静电纺聚乳酸-乙醇酸·蛋壳膜蛋白纤维膜体外降解性能的研究

目的:观察静电纺聚乳酸-乙醇酸.蛋壳膜蛋白(PLGA.SEP)混合纤维膜在体外降解过程中结构、性能的变化。方法:采用静电纺丝技术制备PLGA.SEP混合纤维膜和PLGA纤维膜(对照)。将两种纤维膜浸泡在37℃,pH=7.4的模拟体液(simulated body fluid solution,SBF)中进行降解实验,并分别于降解后2、4、6周检测两种电纺纤维膜降解前后的质量、断裂强度、表面形貌和热分解温度。结果:两种电纺纤维膜的质量、断裂强度均随降解时间的延长而逐渐降低,在降解前2周,下降速度较快,从2周到6周速度减慢;在降解2、4、6周各时间点PLGA.SEP纤维膜的失重率、断裂强度降低率均高于PLGA纤维膜,两者有显著性差异(P<0.05)。两种纤维膜均在降解6周时,纤维吸水发生溶胀,纤维之间粘连,孔径变小,但是结构仍完整,没有出现纤维断裂现象。PLGA.SEP和PLGA电纺纤维膜降解前后均有一个吸热峰,并且随着降解时间的延长,热分解温度逐渐降低,其中PLGA纤维膜在降解各时间点的热分解温度均高于PLGA.SEP纤维膜。结论:PLGA.SEP纤维膜在SBF中降解6周时结构仍完整并保持一定力学强度,可作为一种具有发展潜力的可吸收性引导组织再生(guided tissue regeneration,GTR)膜。     

国产微型钛钉正畸种植支抗即刻负载的稳定性

目的:探讨国产微型钛钉正畸种植支抗即刻负载的稳定性.方法:选择恒牙列正畸病例需要最大支抗者,采用国产自攻型(钛合金)和非自攻型(纯钛)2种微型钛钉作为正畸支抗,前者采用自攻法植入,后者采用非自攻法植入.2种钛钉均为即刻种植、即刻加载.结果:共计种植国产微型钛钉正畸支抗20例52枚,直径(mm)×长度(mm)分别为1.5×12、1.2×7、1.6×11.3种规格.其中成功47枚,失败5枚.在体负载时间3～8个月,平均5.5个月.结论:2种国产微型钛钉用作种植支抗可以满足临床正畸需要.但微型种植钛钉植入后即刻加载约有10.4%的松动失败率,特别是1.2mm×7mm的微型种植钛钉.     

自攻型微种植支抗钉在矫治下颌磨牙舌倾中的应用

目的评价自攻型微种植支抗钉治疗下颌磨牙舌倾的有效性。方法 选择8例下颌磨牙舌倾的正畸患者,应用自攻型微种植支抗钉牵引11颗舌倾的下颌磨牙。分别在微种植支抗钉植入前和取出后拍摄曲面断层片和头颅侧位片,并进行头影测皱及模型测绩分析。结果8例患者所植入的自攻型微种植支抗钉在矫治过程中均保持稳定;舌倾的磨牙均得到有效的直立,矫治后下颌磨牙间宽度增加4．5mm,与矫治前相比下颌磨牙宽度变化差异有统计学意义（P〈0．01）;下颌磨牙高度降低1．2mm,有统计学意义（P〈0．05）;而下颌平面角（MP—SN）及面下高与全面高之比（ANS—Me／N—Me）变化差异无统计学意义（P〉0．05）。结论自攻型微种植支抗钉可有效地直立舌倾的下颌磨牙,避免磨牙伸长,磨牙咬合关系良好。     

