Pathological Examination of Experimentally Induced Periodontal Polyp in Mice

The mechanism in the formation of periodontal polyp has been established in several histological studies but details on cell differentiation and/or proliferation have not been elucidated. In the present study, we established a convenient and possible experimental system using ddY mice. Briefly, pentobarbital sodium (Somnopentyl) was injected into the abdominal cavity of the mouse followed by access cavity preparation on maxillary first molar using low speed ½ round bur (Merufa Inc), exposing the pulp and then allowed to perforate the floor of the pulp chamber. Observation was done over time until 6 months using micro CT (m_CT) image photography. Results with transmission image using m_CT showed theexpansion in the width of the periodontal ligament in the furcation area. The lesion was excised as one mass and examined histopathologically. The granulation tissue was covered with stratified squamous epithelium. The present experimental technique has been confirmed to be effective in analyzing the formation of periodontal polyp induced by mechanical perforation

マウスにおける実験的根尖部炎症病変の確立

Abstract: Although studies on the formation of apical periodontitis have somehow been carried out but detailed cellular dynamics remain unclear. We recently established an experiment that could easily be performed using ddY mice. First, under general anesthesia using isoflurane inhalation, the coronal portion of the maxillary first molar was penetrated using a round bur and drill with water irrigation causing pulp exposure until the root apex. Micro computed tomography (R_mCT) was taken over time during observation. Four weeks later, R_mCT confirmed the presence of a radiolucent image at the apex of the tooth, which was then removed for histological examination. The results showed that granulation tissue with fibrosis had gradually formed at the periphery of the abscess. The present method confirmed the effectiveness of the experimental mode to exmine the formation of chronic inflammatory lesions at the root apex.根尖部炎症病変のマウスモデルを作製した。マウスをイソフラン吸入により麻酔し、上顎第1大臼歯の歯冠部をラウンドバーにより貫通させた後、水の灌注により穴をあけて根尖まで歯髄を露出させた。処置の4週間後、根尖部にX線透過性部位が存在することが、マイクロコンピュータートモグラフィーにより確認された。この部位について組織学的検査を行った結果、線維増生を示す肉芽組織が膿瘍の周辺に徐々に形成されることが明らかになった。以上より、本モデルは根尖部の慢性炎症病変の形成を調べる上で有用であることが示された

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

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

A case of occlusal guidance with supernumerary tooth and odontoma

Supernumerary teeth and odontoma are frequently noted in clinical pedodontic cases,and it is necessary to treat them at an early stage. In this study, we encountered a patient in whom occlusal abnormalities occurred due to the existence of a supernumerary tooth and odontoma in an adjacent area. Regarding treatment, we extracted the supernumerary tooth and excised the odontoma under general anesthesia. Thereafter, in the following year, we initiated a dynamic approach to resolve the malocclusion using the multi–bracket method. We will continue treatment, while carefully observing the patientʼs dentition and occlusal growth. Because there have been few clinical reports on such cases, treatment may be difficult ; therefore, it is expected that other similar cases will be reported in the futur

Effects of the development changes in dentition on the retention of mouthguards

Summary The use of mouthguards is one of the main strategies that are considered effective in preventing sports–related trauma.Although mouthguards are recommended for use in children during sports activities,little is known as to how growth and developmental changes in the oral cavity, jaw, and dentition affect the retention of mouthguards. In the present study, we designed mouthguards for primary,mixed(4 types),and permanent detention stages and performed tensile testing to determine the effects of dental growth and development on their retention.We also designed mouthguards for the left maxillary second milk molar,left maxillary second premolar, and left maxillary first molar to determine how the shape of the teeth affects their retention.Data was analyzed statistically,and the following results were obtained:1.Mouthguards for permanent detention stage had a significantly higher level of retention than those for primary and mixed detention stages.2.Mouthguards for primary detention stage had a significantly lower level of retention than those for mixed and permanent detention stages. 3.The retention of mixed detention stage mouthguards became poorer with the number of teeth requiring relief.4.Differences in the shape of the teeth(left maxillary second milk molar, left maxillary second premolar, left maxillary first molar)had no significant effect on the retention of mouthguards.These findings indicate that the level of mouthguard retention is lower in children at primary and mixed detention stages than in adults and children with complete eruption of central incisor to second molar.This difference may be attributed to the differences in the coverage areas of mouthguard