Factors influencing root resorption in retained mandibular second deciduous molars with congenital absence of second premolars: a cross-sectional study.

BACKGROUND: There are currently no studies that quantitatively compare the relationship of root resorption to the patient's systemic history or craniofacial and intraoral morphology, especially in relation to possible host factors. Thus, this study aimed to clarify the factors associated with root resorption in retained mandibular second deciduous molars with the congenital absence of second premolars and predict the prognosis of retained mandibular second deciduous molars. METHODS: A cohort of 5547 patients who visited the orthodontic clinic at Tokyo Medical and Dental University Dental Hospital between 2013 and 2022 was screened. Lateral cephalometric radiographs, panoramic radiographs, upper and lower dental models, and orthodontic treatment questionnaires were used as reference materials to apply the inclusion and exclusion criteria. Ultimately, 111 patients were included in the analyses. The patients were divided into two groups based on the root resorption levels of the retained mandibular second deciduous molars. Those with less root resorption were classified under the good condition (GC) group, whereas those with more root resorption were classified under the poor condition (PC) group. Demographic, clinical, and cephalometric parameters were compared between the groups. A multivariate logistic regression model was used to predict the probability of root resorption. RESULTS: The prevalence of congenitally missing mandibular second premolars with persistent mandibular second deciduous molars was 2.0%. In a total of 111 patients, eighty-three teeth (53.2%) were classified into the GC group, whereas 73 teeth (46.8%) were classified into the PC group. The Frankfort-mandibular plane angle (FMA) [odds ratio (OR): 0.87], Frankfort-mandibular incisor angle (FMIA) (OR: 0.93), overbite (OR: 1.38), adjacent interdental space (OR: 1.46), distance from occlusal plane (OR: 0.80), and caries treatment (OR: 7.05) were significantly associated with the root resorption of the retained mandibular second deciduous molars. CONCLUSIONS: Our findings suggest that skeletal morphology, oral morphological patterns, and history contribute to root resorption in retained mandibular second deciduous teeth with congenital absence of subsequent permanent teeth.

Development of a heat-stable alkaline phosphatase reporter system for cis-regulatory analysis and its application to 3D digital imaging of Xenopus embryonic tissues.

Xenopus is one of the essential model systems for studying vertebrate development. However, one drawback of this system is that, because of the opacity of Xenopus embryos, 3D imaging analysis is limited to surface structures, explant cultures, and post-embryonic tadpoles. To develop a technique for 3D tissue/organ imaging in whole Xenopus embryos, we identified optimal conditions for using placental alkaline phosphatase (PLAP) as a transgenic reporter and applied it to the correlative light microscopy and block-face imaging (CoMBI) method for visualization of PLAP-expressing tissues/organs. In embryos whose endogenous alkaline phosphatase activities were heat-inactivated, PLAP staining visualized various tissue-specific enhancer/promoter activities in a manner consistent with green fluorescent protein (GFP) fluorescence. Furthermore, PLAP staining appeared to be more sensitive than GFP fluorescence as a reporter, and the resulting expression patterns were not mosaic, in striking contrast to the mosaic staining pattern of ß-galactosidase expressed from the lacZ gene that was introduced by the same transgenesis method. Owing to efficient penetration of alkaline phosphatase substrates, PLAP activity was detected in deep tissues, such as the developing brain, spinal cord, heart, and somites, by whole-mount staining. The stained embryos were analyzed by the CoMBI method, resulting in the digital reconstruction of 3D images of the PLAP-expressing tissues. These results demonstrate the efficacy of the PLAP reporter system for detecting enhancer/promoter activities driving deep tissue expression and its combination with the CoMBI method as a powerful approach for 3D digital imaging analysis of specific tissue/organ structures in Xenopus embryos.

Reduced mastication during growth inhibits cognitive function by affecting trigeminal ganglia and modulating Wnt signaling pathway and ARHGAP33 molecular transmission.