不同牙周表型对微种植支抗钉稳定性的影响

目的:探讨不同牙周表型对正畸微种植支抗钉稳定性的影响。方法:筛选100例骨性Ⅱ类错(牙合)年轻女性患者,其中薄龈型50例,厚龈型50例,以上患者均拔除上颌双侧第一前磨牙,并在上颌第二前磨牙和第一磨牙之间植入微种植钉加强支抗,即刻加力,力值200 g,记录6个月后两组菌斑指数(PLI)、龈沟出血指数(SBI)、探诊深度(PD)以及成功例数并进行对比分析。结果:薄龈型组微种植支抗钉PLI、SBI、PD以及微种植钉周围炎发生率均高于厚龈型组(P<0.05),微种植支抗钉稳定性显著低于厚龈型组(P<0.05)。结论:牙周表型是影响正畸微种植钉稳定性的重要因素,薄龈型者稳定性显著低于厚龈型者,此结果可用来指导正畸医生临床实践。     

微型种植支抗钉增强后牙支抗的临床观察

目的探讨影响微型种植支抗成功的主要因素。方法对18例须加强支抗的正畸治疗患者,植入微型支抗钉共60枚,术后1周使用弹力橡皮圈牵引加载150-200 g力,远中牵引尖牙及两步法关闭间隙,观察种植钉产生的牵引效果和临床的不适症状。结果60枚种植钉中,1枚术中折断,取出重新种植后获得成功;3枚龈黏膜轻度肿胀,2枚颊黏膜溃疡,对症处理后均自愈;2枚支抗轻度松动,旋紧后继续使用;1枚植入后局部疼痛,2枚加力末期松动明显,都给予拔除;1枚后期支抗钉头移位后去除重新植入。3-6个月内双尖牙间隙关闭速度为每月0.8-1.8 mm。结论种植支抗钉的临床不良反应主要是初期稳定性不足,以及局部软组织反应;稳定的种植支抗可以有效地快速关闭拔牙间隙,增强后牙支抗。     

正畸支抗用微种植钉对牙根和牙周组织造成的损伤及损伤后的组织学变化

正畸支抗用微种植钉作为绝对支抗装置已广泛应用于临床正畸治疗中，但是微种植钉存在损伤牙根和牙周组织的风险，其中种植钉的材质、直径、长度、植入角度、加载方式、加力大小、方向、时机与损伤的发生有关。本文就微种植钉损伤牙齿的影响因素、最佳植入位置、最易发生损伤的植入部位、损伤后的组织学变化、临床转归、并发症和预防措施等作一综述。     

正畸用微种植钉种植成功的多因素分析

目的:探讨影响正畸支抗用微种植钉临床成功的因素。方法:选择固定正畸治疗中的种植微种植钉患者114例,微种植钉253颗。应用Logistic回归(Logistic Regression)统计方法对15个与微种植钉种植失败有关的指标(性别、年龄、垂直骨面型、矢状骨面型、植入部位、上下颌骨、软组织类型、口腔卫生状况、种植体长度和直径、植入方式、植入角度、加载时机、加载强度、临床用途)进行回归分析。结果:种植成功224颗,16例共计29颗脱落失败,种植成功率88.54%。年龄、口腔卫生情况、垂直骨面型和上下颌骨是影响微种植钉成功的独立指标(P＜0.05)。结论:为了减少正畸支抗用微种植钉的失败,要对患者加强口腔卫生的宣教和监督,特别是对年轻(尤其是<12岁)的高角患者的下颌植入时。     

口腔正畸学

自攻型微螺钉种植体支抗稳定性的临床研究;支抗种植体在上颌前牵引中的组织学研究;转矩力作用下托槽槽沟变形的实验研究;微型支抗种植钉愈合期骨结合状态的组织学观察;使用正畸菌斑指数评价固定矫治器患者的菌斑分布状况     

微种植体支抗在治疗上颌前突中的应用

目的探讨微种植体支抗在正畸临床内收上颌前牙的应用要点和临床效果。方法本研究包括10例正畸患者,患者分为女性8例,男性2例,根据治疗需要在上颌磨牙颊侧的部位应用微种植钛钉作为支抗,内收前牙完成正畸治疗。结果所有患者均获得满意的治疗效果。应用微种植体支抗技术内收前牙,使磨牙尖牙达到Ⅰ类关系,头影测量A点、B点有明显变化,侧貌有明显改善。结论微种植体能提供正畸临床所需的强支抗,是一种有效的治疗方法。     

