Immunohistochemical investigation of nerve distribution in mature parotid and submandibular glands of rats with a liquid diet.

BACKGROUND: Although feeding with a liquid diet does not affect the growth of rat submandibular glands, it inhibits the growth of rat parotid glands during growth periods. In these growth-inhibited parotid glands, the growth of parasympathetic nerves is also suppressed. Meanwhile, the mature parotid glands of animals maintained on a liquid diet become morphologically and functionally atrophic, however, there is no effect of a liquid diet on mature submandibular glands. The objective of the present study was to clarify whether the nerve distribution in the mature salivary glands of rats was affected by a liquid diet. MATERIALS AND METHODS: Seven-week-old male Wistar rats were used in this study. Half of the rats were kept on a pellet diet, and half were kept on a liquid diet, for 3, 7, 14, or 21 days. All rats were euthanised by isoflurane at each endpoint. Then, the parotid and submandibular glands were removed, frozen in liquid nitrogen, cryosectioned, and stained with antibodies against protein gene product 9.5 (PGP 9.5; general nerve marker), tyrosine hydroxylase (TH; sympathetic nerve marker), or neuronal nitric oxide synthase (nNOS; parasympathetic nerve marker). RESULTS: In parotid and submandibular glands of the pellet diet group, PGP 9.5- and TH-like immunoreactivity were seen around acini and ducts, and nNOS-like immunoreactivity was lower than PGP 9.5- and TH-like immunoreactivity. In the parotid glands of the liquid diet group, similar immunoreactivities were seen throughout the experimental period. The distribution of antibody labelling in the submandibular glands of the liquid diet group was similar to that of the pellet diet group and remained unchanged during the experimental period. CONCLUSIONS: The present study demonstrated no regressive effects of a liquid diet on the distribution of sympathetic or parasympathetic nerves in mature parotid glands and submandibular glands. This differed from inhibitory effects on the growth of parotid glands seen during growth periods.

Responses of salivary glands to intake of soft diet.

BACKGROUND: Modernization has made individuals prefer processed and cooked foods (soft food), but this eating habit may have negative effects on the oral cavity. However, laboratory animals fed with soft diet are commonly used in an attempt to clarify this issue, and various oral tissues, including the salivary glands have been examined. In this review, we summarize the findings of previous studies concerning the responses of salivary glands to daily intake of soft diet. HIGHLIGHT: The weight of the parotid glands decreased in rodents fed with soft diet (liquid or powder). In atrophic parotid glands, acinar cell shrinkage is histologically observed and the DNA content is reduced, showing that the atrophy is caused by a decrease in the size and number of acinar cells. Immunohistochemical examinations showed that the decrease in the acinar cell number was induced by suppression of acinar cell proliferation and acceleration of apoptosis. The atrophic parotid glands recovered following a change from soft to pellet diet. Other salivary glands, such as the submandibular, sublingual, and palatine glands, responded only slightly to the soft diet feeding. CONCLUSION: Accumulated research data showed that a soft diet negatively affects the parotid glands much more than other salivary glands and that atrophic parotid glands are able to recover by switching to a hard diet. Therefore, it should be emphasized that good eating habits are important for not only digestion but also the health of oral tissues, including the salivary glands.

Amyloid Variant of Central Odontogenic Fibroma in the Mandible: A Case Report and Literature Review.

BACKGROUND Odontogenic fibroma is a rare mesenchymal odontogenic tumor. It can be classified as central odontogenic fibroma (COF) or peripheral odontogenic fibroma (POF) based on clinical features. There are several variants of COF, including amyloid, ossifying, and giant cell. It grows slowly and exhibits painless cortical expansion of the jawbone. Radiographically, COF appears as a radiolucent unilocular or multilocular lesion with well-defined borders. COF may be associated with unerupted or displaced teeth and root resorption. CASE REPORT A 35-year-old man was referred to our hospital for submandibular swelling. Panoramic radiography and contrast-enhanced computed tomography revealed a unilocular area of bone resorption with a well-defined border and equal enhancement from the canine to first molar on the right side of the mandible. Root resorption of the first premolar and root separation of the first and second premolars were also evident. The lesion was asymptomatic. Histopathological examination of a biopsy of the lesion was suggestive of OF. Enucleation of the tumor, curettage of the bone around the tumor, and extraction of the premolar were then performed. Histopathological examination of the tumor showed fibrous connective tissue with inactive-looking odontogenic epithelial islands and strands, amyloid deposit, intercalation of Langerhans cells into the tumor epithelium, and no calcification. The final diagnosis of amyloid variant of COF was made. The postoperative course is going well. CONCLUSIONS Herein we describe and discuss the clinical, radiological, and pathological features of the amyloid variant of COF. This report will enhance understanding of this extremely rare variant.