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Oral lichen planus (OLP) is classified into 3 major types: plaque (PLA), reticular (RET), and atrophic (ATR). This study was designed to examine the clinical and histopathological characteristics of these three types of OLP in the buccal mucosa. A total of 375 specimens of OLP (20 PLA, 20 RET, and 20 ATR) and normal buccal mucosal (NBM) were examined histopathologically. Epithelial thickness was less in ART and RET than in NBM. Epithelial thickness in RET was greater than in ATR. Mean numbers of PCNA-positive cells and CD1a-positive cells in the covering epithelium were higher in RET and PLA than in ATR and NBM. PLA, RET, and ATR types of OLP have different histopathological characteristics. Differences among these types might reflect distinct stages of disease.

Objective: This study evaluated the effects of enamel matrix derivative, a material recently used for the treatment of periodontal disease, on the healing of subepithelial atelocollagen grafts. Patients and Methods: Fourteen male Wistar rats were used. A silicone container with 4 pillarshaped holes was implanted beneath the back skin. The 4 holes were respectively filled with atelocollagen, enamel matrix derivative, a mixture of atelocollagen and enamel matrix derivative, and saline as control. The materials were evaluated histologically and immunohistochemically, and the number of capillaries immunostained with anti-alpha-smooth muscle actin or anti-vascular endothelial growth factor antibodies were determined at l, 2, and 4 weeks. Results: The whole amounts of remaining materials and newly formed tissue in the atelocollagen and the atelocollagen and enamel matrix derivative groups were larger than those in the control and enamel matrix derivative groups at each week studied. The mean number of alpha-smooth muscle actin positive vessels was greater than the mean number of vascular endothelial growth factor antibody positive vessels. The mean numbers of both alpha-smooth muscle actin-positive vessels and vascular endothelial growth factor antibody-positive vessels in the enamel matrix derivative group and the atelocollagen and enamel matrix derivative group were greater than those in the atelocollagen group at each week studied. Conclusion: Atelocollagen might contribute to maintaining the volume of implanted materials, while enamel matrix derivative might promote the formation of capillaries and enhance the healing of atelocollagen grafts.

Objective: To evaluate roles of the Akt signaling pathway in oncogenesis and cytodifferentiation of odontogenic tumors, expression of phosphorylated Akt (pAkt), PI3K, and PTEN was analyzed in ameloblastic tumors as well as in tooth germs. Methods: 11 tooth germs, 40 ameloblastomas, and 5 malignant ameloblastic tumors were examined immunohistochemically with antibodies against pAkt, PI3K, and PTEN. Results: Immunoreactivity for pAkt, PI3K, and PTEN was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and ameloblastic tumors. The levels of immunoreactivity for pAkt and PI3K were slightly higher in ameloblastic tumors than in tooth germs. Plexiform ameloblastomas showed significantly higher expression of PI3K than follicular ameloblastomas, and PI3K immunoreactivity in ameloblastomas without cellular variation was significantly higher than that in acanthomatous ameloblastomas. The level of PTEN immunoreactivity was significantly lower in ameloblastomas than in tooth germs. Conclusion: Expression of pAkt, PI3K, and PTEN in tooth germs and ameloblastic tumors suggests that these signaling molecules regulate cell survival and growth in normal and neoplastic odontogenic tissues by mediating growth factor signals. Increased expression of pAkt and PI3K and decreased expression of PTEN in ameloblastic tumors may participate in oncogenesis of odontogenic epithelium by activating the Akt signaling pathway.

BACKGROUND: To evaluate roles of mitogen-activated protein kinases (MAPKs) in oncogenesis and cytodifferentiation of odontogenic tumors, expression of phosphorylated JNK (p-JNK), p38 MAPK (p-p38 MAPK), and ERK5 (p-ERK5) was analyzed in ameloblastic tumors as well as in tooth germs. METHODS: Ten tooth germs, 47 ameloblastomas, and 5 malignant ameloblastic tumors were examined immunohistochemically with the antibodies against p-JNK, p-p38 MAPK, and p-ERK5. RESULTS: Immunoreactivity for p-JNK was detected in epithelial or neoplastic cells detached from the basement membrane in 7 tooth germs and 7 ameloblastomas, and the expression levels of p-JNK in ameloblastic tumors were significantly lower than that in tooth germs. Expression of p-p38 MAPK was found in epithelial or neoplastic cells in tooth germs and ameloblastic tumors except for two ameloblastomas, and increased expression was found in keratinizing cells of acanthomatous ameloblastomas. The expression level of p-p38 MAPK in ameloblastomas was significantly higher than the levels in tooth germs and malignant ameloblastic tumors. Immunoreactivity for p-ERK5 was found predominantly in epithelial or neoplastic cells near the basement membrane in tooth germs and ameloblastic tumors. The expression levels of p-ERK5 in ameloblastic tumors were slightly higher than that in tooth germs, and plexiform ameloblastomas showed significantly higher p-ERK5 expression than follicular ameloblastomas. CONCLUSION: Expression of p-JNK, p-p38 MAPK, and p-ERK5 in tooth germs and ameloblastic tumors suggests that these MAPK signaling pathways contribute to cell proliferation, differentiation, or apoptosis in both normal and neoplastic odontogenic tissues. Altered expression of these phosphorylated MAPKs in ameloblastic tumors may be involved in oncogenesis and tumor cell differentiation.

BACKGROUND: To evaluate the roles of extracellular matrix (ECM)-degrading serine proteinase in progression of odontogenic tumors, expression of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), plasminogen activator inhibitor-1 (PAI-1), and maspin was analyzed in ameloblastic tumors as well as in tooth germs. METHODS: Tissue specimens of 10 tooth germs, 45 ameloblastomas, and 5 malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against uPA, uPAR, PAI-1, and maspin. RESULTS: Immunohistochemical reactivity for uPA, uPAR, PAI-1, and maspin was detected in normal and neoplastic odontogenic tissues: uPA was recognized predominantly in mesenchymal cells, uPAR was evident in epithelial cells, PAI-1 was found in both epithelial and mesenchymal cells, and maspin was expressed only in epithelial cells. The levels of uPA and uPAR immunoreactivity in ameloblastic tumors were slightly higher than the levels in tooth germs, while PAI-1 reactivity in ameloblastomas tended to be lower than that in tooth germs. The level of maspin immunoreactivity in ameloblastomas was significantly higher than that in tooth germs, and ameloblastic carcinoma showed decreased maspin reactivity. CONCLUSION: Expression of uPA, uPAR, PAI-1, and maspin in tooth germs and ameloblastic tumors suggests that interactions among these molecules contribute to ECM degradation and cell migration during tooth development and tumor progression. Altered expression of the serine proteinase and its associated molecules in ameloblastic tumors may be involved in oncogenesis of odontogenic epithelium.

Background: To evaluate the roles of growth factors in oncogenesis and cytodifferentiation of odontogenic tumors, expression of insulin-like growth factors (IGFs), platelet-derived growth factor (PDGF), and their receptors was analyzed in ameloblastic tumors as well as in tooth germs. Methods: Tissue specimens of 10 tooth germs, 47 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against IGF-I, IGF-II, IGF-I receptor (IGF-IR), PDGF A-chain, PDGF B-chain, PDGF α-receptor, and PDGF β-receptor. Results: Immunohistochemical reactivity for IGFs, PDGF chains, and their receptors was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. The expression levels of IGF-II and PDGF chains were significantly higher in ameloblastic tumors than in tooth germs. Malignant ameloblastic tumors showed higher reactivity for PDGF chains than benign ameloblastomas and higher reactivity for platelet-derived growth factor receptors than tooth germs. The expression levels of PDGF chains were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. Desmoplastic ameloblastomas showed higher expression of IGFs and IGF-IR when compared with other ameloblastoma subtypes. Conclusion: Expression of IGFs, PDGF, and their receptors in tooth germs and ameloblastic tumors suggests that these growth factor signals contribute to cell proliferation or survival in both normal and neoplastic odontogenic tissues. Expression of these molecules in odontogenic tissues possibly affects interactions with the bone microenvironment during tooth development and intraosseous progression of ameloblastic tumors. Altered expression of the ligands and receptors in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation.

