牙本质混合层原位再矿化模型的构建及作用

目的：构建牙本质混合层原位再矿化诱导模型,并从微观形态学角度探讨其矿化效果,为仿生再矿化技术的临床应用提供实验依据。方法采用5 mm ×5 mmⅠ型胶原海绵块作为3D胶原支架,结合电镜观察和傅里叶红外光谱分析技术,快速评估成核诱导物多聚磷酸钠（STTP）和硅酸盐水门汀树脂的仿生矿化诱导潜能。在此基础上,将仿生矿化技术与牙本质粘接程序结合,以STTP作为治疗性底剂应用于酸蚀脱矿牙本质面,在完成常规粘接处理后以硅酸盐水门汀树脂为洞衬剂,构建临床相关的混合层原位再矿化模型。采用透射电子显微镜观察矿化1～3个月后树脂牙本质粘接界面再矿化区域的分布和再矿化程度。结果矿化诱导28 d后的3D胶原样本,纤维内可见磷灰石纳米晶体的有序沉积,纤维重现了与天然矿化胶原结构类似的横纹特征。红外光谱分析结果显示,在900～1200 cm-1和500～600 cm-1区域,矿化胶原基质出现与纯羟基磷灰石特征峰相吻合的吸收峰,提示矿化胶原中形成的无机物是磷灰石。混合层原位矿化诱导1～3个月后,混合层内可见纤维内再矿化现象的存在,纳米晶体在胶原纤维内呈现迭序排列特征。结论在牙体粘接修复过程中,以矿化诱导物STTP和硅酸盐水门汀树脂作为治疗性底剂和洞衬剂,能使混合层内树脂渗透不良的胶原基质发生纤维内矿化。通过混合层原位再矿化模型的成功构建,初步证实仿生矿化技术应用于临床树脂牙本质粘接界面损伤修复的可行性,建立了研究方法学,为仿生再矿化技术的最终临床应用提供充分的科学依据。     

牙颈部非龋性硬化牙本质粘接的超微形态研究

目的观察牙颈部非龋性硬化牙本质经自酸蚀牙本质粘接剂处理后，树脂一牙本质界面的超微结构。方法选择有典型牙颈部非龋性缺损且因牙周病拔除的上颌前磨牙，使用两步法的自酸蚀粘接剂Contax粘接处理。扫描电镜观察硬化牙本质表面超微形态以及树脂一牙本质界面的混合层和树脂突的微观表现。结果硬化牙本质的牙本质小管大部分被柱状的矿化结晶体堵塞。粘接界面也可见到清晰的混合层和树脂突，但树脂突较短。结论硬化牙本质的粘接与正常牙本质存在差异，牙本质小管内的矿化结晶可能影响粘接效果。自酸蚀粘接剂对硬化牙本质具有一定的粘接能力。     

硬化牙本质粘接界面的激光扫描共聚焦显微镜观察

目的使用激光扫描共聚焦显微镜（CLSM）观察牙颈部硬化牙本质在全酸蚀和自酸蚀粘接系统形成粘接界面的超微结构。方法选用12颗因牙周病拔除的具有典型楔状缺损的上颌前磨牙为实验组;12颗新鲜拔除的无龋人上颌前磨牙为对照组,制备人造楔状缺损。使用Single Bond （SB,全酸蚀单瓶系统）、Clearfil SE Bond（CB,自酸蚀底胶系统）、Xeno Ⅲ（XB,自酸蚀一步粘接系统）粘接系统处理牙面,以罗丹明B异硫氰酸盐为荧光素,使用CLSM观察粘接界面的混合层与树脂突的微观结构。结果双因素方差分析表明粘接剂种类、牙本质类型对粘接界面树脂突长度、混合层厚度有显著影响（P<0.05）。无论是正常牙本质还是硬化牙本质,全酸蚀粘接剂（SB）产生的树脂突长度、混合层厚度均大于自酸蚀粘接剂（CB、XB）,并且其差异具有统计学意义（P<0.05）;而CB和XB间树脂突长度、混合层厚度相差不多,二者间无统计学意义。结论硬化牙本质相对于正常牙本质形成的混合层较薄或者没有,树脂突短、少。全酸蚀粘接系统与自酸蚀粘接系统作用同类型的牙本质上,自酸蚀比全酸蚀形成的混合层薄,树脂突短。     

