模拟髓室压力对中层牙本质树脂微拉伸粘结强度的影响

目的评价髓室压力对中层牙本质树脂粘结强度的影响。方法32颗第三磨牙随机分组,实验组以15cm水柱模拟髓室压力。Clearfil S~3 Bond粘结剂作树脂光固化后微拉伸力学测试。结果实验组粘结剂应用时间为300 s时,微拉伸粘结强度明显下降。实验组和对照组相比较,150 s组和300 s组的微拉伸粘结强度差异均有统计学意义。结论模拟髓室压力会影响中层牙本质树脂微拉伸粘结强度。     

Effect of saliva contamination on bond strength of resin luting cements to dentin

Objectives

This study examined the effect of saliva contamination on the microtensile bond strength (μTBS) of resin luting cements to dentin.

Methods

For RelyX ARC (ARC, 3M ESPE), dentin surfaces were etched with 32% phosphoric acid. The subgroups were: ARC-control (uncontaminated), ARC-I (saliva contamination, blot-dried), ARC-II (saliva contamination, rinse, blot-dried) and ARC-III (saliva contamination, rinse, re-etch, rinse, blot-dried). For Panavia F 2.0 (PF, Kuraray), the subgroups were: PF-control (uncontaminated), PF-I (saliva contamination, dried), PF-II (saliva contamination, rinse, dried), PF-III (primer, saliva contamination, dried), PF-IV (primer, saliva contamination, dried, primer re-applied) and PF-V (primer, saliva contamination, rinse, dried, primer re-applied). Composite blocks were luted onto dentin using the two cements. Bonded specimens were sectioned into 0.9 mm × 0.9 mm beams for μTBS testing. Representative fractured beams were prepared for fractographic analysis.

Results

For ARC, salivary contamination of etched dentin (ARC-I) significantly lowered bond strength (p = 0.001). Rinsing saliva off with water (ARC-II) restored bond strength to control level. Re-etching dentin surface after rinsing (ARC-III) resulted in the lowest bond strength (p < 0.001). For PF, salivary contamination of dentin before (PF-I) and after application of primer (PF-III and PF-IV) significantly lowered bond strength (p < 0.001). Rinsing saliva off with water and re-application of primer (PF-II and PF-V) improved bond strength.

Conclusion

Saliva contamination during luting deteriorated the bond quality of resin cements. Decontamination by rinsing with water was most effective in restoring the bond strength of RelyX ARC. Decontamination by water-rinsing and primer re-application after rinsing improved the bond strength of Panavia F 2.0.     

Effect of surface preparation on bond strength of resin luting cements to dentin

This study examined the effects of using two different burs for dentin surface preparation on the microtensile bond strength (microTBS) of three resin luting cements. Flat, deep dentin surfaces from 45 extracted human third molars were divided into three groups (n = 15) according to bur type: (i) diamond bur and (ii) tungsten carbide bur. The controls were abraded with #600-grit SiC paper. Both burs operated in a high-speed handpiece under water-cooling. Composite blocks were luted onto the dentin using one of three cements: RelyX ARC (ARC, 3M ESPE), Panavia F2.0 (PF, Kuraray) and RelyX Unicem (UN, 3M ESPE) following the manufacturers' instructions. For ARC, the dentin surface was treated with 32% phosphoric acid. The bonded specimens were stored at 37 degrees C for 24 hours and sectioned into 0.9 x 0.9 mm beams for microTBS testing. The data were analyzed using the two-way ANOVA and Student-Newman-Keuls tests. Representative fractured beams from each group were prepared for fractographic analysis under SEM. Two-way ANOVA revealed that the effects of "dentin surface preparation" and "luting cement" were statistically significant (p < 0.001); however, the interaction of these two factors was not significant (p > 0.05). ARC showed no significant difference in microTBS among the three differently prepared dentin surfaces. The microTBS of PF and UN was significantly lower when bonding to dentin prepared with a diamond bur (p < 0.05), compared to the control. For Panavia F2.0, higher bond strengths were achieved on the dentin surface prepared with a tungsten carbide bur. Proper bur selection is essential to optimizing the dentin adhesion of self-etch resin luting cements.     

