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BACKGROUND: Suprahyoid muscles behavior during the tongue lifting movement has not yet been elucidated. OBJECTIVE: The purpose of this study was to investigate the potential of elastography imaging to examine developmental oral dysfunction in children and oral hypofunction in older adults using sonography. METHODS: Tongue pressure was measured using a manometer with a probe. The tongue pressure was measured with simultaneously scanning the geniohyoid muscle (GHM) and the anterior belly of the digastric muscle (DGM) using sonographic elastography. Sagittal images of the GHM and coronal images of the DGM were used for the strain ratio measurement. The strain ratio of the muscles was measured three times for each subject with the tongue pressure values of 0–30 kPa. RESULTS: The strain ratio of the GHM were higher than those of the DGM at tongue pressure of 10, 20 and 30 kPa. The strain ratio of the GHM increased as the tongue pressure increased in all participants. In contrast, the strain ratio of the DGM tended to slowly decrease as tongue pressure increased in female participants. CONCLUSION: Sonographic elastography is useful for visual and quantitative evaluation of elastic properties in suprahyoid muscles during tongue lifting movements.

Suprahyoid muscles behavior during the tongue lifting movement has not yet been elucidated.The purpose of this study was to investigate the potential of elastography imaging to examine developmental oral dysfunction in children and oral hypofunction in older adults using sonography.Tongue pressure was measured using a manometer with a probe. The tongue pressure was measured with simultaneously scanning the geniohyoid muscle (GHM) and the anterior belly of the digastric muscle (DGM) using sonographic elastography. Sagittal images of the GHM and coronal images of the DGM were used for the strain ratio measurement. The strain ratio of the muscles was measured three times for each subject with the tongue pressure values of 0-30 kPa.The strain ratio of the GHM were higher than those of the DGM at tongue pressure of 10, 20 and 30 kPa. The strain ratio of the GHM increased as the tongue pressure increased in all participants. In contrast, the strain ratio of the DGM tended to slowly decrease as tongue pressure increased in female participants.Sonographic elastography is useful for visual and quantitative evaluation of elastic properties in suprahyoid muscles during tongue lifting movements.

Early detection of oral disease is important to reduce its severity and increase the likelihood of successful treatment. This study aimed to perform a quantitative assessment of the saliva components as a first stage of the research to screen oral homeostasis. Here, saliva secretions collected from children were evaluated, and their constituents were analyzed to investigate the potential correlations between the buffering capacity and a range of salivary factors. Subjects aged 3-16 years in the primary, mixed, or permanent dentition stage, were selected for this study. The following salivary factors were analyzed: flow rate, total protein, total sugar quantifications, and constituent analyses using RT-PCR and western blotting. The associations between each factor and the buffering capacity were then analyzed using multiple regression analysis. Flow rate, BPIFA2 RNA level, histatin 1 and BPIFB1 protein levels as well as female sex were positively associated with buffering capacity. In contrast, total sugar concentration and MUC7 RNA levels showed a negative relationship with the buffering capacity. Some of these constituents may indicate oral homeostasis and are therefore potential biomarkers of oral health status. These results suggest that the analyses of the correlations between oral homeostasis and salivary factors are an effective strategy for identifying the susceptibility to oral diseases.

The present study was performed to investigate the mineral density distribution in enamel and dentin for both permanent and primary teeth and to establish the standard density per tooth type using micro-computed tomography (CT). Fifty-seven extracted human teeth (37 permanent, 20 primary) were evaluated in the present study. The enamel and dentin mineral densities in the extracted teeth were measured using micro-CT. Cubic regression curves were used to determine the mineral density distribution in the enamel and dentin for each tooth type. The mean values, distributions, and regression equations of the mineral densities were obtained. The mean mineral density values for permanent enamel and dentin were significantly higher than those for their primary counterparts for each tooth type. In the present study, we demonstrated the distribution of mineral density in sound enamel and dentin and attempted to determine the standard mineral density for each tooth type using micro-CT. The mineral density distributions found in this study contribute to our understanding of the mechanical properties of enamel and dentin. A positive correlation suggests that the systemic bone mineral density could be predicted based on the analysis of exfoliated teeth, such as in patients with hypophosphatasia. The present results may be useful in establishing a numerical standard for the mechanism involved in root fracture and for early detection of root fracture risk.

