Sleep is essential to brain function and mental health. Insomnia and obstructive sleep apnea (OSA) are the two most common sleep disorders, and are major public health concerns. Proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive method of quantifying neurometabolite concentrations. Therefore, 1H-MRS studies on individuals with sleep disorders may enhance our understanding of the pathophysiology of these disorders. In this article, we reviewed 1H-MRS studies in insomnia and OSA that reported changes in neurometabolite concentrations. Previous studies have consistently reported insomnia-related reductions in γ-aminobutyric acid (GABA) levels in the frontal and occipital regions, which suggest that changes in GABA are important to the etiology of insomnia. These results may support the hyperarousal theory that insomnia is associated with increased cognitive and physiological arousal. In addition, the severity of insomnia was associated with low glutamate and glutamine levels. Previous studies of OSA have consistently reported reduced N-acetylaspartate (NAA) levels in the frontal, parietooccipital, and temporal regions. In addition, OSA was associated with increased myo-inositol levels. These results may provide evidence that intermittent hypoxia induced by OSA may result in neuronal damage in the brain, which can be related to neurocognitive dysfunction in patients with OSA. The current review summarizes findings related to neurochemical changes in insomnia and OSA. Future well-designed studies using 1H-MRS have the potential to enhance our understanding of the pathophysiology of sleep disorders including insomnia and OSA.

It is well known that sex hormones are potential modulators of brain functions and women experience dynamic hormonal changes during the menstrual cycle. Previous animal studies have reported that the variations in sex hormones over the menstrual cycle may affect cognitive function, emotion, and behavior by altering structures and functional connectivity of the brain. Considering the prevalence of certain neuropsychiatric disorders such as mood and anxiety disorders is relatively high in women, as compared with men, fluctuations of sex hormones over the menstrual cycle may influence the human brain and potentially underlie sex differences in clinical features of several neuropsychiatric disorders. There is, however, little evidence regarding the exact mechanisms underlying the effects of sex hormones on the human brain. In this review, we focused on studies to examine structural and functional changes over the menstrual cycles in women and aimed to provide an up-to-date overview of neuroimaging studies regarding the effects of sex hormonal fluctuations on the brain and behaviors.

It is well known that sex hormones are potential modulators of brain functions and women experience dynamic hormonal changes during the menstrual cycle. Previous animal studies have reported that the variations in sex hormones over the menstrual cycle may affect cognitive function, emotion, and behavior by altering structures and functional connectivity of the brain. Considering the prevalence of certain neuropsychiatric disorders such as mood and anxiety disorders is relatively high in women, as compared with men, fluctuations of sex hormones over the menstrual cycle may influence the human brain and potentially underlie sex differences in clinical features of several neuropsychiatric disorders. There is, however, little evidence regarding the exact mechanisms underlying the effects of sex hormones on the human brain. In this review, we focused on studies to examine structural and functional changes over the menstrual cycles in women and aimed to provide an up-to-date overview of neuroimaging studies regarding the effects of sex hormonal fluctuations on the brain and behaviors.

Sleep is essential to brain function and mental health. Insomnia and obstructive sleep apnea (OSA) are the two most common sleep disorders, and are major public health concerns. Proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive method of quantifying neurometabolite concentrations. Therefore, 1H-MRS studies on individuals with sleep disorders may enhance our understanding of the pathophysiology of these disorders. In this article, we reviewed 1H-MRS studies in insomnia and OSA that reported changes in neurometabolite concentrations. Previous studies have consistently reported insomnia-related reductions in γ-aminobutyric acid (GABA) levels in the frontal and occipital regions, which suggest that changes in GABA are important to the etiology of insomnia. These results may support the hyperarousal theory that insomnia is associated with increased cognitive and physiological arousal. In addition, the severity of insomnia was associated with low glutamate and glutamine levels. Previous studies of OSA have consistently reported reduced N-acetylaspartate (NAA) levels in the frontal, parietooccipital, and temporal regions. In addition, OSA was associated with increased myo-inositol levels. These results may provide evidence that intermittent hypoxia induced by OSA may result in neuronal damage in the brain, which can be related to neurocognitive dysfunction in patients with OSA. The current review summarizes findings related to neurochemical changes in insomnia and OSA. Future well-designed studies using 1H-MRS have the potential to enhance our understanding of the pathophysiology of sleep disorders including insomnia and OSA.