Binding of brain-derived neurotrophic factor (BDNF) to its receptor tyrosine kinase B (TrkB) is essential for the development of the hippocampus, which regulates memory and learning. Decreased masticatory stimulation during growth reportedly increases BDNF expression while decreasing TrkB expression in the hippocampus. Increased BDNF expression is associated with Wnt family member 3A (Wnt3a) expression and decreased expression of Rho GTPase Activating Protein 33 (ARHGAP33), which regulates intracellular transport of TrkB. TrkB expression may be decreased at the cell surface and affects the hippocampus via BDNF/TrkB signaling. Mastication affects cerebral blood flow and the neural cascade that occurs through the trigeminal nerve and hippocampus. In the current study, we hypothesized that decreased masticatory stimulation reduces memory/learning in mice due to altered Wnt3a and ARHGAP33 expression, which are related to memory/learning functions in the hippocampus. To test this hypothesis, we fed mice a powdered diet until 14 weeks of age and analyzed the BDNF and TrkB mRNA expression in the right hippocampus using real-time polymerase chain reaction and Wnt3a and ARHGAP33 levels in the left hippocampus using western blotting. Furthermore, we used staining to assess BDNF and TrkB expression in the hippocampus and the number of nerve cells, the average size of each single cell and the area of intercellular spaces of the trigeminal ganglion (TG). We found that decreased masticatory stimulation affected the expression of BDNF, Wnt3a, ARHGAP33, and TrkB proteins in the hippocampus, as well as memory/learning. The experimental group showed significantly decreased numbers of neurons and increased the area of intercellular spaces in the TG. Our findings suggest that reduced masticatory stimulation during growth induces a decline in memory/learning by modulating molecular transmission mechanisms in the hippocampus and TG.

Pre-Adolescent Diet Normalization Restores Cognitive Function in Young Mice.

Mastication is a fundamental function critical for human health. Controlled by the central nervous system (CNS), it influences CNS development and function. A poor masticatory performance causes cognitive dysfunction in both older adults and children. Improving mastication may prevent cognitive decline. However, no study has determined the period of masticatory dysfunction that impairs children's later acquisition of cognitive function. Herein, we developed an animal model wherein a soft diet was switched to a normal diet at early and late time points in young mice. We aimed to investigate the impact of restored mastication on learning and memory function. Behavioral studies were conducted to evaluate learning and memory. Micro-CT was used to evaluate orofacial structural differences, while histological and biochemical approaches were employed to assess differences in the hippocampal morphology and function. Correction to a hard-textured diet before adolescence restored mastication and cognitive function through the stimulation of neurogenesis, extracellular signal-regulated kinases, the cyclic adenosine monophosphate-response element-binding protein pathway, and the brain-derived neurotrophic factor, tyrosine receptor B. In contrast, post-adolescent diet normalization failed to rescue full mastication and led to impaired cognitive function, neuronal loss, and decreased hippocampal neurogenesis. These findings revealed a functional linkage between the masticatory and cognitive function in mice during the juvenile to adolescent period, highlighting the need for adequate food texture and early intervention for mastication-related cognitive impairment in children.

Effect of Obesity on Masticatory Muscle Activity and Rhythmic Jaw Movements Evoked by Electrical Stimulation of Different Cortical Masticatory Areas.

This study investigates rhythmic jaw movement (RJM) patterns and masticatory muscle activities during electrical stimulation in two cortical masticatory areas in obese male Zucker rats (OZRs), compared to their counterparts-lean male Zucker rats (LZRs) (seven each). At the age of 10 weeks, electromyographic (EMG) activity of the right anterior digastric muscle (RAD) and masseter muscles, and RJMs were recorded during repetitive intracortical micro-stimulation in the left anterior and posterior parts of the cortical masticatory area (A-area and P-area, respectively). Only P-area-elicited RJMs, which showed a more lateral shift and slower jaw-opening pattern than A-area-elicited RJMs, were affected by obesity. During P-area stimulation, the jaw-opening duration was significantly shorter (p < 0.01) in OZRs (24.3 ms) than LZRs (27.9 ms), the jaw-opening speed was significantly faster (p < 0.05) in OZRs (67.5 mm/s) than LZRs (50.8 mm/s), and the RAD EMG duration was significantly shorter (p < 0.01) in OZRs (5.2 ms) than LZR (6.9 ms). The two groups had no significant difference in the EMG peak-to-peak amplitude and EMG frequency parameters. This study shows that obesity affects the coordinated movement of masticatory components during cortical stimulation. While other factors may be involved, functional change in digastric muscle is partly involved in the mechanism.

