We examined whether the superior margin of the left main bronchus is the best landmark for the starting position of computed tomography coronary angiography（CTCA）. We retrospectively evaluated 693 consecutive CTCAs. From the scout scanogram, the superior margin of the left main bronchus was noted. The relationships among and distance between the superior margin of the left main bronchus and the left coronary system were analyzed. The superior margin of the left main bronchus extended caudally to the superior margin of the left coronary system in 13 patients（1.9％）. The addition of 1cm to the superior margin of the left main bronchus kept it caudal to the superior margin of the left coronary system in only one patient（0.1％）. On the scout scanogram, 1cm above the superior margin of the left main bronchus is the most appropriate starting position for CTCA.

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Autogenous bone grafting is the most widely accepted approach for repairing bone defects, yet limitations in the donor site and subsequent morbidity associated with harvesting bone from other sites remain as major concerns. Consequently, synthetic bone-like biocomposites have drawn much attention as a novel regenerative strategy. This study evaluated the regenerative properties of our prototype β-TCP/collagen composite in an animal model. We prepared the original β-TCP/collagen composite by mixing an acidic atelocollagen gel and alkaline colloidal β-TCP, and Raman microspectroscopy of the composite revealed the typical spectral features attributable to bone after manual mixing. We then transplanted either the composite or collagen alone into a full-thickness trephine defect made in the calvarial bone of rats. At 8 weeks after implantation, the elastic modulus of regenerated bone that developed alongside the composite was comparable to that of native cortical bone. Decalcification and processing of the calvarial bones for histological observation revealed that the β-TCP/collagen enabled better bone regenerative properties compared to collagen alone. Our newly developed β-TCP/collagen composite imitates the structural properties of bone, and thus provides a potentially useful scaffold material to support the mechanical integrity of regenerated bone.

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To determine the permissibility of piloting an aircraft with vasovagal syncope （VVS） is a complex responsibility, because it is difficult to evaluate VVS quantitatively. There are no clear guidelines for aircraft pilots with VVS. In some facilities, Head-up Tilt Test （HUTT） is used to determine its reproducibility and treatment effect. In most cases, permission is dependent on the strict examinations by specialists and judgement of the committee established for each country. Therefore, we assessed pilots with VVS and designed an algorism of permission for piloting an aircraft. Here, we describe 7 consecutive regular passenger aircraft pilots with VVS who were restricted to fly. All patients were men and their mean age was 37 years. All pilots were permitted to fly after at least two or more tilt-tests. The observation period was two years after flight permission. None of the pilots in the present study fainted after receiving flight permission. We can make a risk stratification to determine hypotensive susceptibility by multiple tilt tests. Based on the results of multiple HUTT, we can more quantitatively make the judgement as to whether the pilot’s VVS is well managed.

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Dentin is altered in an age-related manner, such that transparent dentin in the tooth root forms during the aging process. Notably, fractures are more likely to occur in aged teeth. However, few studies have examined the mechanical properties of aged dentin. The purpose of this study was to investigate the structural and mechanical properties of the transparent dentin region, by analysis of the mineral density, using micro-computed tomography （micro-CT）, the tensile strength, and nanohardness to understand tooth fracture. As experimental samples, 10 caries-free, human molars were extracted from patients aged >50 years because of periodontal disease. As controls, bovine lower central incisors were extracted immediately after sacrifice from animals estimated at 2–2.5 years of age. Mineral density was quantified with X-ray micro-CT analysis of transparent human dentin and normal bovine dentin. Specimens were prepared from each tooth （human and bovine） and subjected to tensile strength testing; maximum load was used to calculate strength, and mean tensile strength of the specimens was calculated in each group. Finally, the nanohardness and Young’s modulus of intertubular dentin of the upper and apex root regions were investigated. All results were compared by paired Student’s t-test （α=0.05）. The mineral density of transparent dentin was significantly greater than that of normal dentin. Importantly, the tensile strength of the transparent regions was significantly lower than that of the normal regions, whereas the nanohardness and Young’s modulus of transparent intertubular dentin were significantly greater than those of normal intertubular dentin. Fractures of the teeth remain a major problem in clinical practice. Notably, transparent dentin is weaker than normal opaque dentin, which may explain the occurrence of apex root dentin fractures in aged individuals.

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Improvement of the dentin surface is an important factor in successful restorative or endodontic treatments because of the requirement for adhesion to dental tissue, or increased bonding strength. This study was undertaken to observe the radicular dentin surface contact angle during exposure to ultraviolet （UV） light from an excimer lamp. Additionally, we investigated the structural and mechanical properties of dentin after UV lamp irradiation. The roots of 30 bovine lower central incisors were sectioned 1.5mm below the cementoenamel junction, and a 1-mm-thick radicular dentin slab was cut from each tooth. Polished specimens were randomly divided into three groups: no treatment （n＝10）, irrigation with NaOCl and EDTA （3％ NaOCl for 1min, 17％ EDTA for 1min, then 3％ NaOCl for 1min; n＝10）, and xenon excimer UV irradiation for 180sec （n＝10）. Pure water was dropped onto the dentin slabs and water contact angles were immediately measured for each specimen. For nanohardness and Young’s modulus, the dentin at the center, between the outer surface and the pulp chamber, was measured. Results were statistically analyzed by one-way ANOVA and Tukey tests （P<0.05）. The contact angle of dentin exposed to endodontic irrigants was significantly lower than that of normal dentin. Furthermore, the contact angle of dentin exposed to excimer UV irradiation was significantly lower than that of dentin exposed to endodontic irrigants. Mean hardness and mean Young’s modulus measurements did not differ between the groups. UV-irradiated dentin exhibited increased surface wettability. However, UV irradiation did not change the mechanical or structural properties of dentin. Thus, excimer UV irradiation might be useful in endodontic treatment.

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