Background: To clarify the roles of cell cycle regulation in oncogenesis and cytodifferentiation of odontogenic tumors, expression of retinoblastoma protein (RB) and E2 promoter-binding factor-1 (E2F-1) was analyzed in ameloblastomas as well as in tooth germs. Methods: Tissue specimens of 10 tooth germs, 40 benign ameloblastomas, and five malignant ameloblastomas were examined immunohistochemically with the use of antibodies against RB, E2F-1, and phosphorylated RB. Ki-67 antigen immunostaining was made as a marker of cell proliferation. Results: Immunohistochemical reactivity for RB, E2F-1, phosphorylated RB, and Ki-67 was detected in the nuclei of odontogenic epithelial cells near the basement membrane in tooth germs and benign and malignant ameloblastomas. The number of cells positive for phosphorylated RB was nearly equal to or slightly less than the number of cells positive for RB or E2F-1. The number of Ki-67-positive cells was slightly more than the numbers of cell positive for RB, E2F-1, or phosphorylated RB. The levels of immunoreactivity for RB, E2F-1, phosphorylated RB, and Ki-67 were slightly higher in benign and malignant ameloblastomas than in tooth germs. Plexiform ameloblastomas showed significantly higher expression of RB than follicular ameloblastomas. Ki-67 immunoreactivity was significantly higher in ameloblastic carcinomas than in metastasizing ameloblastomas. Conclusion: Similar immunoreactivity for RB, E2F-1, phosphorylated RB, and Ki-67 in tooth germs and ameloblastomas indicated cellular expression of phosphorylated RB and active-free E2F-1 in both normal and neoplastic odontogenic tissues. Expression of RB, E2F-1, and phosphorylated RB was considered to be involved in cell proliferation and differentiation of odontogenic epithelium via control of the cell cycle.

This study investigated the differences of weight distribution on the sole of the feet in the primary and the early permanent dentition by the modifying Morton staticometer. The distribution of body weight in the outer forward part on soles of feet in the permanent dentition group was significantly greater than that in the primary dentition group. The distribution of body weight in the heel on soles of feet in the permanent dentition group was significantly smaller than that in the primary dentition group. These results indicated that the weight was shifted from the heels to the forefeet from primary to permanent dentition

Background To clarify the role of p53 homologs in oncogenesis and cytodifferentiation of odontogenic tumors, expression of p63 and p73 was analyzed in ameloblastomas as well as tooth germs. Methods Tissue specimens of nine tooth germs and 48 benign and five malignant ameloblastomas were examined by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) for the expression of p63 and p73. Results Immunoreactivity for p63 and p73 was evident in epithelial cells neighboring the basement membrane in developing and neoplastic odontogenic tissues. p63 expression in desmoplastic ameloblastomas was significantly higher than in acanthomatous and granular cell ameloblastomas, and ameloblastic carcinomas showed higher p63 expression than metastasizing ameloblastomas. p73 expression was significantly higher in plexiform ameloblastomas than in follicular ameloblastomas, and basal cell ameloblastomas showed higher p73 expression than granular cell ameloblastomas. mRNA transcripts for Delta Np63 and TAp73 were detected in all developing and neoplastic odontogenic tissues. TAp63 mRNA was expressed in five of eight tooth germs, 16 of 34 ameloblastomas, and one of one malignant ameloblastoma, whereas Delta Np73 mRNA was recognized in one of eight tooth germs, nine of 34 ameloblastomas, and one of one malignant ameloblastoma. Conclusion The expression of p63 and p73 suggests that these p53 homologs play a role in differentiation and proliferation of odontogenic epithelial cells. Variations of predominantly expressed isoforms suggest that p63 and p73 might differentially function in odontogenic tissues.

This experimental study evaluated the effects of deproteinized bone grafts on guided bone regeneration (GBR). A groove was made in the bone marrow of the external cortical plate of the skull. A dome of non-resorbable membrane was placed on the groove and secured with titanium pins. The secluded graft space was filled with autogenous blood clots (control group) and deproteinized bone particles (experimental group). The rabbits were sacrified 2, 4, 8 and 12 weeks after the operation. Decalcified and paraffin-embedded, transverse 3-μm-thick sections were made and stained with hematoxylin and eosin. The proportions of newly formed bone and newly formed bone-graft particle contact surfaces were histomorphometrically measured in the basal, central, and peripheral areas from the cortical plate to the top of the dome. In the control group, the basal area showed a significant increase at 4 weeks (P

The Patched (PTC) gene is responsible for basal cell nevus syndrome (BCNS) accompanied by multiple odontogenic keratocysts (OKCs), and its product plays a role in the Sonic hedgehog (SHH) signaling pathway involving smoothened (SMO) and GLI-1. To clarify the role of SHH signaling in OKCs, the expression of SHH, PTC, SMO, and GLI-1 and mutations of PTC were examined in 18 sporadic, 4 BCNS-associated OKCs and 7 control gingivae. SHH, PTC, SMO, and GLI-1 were detected in all OKC and gingiva samples by reverse transcriptase-polymerase chain reaction (RT-PCR). Immunoreactivity for SHH and GLI-1 was markedly higher in epithelial components than in subepithelial cells, while immunoreactivity for PTC and SMO was similar in epithelial components and subepithelial cells in OKCs. The positive rate of PTC and SMO expression in subepithelial cells of OKCs was significantly higher than that in gingivae. The positive rate of GLI-1 expression in subepithelial cells of BCNS-associated OKCs was significantly higher than that in primary OKCs. These results suggest that the SHH signaling might be involved in the pathophysiologic nature of OKCs. While mutations of the PTC gene could not be detected in 4 BCNS-associated OKCs by direct DNA sequencing, 3 of 5 primary and 4 of 4 recurrent OKCs had several mutations of this gene. These results suggest that PTC mutations are probably related not only to BCNS-associated OKCs but also to sporadic OKCs.

Background: To clarify the roles of rat sarcoma (Ras)/mitogen-activated protein kinase (MAPK) signaling pathway in oncogenesis and cytodifferentiation of odontogenic tumors, K-Ras gene status and expression of Ras, Raf1, MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK)1, and ERK1/2 proteins were analyzed in ameloblastomas as well as in tooth germs. Methods: Paraffin sections of 10 tooth germs and 46 benign and 6 malignant ameloblastomas were examined immunohistochemically for the expression of K-Ras, Raf1, MEK1, and ERK1/2. Frozen tissue samples of 22 benign ameloblastomas and 1 malignant (metastasizing) ameloblastoma were analyzed by direct DNA sequencing to detect K-Ras gene alteration. Results: Immunohistochemical reactivity for K-Ras, Raf1, MEK1, and ERK1/2 was detected in both normal and neoplastic odontogenic epithelium, and these molecules were reactive chiefly with odontogenic epithelial cells neighboring the basement membrane. Plexiform ameloblastomas showed slightly stronger expression of these Ras/MAPK signaling molecules than follicular ameloblastomas. Keratinizing cells and granular cells showed decreased reactivity for the signaling molecules. Basal cell ameloblastomas showed slightly stronger reactivity for the signaling molecules than did the other subtypes. K-Ras immunoreactivity in malignant ameloblastomas was lower than that in dental lamina of tooth germs. Direct DNA sequencing showed a GGT to GCT point mutation at codon 12 of K-Ras gene in one ameloblastoma. Conclusion: Expression of K-Ras, Raf1, MEK1, and ERK1/2 in tooth germs and ameloblastomas suggests that Ras/MAPK signaling pathway functions to regulate cell proliferation and differentiation in both normal and neoplastic odontogenic epithelium. K-Ras gene status implied that K-Ras mutations might play a minor role in oncogenesis of odontogenic epithelium.