Histological and contractile changes in the genioglossus muscle after nasal obstruction in growing rats.

The aim of the study was to address the genioglossus muscle physiological and histological changes after unilateral nasal obstruction in growing rats. Fifty-four 6-day-old male Wistar albino rats were randomly divided into control (n = 27) and experimental (n = 27) groups. Unilateral nasal obstruction was performed at 8 days old. Contractile properties of the genioglossus whole muscle were measured at 5-, 7- and 9-week-old, including the twitch and tetanic forces, contraction time, half-decay time, and fatigue index. The histological characteristics of the genioglossus were also evaluated at 5-, 7- and 9-week-old, analyzing the myosin heavy chain composition of the slow, fast, IIa and IIb muscle fiber type, by measuring the number, rate, diameter and cross-sectional area. The maximal twitch force, and tetanic force at 60 Hz and 80 Hz force was significantly increased at all ages after nasal obstruction. The fatigue index was decreased at 5 weeks-old after nasal obstruction. The diameter and cross-sectional area of the fast, IIa and IIb muscle fiber types were increased at 7 and 9 weeks after nasal obstruction, while only the diameter of IIa type and cross-sectional area of IIb type were increased at 5 weeks-old after nasal obstruction. Nasal obstruction during growth affects the whole genioglossus muscle contractile properties and histological characteristics, increasing its force, the diameter and area of its muscle fibers. These changes in the genioglossus muscle may affect the normal growth, development and function of the craniofacial complex.

Does Orthodontic Treatment Change the Preferred Chewing Side of Patients with Malocclusion?

Whether orthodontic treatment can change the preferred chewing side (PCS) is unknown. This study examined (1) if the PCS changes after orthodontic treatment and (2) which factors contribute to this change. Two hundred fifty patients who visited the orthodontic clinic at Tokyo Medical and Dental University Hospital between 2017 and 2020 were included in the study. Mandibular kinesiograph (MKG) was taken at pre- and post-treatment, and PCS was determined. Patients who showed a change in PCS to the opposite side and those who showed no change in PCS at post-treatment were pooled into the PCS-changed and PCS-unchanged groups, respectively. The demographic, clinical, and cephalometric parameters were compared between the groups. Significant factors associated with changes in were of age < 20 years at the beginning of orthodontic treatment (odds ratio (OR), 2.00), maximum lateral mandibular movement to PCS ≥ 10.0 mm at pre-treatment (OR, 6.51), and change in occlusal canting of ≥1.0° (OR, 2.72). The predicted probability of change in PCS was 13.2%, 36.0%, and 67.5% for no factor, one factor, and two factors associated with PCS change, respectively. Orthodontic treatment may change PCS due to patient age, maximum lateral mandibular movement to PCS, and change in occlusal canting.

The impact of sleep-wake problems on health-related quality of life among Japanese nursing college students: a cross sectional survey.

