The early development of palatal rugae in the rat

The palatal rugae in rats are contained in two of three zones of morpho-differentiation and develop around the time of palatal closure. Previous studies in humans and pigs have been based on crown-rump lengths but now controlled breeding in rats has allowed exact timing to be established. Twenty-nine female DB IX rats were fertilized and sacrificed in a controlled procedure and foetuses processed for light microscopy and SEM. Serial sagittal sections were made and stained with haematoxylin and eosin and Verhoef's stains. At day 13 the palate was open and no rugae were visible. At day 14 the palatal shelves had started to migrate medially and the ante-molar rugae appeared. At day 15 the palatal shelves were touching and the inter-molar rugae became visible, and at day 16 fusion was all but complete and the definitive rugal pattern established. The development and differentiation is more advanced than in humans and it is concluded that the rugae probably have a role to play in the oral function of animals whereas in humans they are becoming attenuated and the development timetable is retarded because of redundancy.     

纯钛锥状螺旋型种植体在下颌骨骨折中的应用

采用锥状螺旋型人工牙种植体时对10例下颌骨骨折患者进行了骨折内固定手术，固定骨折18处，植入牙种植体18枚，最小年龄16岁，最大年龄56岁。术后经过3—12个月随访，病例全部成功，骨折愈合良好，咬合关系恢复正常，术区无不良反应，作者讨论了固定手术方法。     

异种烧结骨修复颌骨缺损的临床观察

本文报告了应用异种烧结骨修复颌骨缺损25例,采用手术前后X线及免疫学、r骨显像等观察,进行了较系统的临床研究.经6～12个月追踪观察,结果表明:创口愈合正常,未见免疫排斥反应.术后3周左右植骨成活,2～3个月有新骨形成、与空白对照组比较,烧结骨有明显加快骨缺损部位成骨作用,新生骨出现早,成骨速度快.证实烧结骨具有良好的组织相容性和骨传导能力,具有较高的临床实用性,是一种较理想的骨移植材料.     

A model of periodontitis in the rat: effect of lipopolysaccharide on bone resorption, osteoclast activity, and local peptidergic innervation

OBJECTIVE: To establish and characterise a rat model of periodontitis that reiterates the features of human disease. METHODS: Periodontal inflammation was induced by a single injection of 10 microg liposaccharide (LPS) (Salmonella typhimurium) in 1 microl saline into rat mandibular gingiva at the buccomesial aspect of the second molar. Animals were killed after 3, 7 and 10 days, mandibles dissected and sectioned for histological and immunocytochemical analysis. RESULTS: LPS injection resulted in a significant gingival and periodontal inflammation with inflammatory infiltrate, apical migration of the junctional epithelium, interdental bone loss, and activation of osteoclasts at the site of injection 7 and 10 days after injection. At 10 days post injection, there was a significant trend for bone loss on both sides of the mandible. Periodontal inflammation was associated with alteration in the levels of calcitonin gene-related peptide-like immunoreactivity in nerve terminals innervating the inflamed gingival papilla. CONCLUSION: Intragingival injection of LPS in the rat provides an easily induced reproducible experimental model of periodontal inflammation that reiterates features of human disease.     

A case of Burkitt's lymphoma that presented initially with resorption of alveolar bone

A 16-year-old male was evaluated for a 1-month history of alveolar bone resorption, which had been treated with endodontics by a neighborhood dentist. Intraoral examination showed slight gingival swelling and teeth mobility. However, no tumor mass was seen. The panoramic image showed resorption of alveolar bone and loss of teeth lamina dura. Because he complained of general fatigue, he was introduced to the internist. Biopsies of gingiva and bone marrow aspiration revealed a massive proliferation of lymphoblasts expressing CD10, 19, 20 and HLA-DR antigens on the surface. Their karyotypes were abnormal; 46, XY, t (8;14) (q24;q32). Accordingly, he was diagnosed as Burkitt's lymphoma, and received intensive chemotherapy which relieved his symptoms and decreased his tumor. However, his disease soon became refractory to chemotherapy, and he died 11 weeks after the onset.     

