Cytological kinetics of periodontal ligament in an experimental occlusal trauma model

松本歯科大学大学院歯学独立研究科博士（歯学）学位申請論

Mandibular protrusion with late mandibular growth after orthodontic treatment

This report describes late mandibular growth of patient with mandibular protrusion af-ter orthodontic treatment including consideration about growth and development of man-dibular. A 15–year, 2 month old female patient presented with the chief complaint of crowding of upper and lower anterior teeth. The facial profile was concave type because of a skeletal Class 3 facial profile. The incisors were edge–to–edge bite. The molar relation-ship was Angle Class III protrusion. This patient was diagnosed as skeletal Class III pro-trusion with maxillary and mandibular incisors of edge–to–edge bite and crowding. After orthodontic treatment, the facial profile significantly improved and an acceptable occlusion was achieved. But 3 years later, late growth of mandibular was observed and the lower an-terior teeth were slightly crowding in retention phase

Bone Marrow Mesenchymal Cell Contribution in Maintenance of Periodontal Ligament Homeostasis

In general, remodeling phenomenon of the periodontal ligament (PDL) is occurring in all times. Thus, in the chapter, the word “maintenance” was used, and the chapter title is “Maintenance of Periodontal Ligament Homeostasis.” Our experimental data on the remodeling of the PDL with cell acceleration at the furcation area in this experimental model are recovered using the cells in situ and the bone marrow-derived cells (BMCs). BMC migration into the PDL tissues using green fluorescent protein (GFP) bone marrow-transplanted model mouse was examined. BMCs have abilities of cell migration and differentiation into tissues/organs in the body. The immunohistochemistry revealed that GFP-positive cells were detected in the PDL. GFP-positive cells were also positive to CD31, CD68, and Runx2 suggesting that fibroblasts differentiated into osteoclasts and tissue macrophages. In this way, Notch signaling involvement considered in our tentative examinations revealed that the experimentally induced periodontal polyp was examined; the cytological dynamics of the cells in granulation tissue are mainly from migration of undifferentiated mesenchymal cells of the bone marrow and differentiate into the tissue-specified cells. Furthermore, the data suggest that cell differentiation is due to Notch signaling

Functional Role of HSP47 in the Periodontal Ligament Subjected to Occlusal Overload in Mice

We carried out an experiment to induce traumatic occlusion in mice periodontal tissue and analyzed the expression of HSP47. Continuous traumatic occlusion resulted to damage and remodeling of periodontal ligament as well as increase in osteoclasts and bone resorption. Four days after traumatic occlusion, osteoclasts did not increase but Howship’s lacunae became enlarged. That is, the persistent occlusal overload can destroy collagen fibers in the periodontal ligament. This was evident by the increased in HSP47 expression with the occlusal overload. HSP47 is maintained in fibroblasts for repair of damaged collagen fibers. On the other hand, osteoclasts continue to increase although the load was released. The osteoclasts that appeared on the alveolar bone surface were likely due to sustained activity. The increase in osteoclasts was estimated to occur after load application at day 4. HSP47 continued to increase until day 6 in experiment 2 but then reduced at day 10. Therefore, HSP47 appears after a period of certain activities to repair damaged collagen fibers, and the activity was returned to a state of equilibrium at day 30 with significantly diminished expression. Thus, the results suggest that HSP47 is actively involved in homeostasis of periodontal tissue subjected to occlusal overload

実験的咬合性外傷による歯根膜の細胞動態

Using a model of experimental occlusal trauma in mice, we investigated cytological kinetics of periodontal ligament by means of histopathological, immunohistochemical, and photographical analysis methods. At furcation areas of molar teeth in the experimental group on day 4, the increase of cells in periodontal ligament was seen. The cells with a round-shaped nucleus were deeply stained in the hematoxylin-eosin. Ki67 positive nuclei showed a prominent increase in the experimental groups on days 4 and 7. Green Fluorescent Protein (GFP) positivity also revealed cell movement, but this action was slightly slow compared to Ki67 staining specimens. It was indicated that the homeostasis is mechanism of periodontal ligament receiving the excessive occlusal loading was promoted by osteoclasts and macrophages from bone-marrow-derived cells migrated to the periodontal ligament. The remodeling of periodontal ligament with the acceleration of cell growth was evoked from the experiment for the group on day 4 and after day 7. The findings suggested that periodontal ligament at furcation areas of molar teeth in occlusal trauma model was recovered by using both of the cells in situ and the bone-marrow-derived cells.2015博士（歯学）松本歯科大

Chapter 6 : Bone marrow masenchymal cell contribution in maintenance of periodontal ligament homeostasis.