Objectives: This study investigated the effect of an aluminum chloride hemostatic agent on the shear bond strength (SBS) of a universal adhesive to dentin. Materials and Methods: Eighty extracted human molars were trimmed at the occlusal dentin surfaces and divided mesiodistally. According to hemostatic agent application, specimens were randomly allocated into control (C) and hemostatic agent (Traxodent; H) groups. Each group was divided into 4 subgroups according to the adhesive system (n = 20): Scotchbond Multi-Purpose (SBER), Clearfil SE Bond (CLSE), All-Bond Universal etch-and-rinse mode (ALER), and All-Bond Universal self-etch mode (ALSE). SBS was measured for half of the specimens at 24 hours, and the other half were thermocycled in water baths (group T).Fracture surfaces were examined to determine the failure mode. The SBS was measured, and data were analyzed using 1-way analysis of variance, the Student’s t-test, and the Tukey honestly significant difference test (p = 0.05). Results: No significant differences in SBS were found between groups C and H for any adhesive system at 24 hours. After thermocycling, a statistically significant difference was observed between CT+ALSE and HT+ALSE (p < 0.05). When All-Bond Universal was applied to hemostatic agent-contaminated dentin, the SBS of H+ALSE was significantly lower than that of H+ALER (p< 0.05). The SBER subgroups showed no significant differences in SBS regardless of treatment and thermocycling. Conclusions When exposed dentin was contaminated by an aluminum chloride hemostatic agent before dentin adhesive treatment, application of All-Bond Universal in etch-and-rinse mode was superior to self-etch mode.

Suicide is a leading cause of death worldwide, especially among adolescents and young adults. Considering this fact, it is imperative that we understand the neural mechanisms underlying suicidal thoughts and behaviors in youth from a neurodevelopmental perspective. In this review, we focused on the magnetic resonance imaging studies that examined the neural correlates of suicidal ideations (SI) or attempts (SA) in youth. We reviewed twenty-three cross-sectional studies reporting the structural and functional alterations in association with SI or SA among adolescents and young adults with various mental disorders. The previous literature suggests that the dorsolateral prefrontal cortex, anterior cingulate cortex, and ventral frontolimbic circuit, may play an important role in the pathophysiology of suicidal behavior in youth through altered top-down control over emotion and impulsivity. Future studies with a longitudinal design and using multimodal imaging techniques may be of help to identify novel therapeutic targets specific for youth with suicidal thoughts and behaviors.

Fear conditioning and extinction, which are adaptive processes to learn and avoid potential threats, have essential roles in the pathophysiology of anxiety disorders. Experimental fear conditioning and extinction have been used to identify the mechanism of fear and anxiety in humans. However, the brain-based mechanisms of fear conditioning and extinction are yet to be established. In the current review, we summarized the results of neuroimaging studies that examined the brain changes—functional activity and structures—regarding fear conditioning or extinction in healthy individuals. The functional activity of the amygdala, insula, anterior cingulate gyrus, ventromedial prefrontal cortex, and hippocampus changed dynamically with both fear conditioning and extinction. This review may provide an up-to-date summary that may broaden our understanding of pathophysiological mechanisms of anxiety disorder. In addition, the brain regions that are involved in the fear conditioning and extinction may be considered as potential treatment targets in the future studies.

This study examined the influence of the apical sizes on the sealing ability of a root canal filling. Thirty-six single rooted teeth with a single canal were divided into 3 groups (n = 12) and instrumented with either the Profile(R) or LightSpeed(R) system to achieve three different apical sizes (master apical file [MAF] of #25, #40, or #60). The teeth were filled with gutta percha using a modified continuous wave technique. The level of microleakage was determined by immersing ten teeth from each group into India ink for 1 week followed by clearing with nitric acid, ethyl-alcohol, and methylsalicylate. The microleakage was measured using vernier calipers. The data was analyzed statistically using Kruskal-Wallis one-way ANOVA and a Student-Newman-Keuls Method. Two teeth from each group were sectioned horizontally at 1, 2, 3 and 4 mm from the apex in order to observe a cross section. The apical size was significantly (p < .05) influenced the level of microleakage. In the Student-Newman-Deuls Method, MAF sizes of #25 and #40; and MAF sizes of #25 and #60, respectively showed a statistically significant difference. There was no significant difference between #40 and #60. In most cross sections, oval-shaped canals were observed, and the irregularity of the internal surface increased with decreasing apical size. There was also an increase in the area of recess, which is the area where the canal space is not filled with either gutta-percha or sealer. When the root canals are filled using a modified continuous wave technique, canal filling with more consistent and predictable outcome may be expected as the apical preparation size is increased.
Carbon ; Dental Pulp Cavity ; Gutta-Percha ; India ; Ink ; Nitric Acid ; Salicylates ; Tooth