Search

The purpose of this study was to clarify the characteristics of permanent and primary tooth-crown inclinations. Landmark points from cephalograms and dental casts of two groups; 23 women (mean 20.3 +/- 3.3 years) and 11 girls (mean 5.2 +/- 0.1 years) were digitized, and the coordinates were integrated and transformed to a standardized plane. The 3-dimensional crown inclinations were projected on the sagittal plane, and the angles between the tooth vectors and the FH plane were calculated. An independent-group t-test was used to test for group differences of each tooth inclination, and correlation coefficients were generated for the inclination angles among the permanent and primary teeth. Most maxillary tooth-crown inclinations showed significant age-related differences, while only the second premolar and primary second molar differed significantly in the mandible. The maxillary molars were parallel to the corresponding mandibular molars and correlated with each other, but the primary molars were not. Significant correlations were found between inclinations of most permanent teeth, but not the primary teeth. Maxillary tooth-crown inclinations change during growth, but tooth-crown inclinations of the mandibular teeth do not. [ABSTRACT FROM AUTHOR]

Introduction: Upper airway size is increasingly recognized as an important factor in malocclusion. However, children with Class III malocclusion are somewhat neglected compared with those with a Class II skeletal pattern. Therefore, the purpose of this study was to establish the characteristic shape of the oropharyngeal airway (OA) in children with Class III malocclusion. Methods: The sample comprised 45 children (average age, 8.6 +/- 1.0 years) divided into 2 groups: 25 with Class I and 20 with Class III malocclusions. OA size of each group was evaluated by cone-beam computed tomography. Cluster analysis, based on OA shape, redivided the subjects into wide, square, and long types. The distributions of Class I and Class III subjects were compared among the types. Results: The Class III group showed statistically larger OA area and width compared with the Class I group. Area was positively correlated with Class III severity. The square type included 84% of the Class I malocclusions but only 30% of the Class III malocclusions, indicating that the OA in Class III malocclusion tends to be flat. Conclusions: The Class III malocclusion is associated with a large and flat OA compared with the Class I malocclusion. [ABSTRACT FROM AUTHOR]

Background: There is growing interest in the development of objective methods for assessing lip-closing function in children., Objective: To obtain normative data for healthy children in the developmental stages of lip closure function, we quantitatively evaluated oral movements associated with lip closure in children and adults using a composite sensor (CS)., Methods: Twenty-five normal children (11 boys, 14 girls) aged 8.8 ± 1.6 years and 25 young adults (13 men, 12 women) aged 27.4 ± 3.9 years were asked to perform test movements, maximal lip closure and swallowing of 3 mL of water. Lip-closing pressure (LP), intraoral baro-pressure (IP) and electromyographic (EMG) activity of the upper orbicularis oris muscle were simultaneously recorded using the CS., Results: EMG activity of the upper orbicularis oris muscle during closure was significantly greater in adults than in children. There were significant positive correlations between integral values of LP and EMG for closure in adults (r = .527, p = .008) but not in children, and significant positive correlations between integral values of LP and IP for swallowing in children (r = .508, p = .010) but not in adults., Conclusions: The CS may provide an effective tool for evaluating lip function in children acquiring oral function. For the combination of maxillary orbicularis oculus contraction and formation of intraoral negative pressure, EMG activity of the upper orbicularis oris muscle involvement in LP and IP involvement in LP may differ between children and adults., (© 2024 John Wiley & Sons Ltd.)

Background: This study investigated the correlation between the prevalence of dental caries and the presence and type of abuse., Methods: Participants were 534 children admitted for care at two child guidance centers (CGCs) in Niigata, Japan. Data pertaining to abuse, including the reason for temporary protective care and the type of abuse, and the oral examination results of the children, were collected. These results were then compared with those of a national survey and analyzed in relation to the presence and type of abuse., Results: The odds ratio for decayed teeth was 4.1, indicating a higher risk in children admitted to the CGCs. However, no significant association was found between the presence of decayed, filled, or caries-experienced teeth and the presence of abuse. A significant positive association was observed between dental caries and one type of abuse, indicating a greater prevalence of dental caries in cases of neglect. The findings of this study suggest that the type of abuse, rather than its presence, is associated with dental caries., Conclusions: Our findings suggest that proactive support should be provided to children in problematic nurturing environments, regardless of whether they have been subjected to abuse., (© 2024. The Author(s).)

