Variability in the Epithelial Expression of Ki67 and Polarization Characteristics of Collagen in Odontogenic Cysts and Tumours

ABSTRACT Objective: To assess the proliferation of epithelium (using the Ki67 index) and the polarization pattern of collagen in selected odontogenic cysts and tumours. In addition, an exploratory analysis of the effect of inflammation on the proliferation rate was done. Material and Methods: Following immunohistochemical staining, the labelling/proliferation index of Ki67 was calculated. The thickness and corresponding polarization colour of 100 juxta-epithelial picrosirius red-stained collagen fibers were assessed using linear micrometry with an eyepiece reticule under × 1000 magnification. Inflammation was graded subjectively as mild, moderate, and severe. Results: Overall Ki-67 expression was higher in the radicular cyst, Odontogenic Keratocyst, Ameloblastoma, while suprabasal Ki-67 positivity was maximum in Odontogenic Keratocyst. The stromal collagen fibers in Ameloblastoma showed predominantly green birefringence, whereas Odontogenic Keratocyst had orange birefringence. There was no significant association of inflammation with Ki-67 expression or birefringence patterns. Conclusion: The highest Ki67 expression in the radicular cyst, followed by Odontogenic Keratocyst and Ameloblastoma. Differences in the collagen maturation pattern were noted innately in five lesions studied and were further influenced by inflammatory changes. Epithelial proliferation and concomitant expression of thickness and maturity of the stromal collagen are innate features of the lesion further influenced by inflammation in various odontogenic cysts and tumours and may, in turn, guide the clinical behavior.

An unusual case of non-syndromic occurrence of multiple dental anomalies.

Dental anomalies have been known to occur in humans due to a variety of genetic and environmental factors. Combinations of dental anomalies are known to be associated with specific syndromes. A few cases of multiple dental anomalies have been reported in patients with no generalized abnormalities. This case report describes an unusual occurrence of a combination of dental anomalies in an apparently normal healthy 12-year-old female patient. The dental anomalies in this patient were multiple dens invaginatus, generalized enamel hypoplasia, generalized microdontia, root resorption and multiple periapical lesions, shovel shaped incisors, cup shaped premolars, taurodontism, hypodontia and supernumerary teeth.

Quantitative role of mast cells in odontogenic cystic enlargement

Aim: Mast cells have been hypothesized to play a significant role in pathogenesis of odontogenic cysts. The aim of this study was to evaluate mast cell distribution in cystic lining and the capsule to formulate a mechanism of cystic expansion. Methods: Ten formalin-fixed paraffin embedded tissue blocks each of OKC, dentigerous and radicular cysts were selected. Toluidine blue staining (1% in 1% NaCl solution) was done in 5µm thick sections and counting performed in 10 areas using an ocular grid. Areas counted were divided into 4 zones: intraepithelial, subepithelial, intermediate and deep zones (Group I, II, III and IV respectively). Statistical analysis: Mean ±S.D. was calculated in each group followed by paired ‘T’ test. Results: Mast cells had greatest concentration in subepithelial zone. ‘T’ test showed no significant differences between group I and II zones in OKC but a highly significant difference between groups I and II in dentigerous cyst. Radicular cysts showed a significant difference between groups II and III. Conclusion: Mast cell degranulation releases numerous hydrolytic enzymes that facilitate breakdown of capsular matrix increasing the hydrostatic pressure due to raised osmolality. Influx of tissue fluids results in their enlargement coupled with resorption at the bone-cyst interface.

Glass embedded in labial mucosa for 20 years.

Foreign bodies may be deposited in the oral cavity either by traumatic injury or iatrogenically. Among the commonly encountered iatrogenic foreign bodies are restorative materials like amalgam, obturation materials, broken instruments, needles, etc. Few reports of glass pieces embedded in the soft tissues of the mouth have been published. We report a case where glass pieces had been lodged in the lower labial mucosa for 20 years, with consequent peripheral reactive bone formation.