自攻型微钛钉种植体增强磨牙支抗的临床应用研究

目的　介绍自攻型微钛钉种植体用于正畸支抗的临床经验 ,评价该型种植体作为强支抗的有效性。方法　在 6 7例采用自攻型微钛钉种植体作为支抗的临床病例中 ,选择 5例II类骨型、上牙弓前突或双牙弓前突患者 ,矫治设计上颌均为减数双侧第一前磨牙 ,支抗设计为磨牙强支抗。内收前牙阶段的治疗应用自攻型微钛钉支抗种植体 ,种植体植入上颌第一恒磨牙与第二前磨牙颊侧根尖部之间的牙槽间隔 ,以每侧 15 0～ 2 0 0g力滑动法内收前牙。比较内收前后头颅X线侧位片 ,测量前牙内收情况和磨牙支抗的变化。结果　 5例牙弓突度均得到明显改善 ,切牙切缘平均内收 6 4mm ,支抗磨牙平均前移 0 3mm ,均获得磨牙强支抗的效果。治疗过程中种植体均保持了稳定 ,种植体周围软组织健康。结论　自攻微型钛钉种植体能作为稳定的骨性正畸支抗 ,代替口外力的使用 ,起到磨牙强支抗的效能。该型种植体具有操作简单灵活 ,可即刻加力 ,不依赖患者合作的优点     

牙托粉的分子量及其分布对义齿基托性能的影响

目的评价牙托粉分子量及其分布与义齿基托的挠曲强度的冲击强度的关系。方法用凝胶色谱法测定三种自制牙托粉的分子量和分子量分布；用ＷＤ－＝１０Ａ型万能材料试验机和ＸＪ－４型非金属材料冲击试验机测试义在托的挠曲强度和冲击强度。结果分子量最高的第一种材料挠曲强度最高；分子量较高，分子量分布量窄的第二种材料冲击强度最高；分子量最小的第三种材料的其挠曲强度和冲击强度都最低。结论牙托粉的分子量和分子量分布对义齿基托的挠曲强度和冲击强度有较大影响。     

Characterization of glass-ionomer cements. 4. Effect of molecular weight on physical properties.

The properties of glass-ionomer cements are affected by the molecular weight of the polyacid used in their preparation. At equivalent acid concentrations and powder : liquid ratios, polyacids of high molecular weight yield cements of enhanced strength, but the high viscosity of their aqueous solutions imposes a limitation on their use and the working time of the cement pastes is reduced. Moreover, powder : liquid ratios have to be lowered and the polyacids themselves can be used only at relatively low concentrations (about 25 per cent m/m); these are factors which adversely affect cement strength.     

Effect of poly(acrylic acid) architecture on setting and mechanical properties of glass ionomer cements

ObjectiveThis work focuses on the influence of poly(acrylic acid) (PAA) architecture (linear or branched) on setting behavior and compressive strength of glass ionomer cements (GICs).MethodsBranched and linear poly(acrylic acid)s were synthesized according to the Strathclyde methodology or by free radical polymerization. They were characterized by ¹H-NMR spectroscopy and size exclusion chromatography to determine their molecular weight and size distribution. GIC setting was characterized by oscillating rheometry and time-dependent FTIR spectroscopy. In addition, compressive strength was tested on cylindrical samples (6 × 4 mm; n = 8/cement composition) after storage in deionized water at 37 °C for one day.ResultsWe used two different routes to prepare PAA. One direct route in order to provide straightforward access to branched PAA and a two-step approach in order to get more control about the PAA molecular weight using tert-butyl acrylate (tBA) for polymerization with subsequent deprotection. Using the second approach we obtained several linear PAA of which a mixture was used in order to mimic the molecular weight and size distribution of branched PAA. This allowed the direct comparison of properties relying only on the polymer architecture. Comparing linear PAA to branched samples in general led to faster setting but at the same time decreased the compressive strength. Increasing molecular weight of branched PAA resulted in even faster GIC setting while increasing compressive strength and this correlates well with the trends reported for linear PAA in literature. Mixing of branched and linear PAA, however, turned out to be an effective way of tailoring GIC properties. Significance: our results suggest that both molecular weight and dispersity need to be considered when choosing suitable PAA architecture for obtaining specific GIC properties.     

