Influence of NaOCl treatment of etched and dried dentin surface on bond strength and resin infiltration

This study evaluated the effect of NaOCl treatment of etched air-dried dentin on the bond strength and state of monomer penetration. Ten percent NaOCl was applied after rinsing the etchant and air drying the dentin surface. Wet bonded, untreated teeth were used as a control. The resin composite was bonded and stored in 37 degrees C water for 24 hours, then shear tested. One-way ANOVA, followed by the Duncan test, was done. For Raman microscopy, bonded specimens were cut parallel to the dentinal tubules and polished. Raman spectra were successively recorded along lines perpendicular to the dentin-adhesive interface. The decreased bond strengths found with air-dried dentin increased with NaOCl treatment, but the highest bond strength was obtained with wet bonding. From Raman spectroscopy, the widths of demineralized dentin decreased with prolonged NaOCl treatment time. The patterns of gradual transition of components differed among the groups.     

Shear bond strength of two resin cements to human root dentin using three dentin bonding agents

This study compared the bond strength of two resin cements to human root dentin when used with three bonding agents. The materials used were Rely X ARC and Perma Cem, two one-bottle bonding agents (Single Bond, Bond-1) and one self-etching bonding agent (Clearfil SE Bond). The dentin was obtained from single rooted human teeth, and the specimens were treated with either 15% EDTA or 37% phosphoric acid to remove the smear layer, except in groups where the self-etching bonding agent was used. The resin cements were placed on dentin surfaces with the use of bonding agents. Shear bond strength (SBS) was tested using a single plane shear test assembly. The dentin specimens were divided into 10 groups. Eight groups were pre-treated with EDTA or phosphoric acid to remove the smear layer, followed by a bonding agent (Bond-1 or Single Bond) and resin cement (Rely X or Perma Cem). In the two remaining groups, the smear layer was left intact, and the two resins cements were used in combination with the self-etching bonding agent (Clearfil SE Bond). No statistically significant differences were observed among the eight groups treated with one-bottle bonding agents. The mean bond strengths of the two groups treated with the self-etching bonding agent did not differ significantly from each other but were both significantly greater than the bond strengths of all the other groups. The results of this study also showed that EDTA can be used as an alternative to phosphoric acid in bonding procedures for resin cements. However, the bond strengths of resin cements, in combination with a self-etching bonding agent, were significantly greater than those of the same cements when used with one-bottle bonding agents.     

根管壁不同处理方法对纤维桩粘接影响的扫描电镜观察

目的 通过观察根管不同部位粘接界面的微观结构,探讨根管壁表面不同处理方法对纤维桩粘接的影响.方法 9颗完整离体上中切牙截冠后经根管治疗、根管预备和酸蚀后,分别采用0.9%NaCl溶液60 s(对照组,3颗)、10%NaOCl溶液60 s(实验1组,3颗)、17%乙二胺四乙酸溶液60 s与5.25%NaOCI溶液60 S联用(实验2组,3颗)冲洗根管壁;每组1颗牙直接切片;1颗牙使用树脂粘接剂粘接石英纤维桩后切片;1颗牙使用复合树脂核材料粘接石英纤维桩后切片;对粘接界面行扫描电镜观察和能谱分析.结果 无论使用何种粘接剂,相比对照组,实验1组和2组树脂突长度、数量明显增加,树脂突侧支交联明显.能谱分析显示,无论使用树脂粘接剂或复合树脂核材料,实验组Ba含量(1组分别为2.4%和6.7%;2组分别为2.6%和16.6%)均多于对照组(分别为0.9%和3.6%).结论 单独使用10%NaOCl溶液或17%乙二胺四乙酸溶液与5.25%NaOCl溶液联用处理根管壁可产生良好的树脂浸润,粘接界面的树脂突结构以及侧支对粘接效果有积极影响.     

In vitro comparison of 10-minute versus 24-hour shear bond strengths of six dentin bonding systems.

