Human papillomavirus (HPV) cannot be efficiently propagated in tissue cultures or animal models. However, molecular biological technology has made it possible to clone viral genomes, which can then be compared and also used as reagents in clinical and epidemiological studies. Today HPV infections are recognized as being responsible for inducing cancers worldwide and it is expected that HPV-based technologies will provide the tools to prevent and treat HPV-induced cancers. In this review, we focus on the association between oral lesions and HPV infection and the natural history of HPV infection of the oral cavity. We also evaluate the HPV detection methods in this important and fundamental matter for the HPV studies. We then discuss the potential targeted molecular therapies and prevention of a variety of HPVinduced diseases of the oral cavity, including oral cancers.

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This article attempts to clarify the nature of the so-called hybrid odontogenic tumors including pure epithelial tumors with dentinoid induction which caused dilemma in histologic diagnosis. Most of them do not appear in the standard World Health Organization (WHO) classification of odontogenic tumors. The limitations in our current understanding of hybrid tumors principally depend on the fact that they occur sporadically and are rare. In our view, with the few exceptions, these ambiguous tumors should not generally be considered true hybrids; rather they should be identified simply as anomalous histodifferention and/ or morphodifferentiation process. To date, there is no evidence to suggest that such a unique combination has any bearing on the logical WHO classification. Recognition of hybrid odontogenic tumors is probably of academic and research interest only for oral pathologists.

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A total of 21 cases of secondary syphilis presenting mostly as painless oral lesions in ethnic Chinese are reported. All the patients were first diagnosed on presentation with oral lesions. Three cases were initially misdiagnosed as oral candidosis but confirmed as syphilitic infection after biopsy and serology. The most common site of the lesion was the tongue. The significance of oral manifestations of syphilis and the dentist's role in the early diagnosis of syphilis is discussed.

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The immunohistochemical expressions of FGF2, FGFR1, FGFR2, and their possible participation in the apoptosis of myofibroblast were studied in the healing process of a muscle flap transferred into the oral cavity of rats. At 14 days postoperatively, abundant myofibroblasts were observed in the early-granulating muscle flap, and at 18 days postoperatively, they began to gradually disappear. The FGF2 immunopositive area, the number of FGFR2-positive fibroblasts and TUNEL-positive fibroblasts reached a maximum at 18 days postoperatively and gradually decreased thereafter, and there was a significant correlation of expression between the FGFR2-positive fibroblast and TUNEL-positive fibroblast. On the other hand, FGFR1-positive fibroblasts were observed from day 10 to 21 in the granulation tissue formation of the muscle flap. These findings suggest that FGFR1 may participate as a factor affecting tissue remodeling of muscle flap healing, and that FGFR2 may play a role in programmed cell death or apoptosis of myofibroblast.

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The present study utilizing histozymography was undertaken to localize gelatinolytic activities in the epithelium and mesenchyme of embryonic mouse secondary palate. At the stages of vertical position through elevation, the mesenchyme of the palatal shelves exhibited relatively strong gelatinolytic activities, whereas the epithelia covering the palatal shelves did not show distinctive gelatinolytic activities. The location of gelatinolytic activities in the mesenchyme changed markedly after the palatal shelves started reorientation. Modest to strong enzymatic activities were first elicited in the medial edge epithelium (MEE), when the bilateral palatal processes confronted each other prior to their contact. RT-PCR analysis also confirmed the mRNA expression of MMP-2, MMP-9, MT1-MMP, and TIMP-1 in the palatal shelves at the corresponding developmental stages. The results obtained support the view that the spatiotemporal regulation of gelatinolytic activities is a key factor to reorganization of the epithelial and mesenchymal components during embryonic palate morphogenesis.

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The aim of this study was to assess the healing response to the bone implants treated by heating or freezing. Allogenic calvarial implants treated by heating at 65°C for 1 hour, 3 freezes of 3 minutes, or boiling for 10 minutes (65°C, frozen and boiled group respectively) were tested for the potential to fill cranial bone defects of rabbits. Both the 65°C and frozen groups similarly showed more than 60% of new bone formation in terms of the untreated control. Among the three treatment modalities, boiling presented the most remarkable impairment on the reparative capacity of the implants. The autogenous bone segments reimplanted to their original mandibular sites after treatment by heating at 65°C using microwave or by freezing were revealed to similarly incorporate to the host bone in dog experiments. In summary, heat treatment at 65°C for 1 hour is comparable with freeze treatment in terms of preservation of the regenerative potential of bone for simultaneous reimplantation.

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A case of calcifying odontogenic cyst associated with complex and compound odontoma which appeared in the maxilla of a 15-year-o1d Japanese girl was reported with immunohistological examination. Radiologically, the lesion showed a cystic radiolucent area with odontoma-like radiopaque masses. Histopathological examination revealed the presence of ghost cells, calcified tissues and structures of complex and compound odontoma. Immunohistochemically, MIB-1 positive ratio was very low, but significant expression of Bcl-2 was observed in the neoplastic odontogenic epithelium. These results suggest that inhibition of apoptotic cell loss is more important than cell proliferation activity to the growth of the lesion in our case.

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