We previously showed that mRNA expression of BPIFB1 (Bpifb1), an antibacterial protein in the palate, lung, and nasal epithelium clone protein family, was increased in parotid acinar cells in non-obese diabetic (NOD, NOD/ShiJcl) mice, which is an animal model for Sjögren's syndrome. However, we did not previously assess the protein levels. In this report, we confirmed the expression of BPIFB1 protein in the parotid glands of NOD mice. Immunoblotting of subcellular fractions revealed that BPIBB1 was localised in secretory granules in parotid glands from NOD mice, and was almost not in parotid glands from the control mice. BPIFB1 had N-linked glycan that reacted with Aleuria aurantia lectin, which caused two types of spots with a slightly different pI and molecular weight. The expression of BPIFB1 protein was also demonstrated by immunohistochemistry. BPIFB1 was detected in the saliva from NOD mice but not in the saliva from the control mice, indicating individual constitution. BPIFB1 in saliva may be applied to other research as a diagnostic marker.

Objective: Most cases of hypophosphatasia (HPP) exhibit early loss of primary teeth. Results of micro-computed tomography (micro-CT) analysis of teeth with HPP have not yet been reported. The purpose of the present study was to describe the size and mineral density distribution and mapping of exfoliated teeth with HPP using micro CT. Study design: Seven exfoliated teeth were obtained from a patient with HPP. Exfoliated teeth sizes were measured on micro CT images and mineral densities of the mandibular primary central incisors were determined. Results: Partial dentures were fabricated for the patient to replace the eight primary teeth which had exfoliated. Most primary teeth sizes were within the normal range. The mean values of enamel and dentin mineral densities in teeth with HPP were 1.35 and 0.88 g/cm3, respectively, in the mandibular primary central incisors. Conclusion: Mineral density distribution and mapping revealed that the values in teeth with HPP were lower than the homonymous teeth controls in all regions from the crown to apex. Furthermore, it was demonstrated that the differences between HPP and controls were larger on the crown side and the differences tended to converge on the apex side. These results suggested that the present patient showed mild hypomineralization in the primary dentition.

The purpose of the present study was to develop a novel-designed phantom that could be scanned with a sample in the same image, that specialize for quantitative analyses of human dentin mineral density using the X-ray attenuation method. A further attempt was made to demonstrate the intracoronal dentin mineral density using this phantom in mandibular incisors. The phantom prepared with a 15 mm hole in the center of an acrylic resin bar having an outside diameter of 25 mm and 8 small holes (diameter, 3 mm) were made at equal intervals around the center. Liquid dipotassium hydrogen phosphate (K2HPO4) solutions were established at 0.4, 0.6, 0.8 and 1.0 g/cm3, and were arranged to these holes. The mean value of the intracoronal dentin mineral density was 1.486 ± 0.016 g/cm3 in the present study. As the results of the present study corresponded to previous reports, this new phantom was considered to be useful. This phantom enables the analysis of samples that are not readily available by conventional mechanical tests and may facilitate biomechanical investigations using X-ray images. It was suggested that this system is a simple, accurate and novel mineralization measuring system.

Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan’s universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan’s aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation’s oral health by encouraging efficient use of dental CBCT.