OBJECTIVE: Early bond strengths produced by dentin bonding systems should be sufficient to resist the polymerization shrinkage of resin composite. This study compared the 10-minute and 24-hour shear bond strengths of six dentin bonding systems: One-Step (OS), PermaQuik (PQ), Prime & Bond 2.1 (PB), Scotchbond Multi-Purpose (SBMP), Single Bond (SB), and Tenure Quik with Fluoride (TQ). METHOD AND MATERIALS: Each bonding system was used to bond composite to visibly moist dentin at 34 degrees C +/- 2 degrees C. The specimens were debonded at 37 degrees C +/- 1 degree C 10 minutes after the start of light curing of the bonding system, and the results were compared with the 24-hour bond strengths. The mode of failure was recorded. RESULTS: The 10-minute mean shear bond strengths were: OS, 16.4; PQ, 14.3; SB, 14.0; PB, 12.7; TQ, 10.7; and SBMP, 9.3 MPa. The 24-hour mean shear bond strengths were OS, 23.3; PB, 20.8; SB, 20.3; PQ, 19.4; TQ, 11.2; and SBMP, 10.0 MPa. The 10-minute mean shear bond strengths of OS, PQ, PB, and SB bonding systems were significantly less than the 24-hour values. More dentinal fractures and mixed failures were observed with OS, PQ, and PB. Systems with higher bond strengths had more resin penetration into the lateral dentinal branches. CONCLUSION: The 10-minute mean shear bond strengths were all less than 17 MPa, and the 10-minute bond strengths were less than the 24-hour values.     

Alternative adhesive strategies to optimize bonding to radicular dentin

This study tested the hypothesis that bond strengths of filling materials to radicular dentin might be optimized by using an indirect dentin bonding procedure with an acrylic core material. Roots of human teeth were endodontically prepared and obturated with EndoREZ, Epiphany, or the bonding of an acrylic point with SE Bond by using a direct or an indirect bonding technique. Bond strengths of endodontic sealers to radicular dentin were measured with a thin slice push-out test. Push-out strengths of EndoREZ and Epiphany to radicular dentin were less than 5 megapascals (MPa). The direct bonding technique with acrylic points and the self-etching adhesive had push-out strengths of 10 MPa, increasing to 18 MPa with the indirect technique. The use of the indirect bonding protocol with an acrylic point to compensate for polymerization stresses appears to be a viable means for optimizing bond strengths of endodontic filling materials to radicular dentin.     

Effect of removal of surface collagen fibrils on resin-dentin bonding.

OBJECTIVES: The aim of this study was to evaluate the effects of NaOCl at removing the demineralized layer by examining the morphology of the hybrid layer and measuring shear bond strengths after different dentin treatments. METHODS: Dentin disks were treated with: (1) 35% phosphoric acid (PA) 20 s; (2) PA treatment followed by 1.5% NaOCl, 2 min; (3) PA treatment, followed by a 10% NaOCl immersion for 120 h. SEM was used to analyze the morphology of dentin and its interface with dentin bonding agents (DBAs), while shear bond strength tests were used to measure adhesion. All specimens were then fractured into two halves: One half was inspected under SEM; the other half was sequentially placed in 10% PA followed by 12.5% NaOCl for 70 h, to remove all dentin from the resin replica of the original bonded interface. RESULTS: SEM observations showed that collagen fibrils were completely removed from the acid-etched surface by NaOCl treatment. The diameter and the size of dentinal tubules and the number of lateral branches of the tubules were increased following NaOCl treatment. NaOCl applied on dentin smear layers did not significantly modify their SEM morphology. Resin tags were larger in diameter after phosphoric acid/NaOCl treatment than after only phosphoric acid treatment. Resin-infiltrated dentin-layers were only observed after the single phosphoric acid (i.e. conventional etching) procedure, and were not observed after combined phosphoric acid/NaOCl treatment. Etched/NaOCl samples showed a lower bond strength using Scotchbond MP and 3M Single Bond, but were higher in Optibond FL and unmodified in Prime & Bond 2.0 groups when compared with acid-etched controls. Treatment of etched dentin with NaOCl for 120 h produced an unusual type of resin infiltration of mineralized dentin that could be called a "reverse hybrid layer" which may explain the mechanism of resin bonding to NaOCl treated dentin. SIGNIFICANCE: The use of acidic conditioners for exposure of the collagen matrix exposes a soft delicate mesh that can collapse, thereby interfering with resin infiltration. If acid-etching is followed by NaOCl treatment, high bond strengths can be achieved via "reverse hybrid layer" formation, a proposed new mechanism of micromechanical resin retention. This mechanism is not yet recommended for clinical use but demonstrates a new type of resin retention.     