AIM: This study was conducted to examine the impact of sleep-wake problems on health-related quality of life of Japanese nursing college students.  METHODS: This cross-sectional study was conducted in 2019 on 150 third and fourth-year nursing college students from two locations in Japan. Insomnia severity was assessed using the Insomnia Severity Index (ISI) and health-related quality of life using the SF-8 questionnaire. The total sleep time (TST) was divided into 3 groups: < 6 h, 6-7 h (reference), and ≥ 7 h. The total ISI score was divided into 2 groups: ≥ 8 points and < 8 points (reference). Logistic regression analysis was performed to evaluate sleep-wake problems related to decline in mental health. RESULTS: The median mental health indicated in the SF-8 questionnaire was divided into two groups, and the factors causing decline in mental health were investigated. The odds ratios (95% confidence interval) for adjusted ISI ≥ 8 and TST on weekdays < 6 h was 6.51 (2.96-14.30) and 3.38 (1.40-8.17), respectively. Mental health status was significantly lower when ISI ≥ 8 and even lower when TST < 6 h. CONCLUSION: Insomnia and short sleep duration are associated with decreased mental health status in nursing college students. Many tended to lack sleep on weekdays. Sleep-wake problems identified while in university should be comprehensively dealt with.

Deep Learning-Based Noise Reduction Improves Optical Coherence Tomography Angiography Imaging of Radial Peripapillary Capillaries in Advanced Glaucoma.

PURPOSE: We applied deep learning-based noise reduction (NR) to optical coherence tomography-angiography (OCTA) images of the radial peripapillary capillaries (RPCs) in eyes with glaucoma and investigated the usefulness of this method as an objective analysis of glaucoma. METHODS: This cross-sectional study included 118 eyes of 94 open-angle glaucoma patients (male/female = 38/56, age: 56.1 ± 10.3 years). We used OCTA (OCT-HS100, Canon) and built-in software (RX software, v. 4.5) to perform NR and calculate RPC vessel area density (VAD) and skeleton vessel length density (VLD). We also examined NR's effect on reproducibility. Finally, we assessed the vascular structure (PRCs)/function relationship at different glaucoma stages with Spearman's correlation. RESULTS: Regardless of NR, RPC parameters had excellent coefficients of variation (1.7-4.1%) in glaucoma patients and controls, and mean deviation (MD) was significantly correlated with VAD (NR: r = 0.835, p < 0.001; non-NR: r = 0.871, p < 0.001) and VLD (NR: r = 0.829, p < 0.001; non-NR: r = 0.837, p < 0.001). For mild, moderate, and advanced glaucoma, the correlation coefficients between MD and VLD were 0.366 (p = 0.028) 0.081 (p = 0.689), and 0.427 (p = 0.017) with NR and 0.405 (p = 0.014), 0.184 (p = 0.360), and 0.339 (p = 0.062) without NR, respectively. CONCLUSION: Denoised RPC images might have the potential for a closer structural/functional relationship, in which the floor effect of retinal nerve fiber layer thickness affects measurements. Deep learning-based NR promises to improve glaucoma assessment.

Factors associated with the eruption of the impacted maxillary third molars after second molar extraction.

INTRODUCTION: In orthodontic treatment, the space left after extracting the maxillary second molar (MxM2) may be filled by the eruption of the impacted third molar (MxM3). However, little is known about the factors associated with the eruption of the impacted MxM3. We aimed to characterize the clinical factors associated with the time taken for MxM3 eruption after MxM2 extraction. METHODS: We analyzed factors associated with late MxM3 eruption (>500 days after MxM2 extraction) in 84 molars. Prespecified risk factors were entered into logistic regression models to estimate odds ratios (ORs). RESULTS: The median duration between MxM2 extraction and MxM3 eruption was 302 days (interquartile range, 140-424). Significant factors associated with late MxM3 eruption included the proximity of the MxM3 root to the maxillary sinus floor (OR, 51.72), the distance between the occlusal plane of the MxM3 and the apical third of the MxM2 roots (OR, 16.56), MxM3 angulation and depth of ≥20° (OR, 5.58), ANB angle of <2° (OR, 9.05), and ≥1.5 mm distal movement of the maxillary first molar (MxM1) from its original position at the time of MxM2 extraction and MxM3 eruption (OR, 12.9). The probability of late MxM3 eruption was 0% (0 out of 30) with no risk, 6.9% (2 out of 29) with 1 risk factor, and 52% (13 out of 25) with ≥2 risk factors. CONCLUSIONS: We identified 5 clinical factors associated with late MxM3 eruption after MxM2 extraction. The probability of late MxM3 eruption increased as the number of present risk factors increased. These findings can be used for risk stratification during orthodontic treatment.