硬化牙本质粘接界面纳米渗漏的激光扫描共聚焦显微镜观察

目的使用激光扫描共聚焦显微镜（CLSM）观察牙颈部硬化牙本质在全酸蚀和自酸蚀粘接系统形成粘接界面的纳米微渗漏情况。方法选取12颗因牙周病拔除的具有典型楔状缺损的上颌前磨牙为实验组，随机分为3组；选取12颗新鲜拔除的无龋人上颌前磨牙为对照组，人工形成楔状缺损，随机分为3组。选用3种牙本质粘接系统，即Single Bond（SB）、Clearfil SE Bond（CB）、Xeno Ⅲ（XB），按照厂家说明分别应用于牙本质楔状缺损表面。自凝树脂封闭根尖，6组试样分别浸泡于0.1%罗丹明B异硫氰酸盐的50%乙醇溶液中24 h，慢速砂片切割后CLSM下进行观察。结果粘接剂种类、牙本质类型对粘接界面的纳米渗漏长度有显著影响（P<0.05）。无论正常牙本质还是硬化牙本质，SB产生的纳米渗漏长度均大于CB和XB，且差异有统计学意义（P<0.05）。CB、XB之间差异无统计学意义（P>0.05）。正常牙本质上SB产生的纳米渗漏长度与硬化牙本质上SB产生的纳米渗漏长度间差异无统计学意义（P=0.148）；而CB、XB作用于正常牙本质上产生的纳米渗漏长度均大于硬化牙本质，且差异有统计学意义（P<0.05）。结论3种类型粘接系统均有纳米渗漏发生，硬化牙本质的粘接界面下纳米渗漏多发生在树脂与正常牙本质、硬化牙本质三者结合处的树脂与正常牙本质结合界面。     

酸蚀时间对牙本质粘接界面纳米渗漏和粘接强度的影响

目的:研究、比较不同酸蚀时间对4种全酸蚀粘接剂[OptiBond Solo(OB)、Single Bond(SB)、One-Step(OS)、Prime & Bond NT(PB)]牙本质粘接界面纳米渗漏和粘接强度的影响.方法:选取80颗无龋损人磨牙,用600目碳化硅砂纸在流水冲洗下预备出统一的牙本质粘接面玷污层,分别选用4种粘接剂在不同酸蚀时间条件下进行粘接处理;每颗牙齿垂直于粘接面切割出8个1.0 mm×1.0 mm×4.0 mm粘接试件,分别在TEM下观察其粘接界面纳米渗漏以及进行微抗拉强度(μBS)测试.结果:4种粘接剂的牙本质粘接强度OB为(25.36±4.18)MPa、SB为(24.25±3.97)MPa、OS为(28.65±4.93)MPa和PB为(27.12±4.13)MPa,在酸蚀粘接面15 s时均取得高的牙本质粘接强度(P＜0.01),并且牙本质粘接界面纳米渗漏均随粘接面酸蚀时间的延长而增加,呈正相关关系(F OB=0.842,F SB=0.888,F OS=0.877,F PB=0.865;P＜0.01).结论:通过合理控制粘接面酸蚀时间,可以在保证牙本质粘接强度的前提下,减少牙本质粘接界面纳米渗漏.     

