不同涂布方式对牙本质粘结微拉伸强度的影响

目的:观察不同涂布方式对4种牙本质粘结剂牙本质微拉伸粘结强度的影响。方法:选择80个离体前磨牙制备牙本质粘结面后,随机分为16组,每组5个,分别以轻涂(G)、重涂(V)、涂1层(1)、涂2层(2)等不同方式涂布牙本质粘结剂,并修复树脂"冠"。CMT7104型万能材料测试机测试各组试件的微拉伸强度。结果:不同涂布方式下4种牙本质粘结剂的微拉伸粘结强度依次是G2组>V2组>V1组>G1组;G2组明显高于其他3组(P<0.05);V1组和G1组间、V1和V2无明显统计学差异(P>0.05)。结论:不同涂布方式对牙本质粘结剂微拉伸强度具有一定的影响,轻涂2遍(G2)获得的微拉伸强度最高。     

不同振动频率对3种粘接剂粘固种植体基桩时拉伸强度的影响

目的:比较不同振动频率对3种粘结剂粘结种植体基桩与钴铬烤瓷合金基底冠之间拉伸强度的影响。方法:制备90个纯钛种植体基桩及与基桩相匹配的钴铬合金基底冠。按不同的振动频率分为5组,0点组、7点组、8点组、9点组和10点组,分别用氧化锌丁香油水门汀(zinc oxide-eugenol,ZOE)、玻璃离子水门汀(glass ionomercement,GIC)和种植粘结剂(premier implant cement,PIC)粘结金属基底冠和基桩。以握笔式将洁牙机工作头的前端部分与基桩长轴垂直接触颈缘,螺旋振动15min,测试拉伸强度。结果:同一种粘结剂的粘结作用下,随着洁牙机振动频率的增加,种植体的基桩与基底冠产生的脱位力之间存在显著性差异(P<0.05);在同一振动频率作用下,不同粘结剂对种植体基桩与基底冠产生的脱位力存在显著性差异(P<0.05);洁牙机的振动频率与脱位力之间呈负相关关系(P<0.05)。结论:不同振动频率对金属冠与基桩之间拉伸强度有显著性影响。     

对国内外几种玻璃纤维根管桩的力学性能评价

目的比较国内外4种玻璃纤维根管桩材料的力学性能,为国产玻璃纤维桩的研究和临床运用提供理论依据。方法选取FIBIO GLASSFIBER POST 9支、MATCHPOST 10支、LuxaPost 10支及国产玻璃纤维桩9支,采用三点加载系统测定其弯曲强度及弹性模量,并进行比较和统计分析。结果弯曲强度除MATCHPOST组与LuxaPost组、LuxaPost组与国产桩组无统计学差异外,其他各组间均有统计学差异(P0.05)。弹性模量除MATCHPOST组与LuxaPost组无统计学差异外,其他各组间均有统计学差异(P0.05)。LuxaPost的弯曲强度最大,FIBIO GLASSFIBER POST的弹性模量最低,与牙本质的弹性模量最接近。结论试验采用的4种玻璃纤维桩材料均体现出良好的力学性能,达到临床使用标准。     

Ethanol-wet bonding may improve root dentine bonding performance of hydrophobic adhesive

Objectives

The current study aimed to assess ethanol-wet dentine surfaces by atomic force microscopy (AFM), and to evaluate the efficacy of ethanol-wet bonding on root dentine by determining the shear bond strength (SBS) and interfacial nanoleakage expression.

Methods

Flat dentine slices from human premolar roots were randomly grouped into five. All specimens were acid-etched, rinsed, and left moist. They were then treated with 100% ethanol for 0 s (control group), 20 s (Group 1), 60 s (Group 2), three 60 s periods (Group 3), or stepwise ethanol application (Group 4). After treatment, each group was bonded either with Adper™ Scotchbond™ Multi-Purpose (Scotchbond) or experimental hydrophobic adhesive. Nano-scale adhesion forces (Fad) were probed by AFM and analysed using one-way ANOVA. The SBS results were analysed using two-way ANOVA. Tukey's test was employed for multiple comparisons.

Results

Ethanol-wet protocols significantly decreased the value of Fad (p < 0.001). When bonded with Scotchbond, ethanol treatment did not affect the bond strength (p > 0.05), but decreased the interfacial nanoleakage. The SBS values of the groups bonded with hydrophobic adhesive varied with different ethanol-wet protocols (p < 0.05). Decreased nanoleakage was manifested in all experimental groups, except Group 1. Compared with the classical water-wet bonding with Scotchbond in the control group, Group 4 bonded with hydrophobic adhesive exhibited a significantly higher bond strength (p < 0.05).

