Observing the changes in periodontium due to orthodontic force is important to reveal the mechanisms of tooth movement. In order to understand micro-vascular dynamics in regards to bone remodeling, we considered that lymphatics functioning need to be examined along with the blood vessels. The aims of this study were to reveal the lymphatic distribution in the mouse periodontal ligament using immunohistochemical methods. A cryosection film-transfer method was used to produce 2 µm-thick non-decalcified serial sections, and immunohistochemical staining using antibody to lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) which was demonstrated for lymphatics was performed. The number of LYVE-1 immunoreactive vessels in the periodontal ligament were sparser than that of blood vessels in the periodontal ligament. All LYVE-1 positive lymphatics were observed close to the alveolar bone-wall in the apical periodontal ligament. However, their horizontal anastomoses were not observed. Distribution of LYVE-1 positive lymphatics in an umbrella frame-like was observed at the apical region. These lymphatics and the lymphatics in the tooth pulp merged into collecting lymphatics in the mandibular canal. This sparse distribution of lymphatics suggests a very low absorption capacity in the periodontal ligament. [MVRC 3(1): 2-10, 2009]

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The effects of nitric oxide (NO) on microflow and capillary red blood cell (RBC) velocity of the cerebral cortex were examined in 5 urethane-anesthetized rats through an open cranial window. Changes in microflow were evaluated with hemodilution technique with in-house Matlab-domain software, KEIO-IS1, presented as a 2-D microflow-map. When FITC-labeled RBCs were injected into the femoral vein, they appeared in the microvasculature of the cerebral cortex including capillaries. Changes in RBC velocity and attendance in single capillaries were determined with a high-speed camera laser scanning confocal fluorescence microscope before, during and after NO administration. The velocity and number of RBCs in the ROI were calculated with KEIO-IS2. Nitroprusside (a NO donor) was administered topically on the exposed brain surface, additionally microinjected into the tissues in 3 rats, and further intravenously in 2 rats. We found that: 1) NO increased microflow markedly regardless of the routes of administration and when limited to the cases of topical application microflow increased by 182±22 % (mean ± SD) of control (P<0.01). 2) RBC velocity in capillaries remained broadly unchanged, whereas RBC number (attendance) decreased in all cases (P<0.05). We interpreted that NO induced an increase in microflow not through nutritional capillaries but via other pathways from artery to veins, e.g., thoroughfare channels. This finding suggests the presence of an independent velocity-impedance mechanism at the level of individual single capillaries in which excessive increase in capillary flow is somehow prevented. [MVRC 3(1): 11-16, 2009]

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Several studies have described the lymphatic architecture of periodontal tissues, including gingival tissues, using laboratory animals; however, no study has investigated human samples. In the present study, morphological characteristics and architecture of human gingival lymphatic vessels were investigated using clinically healthy gingival tissue with the aim of developing a drug delivery route through lymphatic vessels for clinical application. We collected free gingival tissue excised for therapeutic purposes during periodontal surgery from six patients, and produced frozen serial sections using the film-transfer method. The sections were then stained with 5'-nucleotidase to expose the lymphatic vessels, and three-dimensional images of lymphatic vessels were reconstructed using 3D visualization software. Lymphatic vessels formed networks in the lamina propria on the oral epithelial side in free gingiva, presenting as a layer of rough irregular hexagonal meshes. Blind-ended vessels were observed entering connective tissue papillae through these meshes. The blind-ended vessels did not branch between the base of connective tissue papilla and rod-like structure at the tip, and were positioned at the center of each papilla. The lymphatic architecture of human free gingiva showed a similar distribution to that of blood vessels, although the lymphatic vessels were fewer in number than blood vessels. Activation of drainage through lymphatic vessels in gingiva is considered to be an important therapeutic measure in terms of improvement in edema. [MVRC 3(1): 17-24, 2009]

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Purpose: The aim of this study was to observe morphological changes in the gingival microvasculature after tooth preparation. The conventional dental air turbine and ultrasonic methods were examined as a way of tooth preparation. To visualize the changes in the gingival vasculature, a corrosion resin cast was used and visualization performed with a scanning electron microscope (SEM).
Materials and Methods: The preparations were performed on the premolars in Beagle dogs. A chamfered finishing line was created by a diamond instrument along the gingival margin with either a dental air turbine or an ultrasonic wave.
Results: Immediately after preparation using the dental air turbine, teardrop-shaped resin leakage was seen, indicating that bleeding had occurred in the gingiva. Fourteen days after the preparation, resin leakage was seen on the vascular resincast indicating an acceleration of vascular permeability. After 30 days, the blood vessels constructed glomerulus loops. Immediately after the preparation using ultrasonic waves, the vasculature appeared normal. Fourteen days after the preparation, new vasculature appeared along the finishing line. After 30 days, vascular regeneration was nearly complete.
Conclusions: Our observations suggest that the use of the ultrasonic wave instrument caused minimum damage compared to the use of the dental air turbine. Therefore, in terms of protecting the microcirculatory system in the gingival tissue during tooth preparation, the ultrasonic wave instrument is useful. [MVRC 3(1): 25-31, 2009]

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