Effect of hydrostatic pulpal water pressure on microtensile bond strength of self-etch adhesives to dentin

PURPOSE: To evaluate the effect of pulpal pressure on the microtensile bond strength of four self-etch adhesives to dentin. A total-etch adhesive was added for comparison. METHODS: 60 freshly extracted human third molars were selected. For each tooth, the root was removed below the cemento-enamel junction. A second parallel section was made to remove the coronal enamel to form a crown segment. The root portion of the resulting crown segment was cemented to a Plexiglas platform using cyanoacrylate cement. The crown segment was then connected with a plastic tube to a water column to produce a pressure of 20 cm H2O at the prepared dentin surface of the crown segment. The adhesive materials were: a total-etch adhesive (Scotchbond 1) and four self-etch adhesives (Clearfil SE Bond, Hybrid Bond, Futurabond NR, and AdheSE Bond). The tested adhesives were applied to the dentin surface in three test procedures: applied to dentin without pulpal pressure, applied to dentin with pulpal pressure for 24 hours, and applied to dentin with pulpal pressure and the pressure was maintained for 6 months during storage. Grandio resin composite was placed in 3-4 layers to a height of 5-6 mm to form a crown segment. For bond strength measurement, the composite-dentin segment was removed from the Plexiglas. This segment was then sectioned to prepare the specimens for microtensile bond measurement. RESULTS: None of the tested adhesives showed bond strength reduction when applied to dentin supplied with water pressure. After 6 months of pulpal pressure, Scotchbond 1, Clearfil SE Bond and AdheSE Bond showed significant reduction in bond strength (P < 0.05). In contrast, Futurabond NR and Hybrid Bond were not significantly affected.     

Effect of dentin pretreatment and curing mode on the microtensile bond strength of self-adhesive resin cements

PURPOSEThe aim was to evaluate the effect of curing mode and different dentin surface pretreatment on microtensile bond strength (µTBS) of self-adhesive resin cements.RESULTSFor G-CEM LinkAce cement groups, polyacrylic acid pretreatment showed the highest µTBS in the self-cured group. In the light-cured group, no significant improvements were observed according to the dentin surface pretreatment. There were no significant differences between curing modes. Both dentin surface pretreatment methods helped to increase the µTBS of RelyX U200 resin cement significantly and degree of pretreatment effect was similar. No significant differences were found regarding curing modes except control groups. In the comparisons of two self-adhesive resin cements, all groups within the same pretreatment and curing mode were significantly different excluding self-cured control groups.CONCLUSIONSelecting RelyX U200 used in this study and application of dentin surface pretreatment with EDTA and polyacrylic acid might be recommended to enhance the bond strength of cement to dentin.     

Influence of different drying methods on microtensile bond strength of self-adhesive resin cements to dentin

Objective. This study investigated the effect of different drying methods of dentin surface on the bonding efficacy of self-adhesive resin cements (SRCs). Materials and methods. Three SRCs (RelyX U200, RU; Maxcem Elite, ME; and BisCem, BC) and one resin-modified glass ionomer cement (RelyX Luting 2, RL) were used. The characteristics of the materials were evaluated using thermogravimetric analysis and surface roughness and contact angle measurements. Human dentin surfaces were finished with 600-grit silicon carbide paper and assigned to three groups according to these drying methods: ethanol dehydration, drying by waiting for 10 s after blot-drying and blot-drying. The four cements were used for luting composite overlays to the dried dentin. After 24 h storage at 37°C and 100% relative humidity, stick-shaped specimens with a cross-sectional area of 0.8 mm² were prepared and stressed to failure in tension at a crosshead speed of 0.5 mm/min (n = 27). Failure modes of fractured specimens were assessed by optical and scanning electron microscopy. Results. RL was the most hydrophilic, followed by BC and ME and then RU. All the luting cements luted to ethanol-dehydrated dentin showed zero bond strengths. For the three SRCs, drying by waiting produced higher microtensile bond strengths than blot-drying. RU showed the best bonding performance in the above two dentin conditions. RL showed significantly higher bond strength in blot-drying condition than in drying-by-waiting (p < 0.001). Conclusions. This study suggests that dentin surface moisture has a crucial effect on the bond strength of SRCs.     

