骨形成蛋白2基因转染的人牙周膜成纤维细胞的骨诱导作用

目的　建立表达骨形成蛋白2 (BMP-2)的人牙周膜成纤维细胞(HPDLFs),观察其体内成骨作用,为牙周缺损修复基因疗法的建立提供实验依据。方法　采用脂质体载体将人BMP-2噬菌粒表达载体pBK-B2转染至 HPDLFs。利用免疫组化ABC法检测转染细胞内BMP-2蛋白的表达,并于无菌条件下将转染细胞注射于裸鼠股部肌肉内,21 d后取材,苏木精-伊红染色观察肌肉组织内骨形成情况。结果　BMP-2基因转染后HPDLFs内有BMP- 2蛋白的表达。在注射BMP-2基因转染细胞的肌肉组织内可见明显的新骨形成。结论　BMP-2基因成功转入HP- DLFs中并得到有效表达,转染BMP-2基因的HPDLFs能够在体内诱导新骨形成。     

血管内皮生长因子与牙发生发育的关系

血管内皮生长因子（VEGF）不仅在促进血管内皮细胞分裂与增殖、胚胎发生发育、创伤愈合中发挥着重要的作用,而且在骨的生成与改建过程中,成骨细胞来源的VEGF作用于破骨细胞分化使破骨细胞发生趋化,使局部破骨细胞数目增加并促进局部骨吸收。上皮组织与外胚间叶组织的互相作用贯穿于牙胚发生发育到牙体组织形成的整个过程,内外釉上皮细胞与牙乳头细胞分泌的VEGF及其受体互相作用,促进成釉细胞与成牙本质细胞的分化成熟,影响釉质与牙本质的形成。许多与牙发生相关的基因表达于牙胚中央的釉结中,这些基因涉及的信号转导通路也参与牙的发生。VEGF基因表达受到无翅型小鼠乳房肿瘤病毒整合位点家族/β-连环蛋白信号转导通路的调控。目前,有关VEGF和VEGFR在牙胚发生发育中的认识仅仅停留在表观层面,对于功能及调控机制有待深入的研究。     

Rare genetic diseases affecting skeletal development and oral health disparities among children and adolescents: a pathway analysis

Background: To examine the relationships of rare genetic diseases affecting skeletal development, socio-demographic characteristics, and oral health-related behaviours with dental clinical measures in children and adolescents. Methods: A cross-sectional study paired by age, gender and social class included 61 children and adolescents with osteogenesis imperfecta (n = 40) or mucopolysaccharidoses (n = 21) and those without genetic rare diseases (n = 60). Participants were selected at two referral hospitals for rare genetic diseases in the city of Belo Horizonte, Brazil. Caregivers completed a questionnaire to obtain age, gender, caregiver’s schooling, social class, patterns of dental attendance and duration of breastfeeding. Oral hygiene, dental caries, dental anomalies and malocclusion were assessed through dental examinations. The relationships between variables were estimated through Pathway analysis using the maximum likelihood method. Results: Rare genetic diseases affecting skeletal development were directly associated with dental caries (β = 0.22), dental anomalies (β = 0.36) and malocclusion (β = 0.29). They were also inversely linked to a preventive pattern of dental attendance (β = –0.25). Rare genetic diseases affecting skeletal development were associated with poor oral hygiene (β = 0.28) and shorter breastfeeding duration (β = –0.21). Rare genetic diseases affecting skeletal development were linked indirectly with dental caries, a reduced pattern of dental attendance and poor oral hygiene (β = 0.43). Patterns of dental attendance mediated the link between rare genetic diseases affecting skeletal development and malocclusion (β = –0.05). Conclusion: Rare genetic diseases affecting skeletal development were associated with poor oral health. Patterns of dental attendance and poor oral hygiene mediated the link between rare genetic diseases affecting skeletal development and dental clinical measures.Key words: Dental care for disabled, disabled children, rare diseases, oral health, osteogenesis imperfecta, mucopolysaccharidosis     

变速牵引提高牵引成骨效率的实验研究

目的:观察变换速度牵引兔下颌骨15mm后新骨生成的质量,探讨提高牵引成骨效率的方法。方法:新西兰白兔5只,单侧下颌骨截开。延迟5d后,以0.75mm/次、2次/d的速率牵引6d,共9mm;再以0.5mm/次、2次/d的速率牵引6d,共6mm;固定15周,新骨分别行大体、放射学和组织学观察。结果:牵引结束后新骨逐渐成熟,到固定15周时,牵引区新骨与正常骨接近。结论:变速牵引成骨能够保证新骨的良好生成,缩短牵引时间,提高应用效率。     

兔下颌骨牵张成骨模型的建立

目的建立兔下颌骨牵张成骨动物模型。方法随机选取新西兰大白兔28只,施行双侧下颌骨切开术,安放牵张器,间歇1周后以0.4 mm/12 h的速度牵张,牵张7 d后固定,在不同时间随机处死动物2只,取下颌骨标本分别行影像学和组织学观察。结果实验动物均耐受手术,并基本获得预期牵张距离,影像学和组织学观察发现,裂隙内随时间延长渐有骨形成。结论以兔下颌骨建立牵张成骨模型经济、可重复性好。     