Regional odontodysplasia is a rare, severe, and nonhereditary developmental disorder in tooth formation and involves epithelial and mesenchymal-derived dental tissue. On radiographs, affected teeth have an abnormal morphology, a hypoplastic crown, and only a faint outline of hard tissue, a condition termed “ghost teeth.” We report clinical and radiographic findings from two children with regional odontodysplasia. Using computed tomography (CT), we calculated attenuation coefficients (i.e., Hounsfield units) for affected teeth and assessed the condition of dental follicles. To measure density, regions of interest were delimited and CT values were calculated. In our two patients, the CT values for enamel were lower in affected teeth than in sound teeth, while CT values for dentin were similar for affected and sound teeth. The average CT value for dental follicles in affected teeth was about 65 to 120, which suggests that dense fibrous connective tissues or hard tissue-like structures might be present in dental follicles. Analysis of CT values may be quite useful in the diagnosis and treatment of regional odontodysplasia.

Most cases of hypophosphatasia (HPP) exhibit early loss of primary teeth. Results of microcomputed tomography (micro-CT) analysis of teeth with HPP have rarely been reported. The purpose of the present study was to describe the mineral density distribution and mapping of exfoliated teeth from an HPP patient using micro-CT. Four exfoliated teeth were obtained from a patient with HPP. Enamel and dentin mineral densities of exfoliated teeth were measured on micro-CT. The mean values of enamel and dentin mineral densities in mandibular primary central incisors with HPP were 1.61 and 0.98 g/cm3, respectively. The corresponding values in the mandibular primary lateral incisors were 1.60 and 0.98 g/cm3, respectively. Enamel hypoplasia was seen in the remaining teeth, both maxillary and mandibular primary canines and first and second molars. Micro-CT enables nondestructive, noninvasive evaluation and is useful for studying human hard tissues obtained from patients.

The purpose of the present study was to examine the fracture toughness and Vickers microhardness number of permanent and primary human enamel using the indentation microfracture method. Crack resistance and a parameter indirectly related to fracture toughness were measured in 48 enamel specimens from 16 permanent teeth and 12 enamel specimens obtained from six primary teeth. The Vickers microhardness number of the middle portion was greater than the upper portion in primary enamel. The fracture toughness was highest in the middle portion of permanent enamel, because fracture toughness greatly depends upon microstructure. These findings suggest that primary teeth are not miniature permanent teeth but have specific and characteristic mechanical properties.

In the Japanese population, the second premolars are the secondmost- frequently impacted teeth in the mandible, after the third molars. Although some papers have reported on the treatment of impacted mandibular second premolars caused by abnormal tilting of the tooth germ, there has been little information regarding bilateral horizontal impaction with distal inclination. The purpose of the present report is to describe the treatment course of a rare and severe case of an 11-year, 8-month-old girl without any obvious etiologies whose bilateral mandibular second premolars were inclined to the distal direction at approximately 90 degree angles, with the root formation developed to an approximately half length. After extraction of the retained primary molars, traction was performed in the treatment of the affected teeth. The affected premolars had fully erupted and achieved occlusion one year after the beginning of intervention. In conclusion, it was considered that the present case could obtain a successful outcome by limited traction since no clinical anomalies or discomfort was detectable during the one year of retention.

The purpose of this report was to describe an unusual severe ectopic eruption of the bilateral maxillary canines in a young patient aged 7 years and 8 months and to discuss the effects of early intervention such as extraction of the predecessors and fenestration of the affected canines. The patient was referred to the author's clinic for a consultation regarding bilateral ectopically erupting maxillary canines with an ectopic maxillary right first molar. After improvement of the first molar, the affected canines were fully erupted and aligned in occlusion 3 years and 7 months after the extraction of primary canines. Before treatment, the findings on the orthopantomogram were as follows, there was no direct cause, both canine tooth germs were situated in very high positions, and the cusp tips of both canines were not overlapped with the roots of the adjacent lateral incisors (Sector 1). The maxillary left canine impacted horizontally in a mesio-distal direction (axial angulation: 90 degrees) could be successfully guided to eruption by early intervention such as the extraction of predecessors and three fenestrations. Even in severe ectopic cases, therefore, it is considered that traction may be postponed until no effect of fenestration can be detected in cases of early discovery and intervention when the crown top is situated in Sector 1.