壳聚糖屏障膜机械性能与降解性能的研究

目的 :研究壳聚糖膜的机械性能和降解性能。方法 :制备用于引导组织再生的壳聚糖膜 ,以聚四氟乙烯膜 (e -PTFE)为对照 ,用 1195型Instron电子拉力机测定膜的抗张强度、屈服强度和伸长率 ,并测量其体内、外降解过程中重量丧失率和分子量变化。结果 :充分湿润后 ,壳聚糖膜的机械强度显著降低 ,伸长率显著增高。但即使在湿润状态下 ,壳聚糖膜的机械强度仍显著高于e -PTFE膜 ,伸长率显著低于e -PTFE膜 (P <0 .0 1)。在溶菌酶存在情况下 ,壳聚糖膜具有较快的降解速度 :3 0d时重量丧失约 3 0 % ,40d时重量丧失约 46% ,60d后 ,膜基本破碎溶解。结论 :从材料的机械性能和降解性能上看 ,壳聚糖膜基本符合用于引导组织再生的要求。     

聚乳酸复合物预成乳牙根管桩的体外降解性研究

目的:评估聚乳酸/羟基磷灰石(PLA/HA)复合物的体外降解性。方法:本实验参照我国医疗器械生物学评价标准,将PLA/HA和PLA两种材料分别浸泡到磷酸盐缓冲液(PBS液)和蒸馏水中,分别在不同的时间点对试件进行一系列体外实验评价PLA/HA的体外降解性。结果:肉眼观察试件颜色逐渐变白且出现微裂纹;SEM显示:随降解时间延长,HA颗粒逐渐变小,PLA出现孔隙且大小不一;PLA/HA和PLA分子量逐渐较小;弹性模量和弯曲强度均有所衰减;PLA/HA和PLA中降解液的pH值均逐渐降低,且PLA比PLA/HA要下降的快。结论:PLA/HA具有一定的降解性能,在观察的10个月内,其力学强度能够维持乳牙的咬合力。     

Absence of binding of human salivary glycoprotein to human gingival fibroblast-like cells in vitro

The aim of this study was to determine whether human high molecular weight salivary glycoprotein binds in vitro to human gingival fibroblastlike cells. Primary monolayer cultures of 2 human gingival fibroblastlike cell lines were incubated with a high molecular weight fraction of salivary glycoprotein which expressed blood group A activity and glycoprotein-cell binding probed using an FITC-conjugated mouse monoclonal antibody to human blood group A antigen. Surface fluorescence of protein-treated cells was found to be no greater than that of untreated or serum-treated control cultures. As significant binding of salivary glycoprotein to gingival fibroblast-like cells does not occur in vitro , saliva-mediated inhibition of fibroblast attachment to hydroxyapatite is not dependent on specific ligand-lectin interactions.     