不同粘接剂对二氧化锆桩固位力的影响

目的探讨不同粘接剂对二氧化锆桩与根管内牙本质粘接强度的影响。方法将60颗完整无龋坏的离体上颌中切牙自釉牙骨质界处截断牙冠,根管桩道预备,制作二氧化锆桩核。60颗牙随机分为6组,分别用磷酸锌水门汀、聚羧酸锌水门汀、玻璃离子水门汀i、Bond加LuxaCore双固化树脂、RelyX Unicem树脂、32%磷酸加ESPE RelyX Unicem树脂粘固二氧化锆桩核。万能力学试验机进行推出测试,记录粘接强度,并对数据行统计学分析。结果 32%磷酸加ESPE RelyX Unicem树脂组、ESPE RelyX Unicem树脂组i、Bond加Luxa Core树脂组、聚羧酸锌水门汀组、玻璃离子水门汀组、磷酸锌水门汀组的二氧化锆桩粘接强度分别为（15.06±1.80）MPa、（11.57±1.33）MPa（、10.42±1.24）MPa（、7.30±1.05）MPa（、6.99±0.87）MPa（、3.97±0.95）MPa,固位力依次降低。其中32%磷酸加ESPE RelyX Unicem树脂组的固位力显著高于其他组,两两比较差异均有统计学意义（P〈0.05）;ESPE RelyX Unicem树脂组与Luxa Core树脂组之间（P=0.590）,聚羧酸锌组和玻璃离子组之间（P=0.490）的差异均无统计学意义;磷酸锌水门汀的粘接强度最低,与其它组比较差异均有统计学意义（P〈0.05）。结论临床粘固二氧化锆桩,树脂类粘接剂固位力较强,自粘接系统加用酸蚀技术可以显著提高二氧化锆桩在根管内的粘接强度。     

脱矿牙本质与四种粘接剂的粘接强度测试及粘接界面观察

目的比较脱矿牙本质与4种全酸蚀或自酸蚀粘接剂的粘接强度及粘接界面超微结构的差异,以期对临床治疗有所指导。方法选择20颗面龋坏的离体磨牙,在龋显示剂的指示下去除牙本质龋的感染层,保留脱矿牙本质。平齐龋洞洞底平面,去除冠向牙体组织,作为粘接面。选择临床常用的2种全酸蚀粘接剂:材料A(All Bond2)、材料B(Prime&BondNT)和2种自酸蚀粘接剂:材料C(ClearfilSEBond)、材料D(XenoⅢ),分别按说明书要求粘接。用慢速锯将样本牙切为粘接面积约0.9mm×0.9mm的长方体试件。体视显微镜下将试件分为正常牙本质组和脱矿牙本质组,用微拉伸测试仪检测粘接强度。扫描电镜观察各组试件粘接界面的超微形态。结果方差分析提示牙本质类型和粘接剂对微拉伸粘接强度的影响均有统计学意义(P<0.05)。对正常牙本质,不同粘接剂的微拉伸粘接强度差异无统计学意义(P>0.05);对于脱矿牙本质,材料D的微拉伸粘接强度较其他粘接剂明显降低(P<0.05)。扫描电镜下观察脱矿牙本质的混合层多孔稀疏,树脂突短少,无侧枝形成。结论对脱矿牙本质,本项实验中全酸蚀粘接剂的粘接强度优于自酸蚀粘接剂。     

3种无托槽隐形矫治器附件粘接方法的比较研究

目的 比较全酸蚀粘接剂、自酸蚀粘接剂和树脂加强型玻璃离子水门汀3种材料粘接无托槽隐形矫治器附件的操作时间和临床效果。方法 将采用无托槽隐形矫治器矫治的30例错牙合畸形患者（附件156个）随机分为3组,每组10例。A组采用3M Adper Single Bond 2全酸蚀粘接剂和3M Z350纳米充填树脂粘接附件,B组采用3M Adper Easy One自酸蚀粘接剂和3M Z350纳米充填树脂粘接附件,C组直接采用GC Fuji Ortho LC树脂加强型玻璃离子水门汀粘接附件。记录每个附件的操作时间,评价粘接时、治疗1个月和6个月时3组附件的失败情况。结果 C组附件的操作时间较A、B组短（P<0.01）。3组附件之间的粘接失败率无统计学差异（P>0.05）,同一组内不同时间的粘接失败率也无统计学差异（P>0.05）。结论 3种材料粘接附件的稳定性均能达到满意的效果,但树脂加强型玻璃离子水门汀操作简便,更适宜临床推广。     

