Trauma to primary and/or young permanent teeth has been gradually increasing as the chief complaint of patients visiting pediatric dental clinics in recent years. As a result, dental trauma has received much attention, including as the focus of 270 abstracts and 57 original articles published in the Journal of the Japanese Society of Pediatric Dentistry (JSPD) since its establishment. Furthermore, in 2012 the International Association of Dental Traumatology published three clinical guidelines in its journal “Dental Traumatology” and in 2013 the American Academy of Pediatric Dentistry (AAPD) published three guidelines in its journal “Pediatric Dentistry”. In the present study, JSPD abstracts and articles related to background information and the significance of clinical guidelines are discussed in light of current and future clinical dental guidelines.

In recent decades, improvements in therapeutic modalities for childhood cancer, including chemo­therapy, irradiation, surgery, stem cell transplantation, and their combinations, have increased survival rates, demonstrating their increasing effectiveness. However, along with improved survival, the late effects of antineoplastic therapy deserve more attention. Notably, late effects involving dental disturbances have been reported in patients treated with can­cer therapy. Furthermore, adverse effects of cancer and cancer therapy during childhood on dental health have been reported, such as mineralization disturbances, dental caries, microdontia, hypodontia, root stunting, and taurodontism, as well as dental disturbances caused by chemotherapy and radiation therapy. However, because multimodal therapy is used for nearly all types of childhood cancer, it is difficult to attribute these effects to any single agent or treatment modality. The effects of antineoplastic treatment, particularly those of alkylating drugs, on the oral health of childhood cancer survivors are well known and widely documented. Cyclophosphamide (CY), an N­-mustard derivative, is an alkylating drug widely utilized for treatment of cancer because of its capac­ity to interfere with cancer cell division. However, administration of CY results in certain undesirable secondary effects caused by nonspecific actions on cells with a high mitotic index, resulting in dam­ age to both neoplastic and normal cells. In this study, to evaluate the effects of CY on root development until occlusion completion, we ex­amined the molar teeth of young mice treated solely with CY. Using 3D structural imaging, morpho­logical changes in the molar roots of mice were analyzed to investigate the mechanism underlying the adverse effects of CY on dental root formation. Our results showed that CY administration in the early stages of root formation resulted in impaired root development and early closure of the apical foramen. Additionally, CY inhibited regular formation of Hertwig's epithelial root sheath and might have caused disturbances to the developing molar root. Additional studies are needed to elucidate anticancer treatment effects in relation to dose and age, as well as time­related effects on dental development. The number of long­term survivors following diagnosis of cancer childhood will no doubt show a steady increase in the future. Therefore, oral care programs designed to prevent periodontal disease are vital in consideration of the irreversible condi­tion of shortened tooth roots that often develops.

Streptococcus mutans, known to be a primary causative agent of dental caries in humans, possesses multiple glucan-binding proteins (Gbps) on its bacterial cell surface, of which 4 types have been identified. Among those, GbpC encoded by the gbpC gene has a strong relationship with cariogenicity in relationship to high dextran-dependent activity, though the mechanism of glucan binding remains unknown. Using bioinformatics analysis and molecular techniques, we examined the dextran-binding domain of GbpC. Based on the 3D structure revealed by a Cn3D macromolecular structure viewer, 5 loops were confirmed as possible dextran-binding domains. Next, truncated recombinant GbpC (rGbpC) encoding each region was produced using a protein expression vector and 5 deletion mutant strains, CDGB1 through CDGB5, were generated. The dextran-binding rate of fragment A, which was truncated rGbpC and included the GB1, GB3, GB4, and GB5 regions, was higher than that of fragment B containing GB2. In addition, the rates of dextran-binding for strains CDGB4 and CD1, gbpC deletion mutants, were significantly lower as compared to the other strains, while those of the other deletion mutants were quite similar to that of the parental strain MT8148. Furthermore, biofilm structures formed by CDGB4 and CD1 were not as pronounced as that formed by MT8148, while those produced by other strains had greater density as compared CD1 biofilm. These results suggest that the dextran-binding domain may be located in GB4, mainly in the 7 amino acid sequences DPTKTIF in the center of gbpC.

General anesthesia is sometimes used as a behavior management technique during dental treatment performed for young children or mentally disabled individuals. Recently, the number of patients who undergo treatment under general anesthesia at our clinic has been increasing, suggesting its growing importance for dental treatment of uncooperative children. We surveyed the attitudes of parents in regard to dental treatment under general anesthesia for their children. Parents of children with special needs or without systemic disease but lacking a cooperative attitude were included in this study. The enrolled patients were 56 boys and 44 girls, and their average age was 5 years 3 months. Of those, 78 were considered to be uncooperative with the treatment procedures, 11 were disabled, and 11 had a systemic disease. Forty-nine percent of the parents requested dental treatment under general anesthesia for their child at the initial visit. In a questionnaire regarding parental understanding of dental treatment under general anesthesia, “Satisfied” and “Basically Satisfied” comprised 98% of the answers, indicating that such treatment at our clinic meets the needs of the vast majority of our patients.