定量缓释基因重组碱性成纤维细胞生长因子／聚乳酸-聚羟基乙酸植入片的制备及体外释药研究

目的制备基因重组碱性成纤维细胞生长因子／聚乳酸-聚羟基乙酸（rbFGF／PLGA）定量缓释植入片，观察其一般性质、体外释药特性和rbFGF生物活性维持情况。方法溶剂挥发法制备rbFGF／PLGA植入片，用ELISA双抗体夹心法测定植入片中rbFGF含量，进行体外释药试验，检测rbFGF释放速度和含量，并将植入片植入兔下颌牵张成骨区局部缓慢释放观察rbFGF活性。结果rbFGF／PLGA植入片表面光滑平整，质地均匀，rbFGF含量为3.613μg／片。标准曲线方程为C=1280，54A-99.21（n=7，r^2=0.9952），线性范围15.6，1000pg／ml。植入片体外第1天释放rbFGF 10.70％，第9天累积释放51％，第20天释放达到80％以上。兔下颌牵张成骨实验结果显示植入组新骨形成速度和质量均优于对照组。结论rbFGF／PLGA植入片制备工艺良好，植入片中rbFGF生物活性保存良好，具有定量缓释作用并能促进牵张成骨中新骨形成的速度和质量。     

Stable vertical distraction osteogenesis of highly atrophic mandibles after ablative tumour surgery of the oral cavity – a salvage pathway for mandibular reconstruction prior to oral rehabilitation with dental implants

Mandibular reconstruction is still a challenge for surgeons. Distraction osteogenesis (DO) might contribute in certain instances to solve this problem. A principal advantage of DO is the expansion of the surrounding soft tissues that accompanies the bony regeneration. In addition there is no donor site morbidity when compared with reconstruction by autologous bone grafting. However its application may be limited by the thinness of the mandible and the attendant fracture risk.This article describes a technique that combines stable internal fixation with vertical distraction of the alveolar ridge in six patients with critical mandibular thickness after ablative surgery for cancer of the oral cavity. Prior to implant insertion for further prosthodontic restoration stable vertical mandibular distraction produced an additional 11–20 mm. Improvement of the surrounding soft tissues, especially intraorally was achieved and dental implants were inserted after bony consolidation.This method can be a useful salvage technique for the augmentation of the atrophic mandible in patients who are not able or willing to undergo the risks and disadvantages of established methods such as free autologous bone transfer or microsurgical techniques.     

下颌骨延长术后牵张器拆除时机的实验研究

目的 :研究家兔下颌骨延长术后新生骨回缩情况 ,确定牵张器的拆除时机。方法 :成年家兔 16只 ,体重 2 .4～ 2 .6kg ,随机等分为 4组 ,每组 4只 ;行双侧下颌骨骨切开术 ,采用内置式牵张器对双侧下颌骨同时进行牵引。延迟期 :7d ;牵张期 :10d ;牵引速率 0 .5mm/次 ,2次 /d ;保持期分别为 2周、4周、8周、12周。保持期后行第二次手术取出牵张器 ,并同时植入钛钉为参照 ,判断下颌骨改建后新成骨有无缩短 ,观察期为 8周。结果 :保持期为 2周、4周组的实验动物新生骨在 8周后明显回缩 ,分别为 2 .1± 1.2mm、1.4± 1.3mm ;而保持期 8周、12周组 ,8周后新生骨未见明显回缩。结论 :兔下颌骨牵张延长术后 ,牵张器应在保持期 8周拆除 ;拆除过早 ,新生骨区产生明显回缩。     

The Influence of Surface Roughness on the Displacement of Osteogenic Bone Particles during Placement of Titanium Screw‐Type Implants

Background: Previously, we demonstrated that bone debris, which is translocated during dental implant placement, has osteogenic potential. Therefore, it was hypothesized that implant surface roughness can influence the amount of translocated bone debris/particles and thereby the osteogenic response. Material and Methods: Small titanium implants were left turned (smooth) or blasted and acid etched. The implants were placed in fresh cadaver bone. After explantation, the implants were incubated in a culture medium containing β‐glycerophosphate and dexamethasone up to 24 days. Subsequently, histology, scanning electron microscopy (SEM), DNA analysis, and calcium (Ca) content measurements were performed. Results: For both types of implant during implant placement, bone particles were translocated because of inherent roughness of the implant. SEM and histology confirmed the presence of a bone‐like tissue on the surface of both types of implants, as also confirmed by DNA and Ca measurements. However, the significantly higher roughness of the etched implants accounted for more bone debris and accordingly elevated osteogenic response. Control samples, which had not been placed into bone, did not show mineralization in the same medium. Conclusion: The present study, for the first time, demonstrated that implant surface roughness can increase the amount of the translocated bone particles and thereby also have a beneficial effect on the osteogenic response of these bone particles. It is hypothesized that these bone fragments behave like miniature auto‐grafts and thereby play a significant role to enhance peri‐implant osteogenesis. Optimization of surface topography should be evaluated to take advantage of this additional effect of surface roughness.