This study was designed to evaluate the effects of cortical bone perforation histologically and histomorphometrically on guided bone regeneration (GBR) in rabbits. After elimination of the periosteum, cortical bone defects of two sizes were made in the external cortical plate of the frontal bone (Group A: 1 x 15 mm; Group B: 3 x 15 mm). A non-resorbable membrane filled with autogenous blood was placed in the experimental area and secured with titanium pins. After 1 and 2 weeks, vascularized connective tissue and new bone were generated in the space surrounding the defects in both the groups. The amount of vascularized connective tissue generated in Group B was greater than that in Group A at 1 week. Alkaline phosphatase (ALP) was expressed on the bone surrounding the perforation. The expression of ALP was more extensive in Group B than in Group A and was proportional to the breadth of perforation. At 2 weeks, the perforated region was almost covered with new bone in Group A. ALP was expressed at the periphery of newly formed bone. The expression of ALP was proportional to the breadth and height of perforation. At 6 weeks, semicircular outgrowth of bone towards the periphery of the perforated region was observed in both the groups. Newly formed bone volume and ALP expression in Group B were more extensive than those in Group A. At 12 weeks, the space was filled with bone and connective tissue in both the groups. There was no difference in ALP expression between Groups A and B. Histomorphometric analysis showed significant differences between both the groups (two-way ANOVA, P

The aim of the present study was to assess long-term changes in sinus-graft height after maxillary sinus floor augmentation and simultaneous placement of implants. A total of 191 patients who underwent maxillary sinus floor augmentation were radiographically followed for up to about 10 years. A 2 : 1 mixture of autogenous bone and bovine xenograft (Bio-Oss) was used as the graft material. Sinus-graft height was measured using 294 panoramic images immediately after augmentation and up to 108 months subsequently. Changes in sinus-graft height were calculated with respect to implant length and original sinus height. Patients were divided into three groups based on the height of the grafted sinus floor relative to the implant apex: Group I, in which the grafted sinus floor was above the implant apex; Group II, in which the implant apex was level with the grafted sinus floor; and Group III, in which the grafted sinus floor was below the implant apex. After augmentation, the grafted sinus floor was consistently located above the implant apex. After 2-3 years, the grafted sinus floor was level with or slightly below the implant apex. This relationship was maintained over the long term. Sinus-graft height decreased significantly and approached original sinus height. The proportion of patients classified as belonging to Group III reached a maximum from year 3 onwards. The clinical survival rate of implants was 94.2%. All implant losses occurred within 3 years after augmentation. We conclude that progressive sinus pneumatization occurs after augmentation with a 2 : 1 autogenous bone/xenograft mixture, and long-term stability of sinus-graft height represents an important factor for implant success.

Background: To clarify the roles of Sonic hedgehog (SHH) signal transduction in oncogenesis and cytodifferentiation of odontogenic tumors, expression of SHH, Patched (PTC), Smoothened (SMO), and GLI1 was analyzed in ameloblastomas as well as in tooth germs. Methods: Tissue specimens of 9 tooth germs, 36 benign ameloblastomas, and 1 malignant ameloblastoma were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry for the expression of SHH, PTC, SMO, and GLI1. Results: Expression of SHH, PTC, SMO, and GLI1 mRNA was detected in all tooth germ and ameloblastoma samples. Immunohistochemical reactivity for SHH, PTC, SMO, and GLI1 was detected in both normal and neoplastic odontogenic tissues. Expression of SHH, PTC, and GLI1 was more evident in epithelial cells than in mesenchymal cells, whereas SMO reactivity was marked in both epithelial and mesenchymal components in tooth germs and ameloblastomas. In ameloblastomas, these SHH signaling molecules were expressed more intensely in peripheral columnar or cuboidal cells than in central polyhedral cells; keratinizing cells and granular cells showed no or little reactivity. Conclusion: Expression of SHH, PTC, SMO, and GLI1 in tooth germs and ameloblastomas suggests that these SHH signaling molecules might play a role in epithelial–mesenchymal interactions and cell proliferation in tooth development as well as in growth of these epithelial odontogenic tumors.

Objectives To evaluate the value of deproteinized bone particles on bone resorption in the augmented space after maxillary sinus floor elevation in rabbits. Material and methods A total of 20 rabbits underwent bilateral grafting, using blood clots (control group) and deproteinized bone particles (experimental group), and followed with histologic and histomorphometric analysis. Results Two weeks after grafting, the augmented space was almost completely obliterated by both newly formed bone and fibrous connective tissue in the control group. Some osteoclasts were found on the surface of newly formed bone, especially near the elevated sinus membrane. In the experimental group, newly formed bone was found along the elevated sinus membrane, the cortical wall of the augmented space, and the surface of deproteinized bone particles near the cortical wall. Some osteoclasts were found along the deproteinized bone particles and a few adhered to the surface of the newly formed bone. Eight to 10 weeks after implantation in the control group, most of the newly formed bone had been resorbed. In the experimental group, newly formed bone was found in most parts of the convex augmented space. Histomorphometrical analysis showed that the augmented height was significantly higher in the experimental group than in the control group at all evaluation times. Bone area was significantly higher in the experimental group than in the control group at 6, 8, and 10 weeks after implantation. The area of grafted deproteinized bone particles did not change significantly from 2 to 10 weeks. Conclusion Slowly resorbed deproteinized bone particles contribute to stable augmentation of the maxillary sinus floor by inhibiting bone resorption.

A rare case of benign cementoblastoma involving multiple deciduous and permanent teeth is presented with a review of the literature. A 12-year-old boy was admitted for a swelling in the right maxillary premolar-molar region. A radiologic examination revealed a well-defined, round, radiopaque mass extending from the right maxillary first premolar to the second permanent molar. The tumor was removed with all associated teeth. A histologic examination of the surgical specimen revealed a well-circumscribed tumor composed of cementum-like tissue surrounded by a fibrous capsule. The tumor was attached to the roots of the second deciduous molar, first premolar, and the first and second permanent molars and embedded in the crown and root of the right maxillary second premolar, suggesting that the lesion had arisen from the second deciduous molar. There has been no recurrence of the lesion more than 18 months after the surgical procedure.