Objectives: Weakening of lip-closing strength (LCS) associated with an incompetent lip seal (ILS) may affect the oral balance between the lip and tongue pressures. The purpose of this study was to evaluate the effects of lip-closing training in children with lower LCS and/or abnormal habits across different age groups and to compare its effects on increasing LCS in children with malocclusion and/or oral habits., Material and Methods: Lip-closing training was performed by 154 Japanese children aged 3-12 years using a specialized training device at home for 3 months. Children with oral habits and/or exhibiting less than standard LCS were included. LCS was measured using a digital strain force gauge at a dental clinic at the beginning (T0) and after each month (after 3 months: T3)., Results: Children had higher LCS responses after lip-closing training. The first month of lip-closing training was more effective than the subsequent months. With lip-closing training, the LCS increased from an average of 6.2 N (T0) to 11.4 N (T3) in Group I, 7.9 N (T0) to 12.8 N (T3) in Group II, and 6.8 N to 11.4 N in Group III. Anterior cross bite, including reverse bite, open bite, and tongue thrusting, significantly reduced training effects., Conclusion: Our findings showed that lower LCS in children with ILS resulted in greater responses to lip-closing training in a short period, but oral dysfunction, such as abnormal habits, inhibited the positive effects of training. Our results suggest that less detrimental effects of malocclusion and abnormal oral habits lip-closing training enhances LCS in younger children., (© 2021 The Authors. Clinical and Experimental Dental Research published by John Wiley & Sons Ltd.)

Background/aim: Root length is a critical factor for dental pulp regeneration following tooth replantation. The aim of this study was to analyze the effects of reducing the root length by apicoectomy on the pulp healing process using a model for tooth replantation., Material and Methods: After extraction of the upper first molars (M1) of 3-week-old mice, the roots from the experimental group (EG) were shortened to half to two-thirds of their length before replantation, whereas in the control group (CG) the extracted teeth were immediately repositioned into their alveolar sockets. To determine the effects of root resection on the survival of inherent pulp cells, this study included tooth transplantation with root resection using wild-type (WT) and green fluorescent protein (GFP) transgenic mice. The M1 of GFP transgenic mice were transplanted into the alveolar socket of the M1 of WT mice. The roots of the right M1 were shortened (EG), whereas the left M1 remained untreated (CG)., Results: Apoptotic cells in the EG significantly decreased in number compared with the CG at day 3. Cell proliferative activity in the EG was significantly higher than that in the CG in the root pulp during days 3-5, and nestin-positive odontoblast-like cells began to arrange themselves along the pulp-dentin border in the cusp area at day 5 in the EG but not in the CG. At week 2, tertiary dentin had formed throughout the pulp in the EG, whereas the combined tissue of dentin and bone occupied the pulp space in 60% of the CG. Root resection also positively affected the survival of inherent pulp cells to differentiate into odontoblast-like cells as demonstrated by transplantation using GFP transgenic mice., Conclusions: Reducing the root length accelerated pulp regeneration following tooth replantation due to the better environment for revascularization., (© 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Alpha-thalassemia X-linked intellectual disability (ATR-X) syndrome affects males and is associated with profound developmental delay, facial dysmorphism, genital abnormalities, and alpha thalassemia. Appropriate oral health management for affected patients is important. The purposes of this report are to describe a case involving six years of oral health management, including training in eating, drinking and swallowing, for a patient with ATR-X syndrome, and to discuss the morphological and functional oral characteristics of this disorder. The patient's oral dysfunctions were incompetent lip-closing, inappropriate tongue protrusion, deviation of chewing acquisition, and incompetent oral and pharyngeal bolus propulsion. Other problems included inappropriate ingestion posture, low interest in meals, and poor oral hygiene. A stable oral intake and an improved eating posture were achieved through an intervention; however, the patient's inappropriate tongue protrusion, deviation of chewing acquisition, and incompetent bolus propulsion remained unchanged.