Unilateral nasal obstruction affects development of cortical orofacial motor representation in the cortical masticatory area of growing rats.

The cortical masticatory area (CMA) regulates masticatory movements. However, there is limited information regarding the effect of respiratory disturbances on the functional development of the CMA. This study aimed to examine the effect of chronic unilateral nasal obstruction (UNO) on the CMA during the growth period. Forty-eight 8-day-old male Wistar albino rats were randomized into control (CONT, n = 24) and UNO (n = 24) groups. Arterial oxygen saturation (SpO2) and the number of positive intracortical microstimulation (ICMS) sites in the anterior digastric (AD) muscle were recorded at 5, 7, and 9 weeks of age. ICMS was performed under anesthesia. The CONT group exhibited significantly higher SpO2 values than the UNO group at each age. Furthermore, the number of positive ICMS sites in the AD muscle was significantly higher in the UNO group than in the CONT group at each age. The right AD was more strongly affected by UNO than the left AD. In addition, it was found that the P-area was more strongly affected by UNO than the A-area. These findings suggest that UNO during development induces changes in the motor representation in the CMA, which may affect respiratory and orofacial functions in rats. Therefore, we suggest that the development of respiratory dysfunction needs to be monitored and corrected promptly to avoid complications in physiological function.

Nasal obstruction during the growth period modulates the Wnt/ß-catenin pathway and brain-derived neurotrophic factor production in association with tyrosine kinase receptor B mRNA reduction in mouse hippocampus.

There is accumulating evidence that nasal obstruction induces high-level brain dysfunction, including memory and learning deficits. We previously demonstrated that unilateral nasal obstruction (UNO) during the growth period increases the expression of brain-derived neurotrophic factor (BDNF). The expression of BDNF is regulated by the Wnt/ß-Catenin pathway, which is linked to neuronal differentiation, proliferation, and maintenance. However, little is known about whether Wnt3a protein expression could be an index for modulations analyses in the Wnt/ß-Catenin pathway caused by UNO during the growth period. This study aimed to investigate the effects of UNO during the growth period on the Wnt/ß-Catenin pathway in the hippocampus using combined behavioural, biochemical, and histological approaches. Male BALB/C mice were randomly divided into the control (CONT; n = 6) and experimental (UNO; n = 6) groups. Blood oxygen saturation (SpO2 ) levels were measured, and a passive avoidance test was performed in mice aged 15 weeks. Brain tissues were subjected to immunohistochemistry, real-time reverse transcription-polymerase chain reaction, and western blot analysis. Compared with control mice, UNO mice had lower SpO2 levels and exhibited memory/learning impairments during behavioural testing. Moreover, Wnt3a protein, BDNF mRNA, and tyrosine kinase receptor B (TrkB) mRNA expression levels were significantly lower in the hippocampus in the UNO group than in the CONT group. Our findings suggested that UNO during the growth period appeared to modulate the hippocampal Wnt/ß-catenin pathway and BDNF production in association with TrkB mRNA reduction, thereby resulting in memory and learning impairments.

Effects of low occlusal loading on the neuromuscular behavioral development of cortically-elicited jaw movements in growing rats.

The effect of altered occlusal force on masticatory-related neuromuscular control, which projects from the anterior part of the cortical masticatory area (A-CMA), during growth remains unclear. This study sought to evaluate the effect of occlusal hypofunction on neuromuscular development of jaw muscle activities and cortically-induced rhythmic jaw movements (RJMs) in growing rats. Sixty-four 2-week-old male albino Wistar rats were divided into the control (fed normal diet) and experimental (fed soft diet) groups soon after weaning. Electromyographic activity was recorded at 5, 7, 9, and 11 weeks from the right masseter and anterior digastric along with RJMs. We found a significantly longer onset latency and smaller peak-to-peak amplitude in the experimental group than that in the control group. The RJMs showed an increase in gape size and lateral excursion until up to 9 weeks in both groups. However, both the average gape size and lateral excursion were significantly smaller in the experimental group than that in the control group after 9 weeks. The jaw movement pattern also showed a significant decrease at the maximum opening period in the experimental group. Our findings indicate that inadequate occlusal function during growth alters neuromuscular control of masticatory behaviors and impairs the pattern of RJMs.