Background: To clarify the roles of osteoclast regulatory factors in progression of odontogenic tumors, expression of parathyroid hormone-related protein (PTHrP), osteoclast differentiation factor (ODF)/receptor activator of nuclear factor-κB ligand (RANKL), and osteoclastogenesis inhibitory factor (OCIF)/osteoprotegerin (OPG) were analyzed in ameloblastomas as well as tooth germs. Methods: Tissue specimens of nine tooth germs and 36 benign and one malignant ameloblastomas were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry for the expression of PTHrP, ODF/RANKL, and OCIF/OPG. Results: Expression of PTHrP, ODF/RANKL, and OCIF/OPG mRNA was detected in all tooth germ and ameloblastoma samples. Immunohistochemical reactivity for PTHrP was recognized in both normal and neoplastic odontogenic epithelial cells. In ameloblastomas, PTHrP reactivity in peripheral columnar or cuboidal cells was stronger than that in central polyhedral cells, and keratinizing cells showed increased PTHrP reactivity. ODF/RANKL and OCIF/OPG were expressed predominantly in mesenchymal cells rather than in odontogenic epithelial cells in both tooth germs and ameloblastomas. Epithelial ODF/RANKL and OCIF/OPG expression was slightly lower in ameloblastomas than in tooth germs. Tumor cells in plexiform ameloblastomas showed slightly higher reactivity for PTHrP and ODF/RANKL than tumor cells in follicular ameloblastomas. Conclusion: Expression of PTHrP, ODF/RANKL and OCIF/OPG in tooth germs and ameloblastomas suggests that these factors might locally regulate bone metabolism and dynamics in tooth development as well as in progression of ameloblastomas. These factors might also be involved in tumor cell differentiation and/or tumor tissue structuring in ameloblastomas.

This study compared the osteoconductive capability of deproteinized bone particles of two different sizes (300-500 and 850-1000 microm) in rabbits undergoing maxillary sinus lift. Histologically, deproteinized bone particles of both sizes induced osteoconduction 1 week after implantation. Bone initially formed at the sinus wall and proliferated into the center of the augmented sinus cavity. In the small-particle group, newly formed bone showed many interconnections and appeared in most areas of the cavity 8 weeks after implantation. In the large-particle group, newly formed bone showed limited intercommunications, and the center of the sinus cavity contained fibrous connective tissue with no evidence of ossification 8 weeks after implantation. Histomorphometric analysis revealed a significantly higher density of newly formed bone in the small-particle group than in the large-particle group both 4 and 8 weeks after implantation. The total newly formed bone-particle contact length was also significantly higher in the small-particle group. The total surface length of the small particles was larger than that of the large particles, but the ratio of the newly formed bone-particle contact length to the total particle surface length did not differ significantly between the groups at any time. The interparticular spaces of the small particles were larger than those of the large particles. The bone area ratio in the interparticular spaces of the small particles was significantly higher than that of the large particles both 4 and 8 weeks after implantation. We conclude that graft bone particle size and interparticular space are important determinants of osteoconduction.

This paper reports a rare case of sebaceous adenoma on the right mandibular retromolar mucosa in a 73-year-old Japanese man, with a review of the English literature of sebaceous adenomas of salivary gland origin. A painless and yellowish polypoid lesion in the retromolar mucosa was histologically a relatively well-circumscribed neoplastic mass composed of well-differentiated sebaceous cells with cystic and duct-like structures, and was considered to be a true sebaceous gland neoplasm arising from the minor salivary gland tissue.

Background: Alterations of human patched (ptc) homolog have been proven to be responsible for basal cell nevus syndrome (BCNS). Mandibular cysts in heterozygous ptc knockout mouse (ptc+/− mouse) were microradiologically, histologically, immunohistochemically, and genetically examined to investigate the possible role of the ptc gene and its associates in the jaw cysts. Methods: The mandibular bones were prepared from 63 ptc+/− mice and 6 ptc+/+ mice. Soft X-ray radiographs and histological sections were examined for detection of the presence of mandibular cysts. The mandibular cysts were immunohistochemically investigated using anti-ptc, shh, and smo antibodies. PCR analysis of loss of heterozygosity (LOH) of ptc was performed in genomic DNA from the mandibular cysts. Results: Six ptc+/+ mice showed no pathologic change in any examinations. Microradiologically, ptc+/− mice did not show any apparent lesion. Mandibular cysts were often multiple, and were histologically detected in the alveolar bones or periodontal ligaments of the molars in 16 (25.4%) ptc+/− mice. The mandibular cysts were lined by thin parakeratotic stratified squamous epithelium and contained keratinized materials. Immunohistochemical examination showed sonic hedgehog (shh) protein mainly in cyst lining epithelium, and ptc and smoothened (smo) proteins in cyst lining epithelium, and surrounding fibrous connective tissue. Expression of ptc protein in the cyst lining epithelium tended to be weak as compared with incisor enamel organs and gingival stratified squamous epithelium. LOH of the ptc gene couldn't be found in lining epithelium of mandibular cysts in any ptc+/− mice. Conclusions: Ptc+/− mouse is a useful model of BCNS from the standpoint of occurrence of jaw cysts, and downregulation of ptc protein in cyst lining epithelium caused by gene targeting would be associated with formation of jaw cysts in ptc+/− mice.

To clarify the possible role of tumor angiogenesis, vascular endothelial growth factor (VEGF) and microvessel density (MVD) were immunohistochemically examined in tongue squamous cell carcinomas as well as in normal tongue mucosa and squamous cell carcinoma-adjacent tongue mucosa. Immunoreactivity for VEGF was detected in epithelial cells of several nonneoplastic tongue mucosa tissues and most tongue squamous cell carcinomas, indicating that this angiogenic factor acted on endothelial cells via the paracrine mechanism. VEGF expression in squamous cell carcinoma-adjacent tongue mucosa was greater than that in normal tongue mucosa, and VEGF expression in tongue squamous cell carcinomas was much higher than in squamous cell carcinoma-adjacent tongue mucosa and normal tongue mucosa. Up-regulation of VEGF might be associated with neoplastic or malignant change of epithelial cells in tongue mucosal tissues. MVD in tongue squamous cell carcinoma was higher than that of squamous cell carcinoma-adjacent tongue mucosa and normal tongue mucosa, indicating increased demands for blood supply in the carcinoma tissues. The association of VEGF expression, MVD and clinicopathological parameters of tongue squamous cell carcinomas was not statistically obvious; however, VEGF expression was slightly larger according to T stages or nodal metastasis.

Benign mixed and mesenchymal odontogenic tumors (ameloblastic fibroma, ameloblastic fibrodentinoma, ameloblastic fibro-odontomas, odontogenic fibroma and odontogenic myxoma) were immunohistochemically examined using antibodies against amelogenin, cytokeratin 19, bcl-2, hepatocyte growth factor (HGF), c-Met, transforming growth factor-β (TGF-β), TGF-β receptors and Ki-67 to know cytodifferentiation, epithelial-mesenchymal interaction and proliferative activity. Expression of amelogenin was detected in odontogenic epithelial cells and enamel matrices in ameloblastic fibro-odontomas, and cytokeratin 19 was expressed in odontogenic epithelial cells, indicating odontogenic epithelial properties. Expressions of bcl- 2, HGF, TGF-β, TβR I and TβR II were detected in odontogenic epithelial and mesenchymal cells in mixed and mesenchymal odontogenic tumors, while expression of c-Met was detected in odontogenic epithelial cells. Odontogenic epithelial and mesenchymal cells sporadically showed positive reactions for Ki-67 in mixed and mesenchymal odontogenic tumors, and no apparent differences were obtained among these tumors or between the components. Conclusion: Immunohistochemical localization of HGF, TGF-β and their receptors suggests that these growth factor signaling are effective in the epithelial component in paracrine and autocrine manner in mixed and mesenchymal odontogenic tumors. These results of growth factor signaling suggest that certain epithelial-mesenchymal interactions are related to neoplastic cell growth in these tumors.

