Stress corrosion cracking of NiTi in artificial saliva.

OBJECTIVES: This paper aimed to study the mechanism of the cracking of orthodontic NiTi wire. METHODS: Two orthodontic NiTi wires were subjected: (1) optical and scanning electron microscopy (SEM) to observe the fracture surface; (2) energy dispersive X-ray spectroscopy to determine the composition of the surface product; (3) anodic polarization to remove the surface product. Samples of NiTi alloy were subjected to the constant loading test to study the stress corrosion cracking (SCC) behavior of NiTi shape memory alloy in artificial saliva. RESULTS: The results showed that there were three typical areas at the fracture surface of NiTi orthodontic wire. Area '1' was a tool-made notch. Crack initiated from the root of this notch and propagated to form Area '2', which was perpendicular to the wire axis and covered by surface film. This film consisted of Na, K, Cl, P, S and O except Ni and Ti. The cracking process of NiTi alloy under the constant loading test depended on the pH of saliva and applied stress. The crack length was about 262microm, the longest at 300MPa and pH 3.0. SIGNIFICANCE: A tool-made notch in orthodontic NiTi wires can cause SCC. At high stress and low pH, this NiTi alloy was most sensitive to cracking.     

人牙周膜细胞中内源性骨形成蛋白的流式细胞仪分析

目的：定量检测和分析人牙周膜细胞（ＰＤＬＣ）表达内源性骨形成蛋白（ＢＭＰ）的情况。方法：应用ＢＭＰ单克隆抗体，通过流式细胞仪和免疫组化ＡＢＣ的方法双重判定。结果：在离体培养的人ＰＤＬＣ中有一半左右的细胞能表达ＢＭＰ。结论：牙周膜细胞具有一定的合成和分泌ＢＭＰ的能力；可以进一步认为人的牙周膜细胞是具有成骨潜能的，在牙周组织再生中有积极作用。     

Cephalometric errors: A comparison between repeat measurements and retaken radiographs

This study compares landmark location errors in cephalometric radiography (when re-measuring radiographs) and radiographic errors (when retaking the radiograph). The samples comprised 32 remeasured and re-digitized radiographs and a further series of 22 retaken radiographs drawn from the same overall sample of 12-year-old Chinese children in Hong Kong. All radiographs were recorded in natural head posture with the lips in light contact. The relative size of the errors were assessed by calculating the 'error percentage' for both selected dento-skeletal and soft tissue profile measures. It is suggested that this index is clinically more meaningful than the usually used 'method error'. It expresses the variance of the method error (me2) as a percentage of the variance of the measurement under study (standard deviation2). This error percentage was found to be doubled, on average, for measurements on the retaken radiographs. In general, measures with most landmarks in the mid-sagittal plane showed the least increase in percentage error. The results suggest that errors arising from retaking cephalometric radiographs may effectively be greater than those usually reported. The Frankfort plane, the functional occlusal plane and the incisor long axes displayed poor reproducibility. For the soft tissues the lips served as poor angular landmarks and relatively acute angles with short 'arms' also displayed large errors.     

鼻咽镜、阻塞器在治疗腭咽闭合不全中的应用

目的应用鼻咽纤维镜、腭咽阻塞器治疗腭裂术后腭咽闭合不全。方法腭咽闭合不全患者通过鼻咽镜检查，根据腭咽孔大小、形状制作腭咽阻塞器。结果４５例腭咽闭合不全患者经戴阻塞器治疗后，１００％腭咽闭合不全得到改善，其中１５例（３３％）２年后摘掉阻塞器发音正常。结论联合应用鼻咽镜与腭咽阻塞器是保守治疗腭咽闭合不全的好方法     

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。     

Role of type IV collagene and type IV collagenase in the invasion and metastasis of salivary adenoid cystic carcinoma]

Using immunohistochemical ABC method, the authors studied the distribution of type IV collagen and type IV collagenase in 25 cases ACC. The result showed type IV collagen was found in vascular and epithelial basement membrance, and in partly cyst of sieve-like and tubular pattern, and in cytoplasm of tumor cell. Type IV collagenase was detected in membrance and cytoplasm of tumor cell. Expression of type IV collagen and type IV collagenase were correlated with pathologic type, TNM stage and metastasis. Much positive staining of type IV collagen was found in sieve-tubular pattern, early stage of TNM and without metastasis, but much positive staining of type IV collagenase was found in solid pattern, later stage of TNM and metastasis. The result suggested that the loss of type IV collagen and over-expression of type IV collagenase may be markers of malignance of ACC.     

牙龈卟啉菌荚膜的热敏感性

以细胞计数法观察了牙龈卟啉菌荚膜的热敏感性，结果显示：牙龈卟啉菌荚膜在５０℃下，水浴３０ｍｉｎ，活性基本不受影响，６５℃水浴３０ｍｉｎ半量活性成份丧失，８０℃水浴３０ｍｉｎ活性完全丧失，说明牙龈卟啉菌荚膜是一热不稳定性物质。     

Fluoride retention following topical application of a new APF foam

The oral retention of fluoride (F) following the topical application of a newly developed APF foam was compared with a conventional APF gel. Twenty adults aged 16-26 years participated in the study. Ten of the subjects received the F foam and gel treatments, on separate occasions, with a saliva ejector while another 10 subjects received the same treatment without saliva ejector. Approximately 4 g of the gel, and 0.9 g foam, were dispensed for each treatment. The amounts of fluoride applied, recovered from the mouths, and retained in the mouth were calculated for each treatment.     

异种脱细胞真皮基质修复膜在口腔黏膜下纤维性变手术治疗中的应用

目的:评价异种脱细胞真皮基质修复膜在口腔黏膜下纤维性变手术治疗中的应用效果。方法:8例重度口腔黏膜下纤维性变患者,经鼻腔气管插管全麻下切除双侧颊部翼下颌韧带前方区域纵行的纤维条索,术中被动开口度达正常范围后,剪取相应大小的异种脱细胞真皮基质修复膜覆盖黏膜缺损创面,间断缝合后,碘纺纱包加压固定。术后10～14d拆除纱包与缝线后开始开口训练,定期随访并进行类固醇皮质激素黏膜下局部注射等辅助治疗,通过伤口愈合、瘢痕软化及开口度改善等指标评价手术效果。采用SPSS16.0软件包对数据进行单因素方差分析。结果:8例患者双侧颊部纤维条索切除后形成的手术创面,采用异种脱细胞真皮基质修复膜进行修复均获得成功,无感染或排异等并发症发生。术后随访6～18个月,患者颊部原手术区黏膜红润,质地柔软,开口困难明显改善。术前开口度为(12.04±2.93)mm,术中开口度为(35.46±3.17)mm,术后6个月时的开口度为(29.33±4.28)mm,经统计学分析,差异具有显著性(P<0.05)。结论:应用异种脱细胞真皮基质修复膜修复重度口腔黏膜下纤维性变手术治疗中的黏膜缺损创面,能够起到促进创面早期愈合、减轻瘢痕形成与改善开口困难的作用,其操作简单易行,值得临床推广应用。     

Physical properties of a system for direct acquisition of digital intraoral radiographs

Oral Radiology - To determine technical properties for a direct digital intraoral radiographic system, F1iOX (Fimet Oy, Moninkylä, Finland). A dose response function was calculated from seven...