Rare associations of dens invaginatus and mesiodens.

Dens invaginatus is a developmental variation resulting from an alteration in the normal growth pattern of the dental papilla. Synonyms of this disturbance include dens in dente, invaginated odontome, tooth inclusion, and dentoid in dente. Radiographically, it is observed as infolding of a radiopaque ribbon-like structure, with equal density as enamel, extending from the cingulum into the root canal and sometimes reaching the root apex, assigning the appearance of a small tooth within the coronal pulp cavity.

Enhancement effects of test injection with a small amount of MR contrast medium in the oral and maxillofacial region.

Purpose: To examine whether the signal intensity of dynamic contrast-enhanced MRI (DCE-MRI) is altered by test injection of 1 ml of contrast medium, and if so, whether this change affects the DCE-MRI analysis.

Materials And Methods: Six healthy volunteers were examined by DCE-MRI using a Magnevist syringe and/or an Omniscan syringe for the injection of contrast medium. Each scan was performed 10 times using steady-state free precession (3D-FISP), a sequence for DCE-MRI, before and after intravenous injection of 1 ml of the contrast medium.

Usefulness of contrast enhanced-MRI in the diagnosis of unicystic ameloblastoma.

The radiographic features of unicystic ameloblastoma (UA) are typically unilocular and round area of radiolucency. Therefore, this type of lesion is often misdiagnosed as an odontogenic keratocyst or a dentigerous cyst. UA should be differentiated from odontogenic cysts because the former have a higher rate of recurrence than the latter.

Assessment of ameloblastomas using MRI and dynamic contrast-enhanced MRI.

We retrospectively evaluated magnetic resonance images (MRI) and dynamic contrast-enhanced MRI (DCE-MRI) of ameloblastomas. MRI and DCE-MRI were performed for 10 ameloblastomas. We obtained the following results from the MRI and DCE-MRI.

Role of O6-methylguanine-DNA methyltransferase and effect of O6-benzylguanine on the anti-tumor activity of cis-diaminedichloroplatinum(II) in oral cancer cell lines.

The DNA repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) modulates the effectiveness of alkylating agents. However, the relationship between MGMT and the sensitivities to other agents has not been explored. In the present study, the association between MGMT expression and the cellular sensitivity to the platinum agent, CDDP was examined in four human oral cancer cell lines.

Effects of histone deacetylase inhibitor FR901228 on the expression level of telomerase reverse transcriptase in oral cancer.

We speculated whether or not the expression level of telomerase reverse transcriptase (hTERT) would be modulated by agents targeting epigenetics in oral cancer cell lines. Although hTERT is known to be targeted by epigenetic changes, it remains unclear how chemoagents targeting epigenetics work on hTERT transcription. In the present study, the epigenetic effects of the histone deacetylase (HDAC) inhibitor FR901228 on hTERT transcription in oral cancer cell lines were analyzed by RT-PCR.

Assessment of MRI and dynamic contrast-enhanced MRI in the differential diagnosis of adenomatoid odontogenic tumor.

The radiographical differentiation of adenomatoid odontogenic tumor (AOT) from dentigerous cysts, calcifying odontogenic cysts, calcifying epithelial odontogenic tumors, odontogenic keratocysts and amelobastomas is sometimes difficult. We attempted to differentiate AOT from other lesions similar to AOT in radiographic findings using MRI. The MRI features of AOT in our three cases included homogeneous low SI in the cystic portion and homogeneous intermediate SI in the solid portion on T1WI, homogeneous high SI in the cystic portion and intermediate to slightly high SI in the solid portion on T2WI and enhancement of only the solid portion on CE-T1WI although none of the sequences included SI of calcifications.

Influence of CpG island methylation status in O6-methylguanine-DNA methyltransferase expression of oral cancer cell lines.

It is known that the O6-methylguanine-DNA methyltransferase (MGMT) gene is susceptible to epigenetic regulation associated with an altered frequency of CpG methylation. To investigate whether epigenetic regulation of the MGMT gene might lead to significant reductions in the expression levels of cancer cells, we sought evidence of a link between the methylation status of the MGMT promoter and the expression levels of seven human oral cancer cell lines. We found two frequently methylated regions: the 5' region extending from nt 690 to nt 893 in the promoter, and the more 3' region extending from nt 1060 to nt 1151 in the untranslated first exon.

Effects of demethylating agent 5-aza-2(')-deoxycytidine and histone deacetylase inhibitor FR901228 on maspin gene expression in oral cancer cell lines.