Conclusions

Ethanol-wet bonding using a stepwise ethanol application protocol may have potential benefits in the root dentine bonding of hydrophobic adhesive.     

Assessment of laminate technique using glass ionomer and resin composite for restoration of root filled teeth

Objective

To evaluate the open laminate technique using glass ionomer cements (GIC) in association with a low shrink composite for restoring root filled premolars.

Methods

Extensive MOD cavities plus endodontic access and root filling were performed in intact extracted maxillary premolars. Three restoration types were evaluated: (1) resin composite alone; (2) resin-modified GIC (RM-GIC) open laminate plus resin composite; (3) conventional GIC open laminate plus resin composite (n = 8 for all groups and tests). Three tests were conducted to assess restorations: (A) inward cusp deflection during light curing, using DCDTs; (B) fracture strength using a ramped oblique load at 45° to the long axis in a servohydraulic testing machine in comparison with intact and unrestored teeth; (C) proximal marginal leakage using methylene blue dye and the effect of thermocycling. Data were analysed using 1-way ANOVA for cuspal deflection and fracture strength and Fisher's exact test for leakage.

Results

Laminate restorations resulted in significantly less cuspal deflection compared with resin composite (4.2 ± 1.2 μm for RM-GIC and 5.1 ± 2.3 μm for conventional GIC vs. 12.2 ± 2.6 μm for composite, P < 0.001). Fracture strength was not significantly different among all groups. Failure with all restorations was predominantly adhesive at the tooth-restoration interface. The two laminate groups showed significantly better marginal seal than composite alone, but sealing ability of conventional GIC deteriorated after thermocycling.

Conclusions

Laminate restoration of root filled teeth had beneficial effects in terms of reducing cuspal deflection and marginal seal, with acceptable fracture strength.     

Push‐out bond strength of two root‐end filling materials in root‐end cavities prepared by Er,Cr:YSGG laser or ultrasonic technique

This study compared the push‐out bond strength of mineral trioxide aggregate (MTA) and a new endodontic cement (NEC) as root‐end filling materials in root‐end cavities prepared by ultrasonic technique (US) or Er,Cr:YSGG laser (L). Eighty single‐rooted extracted human teeth were endodontically treated, apicectomised and randomly divided into four following groups (n = 20): US/MTA, US/NEC, L/MTA and L/NEC. In US/MTA and US/NEC groups, root‐end cavities were prepared with ultrasonic retrotip and filled with MTA and NEC, respectively. In L/MTA and L/NEC groups, root‐end cavities were prepared using Er,Cr:YSGG laser and filled with MTA and NEC, respectively. Each root was cut apically to create a 2 mm‐thick root slice for measurement of bond strength using a universal testing machine. Then, all slices were examined to determine the mode of bond failure. Data were analysed using two‐way anova . Root‐end filling materials showed significantly higher bond strength in root‐end cavities prepared using ultrasonic technique (US/MTA and US/NEC) (P < 0.001). The bond strengths of MTA and NEC did not differ significantly. The failure modes were mainly adhesive for MTA, but cohesive for NEC. In conclusion, bond strengths of MTA and NEC to root‐end cavities were comparable and higher in ultrasonically prepared cavities.     

The effect of the application of gaseous ozone and ND:YAG laser on glass‐fibre post bond strength

The aim of this study was to investigate the effects of the application of gaseous ozone and Nd:YAG laser on glass‐fibre post bond strength. Forty‐two madibular premolar roots were cut, endodontically instrumented and irrigated with 2.5% NaOCl. Post spaces were prepared and roots were divided into three groups (n = 14). The antimicrobial pretreatment was conducted as follows: gaseous ozone, Nd:YAG laser and control (no additional disinfection methods). Scanning electron microscope analysis was made for each group (n = 2). A resin cement was used for luting the posts. For push‐out test, each root was cut horizontally (two cervical, two middle and two apical). Statistical analyses were performed with one‐way anova (α = 0.05). Fracture types were observed. There was no statistically significant difference between the groups (P > 0.05). There were statistically significant differences in cervical and apical segments of laser and control groups (P < 0.05). The disinfection of the post spaces with Nd:YAG laser and ozone had no adverse effects on bond strength of glass‐fibre post.     

