The purpose of this study was to verify the mechanism related to correction of an anterior crossbite with a mouthpiece type functional orthodontic appliance. Tooth movements were simulated by use of a finite element method.

Finite element models of the upper and lower dentitions were constructed based on a dental study model. The teeth were assumed to be rigid bodies, the periodontal ligament (PDL) a linear elastic material, and the maxillary and mandibular bones rigid bodies. A finite element model of a mouthpiecetype functional appliance was constructed based on CT imaging. With placement of the appliance onto the dentitions, the maxillary bone was fixed and the mandibular bone moved forward. Tooth movement was simulated by repeating the following two steps. First, initial movements of the teeth,produced by elastic deformation of the PDL, were calculated. Second, movement of the alveolar sockets was performed in the same direction as during the initial movement. The mandibular bone was moved 0.1 mm with each repetition.

Results of the present simulation verified the mechanism for correcting anterior crossbite. The dentitions were located in the working bite by placing the appliance onto them with anterior crossbite. When returning the dentitions to their initial positions, labial and lingual forces acted on the upper and lower incisors, respectively, with the incisors tipping in labial and lingual directions, respectively. The two incisal edges moved in opposite directions, which corrected the crossbite condition. Additionally, the anterior teeth showed slight intrusion, while the other teeth showed nearly no movement.

With the aim of contributing to decision-making regarding resection of the upper labial frenum, we studied the morphology of upper labial frenum attachment and changes in its position in 448 children (age 3-5 years) attending nursery schools and kindergartens in Japan. The morphology and upper labial frenum attachment position were classified as normal or abnormal (Type I-V) type. The following results were obtained.

1.The prevalence of normal-type upper labial frenum was greater than that of the abnormal types in all age groups, though the difference decreased with age.

2.Among the abnormal types, the prevalence of Type I was the greatest in all age groups, followed by that of Type II, with no significant changes in the prevalence of those seen with age. The prevalence of Type III increased more than two-fold, whereas that of Type IV did not change with age. Type V was only noted in 5-year-old subjects.

3.When comparing the prevalence of the normal type with that of Types I and II, and the “high and thick attachment” type, the prevalence of the normal type was significantly greater and that of the “high and thick attachment” type significantly lower in the 3-year-old group. Also, the prevalence of the “high and thick attachment” type was greater in the group aged 5 years.

The most common abnormal types observed in the 3-year-old group were Types I and II, which will likely not improve, while Type IV and V were not seen. Our results suggest that treatment and follow-up examinations comprise an appropriate management strategy for children with such abnormality in the upper labial frenum. Additionally, the prevalence of the “high and thick attachment”type was high in the group aged 5 years, suggesting that this abnormality in the upper labial frenum has a persistent tendency. For affected children, it is necessary to provide treatment while taking into consideration the possibility of midline diastema and the effects of this abnormality on lip closure function at the time of permanent anterior tooth eruption.

Dramatic alterations in the environment surrounding young children in Japan have occurred over the past 3 decades. As the structure of society has transformed, changes in the role of university hospital pediatric dentistry departments, high level medical institutions, have also occurred and they are now expected to respond to a diverse range of needs. A fact-finding survey of patients who received initial examinations from 2015 to 2017 was performed, with the results compared to those of prior surveys conducted in 1989 and 1999. The results obtained indicated the following.

1.The mean annual number of patients receiving initial examinations was 1264, an increase as compared to the two prior surveys (839 in 1989, 750 in 1999).

2.The most common age the time of the initial examination was 1 year, followed by 2 and then 3 years. As compared to the two prior surveys, there was a decrease in age at first examination.

3.With regard to residential location, patients who lived in the area near the hospital accounted for 66.3% of the total.

4.The most common reason for the initial visit was treatment of caries, which accounted for 30.1% of the total. In comparison with the prior surveys, there was a trend toward reduction in occur rence of caries, though it remained the most common complaint. Conditions other than caries changed at roughly the same proportion, though showed considerable diversity.

5.Referred patients comprised 66.1% of the total, which was an increase as compared to the previous surveys.

With changes in society over the past 30 years, pediatric dentistry has come to be recognized as a highly specialized field in which greater levels of specialization are now demanded. In addition, lifestyle guidance for not only the patient but also including the family environment has recently come to be expected. The present results suggest that it is necessary to maintain up-to-date knowledge for meeting a wide variety of needs and providing an appropriate response to the individual situations of patients.

The purpose of this study is to determine the number of cases with dental care and/or dental needs treated at perinatal medical centers. A questionnaire was sent to 30 comprehensive perinatal medical centers and 70 regional perinatal medical centers in then National Capital Region, and the response rate was 55.0%. Among hospitals with a possible dental division, 87.5% were comprehensive perinatal medical centers and 66.7% were regional perinatal medical centers, and the actual cooperation rates were 23.8% (median 10.0%) and 21.7% (median 10.0%), respectively. Following discharge from hospitals with a possible dental division, 13.6% of the cases were cared for by comprehensive perinatal medical centers and 23.3% by regional perinatal medical centers, though the actual cooperation rates were 22.0% (median 10.0%) and 13.5% (median 10.0%). Comprehensive perinatal medical centers were accessed for hospital and post-discharge dental needs by 68.8% (median 80.0%) and 70.0% (median 90.0%), respectively, while regional perinatal medical centers were accessed for those by 48.5% (median 50.0%) and 60.8% (median 70.0%), respectively. The results of this study revealed that children with medical care needs may also require dental care while in the hospital and after discharge. However, the actual rates of cooperation were often quite low. It is necessary improve to improve medical and dental staff cooperation for treating the needs of child patients. Moreover, dental resources are necessary to examine children for medical care needs when in the hospital or residing at home, which should improve corresponding dental needs.

The demands and dental needs of child patients and their parents who come to pediatric dental clinics have changed in recent years. We examined the records of patients who visited the Department of Pediatric Dentistry of Tohoku University Hospital for their initial visit in the period from April 2015 to March 2019 in order to analyze the role of a university dental hospital in the community. The following results were obtained.

1.The total number of new patients during the study period was 1757, an increase as compared to our preceding study. A total of 1154 (65.7%) of the new patients lived in Sendai City.

2.The majority (88.9%) were referral cases. Most of the referrals were from dental practitioners and the most common reason leading to referral was dental caries treatment.

3.The most common chief complaint of the new patients was dental caries (44.6%), followed by malocclusion (14.2%) and anomaly in number of teeth (10.1%).

The mean dft index of the new patients during the study period was 5.02.