The aim of the present study was to examine the prevalence rate and treatment outcome of maxillary canine transposition in Japanese children according to the conventional standard and our new additional consideration of the classification. From 140 cases with ectopic canines diagnosed in the Pediatric Dental Clinic of Niigata University Medical and Dental Hospital, we selected 10 transposition cases as the present subjects. Out of 10 cases, 4 were males and 6 females. Six were classified into type A: the mesio-distal positional interchange of the canine and the first premolar, 2 cases into type B: the mesio-distal transposition of the canine and the lateral incisor, and the other 2 cases into type C: the present new classification that showed the vertical transposition of the canine and the first premolar within the developmental bone. The prevalence rate of types A and B resembled the previous papers regarding the ratio of sex and bilateral occurrence. Although 3 cases in type A, one case in type B and one case in type C could finally be aligned in the normal tooth order, every one of the types A and B cases were aligned in the reverse order. For every one case in types A and C, the transposed canines were extracted. It is recommended that pediatric dentists take an orthopantomogram during early mixed dentition as a routine practice in order to detect anomalies of tooth eruption, such as tooth transposition, as early as possible.

The aim of the present study was to examine retrospectively how best to treat severe cases of ectopically erupting maxillary canines with mesial angulation exceeding 50 degrees. From the ectopically erupting canines diagnosed at the Pediatric Dental Clinic of Niigata University Hospital, we selected for our study 14 severe cases in which mesial angulation exceeded 50 degrees. Nine ectopically erupting canines could be aligned within the arch after traction, and two canines are in the course of treatment, while three canines were removed. In the removed canines, the vertical length from the occlusal line of the crown top was shorter than that in the aligned canines with similar initial condition. This means that the vertical length to the occlusal line of the impacted canine influences the treatment complexity. In four similar ectopically erupting canines in which mesial inclination was nearly 80 degrees or greater and vertical length was over 30 millimeters with Sector 1 or 2 positioning distal to the midline of the root of its adjacent lateral incisor, the initial disruptive conditions were improved after extraction of the predecessor and/or fenestration of the affected canine. It is concluded that traction should be postponed until a few months after extraction of the predecessor if the ectopically erupting canine is located far away from the occlusal line (over 30 millimeters) and its mesial inclination is more than nearly 80 degrees; also that this treatment plan should be limited to cases in which the crown top belongs to Sector 1 and 2.

47, XYY is a sex chromosome-number disorder occurring in males. Pediatric dentists seldom report encountering 47, XYY males, probably because there are no overt signs of the disease. The purpose of this report is to present the clinical oro-facial findings of the case of a 47, XYY boy based on cephalometric analysis and study model examinations as well as micro-CT measurement of tooth mineralization. An 11-year-old Japanese boy was referred to our clinic for extraction of primary teeth because of their prolonged retention. He had 47, XYY disorder, pulmonary hypertension, and slight mental retardation. Cephalometric analysis and study model examinations that included a comparison of tooth size and arch assessments were performed. A further attempt was made to demonstrate the degree of dentin mineralization in primary molars. The boy's height and weight were normal but his head circumference had exceeded the 94th percentile since 2 years of age. The cephalometric analysis showed an increase in the lower facial height and bimaxillary protrusion with a longer mandible. Study model examination revealed that the mesio-distal crown widths of all erupted primary and permanent teeth were larger than the standard values, except for the mandibular permanent canines. The degree of dentin mineralization was almost normal in the crown and root areas. A profilogram showed an increase in the lower facial height and bimaxillary protrusion with a longer mandible. The dental arch showed a remarkably contracted width but an extended length. The crown width was larger than the standard values, but the distribution of the degree of dentin mineralization differed little from normal.

