Stromal phenotype of dental follicle stem cells.

It has been suggested that stem/progenitor cells exist in dental tissue. This study identified adult mesenchymal stem/stromal cell-like populations in the dental follicle of human impacted third molars.The immunohistochemical analysis, of dental follicle using known stem-cell markers: Cytokeratins (AE1-AE3), Smooth Muscle Actin, Ki-67, CD34, CD44, CD45, CD56, and CD133. A positive reaction for at least one of the markers typical of stromal phenotype (CD56, CD44 and CD271) was observed in seven cases . Interestingly, all positive cases showed coexpression of CD44 and CD56, except for one case which was CD56 positive and CD44 negative. Immunohistochemical reaction was negative in all 27 cases for Ki-67, Cytokeratins, Smooth Muscle Actin, CD34, CD133 and CD45. The association: negative for CD34, CD45, CD133, and positive for CD44, CD56 (markers of a subpopulation of stem cells from bone marrow) suggests these may be quiescent mesenchymal stem cells, a hypothesis supported by the negativity of Ki-67 (proliferative index). Our results are compatible with the identification of immature fibroblast cells with phenotypic features of stromal stem cells in the dental follicle.

Frequency and role of HPV in the progression of epithelial dysplasia to oral cancer.

BACKGROUND: Human papillomavirus DNA (HPV DNA) and p16 and p53 protein expressions were investigated for their role in transforming dysplasia into squamous cell carcinoma of the oral cavity in a non-smoker and non-drinker patient group. MATERIALS AND METHODS: A total of 56 oral biopsies from non-smoker and non-drinker patients were analyzed. The specimens were grouped into three categories: group 1 included 31 cases of hyperplastic mucosa and mild dysplasia, group 2 included 14 cases of moderate and severe dysplasia, while group 3 comprised 11 cases of invasive squamous cell carcinomas. In all cases, immunohistochemical methods were performed to detect p16 and p53 protein expressions. The nested polymerase chain reaction for HPV (nested HPV-PCR) and the catalyzed signal-amplified colorimetric DNA in situ hybridization (CSAC-ISH) methods were applied for HPV DNA detection and typing of high-risk genotype. RESULTS: P16 protein, absent from all specimens of group 1, was especially noted in group 2 (92.86%) and in group3 (54.55%). Five out of 14 of group 2 cases (35.71%) and 3/11 (27.27%) of group 3 were HPV DNA positive. The HPVs detected were of both high-risk and low-risk genotype. The analysis of the relationship between HPV and p16 protein expression revealed that all the group 2 and 3 samples with HPV DNA, overexpressed p16 protein. CONCLUSION: The results suggest that HPV could be a molecular marker in group 2 and 3 specimens in non-smoker and non-drinker patients. The virus may play an etiological role in carcinogenesis in the oral cavity. The association between HPV and p16 overexpression suggests a molecular mechanism similar to that found in cervical cancer.

Amyloid deposition in the tongue: clinical and histopathological profile.

AIMS: Oral amyloidosis is a rare and debilitating disease that, whether primary or secondary, may severely impact the quality of a patient's life. The study investigated the characteristics of amyloid deposition in the tongue from the clinical and histopathological profiles. MATERIALS AND METHODS: Biopsy specimens were received from five patients: 2 female, 3 male. All biopsies were taken from the tongue, and all had amyloid deposition in the subepithelial connective tissue, conclusive for a diagnosis of amyloidosis. All patients showed macroglossia and difficulty in eating and impairment of speech. RESULTS: In three cases there was no evidence of systemic involvement or associated disease; these were characterized as localized amyloidosis of the tongue. The other two cases revealed multisystemic involvement. Histologically, the disease was diagnosed through specific staining with Congo red, which examined under polarized light revealed the amyloid deposits as apple-green birefringence. CONCLUSION: The findings show the tongue to be the site most frequently affected in forms of localised amyloidosis, and that a tongue biopsy possess a highly diagnostic value for amyloidosis. There is still no consensus regarding the management of lingual amyloidosis, although numerous therapies have been proposed, including surgical excision and pharmacological treatment. However lesions often persist or recur. The prognosis is uncertain, owing to the rarity of the condition, requiring regular follow-up and monitoring.

Epithelial-myoepithelial carcinoma of the minor salivary glands: immunohistochemical and morphological features.

AIMS: Epithelial-myoepithelial carcinoma (EMC) is a rare malignant salivary gland neoplasm that most commonly occurs in the parotid gland, but can also arise in the minor salivary glands. Three cases are reported of epithelial-myoepithelial carcinoma of the minor salivary glands, with the goal of better defining this entity. PATIENTS AND METHODS: All three cases showed a characteristic nodular/multinodular growth pattern and classic biphasic tubular histology. All parts of each tumor were surrounded by a myoepithelial cell rim and there was evidence of invasion. RESULTS: Immunohistochemical analysis showed the tumor cells to be weakly positive for S100, cytokeratin (CK) CK5/6, CK7, CKAE-1/AE-3 and strongly positive for epithelial membrane antigen (EMA) and p63; they were focally positive for calponin and acute lymphoblastic leukemia antigen (CD10). The tumor cells were negative for vimentin, alpha-smooth muscle actin (SMA) (except one case), glial fibrillar acid protein (GFAP) and MIB1. The tumors were resected completely with wide margins and no recurrence or metastasis had occurred from 6 to 15 months after surgery. CONCLUSION: Three cases of minor salivary gland tumors are described and the differential diagnosis underlined in relation to benign myoepithelioma. The characteristic morphological and immunohistochemical features aided diagnosis of these biphasic tumors.

Evaluation of the cytotoxic and genotoxic effects of orthodontic bonding adhesives upon human gingival papillae through immunohistochemical expression of p53, p63 and p16.

BACKGROUND: Numerous in vitro studies have shown that composite materials, commonly used for restorations in conservative dentistry, and in orthodontics to anchor brackets to the tooth enamel, have cytotoxic and genotoxic effects. The study determined expression of p53, p63 and p16, biomarkers useful for predicting potential genotoxicity. PATIENTS AND METHODS: p53, p63 and p16 expression was determined immunohistochemically in the gingival papillae of 99 patients (69 banded orthodontically for at least one year, brackets bonded to teeth with filled flowable composite resin, 30 without orthodontic banding as controls). The papillae samples were removed surgically and examined to evaluate morphological and biological alterations. RESULTS: In no case were morphological alterations visible by microscopy out of the 69 banded patients; four (5.80%) were positive for p53 and two for p63 expression in the basal and suprabasal layers (2.90%). One patient was positive for p16 (1.45%). No control case was positive for any of the biomarkers (0.00%). CONCLUSION: The significance of p53, p63 and p16 positivity, and whether these proteins may serve as biomarkers to predict the risk of developing oral lesions (dysplasia, oral cancer) is still unclear. Although details of the mechanisms leading to cell death, genotoxicity and cell-cycle delay are not fully understood, resin monomers may alter cell function in the oral cavity.