复合树脂联合两种酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度比较

目的:比较复合树脂联合全酸蚀和自酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度。方法:收集新鲜拔除的滞留乳磨牙48个,随机分为4组,分别制备全酸蚀和自酸蚀粘结剂的釉质和牙本质试件,电子万能试验机测定各组剪切强度;体视显微镜下观察试件断面的破坏模式;扫描电镜观察粘结界面情况。结果:全酸蚀粘结剂组的釉质剪切强度明显高于牙本质剪切强度(P<0.05);自酸蚀粘结剂组釉质与牙本质剪切粘结强度无统计学差异(P>0.05);全酸蚀粘结剂组的釉质、牙本质剪切粘结强度均明显高于自酸蚀粘结剂组(P<0.05);体视显微镜及扫描电镜观察均显示,全酸蚀粘结剂与釉质和牙本质的粘结界面结合程度好于自酸蚀粘结剂。结论:全酸蚀粘结剂处理对乳牙釉质及牙本质的剪切粘结强度高于自酸蚀粘结剂。     

Effect of irrigation solutions on dentin bonding agents and restorative shear bond strength

STATEMENT OF PROBLEM: The presence of irrigation solution prior to the application of dentin bonding agents may be one source of contamination and may adversely affect bond strength. PURPOSE: The purpose of this in vitro investigation was to evaluate the effect of irrigation solutions of different purity levels on the shear bond strength of a hybrid composite to dentin. MATERIAL AND METHODS: Forty extracted, intact human molars were hand-scaled. All soft tissue was removed, and the teeth were stored in room-temperature tap water for 1 week. Subsequently, each tooth was embedded in autopolymerizing acrylic resin with the coronal portion exposed. After complete polymerization of the resin, the dentin surfaces were exposed, and the crown was cut longitudinally on all 4 sides to produce flat dentin surfaces for bonding. The prepared specimens were assigned to 4 groups of irrigation solutions: tap water (control), sterile water, 0.9% NaCl irrigation solution, and filtered water. Within each irrigation group were 4 dentin bonding agent subgroups: Prime & Bond NT, One-Step, Single Bond Adhesive, and OptiBond Solo. The dentin surfaces (n = 10 per irrigation/bonding agent pair) were etched with 37% phosphoric acid, rinsed with the assigned irrigation solution for 15 seconds, and then dried. Plastic cylinders (3 mm long x 3 mm inner diameter) were filled with a hybrid composite (Herculite XRV) and bonded to the dentin. Specimens were loaded in a universal testing machine, and shear force was applied to the base of the composite cylinders, parallel to the dentin surfaces, at a crosshead speed of 0.05 in/min until fracture. Failure loads were recorded. Bond strength data were compared with analysis of variance (P<.05). Post-hoc comparisons of means were performed with t tests and P values adjusted for multiple comparisons (Bonferroni method). RESULTS: Tap water irrigation (control) produced no significant difference in bond strengths for all dentin bonding agents tested. When other irrigation solutions were used, One-Step consistently produced significantly lower bond strengths than other dentin bonding agents (P<.05). No preferential choice of irrigation solution could be made for Prime & Bond or Single Bond Adhesive. However, when One-Step or Solo was used, irrigation with normal saline significantly reduced bond strengths (P<.05). CONCLUSION: Within the limitations of this study, the bond strength to dentin of a hybrid composite irrigated with different solutions was dependent on the dentin bonding agent used.     