In general, remodeling phenomenon of the periodontal ligament (PDL) is occurring in all times. Thus, in the chapter, the word “maintenance” was used, and the chapter title is “Maintenance of Periodontal Ligament Homeostasis.” Our experimental data on the remodeling of the PDL with cell acceleration at the furcation area in this experimental model are recovered using the cells in situ and the bone marrow-derived cells (BMCs).BMC migration into the PDL tissues using green Ěuorescent protein (GFP)bone　marrow-transplanted model mouse was examined. BMCs have abilities of　cell migration and diěerentiation into　tissues/organs in the body. The immunohistochemistry revealed that GFP-positive cells were detected in the PDL.GFP-positive cells were also positive to CD31, CD68, and Runx2 suggesting that ębroblasts diěerentiated into osteoclasts and tissue macrophages. In this　way, Notch signaling involvement considered in our tentative examinations revealed　that the experimentally induced periodontal polyp was examined; the cytological　dynamics of the cells in granulation tissue are mainly from migration of　undiěerentiated mesenchymal cells of the bone marrow and diěerentiate into the　tissue-specięed cells. Furthermore, the data suggest that cell diěerentiation is due to　Notch signaling.Edited by Thomas Heinbockel and Vonnie D.C. Shields : Published in London : IntechOpen, 2019

Author Correction: Fish proliferation and rare-earth deposition by topographically induced upwelling at the late Eocene cooling event (Scientific Reports, (2020), 10, 1, (9896), 10.1038/s41598-020-66835-8)

金沢大学理工研究域地球社会基盤学系An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2020, The Author(s)

Fish proliferation and rare-earth deposition by topographically induced upwelling at the late Eocene cooling event

金沢大学理工研究域地球社会基盤学系The deep-sea clay that covers wide areas of the pelagic ocean bottom provides key information about open-ocean environments but lacks age-diagnostic calcareous or siliceous microfossils. The marine osmium isotope record has varied in response to environmental changes and can therefore be a useful stratigraphic marker. In this study, we used osmium isotope ratios to determine the depositional ages of pelagic clays extraordinarily rich in fish debris. Much fish debris was deposited in the western North and central South Pacific sites roughly 34.4 million years ago, concurrent with a late Eocene event, a temporal expansion of Antarctic ice preceding the Eocene–Oligocene climate transition. The enhanced northward flow of bottom water formed around Antarctica probably caused upwelling of deep-ocean nutrients at topographic highs and stimulated biological productivity that resulted in the proliferation of fish in pelagic realms. The abundant fish debris is now a highly concentrated source of industrially critical rare-earth elements. © 2020, The Author(s)

Two cases of impaction of mandibular second molars

Summary An impacted mandibular second molar is rare. Here,we report two cases of such impacted molars.Case 1:A 22–year–old man presented at our university hospital upon　referral from his family dental clinic.A panoramic image revealed horizontal impaction of the left mandibular second molar.Since the patient preferred surgical extraction,the left mandibular second molar was extracted. Case 2:A 54–year–old man presented at our health and dental checkup center.Based on the results of a panoramic image,a dentist from oral radiology diagnosed him with impacted bilateral mandibular second molars.He suggested conducting a complete examination;however,these molars were simply observed and no treatment was provided

The tremendous potential of deep-sea mud as a source of rare-earth elements

金沢大学理工研究域地球社会基盤学系Potential risks of supply shortages for critical metals including rare-earth elements and yttrium (REY) have spurred great interest in commercial mining of deep-sea mineral resources. Deep-sea mud containing over 5,000 ppm total REY content was discovered in the western North Pacific Ocean near Minamitorishima Island, Japan, in 2013. This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features. Here, we estimated the resource amount in REY-rich mud with Geographical Information System software and established a mineral processing procedure to greatly enhance its economic value. The resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising area (105 km2 × 0-10 mbsf), which accounts for 62, 47, 32, and 56 years of annual global demand for Y, Eu, Tb, and Dy, respectively. Moreover, using a hydrocyclone separator enabled us to recover selectively biogenic calcium phosphate grains, which have high REY content (up to 22,000 ppm) and constitute the coarser domain in the grain-size distribution. The enormous resource amount and the effectiveness of the mineral processing are strong indicators that this new REY resource could be exploited in the near future. © 2018 The Author(s)