ABSTRACT
<p><b>OBJECTIVE</b>This study aimed to evaluate the morphometric changes in the alveolar bone of the maxillary and mandibular anterior regions after retraction in adolescents.</p><p><b>METHODS</b>The sample size comprised 30 adolescent patients with class 1 bimaxillary protrusion (12 males and 18 females, age: 12-18 years old) and were treated by extracting four first pre-molars. Cone beam computed tomography (CBCT) was performed 1 month before and 1 month after the retraction. For each maxillary and mandibular anterior tooth, the labial and palatal alveolar plates at cervical 1/3, middle 1/3, and apical 1/3 levels for bone thickness changes during the retraction of the maxillary and mandibular anterior regions were checked. The movements of cervical 1/3, middle 1/3, and apical 1/3 levels of the maxillary central incisor were measured. Statistical analyses were performed with SPSS 16.0.</p><p><b>RESULTS</b>For the adolescents, alveolar bone thickness increased on the labial side and decreased on the palatal side. The alveolar bone thicknesses of cervical 1/3 and middle 1/3 of maxillary central incisor, cervical 1/3 and apical 1/3 of maxillary lateral incisor, middle 1/3 of mandibular central incisor, apical 1/3 of mandibular lateral incisor, and middle 1/3 and apical 1/3 of mandibular canine all increased after retraction. By contrast, the alveolar bone thickness of the apical 1/3 of maxillary canine and the cervical 1/3 of mandibular canine decreased after retraction. No statistically significant difference was observed in other region.</p><p><b>CONCLUSION</b>During retraction, a controlled tipping movement occur in adolescents. After retraction, the alveolar bone thickness of the labial side increase, whereas that of the palatal side decrease. Moreover, the thicknesses of major areas in the alveolar bone significantly increase.</p>
Subject(s)
Adolescent , Child , Female , Humans , Male , Cone-Beam Computed Tomography , Cuspid , Incisor , Maxilla , Molar , Palate , Tooth Movement TechniquesABSTRACT
BACKGROUND: It remains unclear whether ectomesenchymal cells also derived from neural crest stem cell in mammals.OBJECTIVE: To understand the specific markers and differentiation directions of maxillofacial and mandibular processes progenitor cells,and to explore the source and differentiation phenotype of ectomesenchymal stem cells.METHODS: The expression and changes of expression profiles of rat ectomesenchymal cells at E9.5,E10.5,E11.5,and E12.5days were observed by immunohistochemistry and flow cytometry.RESULTS AND CONCLUSION: The progenitors expressed multi-lineage markers,including neural system and several rnesenchymal tissue types,importantly the facts that molecule profiles were changed with time prolonged,suggesting these progenitors were in active differentiating stage,so they were stem like cells or contain stem like cells.Moreover,small populations(2%-3%)of CD57 and P75 phenotypes were detected by flow cytornetry,suggesting that ectomesenchymal stem cells were derived from neural crest,which maintained a quantitative stabilization though it is gradually differentiate after localization.
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Objective:To study the function of ectomesenchymal stem cells(EMSC) in periapical tissues regeneration. Methods:Tissue engineering technique was applied to compose EMSC-ceramic bovine bone for repairing of a Sprague-Dawley rat model of the periapical tissues defects. Results were observed by HE staining. Results:New pulp-cement like structures were formed and the result of experimental group was better than that of control group. Conclusion: EMSC participates in the process of the periapical tissues regeneration.
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Objective:To observe the structure and formation of plaque.Methods: A 1 mm in heigth and 3 mm in diameter plastic ring was adhered to enamel slice, then the enamel slices with plastic rings were adhered to right maxillary first molars in order to establish the model of dental plaque.The specimens of dental plaque for 1 day, 5 days and 9 days were serially sectioned and were imaged by TEM. Results:The TEM results showed that there were few microorganisms in early plaques, mainly of which were coccus. With the time went on, the kind and quantity of the microorganisms became more, and bacilli and hyphomycetes also appeared. In mature plaques, there were fence-like structure with coccus in center and bacilli and hyphomyceters at both sides, in which some bacteria went to necrosis. Conclusion:The ultrasrtucture of this dental plaque model was similar to nature's with a certain extent values.