Influence of molecular weight of PMMA in PMMA/MMA-TBB resin on durability of adhesion to titanium against thermal stress in water

The present study examined the effect of the molecular weight of poly(methyl methacrylate) (PMMA) used in PMMA/ MMA-tributylborane (TBB) resin cement on the durability of adhesion to titanium against repeated thermal stress in water. PMMA beads with the same diameter and molecular weights of 1427, 239, 116, 78, and 66 (x 10(3)) were used. Titanium disks bonded to stainless steel or acrylic rods with the PMMA/MMA-TBB resin were subjected to a thermal cycling test (500 and 2,000 cycles) in water followed by tensile testing. Change in molecular weight of the resin cements collected after thermocycling and tensile testing was examined using size exclusion chromatography (SEC). The acrylic specimens exhibited a significant decrease in post-thermocycling bond strength as compared to the stainless steel specimens. It was also found that the molecular weight of PMMA powder in PMMA/MMA-TBB resin had little influence on adhesion durability to titanium. In terms of the molecular weight of resin cements, they decreased and then increased after 500 and 2,000 cycles respectively.     

The influence of fibre placement and position on the efficiency of reinforcement of fibre reinforced composite bridgework

The effect of placement of ultra-high molecular weight polyethylene (UHMWPE) fibres on the flexural properties and fracture resistance of a direct dental composite was investigated. The UHMWPE fibres are increasingly being used for the reinforcement of laboratory fabricated resin composite crown and bridgework. The aim of this study was to assess the effect of a commonly used laboratory fabrication variable on the in vitro strength of beam shaped specimen simulating a three-unit fixed bridge. Four groups (10 specimens per group) of Herculite XRV were prepared for flexural modulus and strength testing after reinforcement with UHMWPE fibres. Two groups of control specimens were prepared without any fibre reinforcement. Half the specimen groups were stored in distilled water and the other groups were stored dry, both at 37 degrees C for 2 weeks before testing. The results of this study showed that placement of fibre at or slightly away from the tensile side improved the flexural properties of the composite in comparison with the unreinforced control specimen groups whilst the mode of failure differed according to fibre position. Scanning electron microscope (SEM) investigation revealed that placement of the fibre slightly away from the tensile side favoured crack development and propagation within the resin bridging the interfibre spaces in addition to debonding parallel to the direction of fibre placement. Laboratory fabrication variables may effect the strength of fibre reinforced bridgework significantly.     

Degradation and formation of bisphenol A in polycarbonate used in dentistry

To study long-term degradation of polycarbonate (PC) and the formation and the release of bisphenol A (BPA) in vivo and in vitro, PC brackets placed in the oral cavity for 18-40 months as well as bracket, denture plate, and temporary crown placed in water at 37 degrees C for 34 months were examined for the changes of BPA content and molecular weight in PC using high performance liquid chromatography and size exclusion chromatography. BPA release in vitro was also monitored. The BPA content and molecular weight for the brackets in vivo showed a tendency to increase from 38-60 microg/g to 324-697 microg/g and to decrease from 49 x 10(3) - 54 x 10(3) to 43 x 10(3) - 45 x 10(3) during 18-40 months, respectively. The content and total release of BPA in vitro after 34 months were 472 and 37.4 microg/g for bracket, 130 and 2.2 microg/g for denture plate, and 50 and 2.8 microg/g for temporary crown, respectively. BPA appeared to be released more in saliva than that expected from the in vitro data. Additives contained in the PC materials were suggested to influence the formation of BPA.     

国产消旋聚乳酸膜大鼠体内降解试验研究

目的通过动物体内降解试验评价国产可吸收的聚乳酸（ｐｏｌｙＤＬ－ｌａｃｔｉｃａｃｉｄ,ＰＤＬＬＡ）膜在引导组织再生术中应用的可能性。方法ＰＤＬＬＡ膜植入大鼠背部皮下组织中,分别于１、２、４、８、１２周５个时段取出观察外形,测量重量丧失,使用凝胶渗透色谱仪测分子量变化。结果ＰＤＬＬＡ膜体内降解重量保持率类似体外,虽然体内的数均分子量不符合Ｐｉｔｔ动力学模型,但两条件下分子量变化一致。结论ＰＤＬＬＡ膜的完整性可维持１２周以上,已达到ＧＴＲ术对膜材料降解速度的要求。