渗透树脂与流体树脂封闭牙本质小管的实验研究

目的：观察渗透树脂与流体树脂在自酸蚀粘接及全酸蚀粘接条件下对暴露牙本质小管的封闭效果。方法：将60颗健康离体牙随机分为4组（n ＝15）,在不同粘接条件下对暴露的牙本质进行粘接,A 组采用 Icon-Etch 酸蚀,渗透树脂 Icon-In-filtrant 粘接;B 组采用 SE-Bond 酸蚀粘接,Icon-Infiltrant 粘接;C 组采用 SE-Bond 酸蚀粘接,流体树脂 Filtek TMZ350XT 粘接;D组采用格鲁玛酸酸蚀,Prime ＆Bond NT 和 FiltekTMZ350XT 粘接,扫描电镜观察各组树脂粘接面形态,测量混合层、粘接剂层的平均厚度及树脂突的平均长度。结果：渗透树脂与流体树脂一样在暴露牙本质表面形成紧密嵌合,D 组混合层厚度最厚,C组的粘接剂层最厚,而 A 组渗入到牙本质小管中的树脂突最长,有统计学差异（P ＜0．05）。结论：渗透树脂可渗透入暴露的牙本质小管形成树脂突,封闭牙本质小管,其作用优于自酸／全酸粘接的流体树脂。     

三种粘接剂粘接不同牙本质的微拉伸粘接强度比较

目的采用微拉伸粘接强度实验测定3种牙本质粘接剂粘接楔状缺损处硬化牙本质的粘接强度。方法选择有典型楔状缺损并因牙周病拔除的上颌前磨牙30颗作为实验组，正常上颌前磨牙30颗作为对照组，使用粘接剂A（全酸蚀粘接剂Scotchbond Multi—Purpose）、B（一步法自酸蚀粘接剂Adper Prompt L-Pop）和C（两步法自酸蚀粘接剂Contax）处理硬化牙本质和正常牙本质表面，相应树脂修复。测试两组试件的微拉伸粘接强度。结果粘接剂A、B、C粘接硬化牙本质的微拉伸粘接强度分别为46．805MPa、39．045MPa、29．852MPa。粘接剂A和C与硬化牙本质的微拉伸粘接强度低于正常牙本质，而粘接剂B与之相反，差异有统计学意义（P〈0．05）。结论牙颈部楔状缺损处硬化牙本质由于结构上的特殊性可造成粘接困难。酸性强有利于粘接剂与硬化牙本质的粘接。     

Phosphoric acid esters cannot replace polyvinylphosphonic acid as phosphoprotein analogs in biomimetic remineralization of resin-bonded dentin

Polyvinylphosphonic acid (PVPA), a biomimetic analog of phosphoproteins, is crucial for recruiting polyacrylic acid (PAA)-stabilized amorphous calcium phosphate nanoprecursors during biomimetic remineralization of dentin collagen matrices. This study tested the null hypothesis that phosphoric acid esters of methacrylates in dentin adhesives cannot replace PVPA during bimimetic remineralization of resin–dentin interfaces. Human dentin specimens were bonded with: (I) XP Bond, an etch-and-rinse adhesive using moist bonding; (II) XP Bond using dry bonding; (III) Adper Prompt L-Pop, a self-etching adhesive. The control medium contained only set Portland cement and a simulated body fluid (SBF) without any biomimetic analog. Two experimental Portland cement/SBF remineralization media were evaluated: the first contained PAA as the sole biomimetic analog, the second contained PAA and PVPA as dual biomimetic analogs. No remineralization of the resin–dentin interfaces could be identified from specimens immersed in the control medium. After 2–4 months in the first experimental medium, specimens exhibited either no remineralization or large crystal formation within hybrid layers. Only specimens immersed in the second remineralization medium produced nanocrystals that accounted for intrafibrillar remineralization within hybrid layers. The null hypothesis could not be rejected; phosphoric acid esters in dentin adhesives cannot replace PVPA during biomimetic remineralization of adhesive-bonded dentin.     