Effect of curing mode on microtensile bond strength to dentin of two dual-cured adhesive systems in combination with resin luting cements for indirect restorations

This study evaluated the microtensile bond strength (microTBS) of dual-cured adhesive systems when the different components were either light activated or left in the uncured state prior to cementation of an indirect composite restoration. Occlusal dentin surfaces of 40 human third molars were flattened. The teeth were randomly assigned to 8 groups (n = 5) according to the dual-cured systems (bonding agents/resin cements) and curing modes: All Bond 2/Duolink (AB2-BISCO Inc) and Optibond Solo Plus Dual Cure/Nexus 2 (SOLO-Kerr). Resin cements were applied to pre-cured resin composite discs (2 mm thick/Z-250/3M ESPE), which were fixed to dentin surfaces containing adhesive resin in either cured (LP) or uncured states (SP). The restored teeth were light activated according to the manufacturers' instructions (LRC-XL3000/3M ESPE) or allowed to self-cure (SRC). The restored teeth were water-stored at 37 degrees C for 24 hours. They were then both mesial-distally and buccal-lingually sectioned to obtain bonded specimens (1.2 mm2). Each specimen was tested in tension at a crosshead speed of 0.6 mm/minute until failure. Data (MPa (SD)) were analyzed by two-way ANOVA and Tukey's post-hoc test (p < .05). AB2/SP exhibited higher microTBS than AB2/LP (p = .00001); however, no significant differences were noted between SOLO/LP and SOLO/SP. Results suggested that dual-cured adhesive systems were as strong or even stronger when they were left in the uncured state prior to indirect resin composite cementation.     

Shear bond strength of resin cements to human dentin.

OBJECTIVES: The objectives of this in vitro study were (1) to assess the bond strength of the universal cement RelyX Unicem to dentin and to compare it with three conventional resin cements, (2) to test the influence of aging on their bonding capacity and (3) to test the influence of the operator on bonding quality by performing the same test in two different centers. METHODS: 160 third molars, divided into 80 for tests at the University of Zurich (Z) and 80 for tests at the University of Berne (B), were assigned to 2 x 8 subgroups of 10 teeth each. The specimens were prepared with the corresponding bonding agents and acrylic rods were luted either with RelyX Unicem (U), RelyX ARC (A), Multilink (M) or Panavia 21 (P). All specimens were stored in water for 24h (W) and half of the specimens were subjected to 1500 cycles of thermocycling (5 degrees C and 55 degrees C) (T). Bond strength was measured by means of a shear test. RESULTS: After water storage RelyX Unicem exhibited lowest bond strength (UWZ: 9.2+/-1.6 MPa, UWB: 9.9+/-1.2 MPa, AWZ: 15.3+/-6.0 MPa, AWB: 12.2+/-4.3 MPa, MWZ: 15.6+/-3.3 MPa, MWB: 12.4 MPa+/-2.4, PWZ: 13.4+/-2.9 MPa, PWB: 14.9+/-2.6 MPa). Thermocycling affected the bonding performance of all four cements. However, bond strength of RelyX Unicem was least influenced by thermocycling (UTZ: 9.4+/-2.9 MPa, UTB: 8.6+/-1.3 MPa, ATZ: 11.4+/-6.3 MPa, ATB: 13.3+/-3.7 MPa, MTZ: 15.4+/-3.1 MPa, MTB: 10.3+/-2.4 MPa, PTZ: 11.1+/-2.8 MPa, PTB: 11.3+/-2.8 MPa). SIGNIFICANCE: Although the bond strength of RelyX Unicem to dentin was lower in comparison to RelyX ARC, Multilink and Panavia 21, its bond strength was less sensitive to variations in handling and aging.     

Influence of matrix metalloproteinase synthetic inhibitors on dentin microtensile bond strength of resin cements

This study evaluated the effect of dentin pretreatment with 2% chlorhexidine (CHX) or 24% ethylenediamine tetra-acetic acid gel (EDTA) on the dentin microtensile bond strength (μTBS) of resin cements. Composite blocks were luted to superficial noncarious human dentin (n=10) using two resin cements (RelyX ARC [ARC] and RelyX U100 [U100]) and three dentin pretreatments (without pretreatment-control, CHX, and EDTA). CHX was applied for 60 seconds on the acid-etched dentin in the ARC/CHX group, and for the same time on smear layer-covered dentin in the U100/CHX group. EDTA was applied for 45 seconds on smear-covered dentin in the U100/EDTA group, and it replaced phosphoric acid conditioning in the ARC/EDTA group for 60 seconds. After storage in water for 24 hours, specimens were prepared for microtensile bond strength testing. The results were submitted to two-way analysis of variance (ANOVA) followed by Tukey test. ARC produced significantly higher μTBS (p<0.05) compared to the U100, except when EDTA was used. For ARC, no pretreatment and CHX produced higher μTBS than EDTA. For U100, EDTA produced higher μTBS; no statistical difference occurred between CHX pretreatment and when no pretreatment was performed. While CHX did not affect immediate dentin bond strength of both cements, EDTA improved bond strength of U100, but it reduced dentin bond strength of ARC.     