Background: To clarify the possible role of nitric oxide (NO) and stress proteins in oncogenesis and cytodifferentiation of odontogenic epithelium. Inducible NO synthase (iNOS) and heat shock proteins (HSPs) were analyzed in ameloblastomas as well as in tooth germs. Methods: Specimens of seven tooth germs, 36 benign ameloblastomas and five malignant ameloblastomas were examined by immunohistochemistry using antibodies against iNOS and 27-, 60- and 70-kDa HSPs (HSP27, HSP60 and HSP70). Results: Immunoreactivity for iNOS was detected in normal and neoplastic odontogenic epithelial cells and was higher in malignant ameloblastomas than in tooth germs and benign ameloblastomas. HSP27 was expressed constitutively in all odontogenic epithelial cells in tooth germs and benign and malignant ameloblastomas. Expression of HSP60 and HSP70 was detected in normal and neoplastic odontogenic epithelial cells and was prominent in cells neighboring the basement membrane. HSP60 reactivity showed no apparent difference between normal and neoplastic odontogenic epithelium, whereas HSP70 expression was slightly higher in benign and malignant ameloblastomas than in tooth germs. Conclusions: Activation of iNOS might be associated with malignant potential of epithelial odontogenic tumors. Elevated expression of HSP70 is considered to be involved in neoplastic transformation of odontogenic epithelial cells.

Background Tumors derived from odontogenic epithelium exhibit considerable variation and are classified into several benign and malignant entities. To clarify the role of growth factors in oncogenesis, cytodifferentiation and progression of epithelial odontogenic tumors, expression of hepatocyte growth factor (HGF), transforming growth factor-beta (TGF-beta) and their receptors were analyzed in these tumors as well as in tooth germs. Methods Specimens of five tooth germs, 34 ameloblastomas, three calcifying epithelial odontogenic tumors (CEOTs), two clear cell odontogenic tumors (CCOTs), five adenomatoid odontogenic tumors (AOTs), six calcifying odontogenic cysts (COCs) and six malignant ameloblastomas were examined immunohistochemically with the use of antibodies against HGF, TGF-beta and their receptors. Results In tooth germs and epithelial odontogenic tumors, immunoreactivity for HGF and TGF-beta was detected in both epithelial and mesenchymal cells, while expression of their receptors was found only in epithelial cells. In tooth germs and main types of ameloblastomas, HGF and TGF-beta reactivity was marked in epithelial cells near the basement membrane, and their receptors were diffusely positive in most epithelial cells. In subtypes of ameloblastomas, reduced expression of HGF, c-Met and TGF-beta and increased reactivity for TGF-beta receptors were detected in keratinizing cells in acanthomatous ameloblastomas, and granular cells in granular cell ameloblastomas demonstrated little or no expression of HGF, TGF-beta or their receptors. As compared with main types of ameloblastomas, basal cell ameloblastomas showed high HGF reactivity, and desmoplastic ameloblastomas exhibited elevated reactivity for TGF-beta and its receptors. Neoplastic cells in CEOTs, AOTs and COCs showed reactivity for HGF, TGF-beta and their receptors. Elevated HGF and TGF-beta reactivity was found in pseudoglandular cells in AOTs, and high expression of their receptors was noted in ghost cells in COCs. Metastasizing ameloblastomas showed similar expression patterns of HGF, TGF-beta and their receptors to those of benign ameloblastomas, while CCOTs and ameloblastic carcinomas had increased HGF expression and low reactivity for TGF-beta and its receptors as compared with benign ameloblastomas. Conclusions Immunohistochemical localization of HGF, TGF-beta and their receptors in tooth germs and epithelial odontogenic tumors supports the hypothesis that HGF and TGF-beta act on epithelial cells via paracrine and autocrine mechanisms. Altered expression of the agents in these epithelial odontogenic tumors, especially subtypes of ameloblastomas, AOTs and COCs, suggests that HGF and TGF-beta signaling might affect differentiation of neoplastic odontogenic epithelial cells. Activated HGF/c-Met pathway and reduced TGF-beta signaling in CCOTs and ameloblastic carcinomas may be associated with the malignant potential of these epithelial odontogenic tumors.

OBJECTIVE: Histopathological and lectin-histochemical characteristics were studied in the lining epithelium of postoperative maxillary cysts (POMC). MATERIALS AND METHODS: Histological (HE, PAS, AB), immunohistochemical (CD3 and L26) and lectin (wheat germ agglutinin, WGA; Ulex europaeus agglutinin I, UEA-I; concanavalin A, ConA) stainings were performed in the 360 POMC specimens. The number of goblet cells and inflammatory cells was counted and statistically analyzed. RESULTS: The lining epithelium was classified into three types based on histopathological characteristics; pseudostratified ciliated epithelium (pSCE), transitional epithelium (TE) and stratified squamous epithelium (SSE). Local infiltration of inflammatory cells into the cyst wall was associated with an increased number of goblet cells in the lining epithelium. The observed association between the infiltration of inflammatory cells and an increase in the number of goblet cells was statistically significant in groups with lining pSCE and TE. Glycoconjugate histochemical analysis revealed that the surfaces of the lining epithelium with squamous metaplasia showed an increased degree of staining reactivity with UEA-I, whereas the staining reactivity with ConA was reduced. Goblet cells were able to be stained with WGA and UEA-I, but showed extremely low reactivity with ConA. CONCLUSION: Changes in the glycoconjugate expression of the metaplastic lining epithelium and goblet cell development play an important role in the local defense mechanisms against inflammatory factors in POMC.

Background: The mechanisms responsible for activation and proliferation of lining epithelium involved in inflammatory processes in periapical inflammatory lesions remain unclear. In this study, the expression and distribution of inducible nitric oxide synthase (iNOS) and heat shock proteins (HSPs) were immunohistochemically investigated in periapical inflammatory lesions. Methods: Control specimens of periodontal ligaments including Malassez epithelial rests from seven teeth and periapical inflammatory lesions (15 apical granulomas (AGs), 16 radicular cysts (RCs), and 10 residual radicular cysts (RRCs)) were prepared and examined by the standard streptavidin–biotin peroxidase complex method using anti-iNOS rabbit polyclonal antiserum, and anti-HSP27, -HSP60, -HSP70 mouse monoclonal antibodies. Results: Immunoreactivity for iNOS was detected in macrophages, lymphocytes, and endothelial cells of granulation tissue and in lining epithelium of periapical inflammatory lesions. Malassez epithelial rests showed no or slight staining for iNOS. The epithelial staining intensity of iNOS in RCs was greater than that in Malassez epithelial rests and RRCs. Immunoreactivity for HSP27 was recognized in inflammatory cells, endothelial cells and lining epithelium of periapical inflammatory lesions and in Malassez epithelial rests. HSP60 was detected in some lymphocytes of granulation tissue and in lining epithelium of periapical inflammatory lesions, whereas Malassez epithelial rests showed no staining for HSP60. Epithelial HSP60 reactivity was more intense in RCs than in RRCs. HSP70 was expressed in lymphocytes, endothelial cells and lining epithelium of periapical inflammatory lesions and in Malassez epithelial rests. The staining intensity of HSP70 in Malassez epithelial rests was slightly lower than that in lining epithelium of RCs and RRCs. Conclusions: These data demonstrate that the expressions of iNOS, HSP60, and HSP70 are involved in inflammatory processes and might play a role in the activation and proliferation of lining epithelium, leading to progression of periapical inflammatory lesions.

This study was undertaken to establish an experimental model for maxillary sinus augmentation in rabbits and to clarify the bone response to the occluded nasal ostium. In rabbits without ostial occlusion, the elevation of the sinus mucosa resulted in formation of a subantral hollow space filled with blood clots and granulation tissue 1 week after operation. The newly formed bone filled in the space had a central granulation tissue. The space was almost completely replaced by a normal sinus airspace after 3 weeks. In rabbits with ostial occlusion, a fully formed bone mass was seen after 3 weeks. The mass had both mature trabeculae and peripheral cortical bone containing no sinus airspace after 6 weeks. This animal model for maxillary sinus augmentation may improve our understanding of the bone formation procedure in humans and delineate how sinus air pressure caused by the occluded nasal ostium affects the quantity and fate of newly formed bone.