With the shift in medical education to an outcome-based paradigm, portfolios are now widely used as effective tools for learning of medical students, who record and organize their learning, track their progress, and reflect on their learning experiences. The process of reflection and using “rubrics”,which contain evaluation criteria and quality definitions, are considered essential for development of a learning portfolio. In the present study, we introduced rubrics and reflection process to basic dental practice education for pediatric dentistry and assessed the effectiveness by a questionnaire survey on 4th grade dental students in 2011-2015 and by comparisons between the initial and final average scores of self-evaluation. We found that many of students considered that rubrics and reflection process were helpful for learning the course. In addition, there were significant differences between both average scores for self-learning competence. Our results suggest that introduction of the rubrics and reflection process was effective for learning of dental students.

In studies published prior to 1980 that studied the order of eruption of the central incisors, lateral incisors, and first molars of the lower jaw, the first molar was found to most often erupt first. In contrast, in those published since 1980, the percentage of children in whom a central incisor was first to erupt is the greatest. These findings indicate that the order of eruption of permanent teeth of the lower jaw may have changed after 1980. Here, we investigated the order of eruption of the central incisors,lateral incisors, and first molars in a longitudinal study of 105 pediatric patients in stages ranging from deciduous dentition to Hellman's dental stage III B. The following results were obtained.

1.There was no significant difference in order of eruption between genders or side of the jaw. However, there was a significant difference between the upper and lower jaws.

2.The most frequently observed order of eruption in the upper jaw was first molar (6), central incisor (1), and lateral incisor (2), while that in the lower jaw was 1-6-2.

3.There was no significant difference between the frequencies of 1-2-6 and 1-6-2 in the upper jaw, or between the frequencies of 1-6-2 and 6-1-2 in the lower jaw.

4.There was a significant difference for mesiodistal diameter of the crown of the lateral incisor in the upper jaw between patients in whom a central incisor had erupted first and those in whom a first molar had erupted first in the lower jaw.

We found no significant difference in regard to the first erupted tooth in the lower jaw of our patients. Nevertheless, we cannot conclude that the order of eruption has changed since 1980, as it is possible that the mesiodistal diameter of the crown has effects on the order of eruption, which we intend to examine in future studies.

In recent years, the number of children with severe motor and intellectual disabilities who live at home has been increasing. Although most require medical care such as tube feeding or a mechanical ventilator, the present level of medical support for disabled children living at home is not adequate. We investigated this situation, and evaluated the effectiveness of home-visit dental treatments for children with severe motor and intellectual disabilities who require a mechanical ventilator.

The subjects were 27 patients (≤15 years old, mean age 4.7±4.0 years) with severe motor and intellectual disabilities, and who required a home mechanical ventilator and received home-visit dental treatments provided by Toseikai Healthcare Corporation Life-Long Care Clinic for Disabled people from April 2015 to December 2016. We compiled information regarding basic patient characteristics, oral condition and function, and contents of the home-visit treatments. All were receiving multiple types of medical support. Nineteen patients were using a tracheostomy ventilator and 8 a nasal mask ventilator, while 22 received nutrition via a gastrostomy, 4 from naso-enteric feeding, and 1 from oral intake. Several had gingivitis or calculus deposition, and their oral functions were severely disordered. As for dental treatments, we mainly conducted oral care instruction and dysphagia rehabilitation. In cases that were difficult to treat at home, we cooperated with the related hospital. Most of the patients had no experience with visiting a dentist or had quit regular dental visits, though they were able to receive regular oral management through our home-visit dental treatment program. Our findings indicated that home-visit dental treatments are effective for children with severe motor and intellectual disabilities living at home and using a mechanical ventilator.

Developments in regenerative medicine using induced pluripotent stem (iPS) cells are rapidly and widely progressing, with transplantation therapy using iPS cells initiated in Japan. A questionnaire regarding tissue engineering and regenerative medicine was given to guardians of patients visiting the pediatric dental clinic of a university hospital in 2010 and again in 2014. In this study, we compared responses to the questionnaire between the administered years in order to understand changes in awareness of regenerative medicine and the level of interest in dental pulp cell banking among the guardians of the patients. Our results indicate that awareness regarding the terms “regenerative medicine” and “iPS cells” has been raised, indicating the spread of related information. However, awareness regarding the use of dental pulp cells in regenerative medicine and for generation of iPS cells was found to be quite low, and scarcely increased between 2010 and 2014. The percentage of guardians who had knowledge about dental pulp cell banking was also quite low in both periods. However, among those with awareness of banking of dental pulp cells, interest was high regardless of the year of survey. Wide dissemination of information showing that cells derived from teeth and oral tissues can be an effective resource for use in regenerative medicine will be indispensable for promotion of modern techniques in the field of dentistry.

Lesch-Nyhan syndrome is a rare X-linked recessive disorder of purine metabolism caused by a deficiency of hypoxanthine guanine phosphoribosyltransferase. Affected patients are characterized clinically by hyper-uricemia, mental retardation, involuntary movements, and self-mutilation. We began treatment of a 1-year-9-month boy with Lesch-Nyhan syndrome in whom difficulty in preventing self-mutilation behavior was noted, which resulted in severe lower middle lip destruction. At the age of 4 years, the lower right side lateral deciduous incisor and deciduous canine became extruded due to bruxism from daily clenching. We attempted to reduce oral stress by concomitant use of soft-type and hard-type mouth guards, however, the maxillary dentition expanded and biting of the buccal mucosa was recognized. Thereafter, the patient became accustomed to a hard-type mouth guard and recently has not demonstrated excessive self-mutilation behavior leading to a large amount of oral destruction. Nevertheless, continued observations are required.