修复方式及粘接剂类型对牙本质粘接微拉伸强度的影响

目的 :研究不同修复方式及粘接剂类型对牙本质粘接微拉伸强度的影响。方法 :18个离体牙按牙体预备方法分为窝沟预备及冠部平切两组 ,每组分别使用One StepPlus、Primer&BondNT和SingleBond三种粘接剂进行牙本质粘接 ,最后均用AELITETMLS复合树脂修复牙体外形。样本包埋切割成块后 ,测试牙本质微拉伸强度。结果 :使用One StepPlus和SingleBond粘接剂时 ,冠部平切组微拉伸强度高于窝洞预备组 ,差异具有统计学意义 ;无论何种修复方式 ,One StepPlus和SingleBond的微拉伸强度均高于Primer&BondNT。 结论 :不同修复方式和粘接剂类型对牙本质粘接微拉伸强度存在影响     

Effect of 2% chlorhexidine on dentin microtensile bond strengths and nanoleakage of luting cements

Objectives

The aim of this study was to investigate the effect of pre-treatment by chlorhexidine on the microtensile bond strength (mTBS) of resin cements and nanoleakage at the resin–dentine interfaces.

Methods

Cylindrical composite blocks were luted to human dentine using resin cements (RelyX ARC, 3M ESPE: ARC; Panavia F, Kuraray Medical Inc.: PF; RelyX Unicem, 3M ESPE: UN) with/without pre-treatment by 2% chlorhexidine digluconate (CAVITY CLEANSER, Bisco, Inc., Schaumburg, IL, USA). CAVITY CLEANSER was applied on the acid etched dentine for 60 s in the ARC group, and on smear layer-covered dentine in the PF and UN groups. After storage in water for 24 h, the bonded teeth were sectioned into 1 mm thick slabs and further into 0.9 mm × 0.9 mm beams. After immersion in water or ammoniacal silver nitrate for 24 h, the beams were stressed to failure in tension. The fractured surfaces were examined by field-emission scanning electron microscopy (FE-SEM) using backscattered electron mode. The silver-stained slabs were used to examine nanoleakage within the bonded interface by FE-SEM.

Results

The resin cement and chlorhexidine treatment had significant effects (p < 0.0001) on mTBS; while the storage media had no significant effect (p = 0.435). The mTBS of ARC was significantly higher than the other cements. Chlorhexidine reduced mTBS and produced pronounced nanoleakage when PF and UC were luted to dentine.

Conclusions

Pre-treatment with chlorhexidine affected the integrity of dentine bonding with PF and UC, while there was no adverse effect on coupling of ARC.     

In vitro shear bond strength of resin-based luting cements to dentin

The aim of this study was to determine how resin cement, self-adhesive resin cement, and resin-modified glass ionomer cement affected shear bond strength to dentin. Sixty composite resin disks (3 mm in diameter x 3 mm in length) were prepared and divided into four groups (n = 15): Group 1, composite disk bonded to dentin with composite resin and a bonding agent; Group 2, composite disk bonded to dentin with a self-adhesive resin cement; Group 3, composite disk bonded to dentin with a different self-adhesive resin cement; and Group 4, composite disk bonded to dentin with a resin-modified glass ionomer cement. The composite resin was loaded into a syringe (internal diameter 3 mm), photocured in an oven, and cut into 3 mm slices with a low-speed saw. The samples were bonded to dentin per the manufacturer's instructions. All specimens were stored in distilled water (at 37 degrees C) for 24 hours. The shear bond strength test was conducted using a universal testing machine at a crosshead speed of 0.5 mm/min until failure. Conventional resin cement and a bonding agent exhibited significantly higher shear bond strength values than all other materials tested.     