This article describes the unusual case of an intraoral pigmented naevus with pseudoepitheliomatous hyperplasia of the gingiva. A 62-year-old man presented with an almost coal-black pigmented and partly white, spotted, dome-shaped swelling on the lingual gingiva of the mandible. Histologically, the lesion consisted of clusters of round-shaped naevus cells containing melanin granules, reactive with both S-100 immunohistochemical stain and Masson-Fontana silver stain, and pseudoinvasive squamous nests, reactive with cytokeratin. The pathogenesis of the present lesion and problems encountered in its differential diagnosis are discussed.

To clarify the possible role of Langerhans cells (LCs) in oral verrucous carcinoma (OVC), LCs and anti-tumor immune cells in OVCs were immunohistochemically investigated with the use of anti-CD1a, 3, 4, 8, 68, and 79α antibodies. In OVCs, mucosa adjacent to OVCs, and normal oral mucosa, most intraepithelial CD1a-positive LCs were located in parabasal regions. Subepithelial LCs were scatteredly throughout the lamina propria. The densities of intraepithelial and subepithelial CD1a-positive LCs in OVCs were significantly higher than those in adjacent mucosa or normal oral mucosa. The density of CD1a-positive LCs in T3 stage OVCs was slightly lower than those in T1 and T2 stage OVCs. The majority of infiltrating CD3-, CD4-, and CD8-positive T lymphocytes, CD79α-positive B lymphocytes, and CD68-positive macrophages were observed in subepithelial portions of OVCs, but scattered CD3-, CD4-, and CD8-positive T lymphocytes were observed in intraepithelial portions of OVCs. CD8-positive T lymphocytes were more numerous than CD4-positive T lymphocytes in subepithelial portions of OVCs. In mucosa adjacent to OVCs and in normal oral mucosa, infiltration by CD3-, CD4-, and CD8-positive T lymphocytes, CD79α-positive B lymphocytes, and CD68-positive macrophages was minimal in both intraepithelial and subepithelial regions. LCs were slightly more numerous in CD8-positive T-cell dominant OVCs than in CD4-positive T-cell dominant OVCs. These results suggest that CD1a-positive LCs are related to CD8-positive T lymphocytes and that CD1a-positive LCs play a role in the anti-tumor immune response in OVCs.

Fourteen patients with oral chronic graft-versus-host disease (GVHD) who received allogenic bone marrow transplantation were clinically and histopathologically studied. Most patients had lichenoid lesions on the oral mucosa and xerostomia. Two patients displayed multiple superficial mucoceles of the buccal mucosa as vesicular lesions. These clinical features resembled those of autoimmune diseases, such as lichen planus and Sjogren's syndrome. Histopathologically, all cases showed oral mucosal and minor salivary gland involvement characteristic of chronic GVHD, irrespective of the presence or absence of systemic lesions. The oral mucosa showed subepithelial lymphocytic infiltration with epithelial recessive changes, and the minor salivary glands displayed inflammatory changes or fibrosis with destructive alteration of epithelial cells. Immunohistochemically, CD3-positive cells were more numerous than CD79α-positive cells in the oral mucosa, while CD3- and CD79α-positive cells were equally observed in the minor salivary glands. CD4- and CD8-positive cells were detected equally in both the oral mucosa and the minor salivary glands. CD1a- and CD68-positive cells were scattered throughout the oral mucosa and the minor salivary glands. Cellular and humoral immune systems may differ between the oral mucosa and salivary glands in patients with chronic GVHD. CD1a- and CD68-positive cells may play a role in antigen presentation in oral lesions involved in chronic GVHD.

Age-related morphological changes in the inner and outer surfaces of the squamous and parietomastoid sutures were examined in 65 skulls (35 male, 30 female) obtained from Japanese subjects 5–90 years of age at the time of death. Dimensions were measured in both the horizontal and sagittal planes. Wavelength analysis was done by three-dimensional construction. Irregularities were evaluated by calculating fractal dimensions. The outer squamous suture showed no significant age-related changes in size, but wavelength increased because of the development of bony interdigitations with aging. The posterior part of the outer squamous suture showed significant age-related increases in both wavelength (p < 0.01, R2 = 0.164) and fractal dimension (p < 0.01, R2 = 0.101) in males. The parietomastoid suture showed significant age-related changes in size (p < 0.05), but not in wavelength or fractal dimension. These distinct morphological changes found on both the inner and outer surfaces of the squamous and parietomastoid sutures suggest that the age-related morphological characteristics of these sutures are affected by extrinsic mechanical forces.

Background: Expression of vascular endothelial growth factor (VEGF), a major angiogenic factor, and microvessel density (MVD), assessed by the use of anti-CD34 antibody, were immunohistochemically examined in benign and malignant ameloblastomas, as well as tooth germs, to clarify the possible role of angiogenesis in epithelial odontogenic tumors. Methods: Specimens of 5 tooth germs, 35 benign ameloblastomas and 5 malignant ameloblastomas were examined by immunohistochemistry using anti-VEGF and CD34 monoclonal antibodies. Results: Immunoreactivity for VEGF was detected in both normal and neoplastic odontogenic epithelial cells, and weakly in microvessels near odontogenic epithelial cells, suggesting that this angiogenic factor acts on endothelial cells via a paracrine mechanism in odontogenic tissues. Both benign and malignant ameloblastomas showed elevated VEGF expression as compared to tooth germs. VEGF expression was low in keratinizing cells in acanthomatous ameloblastomas and granular cells in granular cell ameloblastomas, and acanthomatous ameloblastomas showed the lowest VEGF reactivity among the subtypes of ameloblastomas. MVD in both benign and malignant ameloblastomas was higher than that in tooth germs, indicating increased demands for blood in the neoplastic tissues. CD34-positive microvessels in follicular ameloblastomas were numerous and small, whereas those in plexiform ameloblastomas were scattered and dilated. MVD tended to depend on VEGF expression levels in both benign and malignant ameloblastomas. Conclusions: VEGF was considered to be an important mediator of angiogenesis in these epithelial odontogenic tumors, and up-regulation of VEGF might be associated with neoplastic or malignant changes of odontogenic epithelial cells.

Method and Results: Calcifying odontogenic cysts (COCs) were examined histopathologically and immunohistochemically to characterize the histological and cytological properties of these lesions. Histopathologically, COCs showed thin or thick lining epithelium with ghost cells. COCs were classified according to proliferative type or nonproliferative type lining epithelium, the presence or absence of ameloblastomatous appearance, and the presence or absence of odontoma in the cyst walls. Immunohistochemically, amelogenin protein was expressed chiefly in ghost cells, whereas cytokeratin 19 (CK19) and bcl-2 proteins were expressed chiefly in lining epithelial cells. The proportion of cases positive for bcl-2 protein was slightly higher in COCs with odontoma than in those without odontoma. Lining epithelial cells sporadically showed positive reactions for Ki-67 antigen. Mean Ki-67 labeling index was slightly greater in COCs with proliferative type lining epithelium, COCs with ameloblastomatous appearance of the cyst walls, and COCs with odontoma of the cyst walls than in COCs without these histological features. Our results suggest that ghost cells or lining epithelial cells show ameloblastic cytodifferentiation or odontogenic epithelial characteristics, that bcl-2 protein is associated with survival of lining epithelial cells in COCs, and that high proliferation potential is associated with ameloblastomatous proliferation or combined odontoma. COCs exhibited various histological features with several transitional forms, and immunohistochemical examinations revealed little or no difference in cytodifferentiation and cellular activity among COCs. Conclusion: We conclude that COCs with various histological features have neoplastic potential and may not be separate entities within the same histological spectrum.

