We investigated the development of lip closing force and other forces, and their relationships to elucidate their effects on dentition formation, as well as dental occlusion and swallowing. Method : A total of 45 subjects with normal occlusion ranging in age from 8-25 years old were investigated. Lip closing force was determined using a multidirectional lip closing force measurement system. Tongue and buccal pressure measurements were obtained with a simple tongue pressure measurement device, and grip strength with a Smedley hand dynamometer. Results : Subjects in the 8-year-old age group had significantly greater lip closure force from the lower jaw in all 8 directions of lip closing force as compared to subjects older than 11 years. As for the correlation of lip closure force with other forces, tongue pressure on the palate had a greater positive correlation with lip closure force in older subjects in an age-dependent manner. In addition, a positive correlation of buccal force with dentition and grip strength was observed in all age groups. Discussion : Our findings revealed that lip closing function in younger ages occurs mainly in conjunction with lip closing force from the lower jaw, while the lip as a whole moves in a more coordinated manner with maturity. Furthermore, they suggest a correlation of lip closing force with tongue and buccal pressure, each of which work in coordination for oral function.

Dietary issues in toddlers and preschool children are not limited to those with autism spectrum disorder (ASD), but are also encountered in neurotypical children. In this study, we examined the diets of children with ASD, as well as neurotypical toddler and preschool-aged children attending nursery school (school children) to elucidate these issues. The subjects were 61 ASD and 55 school children who used dietary counseling. We compared consultation documents available for the ASD group with questionnaires obtained from the guardians of the school children, and found that 74.5% of that latter group had issues with diet. Items of concern for the guardians included a small number of questions regarding eating function,such as “not chewing food” and “shoving food”, which were of greater concern as compared to eating behavior problems, such as “picky eater” and “taking too much time”. These findings may be associated with hunger and a desire to eat, and dietary issues in toddlers and preschool children should be addressed while taking overall lifestyle into consideration. There were also several cases of guardians of school children who showed concerns over eating behavior, though the breakdown was different and those were more serious in ASD children. We concluded that conditions related to ASD are involved in issues with eating behavior, indicating that a specific response is needed.

This study aimed to clarify eating problems encountered in infants and young children that cause concern in their parents, as well as the importance of dental support for managing eating problems in children. A structured questionnaire was sent to 1001 dentists working as pediatric dentistry administrators,who were randomly selected by prefectural or municipal dental associations, and 1031 parents of preschool-aged children attending kindergarten or day-care centers recommended by the Committee of Emphasis Study, Japanese Association for Dental Science. Of those, 712 dentists and parents of 844 children provided informed consent to participate in this study. A chi-square test was used to analyze differences among several factors included in the questionnaire, by comparing responses between parents of infants and young children, and between children with and without eating problems. Logistic regression analysis with a stepwise forward selection method, adjusted for covariates, was used to calculate the odds ratios (ORs) of factors associated with eating problems of infants and young children. The ethics committee of the Japanese Association for Dental Science reviewed and approved the study protocol, which was performed in compliance with the Declaration of Helsinki and each study participant signed a detailed informed consent form. The risk of eating problems was increased in children who had experienced difficulties during the weaning period (OR＝3.18, p＜0.001), were light eaters (OR＝8.48, p＜0.001), and/or did not eat regular types of meals (OR＝2.46, p＝0.03). The most common reason for counseling noted by parents was “occlusion”. Our results suggested that several factors might be associated with feelings of anxiety by parents regarding eating problems experienced by their children. Parents were quite interested in the amount of nutritious food ingested and types of meals needed for acquisition of acceptable feeding function. Furthermore, there were discrepancies in perspectives regarding the roles of dentists between parents and the dentists themselves. We concluded that dentists should contribute to managing the eating problems of children from the viewpoint of social child-rearing.

Appropriate timing for extraction of mesiodens is generally considered with malocclusion, technical difficulty of the extraction, and psychological stress of the patient in mind. For creation of guidelines for management of mesiodens, it is important to show the standard position of impacted mesiodens in relation to age and developmental stage of the central incisors. We previously reported the relationship of position of impacted mesiodens with age and central incisor development stage using cone beam computed tomography images, and also showed the practicality of evaluating mesiodens position using a radar chat. In the present study, we analyzed 283 additional samples to test the reproducibility of our previous findings. In mesiodens with an inverted direction, the distance from the surface of the maxillary bone surface (Deepness) and alveolar crest (Height) to mesiodens tended to be located deeper and higher in the maxilla, and closer to the developing root apex of the central incisor (Apex) in association with age and Nolla's classification. The present results supported our previous findings. According to measured values for Deepness, Height, and Apex of each sample, we determined a standard scale of the parameters Age, Nolla's classification, Deepness, Height, and Apex using a radar chart graph. All present samples of inverted mesiodens were plotted onto the radar chart, and the proper scale of the parameters was verified. As a result, our radar chart was confirmed to be useful for evaluating the objective position of mesiodens and shown to be a valuable tool for clinical management of inverted mesiodens.

With the declining birth rate in Japan, patient demographics and dental needs have changed. To understand the present role of pediatric dentistry, we surveyed new patients who visited our pediatric dental clinic in the recent 5-year period. The results were compared with those of our previous investigation performed 10 years prior.

