Alveolar bone remodeling after tooth extraction in irradiated mandible: An experimental study with canine model.

OBJECTIVES: The aim of the present study is to investigate the morphological and cellular changes in dental extraction socket that has been irradiated after the tooth extraction and to describe morphological characteristics of the osteocytes and osteocyte-lacunar-canalicular network (LCN) by scanning electron microscopy (SEM). MATERIAL AND METHODS: Five beagle dogs aged 1-2 years were used in this study. One side of each mandible was irradiated in two sessions and the other side of mandible (non-irradiated) served as a control. The mandible bone blocks were processed by bulk staining en bloc in basic fuchsin and the specimens were embedded routinely in polymethyl methacrylate resin without preliminary decalcification. All blocks were subjected to micro-CT imaging, after that the specimens were prepared for light microscopy and SEM. RESULTS: Alterations in bone macrostructure are minimal in irradiated bone, but the changes in LCN are clear. In the area of the tooth extraction socket, the connections of osteocytes to the vessels and to neighboring osteocytes were not observed both in irradiated and nonirradiated bone. However, osteoclasts were located in the bone surface entering inside to the bone between osteons. In the lamellar bone of lateral sides, a decrease in canalicular connections between osteocytes and periosteum was found in irradiated bone as compared to the non-irradiated side. CONCLUSIONS: The novelty of the present study is that radiation disrupts osteocytes and their dendrites.

Microstructure of the superficial epithelial cells of the human oral mucosa.

BACKGROUND: The apical cell membrane of the oral mucosa adjacent to the saliva interface is thrown into membrane folds, termed microplicae (MPL) with variation in morphology. The present study classifies morphological changes undergone by MPL into qualitative and quantitative categories. MATERIAL AND METHODS: Oral mucosal specimens were obtained from 32 healthy patients. Half of each specimen was prepared routinely for light microscopy, and the other part for scanning and transmission electron microscopy. Different measurements of cell structure were presented: the density of MPL, the width and height of MPL, the width of furrows between two adjacent MPL and the distance of the centre of MPL. Morphometric measurements were obtained using a semiautomatic ImageJ analysis software (W Rasband, National Institutes of Health, Bethesda, MD). RESULTS: Parallel and branching MPL was common observation in the area of lining mucosa and in the tongue between the filiform papillae. The density of MPL was higher in the cells of the buccal mucosa than in the cells of the tongue, 43.69 + 11.43% and 31.68 + 10.32%, respectively. The difference was significant (p < 0.001). The width of MPL was 0.16 µm in cells of the buccal mucosa and 0.12 µm in cells of the tongue. CONCLUSIONS: Our findings support the idea that MPL structure is a determining factor for the functionality of the oral epithelium since the values of the MPL were kept relatively stable. The role of MPL structure of the oral mucosal cells is discussed.