Bonding to caries-affected dentin

Dentin adhesive systems have dramatically developed during the past decades. In a prepared cavity for an adhesive composite restoration, large areas of the cavity floor are composed of caries-affected dentin after removal of caries-infected dentin, not normal dentin. Caries-affected dentin is different in morphological, chemical and physical characteristics from normal dentin. Therefore, caries-affected dentin has still problems as bonding substrate compared with normal dentin. That is, caries-affected dentin produces lower bond strength and poor quality of the hybrid layer than normal dentin. In addition, when exposed the adhesive interface of caries-affected dentin in oral environment, the poor quality of the hybrid layer would compromise the longevity of the composite restoration due to hydrolysis of the resin and collagen fibrils. The improvement of bonding potential to caries-affected dentin could lead to reinforcement of tooth-composite restoration complex, protecting secondary caries and tooth fracture.     

Effect of pretreatment with mildly acidic hypochlorous acid on adhesion to caries-affected dentin using a self-etch adhesive

Caries-affected dentin is covered with a thicker and organically enriched smear layer than normal dentin. This may affect the demineralization ability and the infiltration of self-etch adhesives, thus reducing the efficacy of bonding to caries-affected dentin. This study evaluated the adhesion of a two-step self-etching adhesive to normal and caries-affected dentin after pretreatment with mildly acidic hypochlorous acid (HOCl) solutions. We used a microtensile bond strength (μTBS) test to compare the μTBS of Clearfil SE Bond to either caries-affected dentin or to normal dentin, after pretreatment for 5 s with one of three solutions (806 mM NaOCl, or 0.95 or 1.91 mM HOCl). The μTBS of the self-etch adhesive was significantly lower to caries-affected dentin than to normal dentin. Pretreatment with 0.95 mM HOCl improved the μTBS of the self-etch adhesive to caries-affected dentin, but there was no significant difference compared with normal dentin. On the other hand, pretreatment with 806 mM NaOCl or 1.91 mM HOCl did not demonstrate a significant improvement in the μTBS to caries-affected dentin. None of the pretreatments demonstrated a negative effect on adhesion to normal dentin.     

Smear layer-deproteinizing improves bonding of one-step self-etch adhesives to dentin

Objectives

Smear layer deproteinizing was proved to reduce the organic phase of smear layer covered on dentin surface. It was shown to eliminate hybridized smear layer and nanoleakage expression in resin–dentin bonding interface of two-step self-etch adhesive. This study aimed to investigate those effects on various one-step self-etch adhesives.

Effect of dentin pretreatment with mild acidic HOCl solution on microtensile bond strength and surface pH

Objectives

To evaluate the pretreatment effect of mild acidic HOCl solution on the microtensile bond strength (μTBS) of a two-step self-etch adhesive to dentin and the alteration of dentin surface pH.

Methods

Thirty-nine flat ground coronal dentin specimens were divided into one control group and 12 experimental groups, which were treated with 6% NaOCl or 50, 100 and 200 ppm HOCl (Comfosy^®) solutions for 5, 15 and 30 s. After rinsing with running water for 30 s, all the dentin surfaces were bonded with Clearfil SE Bond according to the manufacturer's instructions. After 24 h water storage, the bonded specimens were sectioned and trimmed to an hourglass shape with a cross-sectional area of approximately 1.0 mm² and then subjected to the μTBS test. Thirty-six mid-coronal dentin discs were used for surface pH measurement. Dentin surface pH with or without pretreatment was examined using a pH-imaging microscope (SCHEM-100). The μTBS data were analyzed by one-way ANOVA (Dunnett's T3) and the surface pH data were analyzed by non-parametric statistics (Mann–Whitney U-test).

Results

Pretreatment with Comfosy^® at concentrations of 50, 100 and 200 ppm did not significantly affect μTBS regardless of the application time compared with the control group, however the 100 and 200 ppm Comfosy^® groups showed significantly lower surface pH values. For the NaOCl pretreatment groups, a longer application time significantly decreased the μTBS and increased the surface pH values compared to the control group.

Conclusions

The 50 ppm Comfosy^® pretreatments for 5, 15 and 30 s did not affect the μTBS of the two-step self-etch adhesive to dentin and dentin surface pH.     

