Osteonecrosis is defined as non-vital bone tissue as a result of abnormal process of osseous healing, and is caused by several reasons such as infection, radiation, and medication. Osteomyelitis, osteoradionecrosis, and medication related osteonecrosis of the jaws (MRONJ) which have necrotic bone in common are confused clinically due to similar symptoms and radiographic findings, and are difficult to diagnose definitively. Because each disease represents a separate clinical progress and requires a different treatment approach, it is very important to distinguish each disease. The aim of this study was to analyze the histopathologic features of osteomyelitis, osteoradionecrosis, MRONJ and to understand their different pathogenesis.

A two-year-old, castrated male Jindo dog presented with a three-week history of non-pruritic alopecia and scales on dorsum. The dermatologic lesions were progressive and did not respond to antibiotics and treatment for ectoparasite. Silver-white scales were adhered to the hair shafts and a follicular cast was marked on a trichogram. Findings on histopathologic examination of the skin lesions were consistent with sebaceous adenitis. Treatment with systemic cyclosporine and topical shampoo treatment was recommended for long term management. This case report is the first to describe a sebaceous adenitis in our country and suggests combination treatment approaches to long term management of this disease.

A 10-year-old, castrated male, English cocker spaniel dog was presented for evaluation of a mass in the left forelimb. Physical examination revealed a solitary subcutaneous mass measuring 2.7 × 2.1 × 1 cm in size. Radiographs and ultrasonography showed a well-circumscribed, focally mineralized, non-invasive to muscle layer mass without signs of further bone invasion and periosteal reaction. Cytologic evaluation of the mass through fine needle aspiration revealed a mesenchymal cell type malignant tumor without distant metastasis. An excisional biopsy was performed for definitive diagnosis and the mass was diagnosed as cutaneous hemangiopericytoma. This case report presents disagreement between fine needle aspiration and histopathology during diagnostic procedures of cutaneous hemangiopericytoma in a dog.

The purpose of this study was to investigate the initial bone tissue change and ,to repair on the Miniscrew and surrounding tissue under the various types orthodontic forces by use of niti closed spring through the polarizing φ>larizing microscopic fmdings. For this study, three young adult mongrel dogs(experimental group 1, 2, 3) were used, and 12 titanum miniscrew(a1, a2, a3, b1, b2, b3, c1, c2, c3, d1, d2, d3) were inserted into the palatal bone. The experimental design was consisted of equal opposite group(B), extrusion group(C), double same sided group(D). and group(A) was controlled. Group B, C, D miniscrews were loaded with 150gm of force immediately after placing to palatal side, and group B miniscrews were loaded with changed force of equal amount to buccal side after 10 없ys. and Group C was loaded extrusive force, group D was loaded double amount to palatal side at same time. The experimental animals in each group and control group were sacrified at one, three, and six weeks following implatation the miniscrew to make the samples for polarizing microscofic findings on palatal bone and miniscrew. All samples were examed and compared the 비stologic changes through the polarizing microscpe. The obtained results were as follows. 1. Under equal 01ψ。site force group, the histologic features of tissues around Miniscrew in experimental B group was no difference between the control group under equal opposite force group 2. Under extrusive force after lateral force group, it's bone density was decreased less than control groupunder extrusive force after lateral force group. πùs group was most p∞r bone densi마 ofall. 3. Under double same side group, inital feature was sirnlar to control group , but after 6weeks bone density was decreased along the Miniscrew surfaceunder double same side group. Based on these experimental results, in the prac디ce ， Miniscrew was usefull as skeletal anchorage in immediately load after implantation on alveolar bone under lateral force and opposite lateral force, but at applied extrusive force and double opposite side force were non- useful as skeletal anchorage with long-term treatrnent.

World Health Organization(WHO) revised the classification of neoplasms and other tumours related to odontogenic apparatus in 1992. The aim of this study was to classify the odontogenic tumors of Korean according to the WHO Histologic classification. A total of 271 cases were reviewed for the study which were diagnosed as odontogenic tumors at the department of Oral Pathology, Yonsei University College of Dentistry for the period from Jan. 1997 to March 2003. Clinical and pathology reports were reviewed & radiographic feature were examined. The following results were obtained : 1. Among 271 cases, 269 cases(99.3%) were diagnosed as benign odontogenic tumors, and the remaining 2 cases(0.7%) were malignant tumors, which were diagnosed as odontogenic ghost cell carcinoma and squamous cell carcinoma ex odontogenic cyst. 2. Four cases were not able to classify into the WHO classification. All of them were belonged to mixed odontogenic tumors; two cases of adenomatoid odontogenic tumor with calcifying epithelial odontogenic tumor, one case of adenomatoid odontogenic tumor with odontoma, odotogenic cyst and one case of ameloblastoma with immature odontoma. 3. The most frequent odontogenic tumour was odontoma(45.2%), followed by ameloblastoma (29.2%), odontogenic fibroma(9.2%) 4. One case of atypical amelobalstoma and one case of calcifying odontogenic cyst with ameloblastic fibroma were not able to subclassify histologically. 5. Male to female ratio of odontogenic tumors was 1.2:!. Odontogenic tumors mainly occured in the first and second decade, occurred twice as much as in the mandible than in the maxilla 6. The odontogenic tumors was discovered by routine oral x-ray examination, whereas the chief complaint of ameloblastoma were swelling, pain. 7. Ameloblastoma, adenomatoid odontogenic tumor, calcifying odontogenic cyst and odontoma were related to the impacted teeth and tooth displacement. The root resorption was frequently observed in ameloblastoma and calcifying odontogenic cyst.