Biomimetic remineralization of artificial caries dentin lesion using Ca/P-PILP

ObjectiveTo assess the ultrastructural change of demineralized dentin collagen during calcium phosphate polymer-induced liquid precursor (Ca/P-PILP) mediated remineralization process and to evaluate the biomimetic remineralization potential of high concentration Ca/P-PILP at demineralized artificial caries dentin lesion, additionally to investigate the bond interfacial integrity as well as the bonding strength of the biomimetic remineralized artificial caries dentin lesion.MethodsDemineralized dentin collagen of 5 μm thick was biomimetically remineralized with low, medium concentration Ca/P-PILP for 10 days and high concentration Ca/P-PILP for 10, 15, 20 days. Artificial caries dentin lesion at a thickness of 150 ± 50 μm was biomimetically remineralized with high concentration Ca/P-PILP for 20 days. The biomimetic remineralization of demineralized dentin collagen was observed by scanning electron microscopy (SEM). The biomimetic remineralization intensity and depth of artificial caries dentin lesion was assessed by Electron Probe Micro Analyzer (EPMA). The bonding interfacial integrity between remineralized artificial caries dentin and composite resin was observed by Swept-source optical coherence tomography (SS-OCT) and the bonding strength of remineralized artificial caries dentin was evaluated by micro-tensile bond strength analysis (μTBS).ResultsSolely PAA-PASP solution and solely saturated Ca/P solution can’t achieve dentin collagen remineralization. Increased concentration of Ca/P-PILP and prolonged remineralization time can enhance the biomimetic remineralization intensity of demineralized dentin collagen. After treating with high concentration Ca/P-PILP, a 150 ± 50 μm thick layer of demineralized artificial caries dentin lesion was not fully remineralized, and the biomimetic remineralization intensity reached up to 88.0%. Furthermore, a better bonding interfacial integrity with less microgap and increased bond strength at both baseline level and aging level were observed when artificial caries dentin lesion was biomimetically remineralized with high concentration Ca/P-PILP.SignificanceBiomimetic remineralization of demineralized caries dentin lesion promotes its clinical properties for resin composited adhesive restoration.     

Biomimetic remineralization of dentin

Objectives

Remineralization of demineralized dentin is important for improving dentin bonding stability and controlling primary and secondary caries. Nevertheless, conventional dentin remineralization strategy is not suitable for remineralizing completely demineralized dentin within hybrid layers created by etch-and-rinse and moderately aggressive self-etch adhesive systems, or the superficial part of a caries-affected dentin lesion left behind after minimally invasive caries removal. Biomimetic remineralization represents a different approach to this problem by attempting to backfill the demineralized dentin collagen with liquid-like amorphous calcium phosphate nanoprecursor particles that are stabilized by biomimetic analogs of noncollagenous proteins.

Methods

This paper reviewed the changing concepts in calcium phosphate mineralization of fibrillar collagen, including the recently discovered, non-classical particle-based crystallization concept, formation of polymer-induced liquid-precursors (PILP), experimental collagen models for mineralization, and the need for using phosphate-containing biomimetic analogs for biomimetic mineralization of collagen. Published work on the remineralization of resin–dentin bonds and artificial caries-like lesions by various research groups was then reviewed. Finally, the problems and progress associated with the translation of a scientifically sound concept into a clinically applicable approach are discussed.

Results and significance

The particle-based biomimetic remineralization strategy based on the PILP process demonstrates great potential in remineralizing faulty hybrid layers or caries-like dentin. Based on this concept, research in the development of more clinically feasible dentin remineralization strategy, such as incorporating poly(anionic) acid-stabilized amorphous calcium phosphate nanoprecursor-containing mesoporous silica nanofillers in dentin adhesives, may provide a promising strategy for increasing of the durability of resin–dentin bonding and remineralizing caries-affected dentin.     