根管壁表面处理和不同粘结系统对纤维桩粘结强度的影响

目的研究不同根管牙本质壁表面处理方法及使用不同粘结系统对石英纤维桩粘结时根管不同部位剪切粘结强度的影响。方法36颗完整离体上中切牙唇侧釉牙骨质界冠方2.0mm处截冠后行根管治疗。专用钻根管预备,酸蚀后,分别采用生理盐水60s(对照组)、10%次氯酸钠(NaOCl)溶液60s、17%乙二胺四乙酸(EDTA)溶液60s与5.25%NaOCl溶液60s联用的根管壁处理方法,结合DUOLINK树脂粘结剂或LUXACORE核材料按析因设计配对行石英纤维桩粘结修复。包埋并切片后,置于MTSSynergie综合测试仪上采用1mm微推出法对不同根管段行剪切粘结实验,记录数值并行统计学分析。结果剪切粘结强度依次为(MPa):6.29±3.77,9.67±3.94,8.07±3.59,2.59±2.04,5.46±3.09,5.80±3.56。10%NaOCl处理组、17%EDTA溶液与5.25%NaOCl溶液联用组剪切粘结强度均明显增强(P<0.0001);DUOLINK树脂粘结剂组剪切粘结强度优于LUXACORE核材料组(P<0.0001);所有实验组中,剪切粘结强度自根管冠方向根方逐渐减弱。结论单独使用10%NaOCl溶液、17%EDTA溶液与5.25%NaOCl溶液联用处理根管壁增强了石英纤维桩修复根管不同部位尤其是根尖的剪切粘结强度。     

Effect of water on bonding of one-bottle self-etching adhesives

This study evaluated the effect of water on dentin substrate bonding of one-bottle self-etching adhesives. Dentin substrates were divided into two groups: wet and dry dentin. Wet dentin is the normal substrate for bond testing whereas dry dentin was dehydrated in a desiccator for 24 hours. Bonded dehydrated teeth were then divided into two subgroups: stored in water or in desiccator for 24 hours. Microtensile bond strength of resin to dentin was measured using three one-bottle self-etching adhesives. In addition, nanoleakage evaluation was performed through the analyses of SEM and TEM micrographs. The bond strength of dry-dentin group was significantly greater than that of wet-dentin. Further, the amount of nanoleakage within the adhesive interface of dry-dentin group was less than that of wet-dentin. Results showed that bond strength and nanoleakage formation depended on the bonding substrate (wet versus dry dentin) before bonding. One-bottle self-etching adhesives might suck the water from dentinal tubules during bonding by osmosis, leading to nanoleakage formation and thus a decline in bond strength.     

Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces.

OBJECTIVES: The aim of this study was to evaluate the bonding of four commercially available adhesive systems to ground and intact enamel surfaces. METHODS: Extracted human teeth were used to measure the microtensile bond strength to enamel and a field-emission scanning electron microscopy (FE-SEM) was used to observe the bonded interface and the effect of the surface conditioning of each material. Intact buccal enamel surfaces were cleansed with tooth paste using a rotary dental brush, and the ground enamel surfaces were prepared by reducing approximately 0.5 mm from the buccal enamel surfaces using a high-speed diamond bur. One-Step (OS, Bisco), Single Bond (SB, 3M), Clearfil Liner Bond II (LBII, Kuraray), and Tokuso Mac Bond II (MBII, Tokuso) were evaluated for their ability to bond to enamel. RESULTS: There was no significant difference in bond strengths between the materials when they were applied to ground enamel surfaces (p > 0.05). However, the bond strengths of the self-etching systems, LBII and MBII, had significantly lower bond strengths to intact enamel than the bonding systems OS and SB using phosphoric acid etching (p < 0.05). FE-SEM revealed that the etching pattern of self-etching primers was not deep enough to obtain good penetration of bonding resin when applied to intact enamel surfaces. CONCLUSIONS: Phosphoric acid etching produced good resin adhesion to ground and intact enamel. The self-etching/self-priming systems also produced good adhesion to ground enamel, but had lower bond strengths to intact enamel.     

The bond of resin to different dentin surface characteristics

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.     

