With the present low birthrate in Japan, the relative value of each child is increased and caregivers desire to provide their children with early qualified dental treatment. Although pediatric dental specialists should be recognized as dentists who have both knowledge and skill to meet the needs of their child patients, national consensus in Japan that dental treatment of children should be conducted by pediatric dental specialists has not been reached. In order to develop a suitable strategy toward that end, a survey was conducted regarding awareness of those specialists by caregivers of child patients. The following results were obtained.

1.Eighty-three percent of the caregivers expressed a desire for their child to visit a pediatric dental specialist for treatment.

2.Sixty percent of the caregivers recognized that the dentist caring for their child was a pediatric dental specialist.

3.Thirty-four percent of the caregivers noted “because the dentist is a pediatric dental specialist” as their reason for selecting that dentist.

4.Only 7.5% of caregivers understood the difference between a pediatric dental specialist (“sen-moni” in Japanese) and a dentist who claims to have a pediatric specialty (“hyou-bou-i”)

Our findings indicated that caregivers want their child to visit a pediatric dental specialist, however,the value and merit of seeing such a specialist are not well recognized. It is important to make efforts to form a national consensus that pediatric dental specialists offer high quality dental treatment for children by showing their existence and value. In addition, it is important to investigate methods to increase public awareness as well as quality through mutual sharing of information concerning pediatric dentistry.

Dental cast analysis is indispensable for both dental research and medical practice. The Pediatric Dentistry Department of the School of Dental Medicine at Tsurumi University is planning to employ an R 700 3D Scanner for Orthodontics (3 Shape, Inc. Poland) for three-dimensional scanning as a part of dental cast analysis. However, to the best of our knowledge, the accuracy of data objectively obtained with the scanner and its accuracy for measurements in virtual space have not been reported. For this study, we determined the inherent accuracy of the device, accuracy of the indicator points,and clinical accuracy for measurements of actual dental casts using gauge blocks, dental casts designed for measuring accuracy, and actual dental casts. The following findings were obtained.

1.The accuracy of data obtained in all axial directions with the scanner was within 0.02 mm, thus satisfying the nominal accuracy requirement.

2.The differences for the three-dimensional coordinates of the dental cusp of a canine milk tooth on the right upper jaw between a standard dental cast and its shadow cast were within 0.02 mm in all axial directions, with the deviation significantly smaller for the shadow cast.

3.The results of measurements at eight points in accordance with measurement standards reported by Otsubo et al. showed maximum error and mean error values of 0.52 and 0.22 mm, respectively.

Our results indicate that the accuracy of data obtained using this scanner is satisfactory. It was also demonstrated that the scanner has a measurement accuracy for dental casts of ～0.2 mm in clinical settings. In addition, consistent and highly precise results were easily obtained for measurements of dental casts in virtual space using the scanner.

To examine the evaluation method used for preclinical tooth modeling practice, we examined cavity and abutment tooth preparation technique evaluations performed by teachers and morphometry findings obtained by a 3D laser sensor. Our comparison results and findings of a questionnaire given to students were analyzed, with the following findings obtained.

1.With grading by teachers, the average number of approved evaluation items was 4.2 of 6, with some variations in item-by-item pass/fail results.

2.With evaluation by machine, there was a tendency for difference between students who scored 60 points more and those who scored less than 60 points.

3.With evaluation by machine, the number of approved items per student for the item-by-item evaluation was greater for students who scored less than 60 points as compared to those who scored 60 or more points.

4.In addition to the opinions “Machine grading is highly fair” and “Teacher grading is easier to understand”, “The difference between teacher grading and machine grading was confusing” was com monly noted.

The present study revealed differences between evaluations performed by machine and those performed by teachers. However, half of the surveyed students did not note a difference between machine and teacher grading, and many stated that it would be easier to understand if side-by-side images displaying the model cavity and student-made cavity were available. Thus, we consider it necessary to examine our grading methods using software and provide easily understood feedback regarding grading results to the students.

Recently, production of high-quality simulation scenarios and teaching materials has become indispensable for providing simulation education, which is now widely used in the field of odontology. Problem solving and examinations are both necessary to provide an environment in which the learner can experience a variety of types of cases. For the present study, we created a scenario of a typical case of an ill child and guardian, in which a role play was devised for the training dentist, who was asked to obtain patient agreement, and the process was recorded on video. We concluded that it is important to present the scenario with feedback and a questionnaire afterwards, in order to clearly confirm the degree of preparation concerning the theme by the learner. Moreover, feedback allowed the learners to notice important point that they might have otherwise missed, while the instructors at times could use failure as a learning experience. The method was shown to be convenient, and lends itself to repeated use and increased learner awareness, Futhermore, in addition to the learner, the instructor, mock patient, and other participants are able to benefit from increased awareness.

To investigate parent awareness of their child's dental health in comparison to the actual situation and utilize those results for future health guidance, we conducted an awareness survey of parents of pre-school aged children (3-6 years old). The following results were obtained.