Background: Understanding the refinement of self-feeding skills is useful for the assessment of oral functional development in children., Objectives: To determine normative data on lip closing during food intake in the development of independent spoon-feeding in normal children, we tested the hypothesis that lip-closing pressure and spoon operation differ depending on food type., Methods: Fifteen normal children (eight boys, seven girls; mean age: 6.5 years) were asked to eat test foods (2, 3 and 5 g of yogurt and cream cheese) freely with a spoon. Lip-closing pressures and kinematic data on spoon operation were recorded simultaneously with a strain gauge transducer embedded in the spoon and Vicon motion analysis, respectively., Results: In the most common lip-pressure pattern, only positive pressure was generated. In the second most common pattern, negative pressure occurred first, followed by positive pressure; this pattern was seen infrequently. Positive pressure (P < .001), pressure duration (P < .001) and spoon intra-oral time (P < .05) during intake of cream cheese (an adhesive food) were significantly greater than those during intake of yogurt (a non-adhesive food). Pressure onset occurred at the beginning of the spoon withdrawal period or at the turning point from spoon insertion to withdrawal, depending on the food., Conclusions: Lip-closing force and spoon operation varied depending on food type in preschool and early elementary school children. Our findings suggest the need to consider the importance of food diversity and to pay attention to the spoon withdrawal period when assessing the development and maturation of lip function., (© 2021 John Wiley & Sons Ltd.)

Background: Systemic and local factors may lead to disruption of craniofacial growth and development, causing an imbalance between the orofacial skeleton, muscle and soft tissue, dental occlusion, and the dental arch during growth periods. We aimed to reveal whether the prevalence of incompetent lip seal (ILS) varies with age and region, as well as to clarify the factors related to an ILS, in a national, large-scale epidemiological study., Methods: We surveyed 3399 children, from 3 to 12 years of age, visiting 66 pediatric dental clinics throughout Japan. For this survey, we employed a questionnaire consisting of 44 questions regarding daily health conditions and lifestyle habits. We evaluated the differences in ILS prevalence by age and region (using a Cochran-Armitage test for trend and a Kruskal-Wallis test), and the relationship between ILS and factors investigated in the questionnaire (using Spearman's rank correlation coefficient)., Results: We observed that 30.7% of Japanese children exhibited an ILS and that the ILS rate increased with age (p < 0.001). There were no regional differences in the rate of ILS in Japanese children (p = 0.506). We revealed that 12 of 44 survey items exhibited a statistically significant correlation with ILS (p < 0.001), using Spearman's rank correlation coefficient. These items involved orofacial morphology, mouth breathing, and possibly, allergic rhinitis., Conclusion: The rate of ILS seems to increase with age in children, throughout Japan. Therefore, this disorder may not self-correct during the growth periods in these children. Guidelines are required for pediatric dentists to recognize ILS among children aged 3-12 years.

Pluripotent stem cells are classified as naïve and primed cells, based on their in vitro growth characteristics and potential to differentiate into various types of cells. Human-induced pluripotent stem cells (iPSCs, also known as epiblast stem cells [EpiSCs]) have limited capacity to differentiate and are slightly more differentiated than naïve stem cells (NSCs). Although there are several in vitro protocols that allow iPSCs to differentiate into pancreatic lineage, data concerning generation of β-cells from these iPSCs are limited. Based on the pluripotentiality of NSCs, it was hypothesized that NSCs can differentiate into pancreatic β-cells when placed under an appropriate differentiation induction condition. We examined whether NSCs can be efficiently induced to form potentially pancreatic β cells after being subjected to an in vitro protocol. Several colonies resembling in vitro-produced β-cell foci, with β-cell-specific marker expression, were observed when NSC-derived embryoid bodies (EBs) were induced to differentiate into β-cell lineage. Conversely, EpiSC-derived EBs failed to form such foci in vitro. Intrapancreatic grafting of the in vitro-formed β-cell foci into nude mice (BALB/c-nu/nu) generated a cell mass containing insulin-producing cells (IPCs), without noticeable tumorigenesis. These NSCs can be used as a promising resource for curing type 1 diabetes.