Shear bond strengths of self-etching adhesives to caries-affected dentin on the gingival wall

The purpose of this study was to evaluate the bonding ability of five current self-etching adhesives to caries-affected dentin on the gingival wall. Seventy extracted human molars with approximal dentin caries were employed in this study. In order to obtain caries-affected dentin on the gingival wall, grinding was performed under running water. Following which, specimens mounted in acrylic blocks and composite resins of the bonding systems were bonded to dentin with plastic rings and then debonded by shear bond strength. With Clearfil SE Bond, bonding to caries-affected dentin showed the highest bond strength. With Optibond Solo Plus Self-Etch, bonding to caries-affected dentin showed higher shear bond strength than AQ Bond, Tyrian SPE & One-Step Plus, and Prompt-L-Pop (p<0.05). Further, the bond strengths of Clearfil SE Bond and Optibond Solo Plus Self-Etch to sound dentin were higher than those of Prompt-L-Pop, AQ Bond, and Tyrian SPE & One-Step Plus (p<0.05). In conclusion, besides micromechanical interlocking through hybrid layer formation, bond strength of self-etch adhesives to dentin may be increased from additional chemical interaction between the functional monomer and residual hydroxyapatite. The results of this study confirmed that differences in bond strength among self-etching adhesives to both caries-affected and sound dentin were due to chemical composition rather than acidity.     

Dentin treatment effects on the bonding performance of self-adhesive resin cements

Mazzitelli C, Monticelli F, Toledano M, Ferrari M, Osorio R. Dentin treatment effects on the bonding performance of self-adhesive resin cements. Eur J Oral Sci 2010; 118: 80–86. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci
The effects of dentin surface treatments on the microtensile bond strengths and on the interfacial characteristics of self-adhesive resin cements were investigated. Flat dentin surfaces were obtained from human molars and were treated as follows: (i) no treatment of dentin; (ii) 0.1 M EDTA scrubbed for 60 s; or (iii) 10% polyacrylic acid applied for 30 s. Three self-adhesive cements were used to lute composite overlays on deep-coronal dentin surfaces in the presence of simulated pulpal pressure (15 cm of H₂O). Bonded specimens were cut into beams 1 mm thick and stressed in tension until failure. Fractured sticks were examined under a scanning electron microscope. Additional specimens were stained with Masson's trichrome and observed under light microscopy for interfacial evaluations. The bond strength to dentin of the hydrophobic and solvent-free cement (RelyX Unicem) was unaffected by the tested dentin treatments. The bond strength of the 2-hydroxyethyl methacrylate (HEMA)-based cement (Bis-Cem) decreased after treatment of dentin with EDTA and/or polyacrylic acid. The hydrophilic and water-containing cement (G-Cem) attained a higher bond strength when luted on polyacrylic acid-conditioned dentin. In conclusion, smear layer removal, opening of dentinal tubules, and the water content of dentin differently influence the bond strengths and the interfacial characteristics of self-adhesive cement–dentin interfaces.     

Influence of eugenol-containing temporary cement on bonding of self-etching adhesives to dentin

PURPOSE: To investigate the influence of eugenol-containing temporary cement on bonding of resin composite to dentin mediated by self-etching adhesives. MATERIALS AND METHODS: Flat dentin surfaces were produced by grinding of extracted human molars. The dentin surfaces were either used directly or after a one-week exposure to a zinc oxide-eugenol cement (IRM). A resin composite (Herculite XRV) was bonded to the dentin surfaces following treatment with 1 of 6 self-etching adhesives (AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, iBond, OptiBond Solo Plus - Self-Etch Adhesive System, and Xeno III). An adhesive system containing 0.5 M EDTA as dentin conditioner (Gluma Classic) was included as negative control, and an etch-and-rinse adhesive system (OptiBond FL) was included as positive control. After storage in water at 37 degrees C for 1 week, the bonded specimens were fractured in shear (n = 8 in each group). RESULTS: Previous contact of dentin with zinc oxide-eugenol cement significantly decreased the bond strength mediated by the negative control and did not affect the bond strength mediated by the positive control. For the self-etching adhesives, no effect was found of previous contact with zinc oxide-eugenol cement. With and without previous contact with zinc oxide-eugenol cement, the etch-and-rinse adhesive system yielded a significantly higher bond strength than all other adhesive systems. CONCLUSION: Previous contact with zinc oxide-eugenol cement did not decrease the bond strength of resin composite to dentin mediated by self-etching adhesives. This finding suggests that eugenol-containing temporary cements may be safe to use in combination with self-etching adhesives.     

