Tc-99m hydroxymethylene diphosphonate scintigraphy, computed tomography, and magnetic resonance imaging of osteonecrosis in the mandible: Osteoradionecrosis versus medication-related osteonecrosis of the jaw.

Purpose: To present characteristic findings of Tc-99m hydroxymethylene diphosphonate (HMDP) scintigraphy, computed tomography (CT), and magnetic resonance (MR) imaging for osteonecrosis in the mandible, especially osteoradionecrosis (ORN) and medication-related osteonecrosis of the jaw (MRONJ).

Materials And Methods: Thirteen patients with MRONJ and 7 patients with ORN in the mandible underwent Tc-99m HMDP scintigraphy, CT, and MR imaging (T1-weighted images [T1WI], T2-weighted images [T2WI], short inversion time inversion recovery images [STIR]), diffusion-weighted images [DWI], and apparent diffusion coefficient [ADC] mapping). The associations of scintigraphy, CT, and MR imaging findings with MRONJ and ORN were analyzed using the chi-square test with the Pearson exact test.

Structural Variations in Parotid Glands Induced by Radiation Therapy in Patients with Oral Carcinoma Observed on Contrast-Enhanced Computed Tomography.

Background: Xerostomia is one of the commonest radiation-induced complications in patients with head and neck carcinoma. The aim of this study was to assess structural variations in parotid glands induced by radiation therapy in patients with oral carcinoma with contras-enhanced computed tomography (CECT).

Material/methods: A retrospective study was performed in 41 patients with oral carcinoma who underwent CECT for head and neck malignancies before and after radiotherapy.

Diffusion-Weighted Imaging in the Oral and Maxillofacial Region: Usefulness of Apparent Diffusion Coefficient Maps and Maximum Intensity Projection for Characterization of Normal Structures and Lesions.

Background: The aim of this study was to investigate diffusion-weighted imaging (DWI) in the oral and maxillofacial region, with a special focus on the usefulness of apparent diffusion coefficient (ADC) maps and maximum intensity projection (MIP) for characterization of normal structures and lesions.

Material/methods: Thirty-five patients who underwent magnetic resonance imaging (MRI) for diagnosis of oral and maxillofacial lesions were included in this prospective study. DWI was performed on a 1.

Characteristic Multimodal Imaging of Medication-Related Osteonecrosis of the Jaw: Comparison Between Oral and Parenteral Routes of Medication Administration.

Background: To assess multimodal imaging features of medication-related osteonecrosis of the jaw (MRONJ) and to analyze the differences between oral and parenteral routes of medication administration. We retrospectively reviewed panoramic radiographs, CT, MRI, and bone scintigraphy of patients with MRONJ.

Material/methods: A retrospective study was conducted in 16 patients with MRONJ who underwent panoramic radiography, CT, MRI, and bone scintigraphy.

Osteosarcoma of the Mandible: a Case Report with CT, MRI and Scintigraphy.

Osteosarcomas are especially rare in the mandible and maxilla, representing 1.6% of all bony malignant tumours. In this article, we described a case of osteosarcoma of the mandible.

A Rare Case of Malignant Melanoma of the Mandible: CT and MRI Findings.

Malignant melanoma of the mandibular gingiva is extremely rare. It is a malignant tumour of melanocytes or their precursor cells, and often misinterpreted as a benign pigmented process. A few reports have described computed tomography (CT) and magnetic resonance imaging (MRI) findings of malignant melanoma in the oral cavity.

Abnormal DNA end-joining activity in human head and neck cancer.

In human cells, DNA double-strand breaks (DSBs) are repaired primarily by the DNA end-joining (EJ) process and thus, abnormal DNA EJ activities lead to an accumulation of mutations and/or aneuploidy, resulting in genetic instability of cells. Since genetic instability is the hallmark of cancer cells, we studied the DNA EJ activities of normal, non-malignant immortalized and malignant human epithelial cells to investigate the association between DNA EJ and carcinogenesis. We found a significant diminution of precise (error-free) DNA EJ activities in non-malignant immortalized human oral keratinocytes (HOK-16B) and human head and neck squamous cell carcinoma (HNSCC) cells compared to that in normal human oral keratinocytes (NHOK).

Immunohistochemical localization of parathyroid hormone-related protein (PTHrP) and serum PTHrP in normocalcemic patients with oral squamous cell carcinoma.

Cancer cells produce parathyroid hormone-related protein (PTHrP) in the early phase of malignancy development, before hypercalcemia occurs. The relationship between PTHrP and the clinicopathologic features of oral squamous cell carcinoma is poorly understood. We studied 60 patients (43 men, 17 women; mean age, 64.

Senescence occurs with hTERT repression and limited telomere shortening in human oral keratinocytes cultured with feeder cells.

We investigated the phenotypic and molecular alterations in normal human oral keratinocytes (NHOK) during in vitro replication in two different culture conditions. The cells were cultured either in chemically defined Keratinocyte Growth Medium (KGM) without feeder layers or in serum-containing flavin-adenine dinucleotide (FAD) medium with feeder layers. Primary NHOK underwent 22 +/- 3 population doublings (PDs) in KGM and 42 +/- 4 PDs in FAD medium, reflecting 52% increase in replication capacity with feeder layers.

Introduction of human telomerase reverse transcriptase to normal human fibroblasts enhances DNA repair capacity.

Purpose: From numerous reports on proteins involved in DNA repair and telomere maintenance that physically associate with human telomerase reverse transcriptase (hTERT), we inferred that hTERT/telomerase might play a role in DNA repair. We investigated this possibility in normal human oral fibroblasts (NHOF) with and without ectopic expression of hTERT/telomerase.

Experimental Design: To study the effect of hTERT/telomerase on DNA repair, we examined the mutation frequency rate, host cell reactivation rate, nucleotide excision repair capacity, and DNA end-joining activity of NHOF and NHOF capable of expressing hTERT/telomerase (NHOF-T).

Telomere shortening does not occur during postmaturational aging in situ in normal human oral fibroblasts.

We investigated whether the telomere length, i.e. mean terminal restriction fragment (TRF) length, decreases during in situ aging in normal human oral fibroblasts (NHOF).

Senescence-associated genes in normal human oral keratinocytes.

The current study was undertaken to identify senescence-associated (SA) genes in cultured normal human oral keratinocytes (NHOK). Primary NHOK were serially subcultured in vitro as dispersed cells in low (0.15 mM) Ca(2+) medium until senescence.

Absence of hamTERT gene expression is associated with promoter hypermethylation in immortal hamster buccal pouch epithelial cells.

This study describes the first example of spontaneously immortalized, telomerase-negative hamster cells which replicated in the absence of telomere shortening. Primary hamster buccal pouch epithelial (HBPE) cells were subcultured for approximately 10 population doublings (PDs) before they ceased to divide. Among the non-replicating HBPE cells, a colony of proliferating cells had appeared.