Maspin, which belongs to the serine protease inhibitor (serpin) superfamily, has been proposed as a potent tumor suppressor that inhibits cell motility, invasion, angiogenesis, and metastasis. In the present study, we examined the effects of 5-aza-2(')-deoxycytidine (5-aza-dC), a demethylating agent, and FR901228, a histone deacetylase (HDAC) inhibitor, on maspin expression in oral cancer cell lines. The expression levels of maspin mRNA were divided into two groups, which was the maspin low-expressed and high-expressed cell lines in the 12 oral cancer cell lines.

Application of dynamic contrast-enhanced MRI to differentiate malignant lymphoma from squamous cell carcinoma in the head and neck.

Because malignant lymphoma, the second most common malignant tumor of the head and neck, and squamous cell carcinoma (SCC), the most common malignant tumor of the head and neck, require different treatments, it is important to be able to differentiate them. In the present study, we attempted to differentiate malignant lymphomas from SCCs using dynamic contrast-enhanced MRI (DCE-MRI). Seventeen lesions (in 8 cases) of malignant lymphoma and 30 cases of SCC were compared by DCE-MRI.

The value of dynamic contrast-enhanced MRI in diagnosis of malignant lymphoma of the head and neck.

In this study, we attempted to diagnose malignant lymphoma on the basis of magnetic resonance imagings (MRIs) and dynamic contrast-enhanced MRI (DCE-MRI). Eighteen lesions (in eight patients), all of which had been proven histopathologically, were detected on MRI. The eight patients included five patients with diffuse large B-cell lymphoma, one with B-cell low-grade MALT lymphoma, one with follicular lymphoma, and one with Hodgkin's lymphoma.

MR imaging of epithelial cysts of the oral and maxillofacial region.

The aim of the present study was to review the magnetic resonance (MR) appearance of primary epithelial cysts in order to distinguish the cysts from other possible lesions. MR images were obtained in 27 cases of epithelial cysts, including 7 odontogenic keratocysts, 3 dentigerous cysts, 1 glandular odontogenic cyst, 10 radicular cysts, 4 nasopalatine duct cysts, and 2 nasolabial cysts. In addition, contrast enhanced MR imagings were performed in 12 cases, including 3 odontogenic keratocysts, 1 dentigerous cyst, 1 glandular odontogenic cyst, and 7 radicular cysts.

Incidentally found and unexpected tumors discovered by MRI examination for temporomandibular joint arthrosis.

We examined the frequency of incidentally found or unexpected tumors discovered at the time of magnetic resonance imaging (MRI) examinations in the temporomandibular joint (TMJ) region for patients with suspicion of TMJ arthrosis. Five MR images (T1-weighted transverse scout image and proton density and T2-weighted oblique sagittal images at the open and closed mouth) were acquired. In 2776 MRI examinations of TMJ arthrosis, two tumors were discovered.

Assessment of pleomorphic adenomas using MRI and dynamic contrast enhanced MRI.

We evaluated magnetic resonance images (MRI) and the value of dynamic contrast enhanced MRI (DCE-MRI) of pleomorphic adenomas retrospectively. MRI was performed for 18 pleomorphic adenomas, including 11 cases with DCE-MRI. We obtained the following results on the MRI and DCE-MRI.

Effects of p53 gene therapy in radiotherapy or thermotherapy of human head and neck squamous cell carcinoma cell lines.

We report herein the effects of p53 gene therapy in the radiotherapy or thermotherapy of eight human head and neck squamous cell carcinoma (SCC) cell lines. The discrepancy between radiosensitivity combined with p53 gene therapy than that without p53 gene therapy increased among the eight SCC cell lines. The discrepancy increased in the thermosensitivity at 43 degrees C and decreased in that at 44 degrees C among the eight SCC cell lines.

Evaluation of tumor proliferation using dynamic contrast enhanced-MRI of oral cavity and oropharyngeal squamous cell carcinoma.

We investigated the relationship between the enhanced patterns acquired by dynamic MRI and the tumor cell proliferation estimated by immunostaining proliferating cell nuclear antigen (PCNA) in oral squamous cell carcinoma (SCC). Thirty patients with primary oral SCC underwent dynamic contrast enhanced (DCE)-MRI using a three-dimensional fast imaging with steady-state precession sequence. Tumor cell proliferation of all surgical specimens was evaluated using immunohistochemical staining with the anti-PCNA antibody.