Microtensile bond strength of a filled vs unfilled adhesive to dentin using self-etch and total-etch technique

OBJECTIVE: The purpose of this study was to evaluate the effect of a filled adhesive (One-Step Plus; Bisco) versus an unfilled adhesive (One-Step; Bisco) on the microtensile bond strength (muTBS) to dentin using total-etch (Uni-etch; Bisco) and self-etch (Tyrian SPE; Bisco) techniques. METHODS: Twenty extracted human third molars were ground flat to expose occlusal dentin. After the dentin surfaces were polished with 600-grit SiC paper, the teeth were randomly assigned to four groups according to the bonding agent and technique being used. Dentin surfaces were bonded with One-Step Plus+total-etch; One-Step Plus+self-etch; One-Step+total-etch and One-Step+self-etch. Composite buildups were performed with Clearfil AP-X (Kuraray Medical). Following storage in distilled water at 37 degrees C for 24 h, the bonded specimens were serially sectioned into 0.7 mm-thick slabs and then trimmed to hour-glass shapes with a 1 mm2 cross-sectional area (n=20). Microtensile bond strengths were determined using the EZ-test (Shimadzu) at a cross-head speed of 1 mm/min. Data were analyzed using two-way ANOVA and Tukey's post hoc test. RESULTS: There were no significant differences in the muTBS between One-Step Plus and One-Step adhesives when they were used with the total-etch and self-etch techniques (p>0.05). However with the total-etch technique both adhesives yielded significantly higher bond strength values than the self-etch technique (p<0.001). CONCLUSION: The filled adhesive One-Step Plus did not show any beneficial effect than the unfilled adhesive One-Step on the muTBS to dentin with total-etch and self-etch techniques. Irrespective from the adhesive type, self-etch technique revealed lower bond strengths than the total-etch technique.     

Effect of conditioners on bond durability of resin composite to Nd:YAP laser-irradiated dentin

The aim of this study was to evaluate the effect of conditioners (sodium hypochlorite (NaOCl), Roth's ethylenediaminetetraacetic acid (EDTA), and phosphoric acid) on shear bond strength and morphology of Nd:YAP laser-irradiated dentin. In particular, the key focus was on the bond durability between resin composite and treated dentin after being subjected to thermocycling in artificial saliva between 5 degrees C and 55 degrees C. Results indicated that the application of phosphoric acid to laser-irradiated dentin produced a bond strength comparable to those using NaOCl and EDTA. Further, dentinal tubules which were closed after laser irradiation opened following the treatment with conditioners. When subjected to 3,000 thermocycles, the mean shear strength of the samples treated by the three conditioners following laser irradiation ranged from 9.7 to 12.6 MPa with a reduction of 25-33%--a reduction rate lower than that obtained using acid etching alone (50%). Among the three conditioners tested, only phosphoric acid treatment demonstrated an enhanced effect on bond durability of laser-irradiated dentin.     

Effect of three radicular dentine treatments and two luting cements on the regional bond strength of quartz fibre posts