Functional changes in the temporomandibular joint mechanoreceptors associated with experimentally induced condylar resorption in rats.

OBJECTIVES: To evaluate the influence of experimentally induced progressive condylar resorption (PCR) on temporomandibular joint (TMJ) mechanoreception. MATERIALS AND METHODS: Twenty 13-week-old male albino Wistar rats were divided equally into control and PCR groups. A compressive force was loaded on the left TMJ of PCR group rats to induce condylar resorption. Single-unit activities of TMJ mechanoreceptors were also induced through passive jaw movement. Recording was performed for the left Gasserian ganglion at 3 days and 1 week after the establishment of PCR group. The effects of PCR on TMJ units were assessed by measuring the firing threshold, maximum instantaneous firing frequency, and average firing frequency. RESULTS: Compared with the control group, there were no significant differences in the firing threshold of the PCR group after 3 days. The thresholds were significantly higher 1 week after compressive force loading on the condyle. The maximum instantaneous firing frequencies and the average firing frequencies showed no significant differences after 3 days. However, these were significantly lower 1 week after compressive force loading. CONCLUSIONS: The findings suggest that compressive force loading on the condyle may influence the function of TMJ mechanoreceptors.

Characteristics of sleep/wake problems and delivery outcomes among pregnant Japanese women without gestational complications.

BACKGROUND: Frequently observed sleep/wake problems among pregnant women need comprehensive evaluation. This study was conducted to clarify the sleep/wake problems among pregnant women without gestational complications during the second and third trimester and the effects of sleep/wake problems on delivery outcomes. METHODS: A total of 88 Japanese pregnant women participated in this study. In their second and third trimester, subjective sleep quality, insomnia severity, excessive daytime sleepiness (EDS), and restless legs syndrome/Willis-Ekbom disease (RLS/WED) were assessed using questionnaires; also, sleep disordered breathing (SDB) was screened using a pulse oximeter. RESULTS: From the second to the third trimester, an increasing tendency of sleep/wake problems was observed. During the third trimester, the percentages of women experiencing decreased subjective sleep quality, difficulty maintaining sleep (DMS), EDS, RLS/WED, and 3% oxygen desaturation index (ODI) values ≥5/h were 62.5, 45.5, 48.9, 9.1, and 29.5%, respectively. In a logistic regression analysis for EDS in the third trimester, the adjusted odds ratio (95% confidence interval) of total sleep duration < 6 h, moderate to severe DMS, and 3% ODI values ≥5/h were 3.25 (1.16-9.10), 4.74 (1.60-14.00), and 0.90 (0.28-2.89), respectively. Although short sleep durations, decreased subjective sleep quality, EDS, and SDB did not affect delivery outcomes or the infant's condition, the percentage of women undergoing cesarean sections in the severe insomnia group was significantly higher (p = 0.008). CONCLUSIONS: Sleep/wake problems were frequent during pregnancy, especially during the third trimester. EDS among pregnant women was associated with shorter sleep durations and DMS rather than SDB. The effect of factors related to insomnia on delivery outcomes should thus be considered a crucial problem among pregnant Japanese women without gestational complications in clinical practice.

Functional Analysis of Rhythmic Jaw Movements Evoked by Electrical Stimulation of the Cortical Masticatory Area During Low Occlusal Loading in Growing Rats.

