• Korean Journal of Head & Neck Oncology
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• v.7 no.2
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• pp.114-119
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• 1991

Malignant oncocytoma(oxyphil cell adenoma) is a extremely rare malignant tumor of the salivary glands and almost occurs in the parotid gland. A case of malignant oncocytoma of the parotid gland occurring in a 63 year old man is reported. Establishing a diagnosis of malignant oncocytoma essentially requires the application of two sets of criteria to the tumor under examination. First, the tumor cells must be identified as oncocyte and second, malignancy must be determined. Histochemical stains are not as useful as generally believed. Electron microscopy confirms the diagnosis by demonstrating an abundance of mitochondria. The diagnosis of malignant oncocytoma depends on several additional criteria in addition to cellular and nuclear pleomorphism, including lack of encapsulation, local infiltration, perineural and intravascular growth, and regional and/or distant metastasis. Satisfactory results from surgical resection and postoperative radiotherapy in our patient serve as additional experience in the treatment of this rare malignancy.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.554-562
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• 2003

Xylitol has been used as sugar substitute to prevent dental caries. It is not fermented by most dental plaque bacteria and interferes with the growth of mutans streptococci. Therefore the production of acidic metabolites and the growth of mutans streptococci are inhibited. S. mutans strains which are inhibited to grow under the presence of xylitol are referred as xylitol-sensitive ($X^S$) strains. However, experimental and clinical studies have shown that there were mutated groups of S. mutans strains that are not affected by xylitol. They are referred as xylitol-resistant($X^R$) strains. The aim of the present study was to investigate that emergence of $X^R$ strain would effect on the anticariogenecity of xylitol by comparing the growth rate, the extracellular pH, hydroxyapatite adhesion and the agglutination of the $X^R/X^S$ strains. Overall we came out with following results : 1. No difference in the growth rate and the extracellular pH was found between the $X^S$ strain and the $X^R$ strain. 2. No difference in adhesion to hydroxyapatite surface was found between the $X^R$ strain and the $X^S$ strain (p>0.05) and adhesion of the $X^S$ strain was greater than that of $X^R$ strain in the sucrose-dependent adhesion to hydroxyapatite (p<0.05). 3. The $X^R$ strain was agglutinated in the lower concentration of saliva than that of $X^S$ strains.