The purpose was to investigate by push-out tests and scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) the effect, after first acid etching the post space walls, of three radicular dentine treatments on the regional bond strength of quartz fibre posts placed using two heavily filled resin luting cements. The crowns of 39 extracted maxillary central incisors were sectioned transversely 2 mm coronal to the labial cement-enamel junction and the roots endodontically treated. After standardized post space preparations and etching 15 s with 32% phosphoric acid, 36 roots were randomly divided into six equal groups. Quartz fibre posts (D.T. LIGHT-POST) were placed using three radicular dentine treatments (0.9% sodium chloride (NaCl) for 60 s, 10% sodium hypochlorite (NaOCl) for 60 s, 17% ethylenediaminetetraacetic acid (EDTA) for 60 s followed by 5.25% NaOCl for 60 s) and two resin composite luting cements (ONE-STEP PLUS/DUO-LINK; ONE-STEP PLUS/LuxaCore Dual). Transverse segments (S1–S7), 1.00 mm (SD = 0.05 mm) thick, were sectioned from the coronal 8 mm of each root. Push-out bond strength tests were performed on coronal, middle and apical post space segments (S2, S4, S6) at a crosshead speed of 0.5 mm/min. Data were recorded and analyzed using a two-way mixed ANOVA design (a = 0.05). Three segments (S1, S5, S7) from roots in each group were examined using SEM/EDS. After post space preparation, acid etching and using each of the three radicular dentine treatments, the three remaining roots were sectioned longitudinally for SEM observation of the post space walls. At all root segment sites, the mean bond strengths from using 0.9% NaCl were significantly lower than for the other two radicular dentine treatments (P ≤ 0.02), and DUO-LINK cement had significantly higher mean bond strengths than LuxaCore Dual cement (P ≤ 0.01). There was a significant linear trend for reduced bond strengths from coronal to apical post space segments (P < 0.001), which was supported by the SEM/EDS observations of dentine tubule appearance and resin tag formation. Acid etching followed by either 10% NaOCl or 17% EDTA and 5.25% NaOCl dentine treatments of the post spaces provided good adhesion and resin luting cement tag infiltration of dentinal tubules in the coronal and middle segments in particular.     

Effect of endodontic irrigants on the shear bond strength of epiphany sealer to dentin

This study examined the effects of commonly employed endodontic irrigants on Epiphany-dentin bond strengths. Smear layers were created on dentin discs obtained from human third molars. Five groups of 10 discs each were treated with one of the following: (a) water; (b) 2% chlorhexidine; (c) 6% sodium hypochlorite (NaOCl); (d) 6% NaOCl followed by EDTA and water; or (e) 1.3% NaOCl followed by MTAD. The treated surfaces were air-dried and treated with Epiphany primer. Hollow steel tubes were placed on the dentin surfaces, and Epiphany sealer was applied to dentin inside the tubes. Samples were tested for shear bond strengths after 7 days of storage. Representative specimens were examined using scanning electron microscopy. One-way ANOVA and Tukey's test revealed significant differences among the groups (p<0.05). Using water or chlorhexidine as an irrigant resulted in significantly lower bond strengths when compared with NaOCl, NaOCl/EDTA, or NaOCl/MTAD. Neither EDTA nor MTAD significantly improved Epiphany-dentin bond strengths when compared with NaOCl used alone.     

Nd:YAG激光对水门汀与牙本质剪切强度的影响

目的:评价脉冲Nd:YAG激光对水门汀与牙本质间剪切强度的影响,并观察激光照射前后的牙本质表面结构变化。方法:取人前磨牙30个,暴露牙本质粘接面形成60个测试样本,随机分为激光组和对照组。激光组以0.8W、10Hz脉冲Nd:YAG激光照射牙本质表面25sec,联合3种水门汀充填;对照组直接使用3种水门汀充填于牙本质表面,置于37℃生理盐水24h后,测试剪切强度,并进行统计学分析,在根管显微镜下观察断裂模式并分类。扫描电镜观察激光照射前后的牙本质表面形态。结果:聚羧酸锌组、玻璃离子组和树脂加强玻璃离子组在Nd:YAG激光照射前(后)的剪切强度分别为4.63±1.39(4.77±0.97)MPa、5.15±0.67(5.26±1.21)MPa和0.92±0.46(0.99±0.35)MPa,激光照射前后的差别均无统计学意义(P>0.05)。扫描电镜观察,0.8W、10Hz的Nd:YAG激光照射会使牙本质表面熔融,玷污层基本去除,大部分牙本质小管封闭,且在局部会出现裂纹。结论:Nd:YAG激光(0.8W、10Hz)处理牙本质,对聚羧酸锌和玻璃离子水门汀与牙本质间的粘接强度无影响。