Current Strategies in Dentin Remineralization

Partial caries removal procedures are used clinically in an attempt to conserve tooth structure and prevent pulp damage. Within this approach, the caries‐infected dentin is removed, and the partially demineralized caries‐affected dentin is preserved and sealed with materials that enhance remineralization. Fluoride‐releasing glass ionomers have been commonly used for this purpose. Recent studies have shown potential for other cements and bioactive adhesive materials to promote dentin repair through various strategies. These strategies include ion releasing of Ca‐P and the guided tissue remineralization or biomimetic remineralization of dentin. The latter is potentially useful in the remineralization of the demineralized acid‐etched dentin that is incompletely infiltrated by adhesives in dentin bonding. The purpose of this Critical Appraisal is to provide the clinician with a summary of current literature that clarifies understanding of the process of dentin remineralization and to describe current strategies in this area.     

Tubular occlusion optimizes bonding of hydrophobic resins to dentin

Although hydrophobic resins may be bonded to acid-etched dentin with an ethanol wet-bonding technique, the protocol is sensitive to moisture contamination when bonding is performed in deep dentin. This study tested the hypothesis that the use of oxalate or poly(glutamic) acid-modified, diluted ceramicrete (PADC) for dentinal tubule occlusion prevents fluid contamination and improves the bonding of an experimental hydrophobic adhesive to acid-etched, ethanol-dehydrated dentin. Mid-coronal and deep acid-etched moist dentin pre-treated with oxalate or PADC was dehydrated by ethanol wet-bonding and infiltrated with the experimental three-step etch-and-rinse hydrophobic adhesive under simulated pulpal pressure. Tensile bond strengths to deep dentin without pre-treatment were severely compromised. Conversely, oxalate and PADC pre-treatments reduced dentin permeability, prevented water contamination, and improved bond strengths. Minimal nanoleakage was identified within hybrid layers created in the oxalate- and PADC-pre-treated deep dentin. The use of tubular occluding agents optimized bonding of hydrophobic resins to dentin.     

Dental adhesion: mechanism, techniques and durability

Contemporary dental adhesives show favorable immediate results in terms of bonding effectiveness. However, the durability of resin-dentin bonds is their major problem. It appears that simplification of adhesive techniques is rather detrimental to the long-term stability of resin-tooth interface. The hydrostatic pulpal pressure, the dentinal fluid flow and the increased dentinal wetness in vital dentin can affect the intimate interaction of certain dentin adhesives with dentinal tissue. Bond degradation occurs via water sorption, hydrolysis of ester linkages of methacrylate resins, and activation of endogenous dentin matrix metalloproteinases. The three-step etch-and-rinse adhesives still remain the gold standard in terms of durability. This review discusses the fundamental process of adhesion to enamel and dentin with different adhesive techniques, factors affecting the long-term bonding performance of modern adhesives and addresses the current perspectives for improving bond durability.     

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.     

Novel bioactive adhesive containing dimethylaminohexadecyl methacrylate and calcium phosphate nanoparticles to inhibit metalloproteinases and nanoleakage with three months of aging in artificial saliva

