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

Reactions to Bioabsorbable Suture Thread Embedded in Rat Subcutaneous Tissue

We examined the subcutaneous tissue reactions in rats to bioabsorbable suture thread using histopathological methods. Using Wister rats, Vicryl®, a bioabsorbable suture thread, was embedded into the subcutaneous tissue and histopathological examination was carried out after 4 weeks. Cholesterin crystals were used for the control. Furthermore, immunohistochemistry for CD68 was done. Histopathological examination showed proliferation of granulation tissues inboth experimental and control groups. The majority of cells in the granulation tissues were macrophages and giant cells. Fibroblasts were also observed in the proliferating granulation tissues surrounding the embedded bioabsorbable suturethread. Immunohistochemistry revealed that macrophages and giant cells were positive to CD68. The results suggest that the embedded bioabsorbable suture thread is not only fabricated to undergo absorption but also for phagocytosis bymacrophages and foreign body giant cells

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

Reduced Adult Hippocampal Neurogenesis and Cognitive Impairments following Prenatal Treatment of the Antiepileptic Drug Valproic Acid

SummaryPrenatal exposure to valproic acid (VPA), an established antiepileptic drug, has been reported to impair postnatal cognitive function in children born to VPA-treated epileptic mothers. However, how these defects arise and how they can be overcome remain unknown. Using mice, we found that comparable postnatal cognitive functional impairment is very likely correlated to the untimely enhancement of embryonic neurogenesis, which led to depletion of the neural precursor cell pool and consequently a decreased level of adult neurogenesis in the hippocampus. Moreover, hippocampal neurons in the offspring of VPA-treated mice showed abnormal morphology and activity. Surprisingly, these impairments could be ameliorated by voluntary running. Our study suggests that although prenatal exposure to antiepileptic drugs such as VPA may have detrimental effects that persist until adulthood, these effects may be offset by a simple physical activity such as running

Histochemical Characteristics of Tertiary Dentin Due to Calcium Hydroxide Paste in Rats

Calcium hydroxide is mainly used for dental pulp capping and it is thought that it induces hard tissue formation far better than other materials. Experimentally verifying this fact, Nishikawa et al revealed that bone-like dentin corresponding to tertiary dentin is rapidly formed when calcium hydroxide is applied directly to the pulp. Utilizing the same experimental system, histochemical study of the newly formed hard tissue (reparative dentin) was carried out and the results thereof were reported. Thick and irregular reparative dentin was formed in the pulp cavity and partial narrowing of the root canal was observed in m-CT. Histopathologically, the irregular reparative dentin increased its thickness obliterating the root canal having a diff erent Azan staining of aniline blue compared to primary dentin. Numerous cellular inclusion bodies were also trapped inside the thick dentin. Furthermore, with Schmorl’s thionine picric acid staining,thick reparative dentin was noted around the pulp cavity and dentin. The dentin was densely stained with picric acid with diff erent staining ability from the surrounding dentin. In addition, it was clearly confi rmed that many cells were trapped in reparative dentin. The results of the experiment suggest that the characteristics of the newly formed reparative dentin is comparable to tertiary dentin

A surgical orthodontic case with multiple tooth losstreated by bite splint with CAD/CAM method

Recently, the number of middle–aged and elderly orthognathic surgery patients with un-healthy oral conditions has been increasing. Although an interdisciplinary approach in-volving orthodontist, oral surgeon and prosthodontist is required in orthognathic surgery of these patients, deciding the jaw position after orthognathic surgery is difficult due to unhealthy oral conditions such as edentulous jaw and tooth loss. In the recently study, preoperative simulation methods for orthognathic surgery have been developed through the use of virtual reality computed technology. A male first examined at the age of 36 years and 7 months was diagnosed as having mandibular protrusion with multiple tooth loss and mandibular deviation. The patient was treatedinterdisciplinary by a team of specialists in surgical orthodontic, dental prosthetic and periodontal treatment. Using the interdisciplin-ary approach and haptic device with virtual tactile perception showed satisfactory results loss treated with orthognathic surgery

A case of three supernumerary teeth in the maxillary incisor region

We treated a male elementary School student with 3 supernumerary teeth in the maxillary incisor region detected by radiographic examination.1. The patient underwent radiography for detailed evaluation at dental clinic, was found to have 3 supernumerary teeth in the maxillary incisor region, and was referred to our department.2. There was nothing of note regarding the patient’s history of systemic disorders.3. The patient was aged 7 years and 11 months at the time of the first examination,when the Hellman dental developmental stage was IIC.4. The maxillary right deciduous central incisor was present, and the maxillary left central incisor had already erupted. 5. Three–dimensional examination by radiography and three–dimensional examination using cone–beam CT showed 3 supernumerary teeth and prolonged retention of the maxillary right deciduous central incisor, and ectopia and eruption disorder of the maxillary right central incisor were confirmed.6. At the age of 8 years and 2 months, the maxillary right deciduous central incisor, the maxillary right deciduous lateral incisor and supernumerary teeth were extracted under general anesthesia.7. The postoperative course has been uneventful, but we have decided to continue periodic management because of ectopia of the maxillary right central incisor

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

Immunoglobulin for Treating Bacterial Infections: One More Mechanism of Action

The mechanisms underlying the effects of immunoglobulins on bacterial infections are thought to involve bacterial cell lysis via complement activation, phagocytosis via bacterial opsonization, toxin neutralization, and antibody-dependent cell-mediated cytotoxicity. Nevertheless, recent advances in the study of the pathogenicity of Gram-negative bacteria have raised the possibility of an association between immunoglobulin and bacterial toxin secretion. Over time, new toxin secretion systems like the type III secretion system have been discovered in many pathogenic Gram-negative bacteria. With this system, the bacterial toxins are directly injected into the cytoplasm of the target cell through a special secretory apparatus without any exposure to the extracellular environment, and therefore with no opportunity for antibodies to neutralize the toxin. However, antibodies against the V-antigen, which is located on the needle-shaped tip of the bacterial secretion apparatus, can inhibit toxin translocation, thus raising the hope that the toxin may be susceptible to antibody targeting. Because multi-drug resistant bacteria are now prevalent, inhibiting this secretion mechanism is an attractive alternative or adjunctive therapy against lethal bacterial infections. Thus, it is not unreasonable to define the blocking effect of anti-V-antigen antibodies as the fifth mechanism for immunoglobulin action against bacterial infections