Thermoradiotherapy combined with adenoviral p53 gene therapy in head and neck squamous cell carcinoma cell lines.

We examined effects of recombinant p53-expressing adenovirus combined with thermoradiotherapy in 8 head and neck squamous cell carcinoma (SCC) cell lines to improve the outcomes of the treatment of advanced head and neck cancer. The p53 gene therapy did not improve the discrepancy between thermoradiosensitivities among the 8 SCC cell lines. However, p53 gene therapy improved the effects of thermoradiotherapy in all 8 cell lines, and there were significant differences in four situations of the HSC4 44 degrees C (p=0.

MR features of aneurysmal bone cyst of the mandible and characteristics distinguishing it from other lesions.

Aneurysmal bone cyst (ABC) is a relatively rare, non-neoplastic expansile lesion of bone. Bleeding may occur during an operation or biopsy for ABC, as this cyst is an aneurys with numerous pools of blood. Therefore, it is necessary to diagnose ABC before treatment or biopsy.

Thermoradiotherapy combined with p53 gene therapy of human salivary gland adenocarcinoma cell line.

We report on thermoradiotherapy combined with p53 gene therapy in the human salivary gland adenocarcinoma cell line HSG. HSG cells were successfully infected at a rate of 62.3% with MOIs of 20 of either AxCAip53 or AxCAiLacZ.

Assessment of carcinoma in the sublingual region based on magnetic resonance imaging.

In the present study, we attempted to diagnose and detect the extent of tumors in the sublingual region using magnetic resonance imaging (MRI) and dynamic MRI. MRI with or without gadopentetate dimeglumine (Gd-DTPA)-enhancement in seven lesions of the sublingual regions was performed. The seven lesions included four cases of mucoepidermoid carcinoma (mucoepidermoid Ca), two cases of adenoid cystic carcinoma (ACC), and one case of squamous cell carcinoma (SCC).

Adenoviral p53 gene therapy in head and neck squamous cell carcinoma cell lines.

We reconstructed the recombinant p53-expressing adenovirus and examined its infections and effects in head and neck squamous cell carcinoma cell lines. Eight human head and neck squamous cell carcinoma cell lines were infected by the recombinant adenovirus harboring the lacZ gene (AxCAiLacZ) or the wild-type p53 gene (AxCAip53), and the effects were investigated. The eight cell lines were successfully infected by AxCAiLacZ at a level of more than 50%.

Adenomatoid odontogenic tumor: correlation of MRI with histopathological findings.

Adenomatoid odontogenic tumor is a rare benign and odontogenic tumor that is frequently misdiagnosed as other odontogenic cysts and tumors on radiographic examination. To acquire additional information of adenomatoid odontogenic tumor, we performed magnetic resonance imagings (MRI) at a case of adenomatoid odontogenic tumor. The lesion was divided between the peripheral portion with a thick circular shape and the central portion with a round shape on the basis of the signal intensity (SI) of MRI.

Application of dynamic CT for various diseases in the oral and maxillofacial region.

Objective: To investigate whether dynamic CT enables quantitative differentiation between inflammation, benign tumors, and malignant tumors in oral and maxillofacial regions.

Methods: Sixteen malignant tumors (14 squamous cell Ca, one adenoid cystic Ca, one mucoepidermoid Ca), six benign tumors (one Warthin tumor, two pleomorphic adenomas, one lipoma, one Schwanoma, one hemangioma), and seven inflammation cases (three submandibular adenitis, two osteomyelitis, two perimandibular inflammations) were examined. Contrast agent (0.

Mandibular metastasis presenting as the initial maifestation of malignant pheochromocytoma.

A case of 59-year-old male patient presenting with metastasis to the mandible from malignant pheochromocytoma is described. The conventional radiographs and CT images suggested that the lesion was malignant osteogenic tumors or metastatic tumors due to the existence of calcification and widespread periosteal sunburst spiculation. On MRI, an expansive mass was clearly depicted and the signal intensities of the lesion were low to intermediate on T1 weighted image with intermediate to high signal intensity on T2 weighted image.

Thermoradiotherapy in human head and neck squamous cell carcinoma cell lines.

Thermoradiosensitivity of 8 cell lines of head and neck squamous cell carcinoma (HO-1-u-1, HSC2, HSC3, HSC4, SAS, KB, Hep2, and Ca9-22) was investigated. The differences of radiosensitivity between the cell line with the highest radiosensitivity and the cell line with the lowest radiosensitivity were 1.7-, 7.