Growth hormone regulates nucleolar organizer regions during odontogenesis in the rat

Estimation of silver nucleolar organizer regions in oral lichen planus, oral lichenoid reactions and oral lichenoid dysplasia

Aims and Objective:

(1) To study the clinical and histological features of oral lichen planus, oral lichenoid reaction (OLR) and oral lichenoid dysplasia (OLD). (2) To estimate and compare the silver nucleolar organizer regions in OLR and OLD.

Materials and Methods:

A total of 40 biopsies were studied; sections were divided as study group, which consists of OLP, OLR and OLD each of 10 cases and 10 biopsies of normal oral mucosa as control group. Sections were stained by silver staining technique and total number of silver stained nucleolar organizer regions (AgNORs) were counted in nucleoli of 100 cells in each section under x100 objective (oil immersion).

Results:

Our study revealed that the difference between the (AgNOR) count of OLP (2.272 ± 0.09) and OLR (2.27 ± 0.073) is not statistically significant (P = 0.81). The mean AgNOR count of OLD (2.388 ± 0.043) compared to that of OLP (2.272 ± 0.09) and OLR (2.27 ± 0.073) showed an increase and it is statistically highly significant (P = 0.002 and P = 0.003, respectively).

Conclusion:

AgNOR count is an objective test, which has stronger biological basis for diagnosing epithelial dysplasia. It is easy to perform, inexpensive and is performed on biopsied specimen. However, this technique cannot differentiate OLP and OLR, as there is no much difference in the proliferative activity of cells in these two lesions. It is reasonable to suggest that all biopsy tissues from lichenoid lesions where dysplastic features are observed in routine histopathological sections should be additionally stained by silver technique to ascertain dysplastic status of the lesion.

Clinical Significance:

This is an improved diagnostic parameter, which will help pathologists to formulate more definitive final histopathological diagnosis and will in turn facilitate the formulation of patient treatment and follow-up care by clinicians.

Neuroendocrine alterations impair enamel mineralization, tooth eruption and saliva in rats

Neonatal administration of monosodium glutamate (MSG) in rats causes definite neuroendocrine disturbances which lead to alterations in many organ systems. The possibility that MSG could affect tooth and salivary gland physiology was examined in this paper. Male and female pups were injected subcutaneously with MSG (4 mg/g BW) once a day at the 2nd, 4th, 6th, 8th and 10th day after birth. Control animals were injected with saline, following the same schedule. Lower incisor eruption was determined between the 4th and the 10th postnatal days, and the eruption rate was measured between the 43rd and the 67th days of age. Pilocarpine-stimulated salivary flow was measured at 3 months of age; protein and amylase contents were thereby determined. The animals treated with MSG showed significant reductions in the salivary flow (males, -27%; females, -40%) and in the weight of submandibular glands (about -12%). Body weight reduction was only about 7% for males, and did not vary in females. Saliva of MSG-treated rats had increased concentrations of total proteins and amylase activity. The eruption of lower incisors occurred earlier in MSG-treated rats than in the control group, but on the other hand the eruption rate was significantly slowed down. The incisor microhardness was found to be lower than that of control rats. Our results show that neonatal MSG treatment causes well-defined oral disturbances in adulthood in rats, including salivary flow reduction, which coexisted with unaltered protein synthesis, and disturbances of dental mineralization and eruption. These data support the view that some MSG-sensitive hypothalamic nuclei have an important modulatory effect on the factors which determine caries susceptibility.