The maturation of rhythmic jaw movements (RJMs) and related neuromuscular control has rarely been studied in animals, though this process is essential for regulating the development of stomatognathic functions. Previous studies have shown that occlusal hypofunction during growth alters masticatory performance. However, little is known about patterns of cortically-induced RJMs under conditions of soft-diet feeding during development. The aim of this study is to clarify the effect of low occlusal loading on the pattern of cortically induced RJMs and related neuromuscular responses in growing rats. Sixty-four 2-week-old male albino Wistar rats were randomly divided into two groups and fed on either a normal diet (control) or soft diet (experimental) soon after weaning. At 5, 7, 9, and 11 weeks of age, electromyographic (EMG) activity was recorded from the right masseter and anterior digastric muscles along with corresponding kinematic images in RJMs during repetitive intracortical microstimulation of the left cortical masticatory area (CMA). Rats in both groups showed an increase in gape size and lateral excursion until 9 weeks of age. The vertical jaw movement speed in both groups showed no significant difference between 5 and 7 weeks of age but increased with age from 9 to 11 weeks. Compared to the control group, the average gape size and vertical speed were significantly lower in the experimental group, and the pattern and rhythm of the jaw movement cycle were similar between both groups at each recording age. EMG recordings showed no age-related significant differences in onset latency, duration, and peak-to-peak amplitude. Moreover, we found significantly longer onset latency, smaller peak-to-peak amplitude, and greater drop-off mean and median frequencies in the experimental group than in the control group, while there was no significant difference in the duration between groups. These findings indicate that a lack of enough occlusal function in infancy impedes the development of patterns of RJMs and delays the neuromuscular response from specific stimulation of the CMA.

The impact of rotating work schedules, chronotype, and restless legs syndrome/Willis-Ekbom disease on sleep quality among female hospital nurses and midwives: A cross-sectional survey.

BACKGROUND: Decreases in subjective sleep quality are prevalent among nurses and midwives engaged in rotating shift work. OBJECTIVES: The present study aimed to examine the relationship between differences in work schedules and subjective sleep quality among female nursing staff. DESIGN: A cross-sectional survey design was used for descriptive and logistic regression analyses. Data collection was conducted from December 2016 to September 2017. SETTINGS: Participants were recruited from five regional core hospitals in Japan. PARTICIPANTS: A total of 1253 nurses and midwives were included in the final analysis. METHODS: Subjective sleep quality was assessed using the Japanese version of the Pittsburgh Sleep Quality Index. Chronotype and social jet lag were calculated for both work day and work-free day. Symptoms related to restless legs syndrome/Willis-Ekbom disease were assessed using the Japanese version of the Cambridge-Hopkins questionnaire short form 13. Participants with the urge to move their legs, though not fulfilling the restless legs syndrome/Willis-Ekbom disease criteria, were classified as having leg motor restlessness. Logistic regression analyses for poor sleep were adjusted for age, body mass index, smoking, drinking, menstruation status, the presence of premenstrual syndrome, and the presence of a spouse. RESULTS: Rates of poor sleep (Pittsburgh Sleep Quality Index score ≥6) among those working, day shifts, rotating 12.5 hour night shifts, rotating 16 hour night shifts, and three-shift rotations were 41.2%, 51.1%, 44.5%, and 60.4%, respectively. Approximately 40% of three-shift rotation workers experienced difficulty initiating sleep. Shift workers tended to exhibit evening chronotype, delayed sleep phase, and high social jet lag. The prevalence of restless legs syndrome/Willis-Ekbom disease was 2.5%. Leg motor restlessness was observed in. 15.5% of participants. The adjusted odds ratios (95% confidence interval) of three-shift work (vs. day shift), evening chronotype (vs. morning chronotype), and the presence of leg motor restlessness (vs. no leg motor restlessness) for those with poor sleep were 2.20 (1.47-3.30), 1.95 (1.29-2.94), and 1.66 (1.15-2.39), respectively. CONCLUSIONS: Regardless of the working schedules, rates of poor sleep were high among female hospital nurses and midwives. Our findings suggest that poor sleep quality is influenced by three-shift rotation, the evening chronotype, and leg motor restlessness.