偶联剂和不同粘接剂对纤维桩粘接强度的影响

目的:利用薄片推出实验比较硅烷偶联剂和三种树脂粘接剂对纤维桩剪切粘接强度的影响.方法:60颗因牙周病等原因拔除的上颌单根前牙,根管治疗后行纤维桩修复的桩道预备.随机分为5组,每组12颗牙.分别采用下列粘接剂粘接Matchpost纤维桩:A组:Paracore粘接剂+偶联剂;B组:Paracore粘接剂;C组:Panavia F粘接剂+偶联剂;D组:Panavia F粘接剂;E组:Multilink N粘接剂+偶联剂.纤维桩粘接后,在牙根中部横向切割1.0mm层厚切片2个,在Zwick Z100材料试验机上行薄片推出试验(Push-Out Bond Test),记录失败载荷,计算剪切粘接强度,体视显微镜观察粘接失败类型.结果采用SPSS 11.5进行方差分析和χ2检验.结果:五组样本的剪切粘接强度(MPa)分别为A组:14.69±2.76;B组:9.46±3.11;C组:13.12±3.10;D组:10.40±3.30;E组:13.86±3.81,方差分析提示五组间差异有统计学意义(P <0.01).采用偶联剂处理时,Paracore粘接剂和Panavia F粘接剂与纤维桩间的剪切粘接强度均高于未用偶联剂处理者(P <0.05).采用偶联剂处理时,三种树脂粘接剂与纤维桩的剪切粘接强度间差异无统计学意义(P >0.05).五组粘接失败类型间差异有统计学意义(P <0.05),未采用硅烷偶联剂处理纤维桩表面者,出现纤维桩-粘接剂界面失败者增多.结论:在树脂粘接前,玻璃纤维桩表面氢氟酸酸蚀后,采用硅烷偶联剂处理可显著提高纤维桩与树脂粘接剂间的剪切粘接强度.     

Peel bond strength of resilient liner modified by the addition of antimicrobial agents to denture base acrylic resin

In order to prolong the clinical longevity of resilient denture relining materials and reduce plaque accumulation, incorporation of antimicrobial agents into these materials has been proposed. However, this addition may affect their properties.

Objective

This study evaluated the effect of the addition of antimicrobial agents into one soft liner (Soft Confort, Dencril) on its peel bond strength to one denture base (QC 20, Dentsply).

Material and Methods

Acrylic specimens (n=9) were made (75x10x3 mm) and stored in distilled water at 37ºC for 48 h. The drug powder concentrations (nystatin 500,000U - G2; nystatin 1,000,000U - G3; miconazole 125 mg - G4; miconazole 250 mg - G5; ketoconazole 100 mg - G6; ketoconazole 200 mg - G7; chlorhexidine diacetate 5% - G8; and 10% chlorhexidine diacetate - G9) were blended with the soft liner powder before the addition of the soft liner liquid. A group (G1) without any drug incorporation was used as control. Specimens (n=9) (75x10x6 mm) were plasticized according to the manufacturers'' instructions and stored in distilled water at 37ºC for 24 h. Relined specimens were then submitted to a 180-degree peel test at a crosshead speed of 10 mm/min. Data (MPa) were analyzed by analysis of variance (α=0.05) and the failure modes were visually classified.

Results

No significant difference was found among experimental groups (p=0.148). Cohesive failure located within the resilient material was predominantly observed in all tested groups.

Conclusions

Peel bond strength between the denture base and the modified soft liner was not affected by the addition of antimicrobial agents.     

Laser welded vascular anastomosis

Summary A comparative study was undertaken to investigate the application of a specially adapted microsurgical Neodymium Yag Laser system with a wavelength of 1,319 m and a CO₂ laser system for laser assisted microvascular end-to-end anastomosis (LAMA) of the rat femoral artery. Conventionally sutured anastomoses served as controls. Postoperative investigations included patency tests, light microscopy and tensile strength measurements. Both laser systems seem to be equally suitable for LAMA: The patency rates do not differ from those of sutured anstomoses and formation of microscopically small aneurysms occurred predominantly in control animals and only once in laser groups. The clamp time needed for LAMA was half the time that was needed for sutured anastomoses. Wound healing in all groups was similar with less fibrotic reactions and less foreign body granulomas in laser groups. At all intervals tensile strength was significantly higher for sutured anastomoses while differences between the CO₂- and the ND: Yag-laser groups were not statistically significant. Potential applications in urology include microvascular anastomoses in erectile dysfunction, pediatric and reconstructive urology.Contains parts of a dissertation