Anchorage plays an important role in orthodontic treatment. Recently, some clinicians have tried to use skeletal anchorage system(titanium miniscrews and microscrews) in treatment due to their many advantages such as ease of insertion and removal, low cost, immediate loading, and the ability to place miniscrews in any area of alveolar bone. The purpose of this study was to investigate the histopathologic change of alveolar bone density around miniscrew under variable ortho -donticforceinyoung-adultdogs, throughthepolarizingmicroscopic findings. For this study, three young adult mongrel dogs(6-months in age) were used, 12 titanium miniscrews were inserted into the palatal bone(4 miniscrews placed in each dog), and then miniscrews were loadedwithorthodonticforce [50gm(F1),100gm(F2),250gm(F3), 500gm(F4)] immediately after implantation. After 1, 3 and 6 weeks, the animals were sacrificed. Then the miniscrews and surrounding bone of dogs were removed, respectively. The grinding samples along the long axis of miniscrew were made. The changes of bone density and thrombosis were examined under the polarizing microscope. Bone density was determined as color changes. The results of this study were as follows. 1. There was no thrombosis in the F1 group. But thrombosis was seen in 1 week of T side, 1, 3, 6 weeks of P side in the F2 group, 1, 3 weeks of T side, 1, 3, 6 weeks of P side in the F3 group and 1, 3, 6 weeks of both P and T side in the F4 group. 2. The changes of bone density decreased in P side more than T side in 1 week, while more decreased P side in 3 weeks than 1 week. In 6 weeks, bone density more increased in T side than P side along the middle & apex. 3. As orthodontic force increased, there was severe thrombosis, especially in cervical of P side. As it went up to 3, 6 weeks, thrombosis was decreased but remained. 4. As orthodontic force increased, bone density more severely decreased due to bone destruction in 1 and 3 weeks, but more slowly increased due to bone formation in 6 weeks. Based on the results of this study, in the practice, because of optimal orthodontic force for the most of tooth movement was less than 150gm, I thought that miniscrews could play role of use of skeletal anchorage immediately after implantation. In the more than 250gm & 500gm of orthodontic force, I thought that miniscrews would be delayed as use of skeletal anchorage after loss of bone was restored.

The acetaminophen (APAP), an antipyretic and analgesic agent, induces the hepatotoxicity by increasing influx of calcium and destabilizing the cellular membrane which can be caused by N-acetyl p-benzoquinoneimine generated by cytochrome P-450 (CYP-450) when it is overdosed. Diltiazem (DIL), a calcium channel blocking agent, has been known to suppress the CYP-450 activities. To study the effect of DIL in APAP treated rats, the serum biotransformational enzyme analyses and the liver histopathologic examination were conducted on the rats which had been administered DIL at 3, 6, 9 and 12 hours after the 3,000 mg/kg of APAP administration. Following a single dose of DIL administered 12 hours after APAP administration, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, malondialdehyde and calcium contents of liver and microsome were significantly reduced. Glutathione S-transferase (GST) activity was significantly increased. Histopathologic studies showed that DIL had prevented the development of centrilobular necrosis induced by APAP in liver tissue. Our results suggested that diltiazem could inhibit the formation of free radical and the influx of calcium and could increase GST activity. Therefore, diltiazem can be administered at the time of 12 hours after overdosed APAP to diminish the liver damage.

A primary infection with Toxoplasma gondii is usually asymptomatic, but some patients may have cervical lymphadenopathy and ocular disease. Toxoplasmosis is a common cause of lymphadenopathy. However, histopathologic examination to diagnose it usually does not reveal toxoplasmic cysts. Diagnosis of toxoplasmosis can be established by serological techniques or by direct detection of the parasite. Therefore, it is necessary to recognize the characteristic histopathological findings of toxoplasmic lymphadenitis and to confirm by serological or PCR results for toxoplasmosis. We describe histopathologic features of a case of toxoplasmic lymphadenitis with review of the literature, confirmed by serological evidence in a 50-year-old man.