Bond strength of five current adhesives to caries-affected dentin

Five current dentin adhesives were evaluated for their ability to bond to caries-affected dentin. The materials were: total etch [Solid Bond (SB)], two self-etch [Clearfil SE Bond (CSE), Etch and Prime (EP)], two one bottle [Prime and Bond 2.1 (PB), One Coat Bond (OCB)]. Sixty extracted molar teeth with proximal caries (mesial or distal) extending into mid-dentin were used. By grinding normal and caries-affected proximal surfaces, flat dentin surfaces were obtained. The surfaces were then bonded with each adhesive system and composite resins were added to the surfaces by packing the material into a cylindrical-shaped plastic matrix with an internal diameter of 2.5 mm and height of 3 mm. Shear bond testing was performed following 10 days incubation of specimens in distilled water at 37 degrees C. Results were analysed by Kruskal-Wallis ANOVA, and Mann-Whitney U multiple comparison test and Wilcoxon rank tests. The results obtained with CSE, SB, and EP were similar in caries affected and normal dentin (P > 0.05). But bonds made to normal dentin with OCB and PB were lower (P < 0.05) than bonds to caries-affected dentin. Bonding to caries-affected dentin with CSE (24.49 +/- 5.38), SB (21.49 +/- 9.15), and EP (21.19 +/- 9.17) showed shear bond strengths higher than OCB (17.43 +/- 9.78) and PB (14.10 +/- 7.94) (P < 0.05). Bonding to normal dentin with CSE (29.91 +/- 8.95) was the highest (P < 0.05). SB (21.17 +/- 5.41) and EP (17.45 +/- 6.21) showed shear bond strengths higher than OCB (11.99 +/- 10.15) and PB (10.57 +/- 4.56) (P < 0.05).     

龋影响牙本质粘接强度的研究进展

对于大多数粘接剂而言,龋影响牙本质的粘接强度均低于正常牙本质的粘接强度。本文回顾近几年有关龋影响牙本质粘接强度的文献,着重介绍不同去龋方法、表面处理和粘接剂对龋影响牙本质粘接强度的影响。     

改良自酸蚀粘接剂对龋影响牙本质粘接性能的影响

目的探讨表没食子儿茶素没食子酸酯(EGCG)改良后自酸蚀粘接剂可乐丽Clearfil SE Bond对龋影响牙本质即刻粘接性能影响。 方法选取中龋离体牙20颗,在龋指示剂下去除龋感染牙本质,保留龋影响牙本质。将EGCG配制成100、200、300 μg/ml Clearfil SE Bond粘接剂溶液及水溶液,以不添加EGCG粘接剂及水溶液作为对照组。微拉伸试件分组按照Clearfil SE Bond说明书指导进行粘接,上方堆塑5~6 mm Z350树脂。使用慢速线性切割机沿牙齿长轴进行切割,形成约1 mm × 1 mm试件,进行微拉伸实验。显微硬度试件分组浸泡于EGCG水溶液中24 h后测试显微硬度。使用SPSS 22.0统计学软件,在One-Way ANOVA模式下进行统计学分析。 结果EGCG处理后龋影响牙本质的粘接强度及显微硬度均明显提高,差异有统计学意义(F_粘接强度=24.554,P_粘接强度 < 0.05;F_显微硬度=20.418,P_显微硬度 < 0.05)。 结论EGCG可增强龋影响牙本质的即刻粘接强度及显微硬度。     

Conditioning effect on dentin, resin tags and hybrid layer of different acidity self-etch adhesives applied to thick and thin smear layer

