The supernumerary cheek tooth in tabby/EDA mice-a reminiscence of the premolar in mouse ancestors

OBJECTIVE: A supernumerary cheek tooth occurs mesially to the first molar in tabby/EDA (Ta) mice affected by hypohidrotic ectodermal dysplasia. The supernumerary tooth (S) has been hypothetically homologized to the premolar, which has disappeared during mouse evolution. DESIGN: This hypothesis was tested using available morphological data on the lower cheek teeth in wild type (WT) and Ta mice. RESULTS: The presence of S is accompanied by a reduction in the mesial portion of the M(1) in mutant mice. 3D reconstructions suggest that the S in Ta homo/hemizygous embryos originates from a split off the mesial portion of the first molar (M(1)) cap. In WT embryos, two vestigial tooth primordia are transiently distinct in front of the M(1). The distal vestige has the form of a wide bud and participates during the development of the mesial portion of the M(1). This bud has been homologized with the vestigial primordium of the fourth premolar of mouse ancestors. The premolar disappearance coincided with a mesial lengthening of the M(1) during mouse evolution. The incorporation of the distal premolar vestige into the mesial part of the M(1) in WT embryos can be regarded as a repetition of the premolar disappearance during evolution. CONCLUSION:: Ontogenetic and phylogenetic data support that the S in Ta mice arises due to the segregation of the distal premolar vestige from the molar dentition and thus represents an evolutionary throwback (atavism).     

快速液压热聚合义齿基托材料的实验研究

目的 了解快速液压热聚合义齿基托材料的力学性能。方法 采用自行研制的新型液压自控牙用树脂聚合器和常规水浴两种方法加热固化义齿基托材料，进行挠度、抗弯曲强度、弹性模量、抗冲击强度及硬度的对比分折。结果 快速液压热聚合义齿基托材料的力学性能与水浴法相比无显著性差异，但可以明显缩短热处理时间且全过程自动完成。结论 快速新型液压自控牙用树脂聚合器简化了义齿制作的操作过程，明显缩短了热处理时间，可以准确快速制作出理想的义齿。     

正畸力作用下大鼠牙周组织中表皮生长因子的表达

目的 检测正畸力作用下大鼠牙周组织中表皮生长因子（epidermal growth factor,EGF)及其受体的表达与分布，探讨EGF在正畸牙移动过程中的作用及机制。方法 建立大鼠正畸牙移动模型，分别在受力24h及168h处死，制备左侧上颌第一磨牙及牙周组织的石蜡标本，采用免疫组化HI－SABC法进行检测。结果 EGF与EGFR在正畸组大鼠牙周组织中的表达明显强于对照组（P＜0.01)，受力168h组EGF及EGFR表达的强度高于受力24h组（P＜0.01)；同时间组中，张力侧EGF及EGFR的表达高于压力侧（P＜0.01)；EGF、EGFR在正畸组中的表达主要是位于近远中向的张、压力侧，而生理状态下主要位于根尖及根分叉区的牙周膜。结论 正畸牙移动过程中EGF、EGFR的表达有所增强，提示EGF可能参与了正畸牙移动，并且更多地促进了正畸牙骨改建中的骨形成过程。     

Gingival fibroblast response to cyclosporin A and transforming growth factor β1

This study investigates a potential role for TGFβ₁ in the pathogenesis of cyclosporin A-induced gingival overgrowth (CsA-OG). TGFβ₁ was localized immunohistochemically in the connective tissue of both normal gingiva and CsA-OG. Intense staining for TGFβ₁ was detected at the tips of the dermal papillae of the overgrown gingiva. In addition, fibroblasts derived from healthy gingiva and fibroblasts derived from CsA-OG were cultured both as monolayers or embedded in a 3D-collagen gel. Fibroblast activity was monitored in terms of protein and collagen production in the presence of (i) 1 ng/ml TGFβ₁ (ii) 500 ng/ml CsA, or (iii) 500 ng/ml CsA and 1 ng/ml TGFβ₁. In monolayer culture TGFβ₁ significantly increased protein and collagen production in all cell strains (p<0.05); however, there was no difference in response between fibroblasts from overgrown and healthy tissue. The production of both protein and collagen was significantly lower in the presence of the combination of CsA and TGFβ₁ when compared with the maximal stimulation produced by TGFβ₁ alone. In gel, TGFβ₁ significantly elevated matrix production by all overgrown cell strains (p<0.05) but had little or no effect on the normal cell strains. The combination of CsA and TGFβ₁ in gel cultures reduced protein and collagen production by overgrown cell strains compared with TGFβ¹ alone. It is concluded that the cellular activity of gingival fibroblasts is dependant on culture conditions and that fibroblasts derived from overgrown gingival tissue are more responsive to TGFβ₁ than normal gingival fibroblasts when cultured in type I collagen gel.     