Background: To clarify the possible role of apoptotic cell death in oncogenesis and cytodifferentiation of odontogenic epithelium, apoptosis-related factors – Fas, Fas ligand (FasL), caspase-3 and single-stranded DNA (ssDNA) – were analyzed in ameloblastomas as well as in tooth germs. Methods: Specimens of 5 tooth germs, 29 benign ameloblastomas and 5 malignant ameloblastomas were examined by immunohistochemistry using anti-Fas, FasL, caspase-3 and ssDNA polyclonal antibodies. Results: Immunoreactivity for Fas and FasL was detected in normal and neoplastic odontogenic epithelial cells. Fas expression in ameloblastomas was slightly lower than that in tooth germs, whereas FasL expression was similar in tooth germs and ameloblastomas. Malignant ameloblastomas showed downregulation of Fas expression and upregulation of FasL expression, as compared with benign ameloblastomas, indicating escape from cell death attack by immune cells. Immunoreactivity for caspase-3 was detected chiefly in cells neighboring the basement membrane in tooth germs and ameloblastomas. Expression of caspase-3 and Fas tended to be low in basal cell ameloblastomas and high in desmoplastic ameloblastomas, as compared with other variants of ameloblastomas. Caspase-3 expression was more intense in malignant ameloblastomas than in tooth germs and benign ameloblastomas. Apoptotic bodies reactive with anti-ssDNA antibody were detected in normal and neoplastic odontogenic epithelial cells detached from the basement membrane. Keratinizing cells in acanthomatous ameloblastomas and granular cells in granular cell ameloblastomas showed increased numbers of apoptotic bodies and increased expression of Fas and caspase-3, as compared with other neoplastic cells. Apoptotic reactions in malignant ameloblastomas were less frequent than in benign ameloblastomas, indicating abnormal regulation of cell turnover in odontogenic epithelial cells. Conclusion: These apoptosis-related factors were detected in various patterns in normal and neoplastic odontogenic epithelium, suggesting that these factors might be associated with oncogenesis and cytodifferentiation of epithelial odontogenic tumors.

OBJECTIVE: Distribution and density of CD1a-labeled Langerhans cells (LCs) were examined in human dental periapical inflammatory lesions, and compared with inflammatory cell infiltration or epithelial cell proliferation. MATERIALS AND METHODS: Eighty three periapical lesions (26 apical granulomas (AGs), 8 epitheliated granulomas (EGs), 34 radicular cysts (RCs), 15 residual radicular cysts (RRCs)) were collected. As control, specimens of periodontal ligaments including Malassez epithelial rests were curetted from 21 teeth. LC densities were measured and various degrees of inflammatory cell infiltration were examined immunohistochemically. Labeling indices for the cellular proliferation markers Ki-67 antigen and DNA topoisomerase II α were calculated in the epithelial components. RESULTS: LCs were found in all periapical lesions but not in Malassez epithelial rests. LCs were more abundant in epithelial components than in subepithelial layers. Intraepithelial LCs were more frequent in RCs than in RRCs, whereas subepithelial LCs were less frequent in RRCs than in AGs and EGs. T lymphocytes consistently outnumbered macrophages, plasma cells and B lymphocytes. The range of the CD4/CD8-positive cell ratio differed according to the lesions. Increased LC density was associated with the severity of CD3-positive cell infiltration. Ki-67- and Topo II – LI showed various degrees of epithelial immunoreactivity. There was a significant correlation between LC density and proliferative potential of the epithelium in periapical lesions. CONCLUSION: These findings suggested that LCs appeared to be associated with T lymphocyte infiltration and proliferative potential of the epithelial tissue in periapical lesions.

We examined the immunohistochemical expressions of cell-cycle- and apoptosis-related factors to investigate the possible role of these factors in odontogenic keratocyst (OKC). Expression of cyclin D1 and p16 protein was detected in the basal and parabasal cells in lining epithelium of OKCs and was found more frequently in basal cell nevus syndrome (BCNS)-associated OKCs than in primary or recurrent OKCs. Positivity for p21 protein was detected in basal to superficial cells, whereas that for p27 protein was detected in parabasal to superficial cells in lining epithelium of OKCs. DNA topoisomerase IIalpha reacted with nuclei in basal and parabasal cells of the lining epithelium of OKCs, and positive cells were observed in BCNS-associated OKCs significantly more frequently than in primary or recurrent OKCs. Expression of Fas in suprabasal to superficial cells and expression of Fas-L in basal and parabasal cells were detected in lining epithelium of OKCs. Immunoreactivity for caspase-3 was detected in basal to suprabasal or superficial cells in lining epithelium of OKCs. Single stranded (ss)DNA-positive nuclei were detected in superficial cells in lining epithelium of OKCs. Fas was more broadly distributed in BCNS-associated OKCs than in primary OKCs, and ssDNA-positive cells were observed in BCNS-associated OKCs significantly more frequently than in primary or recurrent OKCs. These results suggest that BCNS-associated OKCs might be a distinguishable entity from solitary OKCs.

To determine whether cell cycle regulation or alteration plays a role in oncogenesis and cytodifferentiation of odontogenic epithelium, cell cycle-related factors, including cyclin D1, p16INK4a, p21(WAF1/Cip1) and p27Kip1 proteins, DNA topoisomerase IIalpha and histone H3 mRNA, were examined in 8 tooth germs and 31 ameloblastomas. Cyclin D1 was expressed in epithelial cells near the basement membrane in tooth germs and ameloblastomas, suggesting that this protein participates in cell proliferation in odontogenic epithelium. Immunoreactivity for p16 protein was observed in most epithelial cells in tooth germs and ameloblastomas. Expression of p21 protein was detected in most epithelial cells in tooth germs and ameloblastomas, but not in keratinizing or granular cells in variants of ameloblastomas. Expression of p27 protein was chiefly found in central polyhedral cells and keratinizing cells in tooth germs and ameloblastomas. These cyclin-dependent kinase inhibitors were well preserved in ameloblastomas as compared with tooth germs, suggesting that the odontogenic epithelium is strictly regulated by these factors. The cell cycle phase/cellular proliferation markers, DNA topoisomerase IIalpha and histone H3 mRNA, were localized in scattered epithelial cells attached to the basement membrane in tooth germs and ameloblastomas.

Telomerase activity is believed to be crucial for cell immortalization and cancerization, and is proven to be induced by c-myc protein. Telomerase reverse transcriptase (TERT) has been recently identified as a catalytic subunit of telomerase, whose expression is closely correlated with telomerase activity. We estimated telomerase activity by the telomeric repeat amplification protocol (TRAP) assay and examined the immunohistochemical expression of TERT and c-myc protein in 21 ameloblastoma tissues. All ameloblastoma samples were positive for telomerase activity, and TERT expression was detected in the nuclei of neoplastic cells but not in those of stromal cells. Numerous peripheral columnar or cuboidal cells, sporadic central polyhedral cells and some granular cells in ameloblastomas reacted with anti-TERT antibody. These results suggest that telomerase activity is associated with the oncogenesis or proliferative potential of odontogenic epithelium. The expression of c-myc protein showed a similar distribution pattern to that of TERT, suggesting that c-myc protein might induce telomerase activity in ameloblastomas.

