treatment for the disabled patients in private practice, we conducted questionnaire surveys and got answers from 450 specialists out of 1404 specialists in private practice that provided pediatric dentistry (a response rate of 32.1%).As the results, on the dental treatments of disabled children, 90% of the specialists of pediatric dentistry in private practice had the second or the third grade dental institution as an introduced dental hospital. Most of the introduced dental institutions were the university dental hospital. However, the specialists with the cooperation with the educational institutes for disabled children was slight 19.1%. Similarly, the specialists with the cooperation with the administration was 24.4%. Therefore, it was shown that the cooperation between the specialists in private practice and the educational institutes for the disabled children or the administration was insufficient. And it seemed that many problems of time, cost, physical strength and facility such as insurance systems which is not suitable for present state, limit in the practitioner and regional differences existed in the dental treatments of the disabled children by the special practitioners.

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The purpose of this study was to evaluate the shear bond strengths of fluoride releasing orthodontic adhesive to human enamel. Also, we examined the release of the fluorine of each adhesion materials and recharge performance. As a result, Superbond orthomite is the strongest (16.7 MPa) which deteriorated in order of Fuji ortho LC (14.2 MPa), Krasper F (12.9 MPa), Beauty ortho bond (10.1 MPa),Beauty ortho bond salivatect (7.4 MPa). As for Beauty ortho bond, the enamel surface was smooth as a result of SEM observation after the shear bond strength test. However, the enamel prism structure was exposed in Superbond orthomite and Krasper F which showed strong adhesive strength, and injury to enamel surface. By the measurement of the amount of release of the fluorine and recharge performance, most fluorine released it after one day of the measurement. On the second day, the amount of fluoride release decreased with the third day and became the equilibrium from day 4 to day 7. The most fluoride ions were released from Fuji ortho LC as resin modified glass ionomer cement. Beauty ortho bond which contained S-PRG filler followed it. It had the same tendency after fluoride recharge. Fluoride releasing orthodontic adhesive has moderate adhesive strength with little effect on enamel surface. These had the ability for the release of larger amounts of fluorine and recharge performance, and it was shown that it was effective materials for dental caries during orthodontic treatment.

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The purpose of this study was to survey the dental caries incidence in children with cleft lip and palate (CLP) and to evaluate the effect of the early caries prevention program on 1- to 3-year-old children with CLP. This program consists of the topical application of fluoride and oral hygiene instruction, and was carried out every 3 months.We investigated the dental caries incidence in 309 children with CLP aged 2-8 years who visited Tohoku University Dental Hospital from July of 2006 to June of 2008. Of these, 204 children had joined this program.1.44.0% of the children with CLP had caries experience in their deciduous teeth and 11.7% in permanent teeth. The mean dft and dfs values were 2.0 and 3.9, respectively. And the mean DFT and DFS values were 0.2 and 2.0, respectively. Those values were low as compared with our previous reports, indicating that our early caries prevention program has succeeded in reducing the number of dental caries in CLP children. Those results were also good score compared to non-CLP children.2.The dental caries incidence in children with isolated cleft palate was higher than that in children with another cleft type at an earlier age.3.In the group with cleft lip and palate, the caries incidence of maxillary deciduous lateral incisor on the cleft side was significantly higher than on the non-CLP side.4.We compared the dental caries incidence of children who joined our program (prevention group) with children who have not joined (non-prevention group). The dental caries incidence of deciduous tooth in the prevention group was significantly lower than that in the non-prevention group. Similar results were observed in permanent teeth. Further, it was found that the dental caries incidence in non-prevention group was higher than that in children without CLP. These results indicate that the early caries prevention program is effective in decreasing the dental caries incidence in children with CLP. However, even in the prevention group, the dental caries incidence increased with age. Therefore, the long-term management for caries prevention might be necessary for children with CLP.

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We experienced a very rare case of three supernumerary teeth in the anterior region of the maxilla and a geminated tooth concrescence of the right mandibular central incisor and a supernumerary teeth of a healthy Japanese girl aged 6 years. At the examination of the geminated tooth, the right mandibular central incisor and the supernumerary teeth has it's own pulp and root canal. After the apex of the right mandibular central incisor had been compleated, the separation of the geminated tooth was performed, and the supernumerary tooth was extracted. The right mandibular central incisor could have been vitally preserved with neither any spontaneous pain nor other symptoms. Further we performed occlusal guidance ,the oral environment could have been improved to be more healthy in function as well as aesthetically.

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Primary tooth impaction is quite rare during the development of primary dentition. Various factors contribute to the impaction of primary tooth, including malposition and malformation of the tooth bud, tumor and cyst. The purpose of this paper is the report of a case of horizontal impaction of mandibular primary central incisors with eruption in proper position. The case was a 1 year 8-months-old female with horizontal impaction of mandibular primary central incisors. In the X-ray examination,root bent was not clear. The patient didn't have any oral habits, such as teething ring or finger sucking. Treatment planning is a follow-up while comparing the position of impacted incisors in gingiva and alveolar bone with photograph. The ridge of lingual gingiva corresponded with the edge of impacted incisors moved to labial direction at the age 2 years 5 months. Left primary central incisor erupted in the proper direction at age 2 years 8 months. Right primary central incisor was also erupted in the proper direction at age 3 years 2 months. The tooth axis of both incisors was changed to a completely normal direction at age 3 year 8 months. Normal growth of the successive permanent central incisors was seen in X-ray image at age 4 years 7 months. In conclusion, it is suggested that the long term precisely follow-up of impacted mandibular primary central incisors at age of around 2 years leads the prospective prognosis.

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We report a clinical case of the replantation of impacted maxillary left canine due to an odontoma.The patient had received dental management since infancy in our hospital. Delayed eruption of maxillary left central and lateral incisors had been noted. From the ages of 9 years and 3 months to 11 years and 5 months, retractions of these incisors were performed using the multi-bracket method. At the age of 12 years and 7 months, due to prolonged retention of the maxillary left primary canine,X-ray photographic examination was conducted. A well-delineated radiopaque image was observed near the root apex of the left primary canine. The cusp of impacted maxillary left canine was present near the root apex of lateral incisor. The retraction of maxillary left canine seemed to have difficulty because of its almost completed root formation and the odontoma. At the age of 12 years and 10 months, the odontoma was surgically removed, and the impacted canine was extracted and replanted into the extraction socket of primary canine. Two months after the replantation, endodontic treatment was started. At the age of 14 years and 8 months, restoration with resin-veneered crown was performed.A long single root of the replanted tooth might be advantageous for replantation. Also, in this case,the removed socket of the odontoma was an appropriate size for the replantaion space of impacted tooth. Further, proper aseptic treatment could be done because the replantation tooth was completely impacted. We considered that these situations might contribute to the success of replantation.

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