1.The total number of new patients during the 5-year period was 1899, an increase from the previous investigation. In particular, the number of those aged 1 and 2 years old was remarkably increased.

2.About half of the new patients were residents of Morioka city.

3.The percentage of referred patients among all new patients was 48.0%, a remarkable increase from our previous investigation. Most referrals were from practitioners and the most common reason for referral was dental caries.

4.The most common reason for new patients to visit our institution was caries treatment (31.7%), followed by oral examination (17.0%), dental trauma (11.0%), and malocclusion (10.0%), among which oral examination and preventive care were remarkably increased from the previous investigation.

5.The dft index of all new patients during the 5-year study period was 3.25, which was higher as compared to that (1.40) reported in the Survey of Dental Disease in 2011. It was remarkably in creased in patients aged 6 years old and younger.

Elucidation of the morphology and morphological changes of the superior labial frenum is clinically significant for predicting changes and onset of abnormal attachment of the superior labial frenum, allowing early measures to prevent oral diseases caused by frenal abnormalities. In this study,we classified 174 healthy boys and girls aged 0 to 6 years who visited the pediatric dentistry of Tsurumi University Dental Hospital according to the morphology of the superior labial frenum and position of frenal attachment with reference to the classification criteria developed by Nosaka et al. (N-, I -, II-, III-, IV-, and V-type). The number of N-type (normal) frena was largest in both boys and girls. Other than N-type, the number of II-type was large in boys, whereas the numbers of I- and II-type were large in girls. Furthermore, the percentage of N-type frena as compared to the others types was high in both boys and girls, while the difference between genders was not significant. In all subjects,N-type showed the highest percentage (69.5%), followed by II-type (10.9%). When divided by age and frenal type, the number of 3-year-old subjects with N-type was significantly large as was that of 1-year-old subjects with an abnormal frenum. In contrast, the numbers of 3-year-olds with an abnormal frenum and 1-year-olds with N-type were significantly small. Craniofacial height was markedly increased in children aged 1 to 3 years. Maxillary alveolar process height is considered to increase with bone development, thus related movement of frenal attachment to a lower position may explain the present findings. In addition, the number of 1-year-old and 3-year-old subjects with normal frena was significantly small and large, respectively, indicating that a course of follow-up observations is the best optionforchildrenaged0to2yearsevenwhendiagnosed with abnormal frenal attachment or morphology, as long as no health-related problems, such as with breast feeding or eating, are present.

Mutans streptococci (MS), are Gram-positive facultatively anaerobic cocci considered to play important roles in the development of dental caries. Although possession of MS is correlated with caries prevalence, quantification of those harbored in dental plaque remains unclear. Furthermore, bacterial microflora known as dental plaque is considered to enhance possession of MS, though related mechanisms have not been reported. In this study, we determined quantitative levels of oral streptococci and total bacteria, as well as specifically Streptococcus mutans (Sm) in plaque samples obtained from children, and assessed their relationships to caries prevalence. Following oral examinations, plaque samples were collected from 98 children and their mothers after obtaining informed consent to participate in this study, and bacterial DNA from each was purified. MS, Sm, and S. sobrinus (Ss) were detected using species-specific conventional PCR (c-PCR) assays,and the levels were quantified using real-time quantitative PCR (q-PCR). In addition, quantification of oral streptococci and total bacteria was also performed using a q-PCR method. In c-PCR results, 49 of the 98 samples had Sm-positive and Ss-negative (Sm^＋‐Ss⁻) results. Notably, the combination of c- and q-PCR findings suggested that the 49 Sm^＋‐Ss⁻subjects could be divided into two groups based on the quantitative levels of Sm, Sm^high-Ss⁻(30/49) and Sm^low-Ss⁻(19/49). Among the 4 groups, the MS-double positive group showed the highest dft score and composition ratios of Sm in oral streptococci and total bacteria, followed by the Sm^high-Ss⁻group. Average dft score was not significantly different between the Sm^low-Ss⁻and Sm⁻-Ss⁻groups. Our results indicate that quantification of MS in plaque samples may be an efficient method to clarify the relationship between MS colonization and caries in children.

We present here the late effects of combined chemotherapy, radiation therapy, and hematopoietic stem cell transplantation on dental development in a patient treated for neuroblastoma at an early age. A 11-year-11-month old girl came to the University of Tsurumi Dental Hospital with a chief complaint of dental caries. Her medical history revealed that the patient was diagnosed with a stage IV neuroblastoma at the age of 3 years 10 months, for which she had been treated with chemotherapy,tumor resection, radiation therapy (left neck 10 Gy, total body 10 Gy), and hematopoietic stem cell transplantation from the age of 3 years 11 months to 4 years 3 months. In addition, oral 13-cis retinoic acid was administered until 6 years 2 months old. Our oral examination revealed dental caries in multiple teeth, while periapical and panoramic x-ray findings showed morphological anomalies in multiple teeth and hypoplasia of all roots. Remarkable tooth dysplasia, and developmental abnormalities of the maxilla and mandible were suggested to be caused by the combination of chemotherapy, radiation therapy, and hematopoietic stem cell transplantation in this patient.