三种分层充填方法对牙本质黏结强度的影响

目的:对比研究3种分层充填方法对牙本质黏结的微拉伸强度的影响。方法:选取因正畸需要拔除的前磨牙15个,随机分为3组。去除面釉质,暴露平的牙本质表面,在其中央制备3.5mm×3.5mm×3mm的盒形洞。使用Single Bond黏结剂,按使用说明进行牙本质黏结,用Z100复合树脂充填窝洞:A组:分3层水平充填;B组:分3层斜向充填(第一层水平充填,第二、三层近远中向斜向充填);C组:分3层斜向充填(第一、二层近远中向斜向充填,;第三层水平充填)。用硬组织切片机将实验牙切成黏结面积约0.9mm×0.9mm的正方形小条作为试件,用以测试牙本质微拉伸黏结强度。在体视显微镜和扫描电镜下观察样本的断裂界面。结果:C组的微拉伸黏结强度测试值(31.99±5.27)高于A组(24.56±4.90)和B组(31.19±3.90),3种分层充填方法对牙本质微拉伸黏结强度的影响有统计学意义(P<0.05)。体视显微镜和扫描电镜下观察测试样本的断裂多数为黏结界面破坏。结论:3种分层充填方法对牙本质黏结的微拉伸强度存在影响,其中C组的分层充填方法略优于另外两组。因此,在修复较深的牙体缺损时,采用合适的分层充填方法有利于获得良好的黏结效果。     

四种树脂水门汀黏结牙本质剪切强度的比较

目的:评价4种树脂水门汀与牙本质黏结剪切强度。方法:新鲜拔除的无龋损人第三磨牙48个,随机分为4组(n=12),制备颊侧牙本质黏结面,分别与4种树脂水门汀(Unicem、Panavia F、VariolinkⅡ、Vitique)黏结处理,测试剪切强度,SEM观察牙本质黏结界面。结果:4种树脂水门汀中RelyX Unicem(12.84±2.29)MPa与Panavia F(14.93±3.73)MPa、Vitique(11.03±2.57)MPa之间无显著性差异(P>0.05),而他们均显著高于VariolinkⅡ(5.43±1.25)MPa(P<0.05)。结论:新型自黏结树脂水门汀RelyX Unicem可以取得与牙本质良好的黏结效果,且美观,易于使用,节省操作时间,为黏结修复体提供了一种新的选择。     

Effect of surface treatments of laboratory-fabricated composites on the microtensile bond strength to a luting resin cement

The purpose of this study was to evaluate the influence of different surface treatments on composite resin on the microtensile bond strength to a luting resin cement. Two laboratory composites for indirect restorations, Solidex and Targis, and a conventional composite, Filtek Z250, were tested. Forty-eight composite resin blocks (5.0 x 5.0 x 5.0mm) were incrementally manufactured, which were randomly divided into six groups, according to the surface treatments: 1- control, 600-grit SiC paper (C); 2- silane priming (SI); 3- sandblasting with 50 mm Al2O3 for 10s (SA); 4- etching with 10% hydrofluoric acid for 60 s (HF); 5- HF + SI; 6 - SA + SI. Composite blocks submitted to similar surface treatments were bonded together with the resin adhesive Single Bond and Rely X luting composite. A 500-g load was applied for 5 minutes and the samples were light-cured for 40s. The bonded blocks were serially sectioned into 3 slabs with 0.9mm of thickness perpendicularly to the bonded interface (n = 12). Slabs were trimmed to a dumbbell shape and tested in tension at 0.5mm/min. For all composites tested, the application of a silane primer after sandblasting provided the highest bond strength means.     

Effect of chlorhexidine application on microtensile bond strength to dentin

This study evaluated the effect on microtensile bond strength (microTBS) of chlorhexidine application to dentin at different times during an indirect restoration luting procedure. Sixty bovine incisors had their superficial dentin subjected to 0.12% and 2% chlorhexidine solutions for 15 seconds before, during and after 37% phosphoric acid etching, resulting in six groups (n=10): 1) 0.12% chlorhexidine + etching; 2) 2% chlorhexidine + etching; 3) etching + 0.12% chlorhexidine; 4) etching + 2% chlorhexidine; 5) etching with 2% chlorhexidine; 6) etching without chlorhexidine (control). An adhesive system (Adper Single Bond 2) was applied and an indirect resin composite restoration (Filtek Z250) was luted using dual cured resin cement (Rely X ARC). After 24 hours of water storage, the specimens were tested by microtensile bond test (microTBS) at 0.5 mm/minute in a universal testing machine. The data were analyzed by one-way ANOVA (alpha=0.05), demonstrating no significant differences among the groups. The microTBS values in MPa were: 6: 22.83+/-3.53; 5: 22.4+/-3.52; 2: 21.62+/-2.5; 1: 21.28+/-3.17; 3: 19.62+/-2.05; 4: 19.55+/-2.34. The use of chlorhexidine at concentrations of 0.12% and 2% before, after or associated with acid etching did not significantly affect the microTBS values to dentin.