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Molecular and Histomorphometric Changes of Buccal Alveolar Bone After Tooth Extraction

出版	Ohio State University, 2015
URL	http://books.google.com.hk/books?id=yZ7xjgEACAAJ&hl=&source=gbs_api

註釋Objectives: We previously found that tooth extraction during adolescence reduces buccal alveolar bone surface growth. This study evaluated post-extraction changes in molecular expression and histomorphometry of intracortical bone of the buccal plate. Methods: Twelve 3-month-old domestic pigs underwent extraction of a mandibular deciduous second molar. Buccal alveolar bone was collected from extraction and contralateral non-extraction (control) sites 2 hours (immediate group) or 6 weeks (chronic group) after extraction. Specimens harvested from the distal-buccal region were frozen in liquid nitrogen, pulverized, and processed for RNA extraction, which was subsequently quantified for expression of sclerostin (SOST), osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaß ligand (RANKL) using real-time PCR with ß-actin normalization. Specimens from the middle-buccal region were decalcified, sectioned, and stained with H & E, and then used to quantify histmorphometric parameters including bone volume fraction (BV/TV), trabecular thickness (TbTh), trabecular number (TbN), and trabecular separation (TbSp). 2-way MANOVA tests were conducted on both real-time PCR and histomorphometric data in order to examine variations caused by site and time factors as well as the interaction between these two factors. Results: Histomorphometrically, intracortical bone of the buccal plate showed a tendency of higher bone density 6 weeks after tooth extraction compared to the non-extraction site; the chronic extraction group exhibited greater BV/TV and TbTh measurements, but smaller TbN measurements. Molecularly, SOST expression was significantly higher in the chronic group (p=0.027) and significantly lower at the extraction site (p=0.003), which is consistent with the histomorphometric data. Conclusions: During adolescence, single tooth extraction can lead to an increase in intracortical bone density of the buccal alveolar process, which may be a compensatory change for decreased periosteal growth at the buccal surface of the extraction site.