Anterior open bite due to temporomandibular joint osteoarthrosis with muscle dysfunction treated with temporary anchorage devices.

Skeletal Class II high-angle open bite is often accompanied by osteoarthrosis of the temporomandibular joint (TMJ-OA). This type of malocclusion is challenging to correct, and it has been reported that patients with TMJ-OA treated with orthognathic surgery often experience skeletal relapse and a poor prognosis. This case report describes the treatment of a 25-year-old woman with retrognathia and TMJ-OA, whose masseter and temporal muscle activities were weak. Temporary anchorage devices were placed in the maxilla and the mandible, and the first molars were intruded. We used improved superelastic nickel-titanium alloy wires with tip-back bends for both arches, and intermaxillary elastics were used to upright the molars. After treatment, intrusion of the maxillary and mandibular first molars, counterclockwise rotation of the mandible, and improvement of occlusion and profile had been achieved. The patient's condyles were repositioned into ideal positions, and masticatory muscle activity was augmented and balanced. After 2 years of retention, the mandibular and condylar positions were stable, and acceptable occlusion was maintained without recurrence of TMJ symptoms; harmonious activity of the masticatory muscles was retained. The findings of this case report suggest that molar intrusion using temporary anchorage devices for a patient with severe anterior open bite and TMJ-OA may be useful for improving stomatognathic function, occlusion, and facial esthetics.

Nasal obstruction during adolescence induces memory/learning impairments associated with BDNF/TrkB signaling pathway hypofunction and high corticosterone levels.

The hippocampus is an important brain region involved in memory and learning. Brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), and phospho-p44/p42 mitogen-activated protein kinase (MAPK) are known to contribute to hippocampal memory/learning. The present study aimed to clarify the effects of nasal obstruction during the growth period on memory/learning in an animal model, using combined behavioral, biochemical, and histological approaches. Male BALB/C mice underwent unilateral nasal obstruction (UNO) by cauterization at 8 days of age and were subjected to Y-maze and passive avoidance tests at 15 weeks of age. The serum corticosterone levels were measured using an enzyme-linked immunosorbent assay, and brain tissues were subjected to hematoxylin-eosin staining and histological analysis or homogenization and Western blot analysis. Compared with control mice, UNO mice had lower blood oxygen saturation levels and exhibited apparent memory/learning impairments during behavioral testing. Additionally, the UNO group had higher hippocampal BDNF levels and serum corticosterone levels, lower hippocampal TrkB and phospho-p44/p42 MAPK levels, and reduced neuron numbers relative to controls. Our findings suggest that UNO during adolescence affects the hippocampus and causes memory/learning impairments.

Maternal and neonatal outcomes in birth centers versus hospitals among women with low-risk pregnancies in Japan: A retrospective cohort study.

AIM: In order for low-risk pregnant women to base birth decisions on the risks and benefits, they need evidence of birth outcomes from birth centers. The purpose of this study was to describe and compare the maternal and neonatal outcomes of low-risk women who gave birth in birth centers and hospitals in Japan. METHODS: The participants were 9588 women who had a singleton vaginal birth at 19 birth centers and two hospitals in Tokyo. The data were collected from their medical records, including their age, parity, mode of delivery, maternal position at delivery, duration of labor, intrapartum blood loss, perineal trauma, gestational weeks at birth, birth weight, Apgar score, and stillbirths. For the comparison of birth centers with hospitals, adjusted odds ratios for the birth outcomes were estimated by using a logistic regression analysis. RESULTS: The number of women who had a total blood loss of >1 L was higher in the midwife-led birth centers than in the hospitals but the incidence of perineal lacerations was lower. There were fewer infants who were born at the midwife-led birth centers with Apgar scores of <7, compared to the hospitals. CONCLUSION: This study was the first to compare important maternal and neonatal outcomes of birth centers and hospitals. Additional research, using matched baseline characteristics, could clarify the comparisons for maternal and neonatal outcomes.