OBJECTIVES: to assess the conditioning effect (CE) of self-etch adhesives of different acidity applied to thick and thin smear layer (SL), the corresponding resin tags (RT) and hybrid layer (HL). METHODS: Twenty-seven molars had their occlusal dentin exposed and were sectioned into two halves. Each of them was ground with a 60 or 600-grit SiC paper, respectively for thick and thin SL production. Three self-etch adhesives: a mild (Clearfil SE Bond), an intermediary (Optibond Solo SE and Solo Plus) and a strong (Tyrian Self Priming Etchant+One Step Plus) and an etch-&-rinse system (Scotchbond Multi Purpose Plus) were used. For CE evaluation, the self-etch primers were applied and rinsed off with acetone and alcohol prior to SEM preparation. For RT and HL specimens self-etch adhesives were applied and restored with Z-250. For RT specimens, dentin was removed with HCl (6N) and NaClO (1%) baths. The HL specimens were fixed, dehydrated, dried with HMDS, embedded, polished and slightly demineralized (6N HCl) and deproteinized (1% NaClO). After gold sputtering they were observed by SEM. RESULTS: The thick smear layer was clearly not totally removed by the mild self-etch primer. RT varied in density and shape among the self-etch adhesives. Thicker HL was observed for the strong self-etch and etch-&-rinse adhesives. CONCLUSIONS: The etch-&-rinse adhesive presented the thickest HL and was the only adhesive to produce RT in high density and uniform distribution along the whole dentin surface, independently of the SL thickness.     

NaOCl effects on primary and permanent pulp chamber dentin

OBJECTIVES: The dentin quality of primary and permanent pulp chamber was inspected by Fourier-transformed Raman spectroscopy (FT-Raman) and scanning electron microscopy (SEM). Fragments of pulp chamber dentin were obtained from 20 human molar crowns (primary and permanent). METHODS: The fragments were assigned to 8 groups (n=5)-Primary teeth: G1, pulp chamber dentin; G2, pulp chamber dentin irrigated with NaOCl 1% (30min); G3, pulp chamber dentin irrigated with NaOCl 1% (30min) and etched by 35% phosphoric acid; G4, pulp chamber dentin etched by 35% phosphoric acid. Permanent teeth: G5, pulp chamber dentin; G6, pulp chamber dentin irrigated with NaOCl 1% (30min); G7, pulp chamber dentin irrigated with NaOCl 1% (30min) and etched by 35% phosphoric acid; G8, pulp chamber dentin etched by 35% phosphoric acid. The spectra were subjected to the Cluster analysis. The SEM images were scored. RESULTS: Inorganic content: There was a difference between primary and permanent dentin. The groups treated with NaOCl were statistically similar between them, but differed from the groups not treated. Organic content: There was no difference between primary and permanent dentin. The groups became similar after NaOCl and phosphoric acid treatments. The microscopic images showed the presence of calcospherites on permanent dentin and their absence on primary dentin. CONCLUSIONS: The NaOCl changed the inorganic content in both dentitions; regardless of the following phosphoric acid etching. However, the chemical changes caused by NaOCl were not detected by SEM when it was followed by etching.     

牙本质表面处理对粘接性能的影响

目的探讨0.5mol/L乙二胺四乙酸（EDTA）和35%的磷酸以及前处理剂对受龋影响牙本质、正常牙本质与光固化复合树脂粘接密合性能的影响。方法实验用牙为拔除的患龋磨牙及正畸拔除的前磨牙各23颗,将受龋影响牙本质（CAD）和正常牙本质（CFD）分别用EDTA和磷酸处理,扫描电镜观察牙本质的超微结构。在离体牙标本上分别制备柱状牙本质洞形,分别经EDTA和磷酸处理后,再各取半数使用前处理剂甲基丙烯酸甘油单酯（GM）处理,全部样本用光固化复合树脂常规充填,光镜测量其洞底粘接断面最大收缩间隙,并对收缩间隙进行扫描电镜观察。结果EDTA和磷酸均能清除牙本质表面的玷污层,CAD表面的牙本质小管大部分被矿化结晶堵塞,EDTA不会使管周高钙化区脱钙;磷酸可使牙本质小管管周脱钙,使CFD牙本质小管呈喇叭口状开放,对CAD的矿化结晶体的影响不大。磷酸较EDTA处理牙本质的粘结断面出现的收缩间隙明显增加（P（0.05）,GM前处理对于降低CFD与复合树脂之间的收缩间隙有明显作用（P（0.05）,而对CAD与复合树脂之间的粘接无明显作用。结论EDTA处理牙本质可提高其与复合树脂之间的封闭性能。前处理剂GM可提高CFD与复合树脂之间的封闭性能,对CAD的作用不明显。对CAD适当的处理,亦可获得良好的粘接性能。     