器官培养中骨吸收因子的相互作用

为了研究不同浓度脂多糖（ｌｉｐｏｐｏｌｙｓａｃｃｈａｒｉｄｅ，ＬＰＳ）、脂磷壁酸（ｌｉｐｏｔｅｉｃｈｏｉｃａｃｉｄ，ＬＴＡ）、肿瘤坏死因子（ｔｕｍｏｕｒｎｅｃｒｏｓｉｓｆａｃｔｏｒ，ＴＮＦ）及前列腺素Ｅ（ｐｒｏｓｔａｇｌａｎｄｉｎＥ，ＰＧＥ）的骨吸收作用和相互作用，采用４５Ｃａ标记的１９天胚胎鼠长骨干器官培养，用样品道比法定量分析。结果表明，上述因子均能在器官培养水平刺激骨吸收，与对照组相比差异有显著性（Ｐ＜０．０５）。低浓度的ＬＰＳ与ＴＮＦ、ＬＰＳ与ＰＧＥ、ＴＮＦ与ＰＧＥ相互作用，超过各因子单独作用之和（期望值）；ＬＰＳ与ＬＴＡ、ＴＮＦ与ＬＴＡ相互作用，等于期望值；而ＬＴＡ与ＰＧＥ相互作用，小于期望值。研究结果提示，多种骨吸收因子的相互作用在牙周病骨吸收发病机理中有重要意义。     

变速牵引成骨对兔下牙槽神经的影响

目的　研究变速牵引兔下颌骨15mm对下牙槽神经的影响。方法　5只新西兰白兔单侧下颌骨截开。延迟5d ,以每天1 5mm ,每天2次牵引9mm ,然后继续以每天1mm ,每天2次牵引6mm ,完成牵引后固定15周,分别行肉眼及组织学观察和电生理学检查。结果　下颌骨延长15mm ,新骨生成良好。下牙槽神经牵长2 1. 99% ,牵引结束时神经变性明显,感觉神经动作电位波幅下降为术前的9. 70 % ,潜伏期较术前有所延长,随后出现恢复趋势,到固定15周时,波幅恢复到术前的33. 85 % ,潜伏期基本恢复正常。结论　下颌骨变速牵引15mm后,下牙槽神经受到明显的影响,到15周时,下牙槽神经的功能有恢复的趋势,但恢复尚不完全。     

不同浓度bFGF对犬骨髓基质细胞增殖、分化影响的实验研究

目的：研究不同浓度的碱性成纤维细胞生长因子（basic fibroblast growth factot,bFGF）对体外培养的beagle犬骨髓基质细胞（bone marrow stromal ceils，BMSCs）增殖和分化的影响。方法：体外培养第2代BMSCs的培养液中分别加入不同浓度（25、50、100、200ng／mL）的bFGF，连续6d倒置显微镜下动态观察BMSCs的形态和生长情况．行MTT比色、碱性磷酸酶（alkalin ephosphatase，ALP）活性定量检测、ALP和Von Kossa染色。结果：浓度为50ng／mL的bFGF可明显促进犬的BMSCs增殖（P〈0．05），但无显著促进犬BMSCs分化的作用（P〉0．051。结论：bFGF能有效促进犬BMSCs的增殖，且与bFGF剂量有关。     

引导组织和骨组织再生术及其生长因子在牙周骨缺损治疗中的应用

引导组织再生术和引导骨再生术广泛用于牙周骨缺损的治疗中,给牙周组织再生开辟了广泛的空间,但二者单独使用却存在一定的局限性。因此,目前的研究多趋向于将骨移植材料和膜材料与多肽生长因子联合应用于牙周骨缺损的修复。下面就引导组织再生膜材料、引导骨再生支架材料和碱性成纤维细胞生长因子的理化性质、生物学功能,以及三者联合应用于牙周骨缺损治疗中的作用作一综述。     

Is the oral health impact profile measuring up? Investigating the scale’s construct validity using structural equation modelling

Abstract – Objectives: The aim of the study was to provide an empirical test of the construct validity of the Oral Health Impact Profile as a measure of Locker’s conceptual model of oral health. Methods: A secondary analysis of data from the Ontario Study of Older Adults was carried out using structural equation modelling to assess the degree to which scale items measured the construct they were supposed to measure (within‐construct validity) and whether relations between constructs were as hypothesized by Locker’s model (between‐construct validity). Results: The findings indicated that the Oral Health Impact Profile as currently conceived does not have adequate within‐construct validity. Scale items did not always measure the construct they were supposed to measure, some items within a construct were redundant, many measured more than one construct, and the scale did not represent seven separate constructs of oral health as originally devised. Following reconceptualization of the scale, the revised six‐factor 22 item version was a better fit to the data. However, the scale did not have adequate between‐construct validity. Conclusion: The present findings do not provide support for the conceptual basis of the Oral Health Impact Profile as a measure of Locker’s model of oral health. The need for further conceptual development of the scale, and Locker’s model, are discussed.