A scissors bite is one of the more unusual malocclusions in primary dentition. The purpose of this report is to describe the unilateral scissors bite in primary dentition and the treatment outcome following the use of constriction appliances. A 5-year, 5-month-old boy developed a scissors bite in the left molar region due to the extended width of the maxillary dental arch. Two types of appliances were used to reduce the width of the maxillary dental arch; one was a removable type modified from a conventional expansion plate, and the other was a fixed type modified from a quad-helix appliance. The left maxillary primary molars were able to bite normally after the treatment using both appliances. As a result, the left first molars also could be guided to a normal occlusion and prevented from becoming a scissors bite. We suggest that improvement of the scissors bite in the primary dentition stage can prevent subsequent malocclusions in permanent dentition.

Objective: Abused children have been reported to have low self-esteem. The aim of this study was to investigate the effects of dental intervention on self-esteem, oral condition, and concern for oral health in abused children admitted to a child protection service facility. Study design: We examined the oral condition of 65 children (34 boys, 31 girls; aged 2–15 years), instructed them in tooth-brushing. Self-esteem was examined using Pope’s five-scale test for children. Before discharge, the children completed questionnaires on concern about their oral health. Results: The findings revealed the reasons for admission were child abuse and neglect (n=45), domestic violence against the mother (n= 20), special needs (n=11), delinquency (n=7), school refusal (n=2), and other reasons (n=3). Thirty-five of the 65 residents (54%) needed treatment for caries. Of these, 24 (69%) were abused children and 11 (31%) were admitted due to other reasons. Mean self-esteem score differed significantly between the resident children (n=43) and an outpatient control group (n=102) (59.16±14.54 vs 73.92±16.81, respectively; p

Tooth impaction is defined as any tooth that fails to erupt into a normal functional position and remains unerupted beyond the time at which it should normally erupt. Reports of impaction and eruption failure in primary teeth are relatively rare compared to permanent teeth. We report 2 rare cases where the second premolar was located on the occlusal side of the impacted mandibular second primary molar. In the first case, the succedaneous permanent tooth erupted after extraction of the primary tooth, fenestration, and traction. In the second case, the succedaneous permanent tooth erupted without fenestration or traction. Although the etiology of the tooth displacement was unknown in both cases, inhibition of the eruptive movement of the primary molar may have been associated with displacement of the succedaneous permanent premolar.

The aims of this report were to determine the nature of eruption disturbances and to establish the pattern of management for these teeth in a group of Japanese children and adolescents. Data were collected from the clinical records of patients in the Pediatric Dental Clinic of Niigata University Medical and Dental Hospital. There were 700 patients (364 males and 336 females) and 748 teeth (26 primary teeth and 722 permanent teeth) who were treated for eruption disturbances between 1979 and 2002. During this period, 17,365 new patients visited the clinic, of whom approximately 4% had eruption disturbances. The most frequently affected permanent teeth were the maxillary central incisors (38.6%), followed by the maxillary canines (15.4%). Of the permanent teeth, 52.5% were in males and 47.5% in females. Although there were more cases of maxillary central incisors in males than in females, the number of cases involving maxillary canines was higher in females. Whereas delayed eruption was noted in 76.7% of maxillary central incisors, 18.6% were impacted and 4.7% demonstrated abnormal direction/position which required treatment. In contrast, a higher percentage (64.8%) of maxillary canines that showed abnormal direction/position was treated. Eruption disturbances were found in 40% of the patients during routine examinations. This suggests that regular routine examinations are important for pediatric dentists to detect and treat eruption disturbances early.

Primary failure of tooth eruption involving primary teeth is unusual. The purpose of this report was to describe uneruption of a single mandibular primary first molar and the treatment outcome following limited orthodontic care.A 5-year, 3-month-old boy was referred to the authors' clinic for treatment of an unerupted primary first molar, 3 months after fenestration by an oral surgeon. Orthodontic traction was performed on the affected molar in the authors' clinic. The affected mandibular primary first molar was fully erupted and in occlusion 16 months after the first fenestration.The histopathological diagnosis of the overlying tissue was pericoronal myxofibrous hyperplasia (PMH) without any calcified obstacles.Of the 26 primary tooth eruption failure cases treated in the authors' clinic between 1979 and 2003, the present case was the only example of a primary first molar.