牙颈部非龋性硬化牙本质经自酸蚀粘结剂处理后的超微形态

目的:观察牙颈部非龋性硬化牙本质经一步法自酸蚀粘结剂处理后树脂—牙本质界面的超微结构变化。方法:实验组选择因牙周病拔除的有典型牙颈部非龋性缺损的前磨牙,使用一步法自酸蚀粘结剂AdperPrompt L-Pop处理硬化牙本质表面,并用树脂修复缺损。对照组为正畸拔除的正常前磨牙,人工机械制备牙颈部楔形缺损。扫描电镜观察自酸蚀处理后硬化牙本质表面的超微形态以及树脂—牙本质界面的微观表现。结果:牙颈部非龋性硬化牙本质表面的牙本质小管大部分被柱状的矿化结晶体堵塞。自酸蚀粘结剂AdperPrompt L-Pop酸蚀不能去除小管内的矿化结晶。硬化牙本质与树脂的粘结界面可见到树脂突,但与正常牙本质比较,树脂突的数量较少、长度较短。结论:硬化牙本质的粘结特性与正常牙本质存在差异。树脂突的数量及长度不足可能影响硬化牙本质的粘结。     

改良第八代粘接剂对龋影响牙本质粘接性能的影响

目的:第八代粘接剂Single Bond Universal(SBU)是最新一代的粘接剂,表没食子儿茶素没食子酸酯(Epigallocatechin gallate,EGCG)是基质金属蛋白酶抑制剂及偶联剂,本研究探讨添加EGCG是否可以提高SBU粘接强度及降低微渗漏.方法:将人中龋离体牙去除冠部釉质,龋指示剂下制备龋...     

即刻牙本质封闭对预备后牙本质敏感程度的影响

目的评价牙本质即刻封闭技术对牙体预备后活髓基牙牙本质敏感程度的影响。方法30例患者行后牙三单位固定义齿修复,每例口内有2颗活髓后牙参与实验,基牙随机分为实验组和对照组。实验组在基牙预备后行即刻牙本质封闭,随后取模。对照组在基牙预备后常规取模,不进行即刻牙本质封闭。1周后行最终修复,全冠粘接后1周、1个月、6个月、12个月和18个月时检查记录患者的牙本质敏感程度,并进行统计学分析。结果固定义齿粘接后1周及1个月,实验组出现敏感基牙数少于对照组（1周：Z=-1.88,P=0.03;1个月：Z=-2.15,P=0.02）。粘接后6、12及18个月两组敏感发生率间差异无统计学意义（6个月：Z=-0.69,P=0.30;12个月：Z=-0.41, P=0.69;18个月：Z=-0.42,P=0.52）。比较两组敏感程度结果显示,实验组敏感的基牙,敏感程度主要为1度;对照组主要为1度及2度。1周及1个月观察点两组疼痛程度差异有统计学意义（1周：P＜0.05,1个月P=0.027）。结论活髓基牙牙体预备后行即刻牙本质封闭,可有效降低术后短期内牙本质过敏的发生率,减小患者的术后不适感。     

The effect of Morinda Citrifolia juice as an endodontic irrigant on smear layer and microhardness of root canal dentin

PurposeThe purpose of this study was to evaluate the effect of Morinda Citrifolia Juice (MCJ) on smear layer removal and microhardness value of root canal dentin in compared with various endodontic irrigants.Material and methodsEighty-four single-rooted human teeth were prepared to apical size of #35. Since decoronation, samples were divided into seven groups of 12 in each (n = 12). Specimens were finally irrigated by either 1: 2.5% NaOCl, 2: 6% MCJ, followed by a final flush of 17% ethylene diaminetetraacetic acid (EDTA), 3: 6% MCJ, 4: 2.5% NaOCl then17% EDTA, 5: MTAD, 6: 2% chlorhexidine (CHX), and 7: saline. After irrigation, all samples were subjected to Vickers microhardness test at 100 and 500-μm depths and then were examined under scanning electron microscopy (SEM) and ImageJ program was used to calculate open dentinal tubules. One way ANOVA and post hoc Tukey tests were used to reveal any significant differences among and between groups respectively.ResultsThe microhardness values at 100 μm and 500 μm for MTAD were significantly lower than for NaOCl + EDTA and MCJ + EDTA groups (p < 0.05). MCJ + EDTA, NaOCl + EDTA, and MTAD protocol significantly removed smear layer in compared with control group (p < 0.05), with no significant differences among these three groups.ConclusionsIt was concluded that 6% MCJ followed by a final flush of 17% EDTA can be regarded as an effective solution on smear layer removal without any adverse influence on microhardness property of root canal dentin.     

