Study of the location of mandibular mental foremen in modern and neolithic adult]

37 cases of mandible of Neolithic adult that both sexes without missing teeth,alveolar bone were studied.The result showed that the location of the mental foramen below the apex of the lower second premolar was the most common(67.97%) in the modern adult,and the location of the mental foramen below between the apex of the lower second premolar and the first molar was the most common (64.86%) in the neolithic adult.     

Surface alteration of human tooth enamel subjected to acidic and neutral 30% hydrogen peroxide

Objectives

To investigate the effects of acidic and neutral 30% hydrogen peroxide (HP) on human tooth enamel in terms of chemical structure, mechanical property, surface morphology and tooth colour.

Methods

Twenty-seven human dental blocks were obtained from premolars and randomly divided into three groups (n = 9): Group acidic HP (30% HP, pH ≈ 3.6), Group neutral HP (30% HP, pH ≈ 7.0) and Group DW (distilled water, pH ≈ 6.8). Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, atomic force microscopy (AFM) investigation, microhardness test and colour measurements were carried out before and after treatments. ATR-FTIR and Raman spectroscopy were analysed and then the carbonate:mineral ratio (C:M), Raman absolute intensity (RAI), Raman relative intensity (RRI), and laser-induced fluorescence intensity (FI) were obtained for evaluation.

Results

The C:M, percentage microhardness and percentage RRI of group acidic HP decreased more significantly than those of group neutral HP (P = 0.02, P = 0.001, P < 0.001, respectively) and group DW (P = 0.01, P = 0.008, P < 0.001, respectively). Whilst group neutral HP and group DW had no statistical difference in above terms (P = 0.818, P = 0.528, P = 0.158, respectively). Significant morphological alterations were observed in group acidic HP. Group acidic HP and neutral HP had no significant difference in percentage FI (P = 0.652) and ΔE (P = 0.906).

Conclusions

This study suggested that neutral 30% HP had the same efficiency in tooth bleaching and it caused less deleterious effects on enamel than acidic 30% HP.     

Evidence of chemisorption of maleic acid to enamel and hydroxyapatite

Maleic acid has been used as an etchant or non-rinse conditioner in adhesive dentistry. However, the inherent mechanisms of the interaction of maleic acid with hydroxyapatite/enamel have never been fully elucidated. The purpose of this study was to provide evidence for the chemisorption of maleic acid onto hydroxyapatite/enamel, and to identify the reaction products obtained following the interaction of maleic acid with hydroxyapatite. Hydroxyapatite particles were dissolved in a 15% (w/v) aqueous solution of maleic acid (pH = 0.98). Half of the solution was dried to obtain a desiccated mixture. This mixture, hydroxyapatite, maleic acid and self-prepared calcium maleate were analysed by X-ray diffraction (XRD). Acetone was added to the other half of the solution to obtain a precipitate. This precipitate, hydroxyapatite, maleic acid, unetched enamel and maleic acid-etched enamel were analysed by X-ray photoelectron spectroscopy (XPS). The precipitate was also analysed by (1)H NMR. A new binding energy, indicating carboxylate groups, was detected by XPS on the precipitate and maleic acid-etched enamel surface. XRD data indicated the formation of calcium maleate and calcium hydrogen phosphate after the reaction. NMR data revealed that one carboxylic group of maleic acid reacted with hydroxyapatite. Hence, maleic acid can chemisorb to hydroxyapatite and enamel via ionic interactions.     

涎腺肌上皮癌的生物学行为及治疗

为了总结涎腺肌上皮癌的生物学行为及有效治疗，作者对１９例涎腺肌上皮癌患者进行临床分析，其临床特点为：发病部位以腮腺为最常见，其次为腭部；部分肿瘤生长迅速，广泛侵犯周围组织；颈部淋巴结转移率不很高，但血行性转移率高；治疗后极易复发；患者预后差。其生物学行为属高度恶性肿瘤。治疗以根治性切除为主，原则上不作选择性颈淋巴清扫术；放射治疗不敏感。对于局限性肿瘤复发灶及时手术可获得较好的效果。     

介绍一种新型口腔正畸托槽定位安放器

研制托槽安放、定位功能融为一体的正畸器械。此新型器械使托槽安放及定位一次完成，取消安放托槽后再进行定位这一破坏粘结强度的步骤，操作方便，值得临床推广应用。     

多孔TiNi合金牙种植材料的制备及性能检测

目的 制备多孔TiNi合金牙种植材料,为该合金进一步进行动物实验及临床应用提供实验依据.方法 采用添加氢化钛和碳酸氢铵做为造孔剂,模压成型(200 MPa),真空烧结.对烧结后的试样进行XRD物相分析、显微观测以及能谱分析.结果 XRD物相分析表明,Ti-Ni合金试样中主要有TiNi、Ti2Ni、TiNi3三相.在烧结工艺相同的情况下,钛含量不同的试样孔隙的数量、大小、均匀程度都相差不多.结论 TiNi合金种植体制备成三维多孔结构是可行的.     

锥形束CT在治疗上颌前牙区埋伏牙中的应用

目的:探讨锥形束CT(CBCT)在治疗上颌前牙区埋伏牙中的临床应用价值。方法:收集我院2009—2010年经普通X线片确定有埋伏牙,但不易具体定位的患者11例,进行CBCT扫描和三维重建,确定埋伏牙在颌骨内的具体位置。结果:经CBCT扫描、三维重建后,所有患者均可直观再现埋伏牙的形态、数目、在颌骨中的具体位置和发育情况。11例患者共16颗埋伏牙,其中既有埋伏阻生牙又有埋伏多生牙,3例(4颗)为埋伏多生牙,1例有2颗埋伏牙;2例为倒置埋伏,2例为水平埋伏,3例为垂直埋伏,4例为斜位埋伏。根据CBCT结果制订治疗方案,获得满意的治疗效果。结论:CBCT三维重建对于上颌前牙区埋伏牙治疗方案的设计及实施具有重要意义。     

牙体预备对牙龈结合上皮损伤后的超微结构观察

目的 :研究烤瓷修复体牙体预备对牙龈结合上皮损伤后 ,牙龈结合上皮在透射电镜下形态学变化的特点。方法 :将 16只家兔的 3 2颗上前牙分别用金刚砂车针和手术刀破坏左侧上前牙的牙龈结合上皮 (JE) ,以右侧同名牙为对照 ,分别于 1、2周取材 ,利用透射电镜观察结合上皮的组织学改变 ,并对 2实验组进行对比观察。结果 :金刚砂车针处理组和手术刀处理组 2周后牙龈结合上皮附着恢复 ,两处理组无明显差别 ,与未经手术处理的JE比较 ,处理组主要超微结构变化是线粒体空泡化 ,基膜不完整。结论 :牙体预备对牙龈结合上皮的损伤 ,可导致结合上皮的超微结构改变     

烤瓷固定基底桥CAD系统标准桥体数据库的研究

目的:建立烤瓷固定基底桥标准桥体三维图形数据库,为基底桥的计算机辅助设计提供基础数据。方法:在Surfacer10.5软件平台上,对国人标准牙冠进行编辑和修改,平缓后牙面和前牙舌面上过陡的沟、窝、尖、嵴,定量预留外部瓷层三维空间。结果:创建了28颗恒牙烤瓷固定基底桥标准桥体三维图形数据库,编辑完成的桥体表面光顺,结构平缓,预留的瓷层空间均匀,符合临床要求。结论:数据库中的标准桥体数据是烤瓷固定基底桥CAD的模板,为自主开发烤瓷固定基底桥CAD/CAM系统奠定了基础。