Influence of smoking on the outcome of periodontal surgery

Abstract. The 5-year outcome following periodontal surgery was evaluated in 57 patients that had received regular maintenance care throughout the follow-up period. The study population included 20 smokers, 20 former smokers and 17 non-smokers in the age range 37–77 years. The clinical characteristics evaluated were supragingival plaque, gingival bleeding and pocket probing depth. The region assigned for surgery was, in addition, radiographically evaluated in terms of periodontal bone height. Furthermore, the occurrence of the periopathogens Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg) and Prevotella intermedia (Pi) and the gingival crevicular fluid (GCF) levels of tumor necrosis factor alpha (TNF-α) were assessed at follow-up. Plaque index was 28.5% at baseline and 32.9% at follow-up, indicating a good standard of oral hygiene, and gingival bleeding 31.7% and 24.9%, respectively, suggesting a low to moderate level of gingival inflammation. In regions assigned for surgery, pocket probing depth decreased significantly from on average 5.6 mm to 4.3 mm ( p <0.0001) and periodontal bone height increased significantly from on average 62.5% to 67.5% ( p <0.0001). In terms of bone height, the outcome was less favorable among smokers compared with non-smokers. There was a predominance of smokers among patients exhibiting loss of bone height after the 5 years of maintenance. No significant associations were found between the therapeutical outcome and supragingival plaque or subgingival occurrence of periopathogens. The associations between GCF levels of TNF-α and probing depth and bone height were unclear, whereas the level of TNF-α was significantly elevated in smokers.     

Immunoexpression of extracellular matrix proteins in human salivary gland development

Immunoexpression of the extracellular matrix (ECM) proteins laminin, fibronectin, tenascin and types I, III and IV collagen was analyzed in the major and minor salivary glands of seven human fetuses at different gestational ages. The results showed the presence and localization of laminin, collagen IV and fibronectin around glandular structures at all stages of development. Tenascin was only detectable around excretory ducts. In the earliest stages of development, type I and type III collagen were presented as fine fibers delineating the glandular structures and delimiting the extension of the future lobule. As glandular development proceeded, the lobule was gradually filled with collagens and glandular tissue.     

糖皮质激素性骨质疏松与口腔疾病

随着糖皮质激素在临床上的广泛应用,糖皮质激素性骨质疏松症发病率明显增加。口腔颌面部作为全身骨组织的重要组成部分,其与糖皮质激素性骨质疏松的联系也日益受到关注。该文就国内外有关糖皮质激素性骨质疏松对颌骨、牙槽骨、牙齿的影响,以及其与牙周炎、牙种植和口腔正畸治疗的关系等方面的研究状况作一综述。     

Probabilistic analysis of peri-implant strain predictions as influenced by uncertainties in bone properties and occlusal forces

OBJECTIVES: The purpose of this study was to examine the influence of variability in bone properties and loading on peri-implant crestal and cancellous bone strains using a probabilistic approach, in combination with finite element (FE) analysis. MATERIAL AND METHODS: Oblique occlusal loading was applied to a single endosseous implant embedded in a two-dimensional (2-D) FE model of a premolar section of a mandible. Perfect bonding was assumed at all interfaces. Five independent parameters (cortical bone thickness (T), cortical (ECORT) and cancellous (ECANC) bone Young's moduli, and vertical (FVERT) and horizontal (FHOR) occlusal forces) were assigned statistical distributions based on data in the literature. Two cancellous bone distribution models were examined, one with a lower mean and range (LM) and the second with a higher mean and range (HM) of cancellous bone Young's modulus values. Sets of randomly chosen values for the five parameters were selected from the distributions and FE analyses were performed for all randomly selected sets. RESULTS: In the LM model, 50% of the cases experienced hyper-physiologic peri-implant crestal strains in the region of commonly reported saucerization, compared with about 25% of the cases in the HM model. Relative probabilistic sensitivities (%) of bone strains to the independent input parameters (T, ECORT, ECANC, FVERT and FHOR) were as follows: 29, 11, 30, 13, and 17 for the LM model, and 17, 11, 35, 21, and 15 for the HM model, respectively. CONCLUSION: Probabilistic analyses of FE models suggest that up to twice as many cases in the LM distribution may be at risk of saucerization as compared with the HM distribution model. Although based on hypothetical distribution values and the limitations inherent to a 2-D analysis, this probabilistic study demonstrated that FE models are very sensitive to the often arbitrarily assigned values for cancellous bone Young's modulus, and also to values used for cortical bone thickness, when the cancellous bone modulus is low.