Dentin treatment with MMPs inhibitors does not alter bond strengths to caries-affected dentin

OBJECTIVES: This study aimed to investigate if the use of protease inhibitors (EDTA and chlorhexidine) may influence microtensile bond strength (MTBS) of an etch-and-rinse adhesive system to caries-affected human dentin. METHODS: Flat middle coronal dentin surfaces with a central region of caries-affected dentin surrounded by sound dentin were bonded with Adper Scotchbond 1 after: (1) etching with 35% H3PO4; (2) etching with 0.1M EDTA and (3) 35% H3PO4-etching followed by 5% chlorhexidine application. Resin composite build-ups were constructed incrementally and trimmed to yield hourglass specimens (0.8mm2 bonded area) that contained sound or caries-affected dentin (confirmed after debonding by microhardness measurements - KHN). Bonded specimens were tensioned at 0.5mm/min. Data were analyzed by ANOVA and multiple comparisons tests (p<0.05). Failure mode analysis was performed by scanning electron microscopy (SEM). RESULTS: H(3)PO(4), EDTA and chlorhexidine pre-treatments yielded similar MTBS values, in both dentin substrates. Bond strength to sound dentin was significantly higher than that to caries-affected dentin after H3PO4-etching. Caries-affected dentin exhibited lower KHN than sound dentin. CONCLUSIONS: Conditioning of caries-affected dentin with EDTA or a combined use with H3PO4 and chlorhexidine may be proposed as these protease inhibitors do not reduce MTBS to caries-affected dentin if compared to conventional H3PO4 treatment.     

可见光固化牙本质粘结剂的制备及其粘结强度研究

目的制备新型的可见光固化牙本质粘结剂,并对其性能进行研究。方法以Bis-GMA和4-META为主要成分,分别选用HEMA和TEGDMA为稀释单体,制备了两种可见光固化牙本质粘结剂,测试了其剪切粘结强度,并对其粘结表面进行了SEM观察。结果以HEMA为稀释单体的粘结剂和以TEGDMA为稀释单体的粘结剂平均剪切粘结强度分别为21.8MPa和7.54MPa,且SEM结果显示含HEMA的粘结剂能更好地渗入牙本质小管中形成树脂突。结论以HEMA为稀释单体的粘结剂具有更好的粘结性能。说明HE-MA在牙本质粘结剂中扮演着非常重要的角色,能极大地改善材料的粘结性能。     

NaOCl degradation of a HEMA-free all-in-one adhesive bonded to enamel and dentin following two air-blowing techniques

OBJECTIVE: Phase-separation within HEMA-free all-in-one dental adhesives may result in the entrapment of droplets within the adhesive resin. Strongly air-blowing prior to polymerization, can remove most of these droplets. The objective of this study was to evaluate the effect these droplets may have on the resistance of the adhesive-tooth interface to NaOCl degradation. METHODS: The micro-tensile bond strength (microTBS) to enamel and dentin was determined when a HEMA-free all-in-one adhesive was applied either following a mild or strong air-blowing technique. The bonds were also exposed to an aqueous sodium hypochlorite (NaOCl) solution for 1h, following a recently introduced methodology to mimic in vivo bond degradation. RESULTS: This study revealed that strong air-blowing of the adhesive only resulted in a significantly higher micro-tensile bond strength (microTBS) to dentin, but not to enamel. Likewise, NaOCl only reduced the microTBS to dentin for both the mild and strong air-blowing technique, but again not the microTBS to enamel. Failure analysis by SEM clearly revealed that strong air-blowing is less effective in droplet removal when the adhesive was applied in small and narrow class-I cavities, as compared to when it was applied to flat surfaces. CONCLUSIONS: NaOCl did preferentially dissolve the hybrid layer at dentin, and more for the mild than for the strong air-blowing technique. A strong air-blowing procedure resulted in a more NaOCl-resistant hybrid layer, so that it can be concluded that a HEMA-free one-step adhesive definitely benefits from a strong air-blowing technique.     

