Oral cytology is becoming increasingly popular due to the improvement of diagnostic quality, and may be used instead of histopathological examination. Though the main purpose of clinical cytology is to distinguish inflammatory parts from tumorous lesions, detailed diagnosis is possible in some cases.
In this paper, the applicability and qualities of oral cytology in the field of oral maxillofacial surgery including ultrafast staining technique as well as morphometrical analysis of oral cancer are described.
Oral cytology may be feasible for the diagnosis of oral and maxillofacial lesions.

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The usefulness and problems associated with liquid based cytology in the cytodiagnosis of oral scratch were investigated with Thin Prep^®.The results indicated that problems with liquid-based cytology included the cost, time for making specimens, and storage conditions of the preservation solution. On the other hand, the benefits of this method were as follows:
1.Sufficient numbers of cells for observation can be obtained.
2.The quality is not reduced by drying or smearing procedures.
3.Although the oral mucosa bleeds easily, such bleeding does not result in unclear regions.
4. Observation is possible even in cases in which a cancerous background, such as necrotic tissue or cancer-related findings (such as Candida infection), is not resolved completely.
5. Deep-layer squamous cells can be collected relatively easily even for the exophytic type of tumors.
6. This method causes less cellular overlap and is useful for morphological and molecular biological analyses and immunohistochemical staining.
The observations discussed above indicate that liquid-based cytology is a highly useful system.

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Oral exfoliative cytology is a very effective screening method because of its small surgical damage, low cost, and repeatable exfoliation. About 8, 800 cases of oral cytological specimens have been experienced since 1988 in the Department of Oral Pathology, Nihon University School of Dentistry at Matsudo. All of the cytological specimens were analyzed statistically. The details and accuracy rate are reported here. The accuracy rate of malignancy (Class V ) was 93.5% and the method showed high suitability for assisting examination of oral cancer. Important factors of false-positive cases were Candida infection, whitish patch and ulcer formation, and that of false-negative cases was whitish protrusions identified macroscopically. We expect an increasing number of private dental clinicians will use oral exfoliative cytology for the examination of oral cancer. Observation of macroscopic findings as mentioned above and sufficient cell collection are key points.

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This study examined the role of histologic examination using fine needle biopsy (FNB) with the new Monopty biopsy instrument (MBI; Bard Urologic Division ; Covington, GA) and FINCORE (Dr. JAPAN Co., Ltd., Tokyo, Japan) in the diagnosis of head and neck lesions. We performed FNB in 87 lesions of the head with MBI or FINCORE and examined the surgically dissected tissue, including lymph nodes, salivary glands, facial skin, and oral tissue. The tissue samples were subjected to histologic examination using routine methods, and the diagnosis of the lesion determined at FNB was compared with the final diagnosis from the surgically dissected tissue. High-quality histologic specimens were obtained with MBI and FINCORE without using any special techniques. No complications such as abnormal hemorrhage or nerve destruction occurred in any case. The targeted lesion was biopsied by FNB in the 87 cases, and diagnoses could be compared with those of surgically resected lesions. The accuracy rate of FNB diagnosis was 81.6 % (of 71 cases) . This technique is a safe, effective means of obtaining adequate tissue for histologic assessment of head and neck lesions.

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The cell population in diseased tissue is remarkably diverse. Molecular analysis of cells is required in view of the cell diversity of diseases. This type of analysis can be called morphological genomics. As one of the analysis methods of morphological genomics, the cell is separated from the tissue section and observed under a microscope; the laser microdissection method is used to draw gene information from a few cells. RNA, DNA, or both and protein are extracted from the recovered cells, and genetic analysis can be carried out using micro arrays and other means. It is therefore possible to identify the peculiar gene and protein expression of cells in an individual lesion.
In this study, cells were recovered from a smear by using dot microdissection. As a result, high-quality RNA was extracted from the recovered cells. In the application of this method, the gene that regulates anticancer drug sensitivity was analyzed.

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Central giant cell granuloma is a localized osteolytic leion of variably aggressive nature that affects the jaws. We describe a case of central giant cell granuloma arising in the mandible.
The patient was a male in his 40s who had been aware of a painless swelling in the anterior portion of the mandible since May 2006, but left it untreated. Since the swelling increased gradually in size, he was referred to our department. On the initial examination, the oral mucosa was not affected, however, parchment swelling with tenderness was palpated in the left posterior portion of the mandible. No abnormal finding was noted in the cervical lymph node. No hypoesthesia was noted in the lower lip. X-ray CT detected an expansile, destructive, clear boundary multilocular lesion in the mandible. A thin shell of cortical bone was preserved around much of the lesion.
Based on the clinical diagnosis of odontogenic myxoma or ameloblastoma, biopsy was performed. In the biopsy specimen, no odontogenic epidermis was obtained in the connective tissue. In consideration of sampling error, ameloblastoma was suspected by the clinical findings. Tumorectomy was performed under general anesthesia. The surgical specimen had an elastic soft consistentcy, and the cut surface was solid, dull red, and showed granulomatous lesion.
Histopathological examination showed a large number of multinucleated giant cells in a highly vascular connective tissue. No cell atypia or mitotic figures were observed. The histopathological diagnosis was central giant cell granuloma.
There was no evidence of local recurrence in about 11 months after the operation.

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