1.As for caries prevention, the most common response by both fathers and mothers regarding what parents most care about besides brushing teeth was “regular checkups”. In addition, “None” was a common response from fathers.

2.For finish polishing for their children, 95.2% of the mothers and 56.8% of the fathers regularly performed that. In homes with working mothers, a higher percentage of fathers performed finish polishing, though the percentage was quite small for fathers as a whole. Also, most fathers performed finish polishing without special awareness of its effects.

3.The highest interest of both mothers and fathers regarding the oral cavity of their child was for “decayed teeth”, followed by “tooth alignment and bite”.

4.Among child-rearing practices that parents are involved in, “finish polishing” showed the highest frequency with both fathers and mothers.

Our findings led us to better understand the awareness of parents regarding the dental health of their children, as well as differences between fathers and mothers. We consider them to be quite meaningful and will accordingly modify our oral hygiene instructions. Despite the recent trend of a shift of child-rearing from primarily the mother to both parents in Japan, the interest of the fathers regarding the oral cavity of their children was lower than that of the mothers. Our results indicate the need for improvements in methods used for checkups and oral hygiene instructions by family dentists to encourage fathers to participate more in finish polishing for their children.

We developed a new method for analysis of mixed dentition in the lower jaw using only tomosynthesis panoramic radiograph (TSPX) findings obtained from 40 children at the Hellman IIIA stage. For this study, mixed dentition analysis using plaster models and the regression equation of Ono was defined as the A method, while that using plaster models and TSPX findings was defined as the B method. There was no significant difference for the average value of dental arch space between the A and B methods. In addition, we produced simple regression equations (E and F methods) and a multiple regression equation (G method) using the values obtained with TSPX. There were no significant differences for the average value of dental arch space among the A, B, E, F, and G methods. When comparing the mean absolute errors for dental arch space measurement between the B method and the E, F, and G methods using leave-one-out cross validation, the mean absolute error of the dental arch space for the F method was smallest (0.735 mm) among all of the methods. In addition, the mean absolute error of the dental arch space for the G method was 1.055 mm, which was nearly the same for the E method, in which the mesio-distal crown diameters of all permanent teeth and arch length were measured using TSPX. Therefore, we concluded that the present G method is most usable for screening at the chair side, as it requires only 6 measurements for mixed dentition analysis.

White spot lesions (WSLs) in teeth can be divided into carious and non-carious. Since a precavitation carious lesion is reversible, early detection and appropriate treatment are important to arrest the demineralization process. Nevertheless, there have been few clinical surveys about the prevalence of WSLs in Japanese children. The aim of this study was to evaluate the prevalence of WSLs in anterior teeth and canines among deciduous, mixed, and permanent dentition. A total of 1130 patients (range 2-18 years old) who came to Asahi University Hospital Department of Pediatric Dentistry for dental recall examinations were enrolled. The labial surfaces of the anterior teeth and canines were investigated for the presence of WSLs by ocular inspection under appropriate illumination. Additionally, history of traumatic injury to deciduous teeth, and other dental and medical incidents were noted. For deciduous dentition, 12.9% of the subjects had WSLs, with the rate of incidence in maxillary teeth significantly higher as compared to mandibular teeth. In addition, 27.7% of the subjects had WSLs in mixed dentition, with the incidence in numbers 11 and 21 significantly higher as compared to other teeth. As for permanent dentition, 23.9% of the subjects had WSLs and the rate of incidence for maxillary anterior teeth was significantly higher as compared to other teeth. Furthermore, the ratio of subjects with a WSL of the cervix was significantly higher in mixed and permanent dentition as compared to deciduous dentition. The ratio of subjects with a history of traumatic injury of the precursor was 14.3% in mixed dentition and 10.0% in permanent dentition. Some WSLs were unidentified enamel hypoplasia. Also, cleft palate, crossbite of anterior deciduous teeth, and apical lesions in deciduous teeth seemed to be causative factors of WSLs. Our results suggest that oral hygiene instruction and preventive treatment are important throughout all dentition stages. Furthermore, treatment of pre-cavitation carious lesions in young permanent teeth is essential to assist remineralization.

Impaction of deciduous teeth is an unusual finding and that of deciduous incisors is more rarely found, with the number of reported cases very limited. The cause of impaction of a permanent incisor can be easily identified in most cases. Injury to and/or apical lesions of the deciduous processor will affect the successor permanent tooth, and change of eruption direction and avoidance of the apical lesion by the successor tooth germ is often noted. On the other hand, there are many uncertainties about deciduous tooth impaction. For example, the presence or absence of past trauma is difficult to precisely determine, and it is also difficult to verify that an indirect injury force through the gingiva can change the position or eruption direction of an unerupted deciduous tooth. Additionally, impaction of a deciduous incisor, even after its extraction, requires management of space and erupting disturbance in permanent predecessors. Here, we report a case of horizontal impaction of the maxillary left deciduous central incisor that disturbed the positioning of permanent incisor germs and caused malalignment of permanent denti tion. In addition, we discuss the cause of impaction including treatment planning by referring to previous reports.