Apoptotic cell death in granular cell ameloblastomas was examined by immunohistochemistry using anti-single-stranded DNA (ssDNA) antibody and transmission electron microscopy. Routinely prepared sections of granular cell ameloblastomas showed various quantities of granular cells with some apoptotic nuclear fragments. Immunoreactivity for ssDNA was higher in granular cells than in other neoplastic cells. Ultrastructural examination revealed abundant lysosomes in the cytoplasm of granular cells. Numerous apoptotic cell fragments with condensed nuclei in granular cell clusters were phagocytosed by adjacent granular cells. On immunohistochemical characterization of cellular differentiation, granular cells were positive for cytokeratin, CD68, lysozyme and alpha-1-antichymotrypsin, but negative for vimentin, desmin, S-100 protein, neuron-specific enolase and CD15, indicating epithelial origin and lysosomal aggregation. These features suggest that the cytoplasmic granularity in granular cell ameloblastomas might be caused by increased apoptotic cell death of neoplastic cells and associated phagocytosis by neighboring neoplastic cells.

To clarify the role of cell adhesion molecules in epithelial odontogenic tumors, expression of integrin α2, α3 and β4 subunits and the standard form of CD44 was immunohistochemically examined in 22 ameloblastomas as well as in 1 clear cell odontogenic tumor (CCOT). Integrin α2 and α3 subunits were expressed on the cell membrane of peripheral columnar or cuboidal cells in ameloblastomas. Most tumor cells in basal cell ameloblastomas and the CCOT were positive for these subunits. These features suggest that CCOT possesses characteristics similar to those of peripheral cells in main type ameloblastoma or neoplastic cells in basal cell ameloblastoma. Integrin β4 subunit was found along the basement membrane in ameloblastomas and the CCOT. The expression of these representative epithelial integrins at the epithelialmesenchymal interfaces suggests that they might mediate parenchymal-stromal cell interactions in epithelial odontogenic tumors. CD44 was detected in most tumor cells of ameloblastomas and the CCOT, but keratinizing areas in acanthomatous ameloblastomas showed decreased CD44 expression. These features suggest that CD44 is involved not only in cell adhesion but also in cellular differentiation in epithelial odontogenic tumors.

An alveolar soft-part sarcoma (ASPS) occurring in the cheek is described, with a review of the literature. The subject was a 25-year-old woman who presented with a large swelling in the left cheek. The lesion, initially diagnosed as a benign tumor on radiographic and computed tomographic examinations, was surgically excised. Histopathological examination of the mass revealed a nest-like or organoid cellular arrangement as confirmed by three-dimensional computer graphic reconstruction. The cytoplasm of the large polygonal tumor cells contained abundant diastase-resistant, PAS-positive inclusions, ultrastructurally confirmed to be crystalloid materials. The tumor cells were immunoreactive for anti-myoglobin, sarcomeric actin, and neuron-specific enolase antibodies, suggesting a myogenic origin.

The proliferative status of lymphoepithelial islands in the labial salivary glands of primary Sjogren's syndrome (pSS) patients was investigated by counting the number of argyrophilic nucleolar organizer regions (AgNORs) in epithelial cells constituting the islands. The islands were classified into four groups and evaluated in terms of total area and three discrete zones of the islands. In each pSS group, the mean AgNOR number per total island epithelial cell nucleus was significantly higher than in control ductal epithelial cells. The zonal AgNOR number fluctuated during the process of island formation but became more uniform as the islands developed. Furthermore, statistically significant trends among the four pSS groups were observed in the ratio of T lymphocytes, B lymphocytes and plasma cells surrounding the islands. The results indicated that the islands are highly proliferative once island formation begins and that zonal island cell proliferation may be associated with the inflammatory cells.

To investigate the role of apoptosis in the development of odontogenic keratocysts (OKCs), apoptosis-related factors and apoptotic cells were examined immunohistochemically and by in situ DNA nick end-labeling. Expression of bcl-2 protein was detected in the cytoplasm of basal cells of OKC lining epithelium, and parakeratinized OKCs showed higher expression than orthokeratinized OKCs. P53 protein was detected sporadically in nuclei of OKC lining epithelium, and expression of Lewisy antigen was detected in the cell membranes of superficial cells of OKC lining epithelium. Ki-67 reactivity in bcl-2 or p53 positive cases was higher than in negative cases, but the correlation between these apoptosis-related factors and apoptotic cells was unclear. Ki-67 antigen was expressed in nuclei of basal and parabasal cells of OKC lining epithelium, while apoptotic cells were found among superficial flattened cells. Many Ki-67 positive and apoptotic cells were observed in basal cell nevus syndrome (BCNS)-associated OKCs.

A case of clear-cell odontogenic tumor with unusual histological features is presented. A 61-year-old Japanese man was admitted because of swelling of the left premolar-molar region of the mandible. Radiological examination revealed a multilocular radiolucency with irregular margins. Histological examination of the resected specimen showed infiltrative proliferation of both clear and eosinophilic cells into the adjacent soft tissue without encapsulation, suggesting the malignant potential of the tumor. The tumor cells sporadically formed cystic lesions. In addition, several tumor cell nests showed duct-like characteristics, and many eosinophilic dentin-like structures were attached to the tumor cell nests, suggesting the potential for epithelial-mesenchymal induction. Histochemically, the clear tumor cells possessed cytoplasmic glycogen granules. Both clear and eosinophilic tumor cells showed positive immunoreactivities for cytokeratin 19, epithelial membrane antigen and filaggrin, indicating an odontogenic epithelial origin.

The enzyme aromatase is involved in the conversion of androgens to estrogens and in the modulation of various androgenic and estrogenic actions. Abnormalities of estrogen metabolism have been postulated to play roles in the development and/or pathophysiology of Sjögren's syndrome. In the present study, aromatase was immunolocalized in 75 cases of inflammatory disorders of human minor salivary glands of the lower lip. These included cases of primary Sjögren's syndrome (19 cases), of chronic sialadenitis (34 cases) and of mucous extravasation cysts (22 cases), in order to clarify the possible involvement of in situ estrogen production in primary Sjögren's syndrome. Aromatase immunoreactivity was detected in myoepithelial cells of acini and in interstitial cells adjacent to acini and ducts in 13/19 (68%) cases of primary Sjögren's syndrome. In contrast, aromatase expression was detected in only six of 34 (18%) cases of chronic sialadenitis and in seven of 22 (32%) cases of mucous extravasation cyst. These results suggest that increased aromatase expression in minor salivary glands with primary Sjögren's syndrome in premenopausal women may be involved in the biological features of primary Sjögren's syndrome through the production of estrogens in situ and possibly through the aggravation of the inflammatory reaction.

A rare case of clear cell odontogenic tumor is presented with an immunohistochemical study using epithelial cell markers. A 35-year-old Japanese man was admitted with a complaint of painless swelling in the anterior region of his mandible. Radiological examination showed a relatively well-defined multilocular radiolucency with root resorption of the adjacent teeth. Despite a subtotal mandibulectomy, the tumor recurred three times. Histologically, the tumor was composed of proliferating clear cells and infiltrated through the cancellous bone. Histochemical and ultrastructural analyses detected cytoplasmic glycogen granules in the clear cells. They showed immunoreactivities for cytokeratin 8, 13 and 19, filaggrin and anti-ameloblastoma antibodies, suggesting an odontogenic epithelial origin.

A patient with B-cell lineage diffuse large-cell lymphoma carrying the t(3;16)(q27;p11) and BCL-6 rearrangement is described. Cytogenetic studies showed 46,XY,t(3;16)(q27;p11.2)[.11]/46,idem,add(18)(q21)[7]/46,XY[2]. The chromosomal translocation involving the 3q27 locus was associated with the BCL-6 gene rearrangement identified by Southern blot analysis. This case involved systemic lymph nodes, as large as 3 cm in diameter, bilaterally in neck, axilla, and inguinal regions. The patient obtained complete remission with chemotherapy.