ObjectivesThe objectives of this study were to: (1) develop a multifunctional adhesive via dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate its ability to provide metalloproteinases (MMPs) deactivation and remineralization for long-term dentin bonding durability.MethodsDMAHDM and NACP were incorporated into Adper? Single Bond 2 Adhesive (SB2) at mass fractions of 5% and 20%, respectively. Degree of conversion and contact angle were measured. Endogenous MMP activity of the demineralized dentin beams, Masson’s trichrome staining, nano-indentation, microtensile bond strength and interfacial nanoleakage analyses were investigated after 24 h and 3 months of storage aging in artificial saliva.ResultsAdding DMAHDM and NACP did not compromise the degree of conversion and contact angle of SB2 (p > 0.05). DMAHDM and NACP incorporation reduced the endogenous MMP activity by 53 %, facilitated remineralization, and increased the Young’s modulus of hybrid layer by 49 % after 3 months of aging in artificial saliva, compared to control. For SB2 Control, the dentin bond strength decreased by 38 %, with greater nanoleakage expression, after 3 months of aging (p < 0.05). However, DMAHDM+NACP group showed no loss in bond strength, with much less nanoleakage, after 3 months of aging (p > 0.05).SignificanceDMAHDM+NACP adhesive greatly reduced MMP-degradation activity in demineralized dentin, induced remineralization at adhesive-dentin interface, and maintained the dentin bond strength after aging, without adversely affecting polymerization and dentin wettability. This new adhesive has great potential to help eliminate secondary caries, prevent hybrid layer degradation, and increase the resin-dentin bond longevity.     

Application of etch-and-rinse adhesives on dry and rewet dentin under rubbing action: a 24-month clinical evaluation

BackgroundResearchers conducting laboratory investigations have reported that bonding to dry demineralized dentin can be feasible technically as long as the adhesives are rubbed vigorously onto the dentin surface. The authors aimed to evaluate the 24-month clinical performance of resin–based composites in noncarious cervical lesions (NCCLs) in teeth restored with two etch-and-rinse adhesives that had been applied with a vigorous rubbing action to both dry and rewet dentin.MethodsThe authors enrolled 40 patients in this study. They inserted 160 restorations and evaluated them at baseline and at six, 12 and 24 months of service. They divided the restorations into four groups: One-Step (OS) Universal Dental Adhesive System (Bisco, Schaumburg, Ill.) (acetone-based adhesive) with rewet dentin; OS with dry dentin; Adper Single Bond (SB) Plus Adhesive (3M ESPE, St. Paul, Minn.) (ethanol/water–based adhesive) with rewet dentin; and SB with dry dentin. The authors used the same resin–based composite for all restorations. They evaluated the restorations according to modified U.S. Public Health Service criteria.ResultsThe 24-month retention rates for the rewet and dry conditions, respectively, were 95.0 percent and 97.5 percent for SB and 97.5 percent and 91.9 percent for OS. The authors detected no significant difference between rewet and dry groups for either adhesive (P > .05). In terms of marginal discoloration, OS performed significantly worse than did SB, irrespective of dentin moisture (P > .05).Conclusions and Clinical ImplicationsDentin moisture seems not to be important for the retention of etch-and-rinse adhesives as long as the adhesives have been rubbed vigorously onto the dentin surface. The ethanol/water–based adhesive showed a better overall performance than did the acetone–based system.     

Effects of potassium oxalate on knoop hardness of etch-and-rinse adhesives

The objective of this study was to determine whether the hardness of etch-and-rinse adhesives may be affected by the pretreatment of acid-etched dentin with potassium oxalate desensitizer. Unerupted human third molars were cut into crown segments by removing the occlusal enamel and roots. The pulp chamber of these crown segments was connected to a syringe barrel filled with phosphate-buffered saline so that the moisture of dentin was maintained during the bonding procedures. Three etch-and-rinse adhesives-two two-step systems (Adper Single Bond 2 [SB], One-Step [OS]) and one three-step system (Adper Scotchbond Multi-Purpose [MP])-were applied to acid-etched dentin that had been treated (experimental groups) or not (control groups) with potassium oxalate (BisBlock). The Knoop hardness (KHN) of adhesives was taken at different sites of the outer surface of the adhesive-bonded dentin. The KHN of the three tested adhesives applied to acid-etched dentin treated with potassium oxalate was significantly lower than that exhibited by the respective controls (not treated with oxalate; p<0.05). Regardless of the adhesive, the treatment with potassium oxalate reduced the adhesives' KHN (p<0.05), with the OS system exhibiting the lowest KHN compared with the MP and SB systems.