The effect of dimethyl sulfoxide (DMSO) on dentin bonding and nanoleakage of etch-and-rinse adhesives

Objective

The objective was to examine the effect of a solvent dimethyl sulfoxide (DMSO) on resin–dentin bond durability, as well as potential functional mechanisms behind the effect.

Methods

Microtensile bond strength (μTBS) was evaluated in extracted human teeth in two separate experiments. Dentin specimens were acid-etched and assigned to pre-treatment with 0.5 mM (0.004%) DMSO as additional primer for 30 s and to controls with water pre-treatment. Two-step etch-and-rinse adhesive (Scotchbond 1XT, 3M ESPE) was applied and resin composite build-ups were created. Specimens were immediately tested for μTBS or stored in artificial saliva for 6 and 12 months prior to testing. Additional immediate and 6-month specimens were examined for interfacial nanoleakage analysis under SEM. Matrix metalloproteinase (MMP) inhibition by DMSO was examined with gelatin zymography. Demineralized dentin disks were incubated in 100% DMSO to observe the optical clearing effect.

Results

The use of 0.5 mM DMSO had no effect on immediate bond strength or nanoleakage. In controls, μTBS decreased significantly after storage, but increased significantly in DMSO-treated group. The control group had significantly lower μTBS than DMSO-group after 6 and 12 months. DMSO also eliminated the increase in nanoleakage seen in controls. 5% and higher DMSO concentrations significantly inhibited the gelatinases. DMSO induced optical clearing effect demonstrating collagen dissociation.

Significance

DMSO as a solvent may be useful in improving the preservation of long-term dentin–adhesive bond strength. The effect may relate to dentinal enzyme inhibition or improved wetting of collagen by adhesives. The collagen dissociation required much higher DMSO concentrations than the 0.5 mM DMSO used for bonding.     

自酸蚀粘结剂治疗牙本质过敏症的临床疗效观察

目的：对比观察3M Adper Prompt自酸蚀粘结剂和75%氟化钠甘油糊剂治疗牙本质过敏症的临床疗效.方法：颈部牙本质过敏症患者110例,共122颗牙,随机分为治疗组55例62颗牙,用3M Adper Prompt自酸蚀粘结剂脱敏治疗,对照组55例60颗牙,用75%氟化钠甘油糊剂脱敏治疗,在统一标准下进行即刻和1个月、3个月后的疗效对照分析.结果：两组之间即刻疗效无显著性差异,而1个月、3个月后的疗效具有显著性差异,3M Adper Prompt自酸蚀粘结剂脱敏效果明显优于氟化钠甘油糊剂的脱敏效果.结论：3M Adper Prompt自酸蚀粘结剂对牙本质过敏症具有较好的临床治疗效果.     

Effect of endodontic irrigation on bonding of resin cement to radicular dentin

The influence of endodontic irrigation on shear bond strengths of resin cement to radicular dentin was investigated. Human radicular dentin blocks were divided into four groups and subjected to one of four endodontic irrigations: ethylenediaminetetraacetic acid (EDTA) group, 17% EDTA for 60 s; EDTA/sodium hypochlorite (NaOCl) group, 17% EDTA for 60 s followed by 10 ml of 5% NaOCl for 15 s; NaOCl group, 10 ml of 5% NaOCl for 15 s; and control group, no treatment. Morphological changes of dentin surface after endodontic irrigation were observed by scanning electron microscopy (SEM). A resin block was bonded to the radicular dentin after irrigation using resin cement with either wet-bonding (Uni-Etch/One-Step; Bisco) or self-etching (Tyrian SPE/One-Step Plus; Bisco) adhesives. Shear bond strengths were measured and the penetration of resin tags into dentinal tubules at resin-dentin interface was observed by SEM. With the wet-bonding system, the shear bond strengths for the EDTA/NaOCl group, in which dentinal tubules openings and uniform resin tag penetration into dentinal tubules were observed, were significantly higher than the EDTA and control groups. With the self-etching system, the shear bond strengths were significantly lower in the EDTA group compared with the NaOCl and control groups. The effects of endodontic irrigation on the bonding of resin cement to radicular dentin depended on the dentin bonding system used.