牙本质粘接界面微渗漏的观察方法比较

目的：比较光镜及扫描电镜观察牙本质粘接界面微渗漏的能力。方法：去除磨牙面釉质,暴露牙本质,分别用2种粘接剂（Prime＆Bond NT、Clearfil S3Bond）粘接牙本质,其上制作复合树脂冠。顺牙齿长轴,在相互垂直的两个方向片切牙齿,制备条状试样,将试样相继浸泡于氨化硝酸银溶液及显影液中,然后测定微拉伸粘接强度。最后在光镜及扫描电镜下观察混合破坏试样的断面。结果：光镜下可观察到断面残留粘接剂下面的银渗漏,而扫描电镜下却看不到这些银渗漏;扫描电镜二次电子图像可清晰显示断面的形貌,背散射电子图像清晰区别银渗漏与其它结构。结论：将光镜和扫描电镜观察相结合,可更全面地了解牙本质粘接断面的微渗漏。     

冷热循环对纳米填料树脂与牙本质粘接界面的影响

目的:探讨冷热循环对纳米填料树脂与牙本质粘接界面密合度的影响。方法:选完整离体人磨牙60颗随机均分3组,备邻洞后,用3M公司粘接剂(Adper Prompt)与该公司的光固化复合体F2000 Compomer(FT)、混合填料树脂FiltekTM Z250(ZT)和纳米树脂FiltekTM Supreme(FS)分别进行粘接充填,各组样本一半经2000次冷热循环(5℃和55℃),冷热循环组和非冷热循环组均经染料渗透实验,在体视显微镜下观测染料渗入界面的深度并用扫描电镜观察各组试件粘接界面的超微形态。结果:冷热循环前3种材料微渗漏深度差异无显著性(P>0.05),冷热循环后3种材料微渗漏深度差异有显著性(P<0.05),FS冷热循环测试前后的微渗漏深度差异有显著性,FT和ZT组冷热循环测试前后的微渗漏深度差异无显著性。扫描电镜下观察发现冷热循环可增大纳米树脂与粘接剂之间的裂隙。结论:冷热循环对纳米树脂与自酸蚀粘接剂的界面有负面影响。     

氯已定预处理对两步法自酸蚀粘接剂牙本质粘接界面稳定性的影响

目的：探讨氯已定预处理对两步法自酸蚀粘接剂的牙本质粘接界面稳定性的影响.方法：40颗离体人磨牙沿垂直于牙长轴的方向切割,暴露冠中部牙本质作为粘接面,牙本质试件随机分为两组,一组在粘接处理前涂布0.2％氯已定为实验组,一组无预处理为对照组,两组经两步法自酸蚀粘接剂SE Bond处理后,堆积复合树脂制备成粘接试件.每组随机抽取2个试件借助微拉曼光谱仪分析粘接剂的双键转化率,剩余的18个试件随机分为两个亚组,分别于即刻和冷热循环5000次后检测微拉伸粘接强度和界面的纳米渗漏情况.结果：0.2％氯已定预处理对SE Bond的树脂双键转化率无显著性影响（P＞0.05）.即刻测试时,对照组和实验组间的微拉伸粘接强度和纳米渗漏差异无统计学意义（PP ＞0.05）.冷热循环老化处理后,实验组的微拉伸粘接强度显著高于对照组,纳米渗漏程度显著低于对照组（P＜0.05）.结论：0.2％氯已定预处理不会干扰SE Bond的树脂聚合,且可提高其与牙本质粘接界面的稳定性.     

单瓶型通用粘接剂在牙本质粘接中的应用评价

［摘要］ 目的 评价2种单瓶型通用粘接剂在自酸蚀模式下应用与牙本质的粘接强度以及纳米渗漏情况。方法 制作40枚牙本质样本,分别使用Singlebond Universal和All-Bond Universal 2种单瓶型通用粘接剂在自酸蚀模式下处理牙本质表面,与复合树脂粘接制作粘接试件。各组粘接试件一半于24 h水储后（未老化）切割成细条,测试微拉伸粘接强度,另一半经受10 000次冷热循环后（老化）测试微拉伸粘接强度。数据以单因素方差分析和Tukey多重比较进行检验分析。各组代表性试件处理后以扫描电镜观察粘接界面,检测纳米渗漏情况。结果 不论是否经过老化,2种粘接剂组均获得了较高的粘接强度值,但扫描电镜均能发现纳米渗漏存在。结论 两种单瓶型通用粘接剂在自酸蚀模式下应用均能提供较好的粘接性能,但无法避免纳米渗漏的发生。     

不同粘接系统粘接Ni-Cr合金与牛牙釉质的疲劳破坏研究

目的 通过体外冷热循环机械载荷（TCML）咀嚼模拟实验，比较三种不同树脂粘接系统粘接Ni—Cr合金与牛牙釉质的抗疲劳破坏能力。方法 制作30个Ni—Cr合金试片，分别用Panavla F，Super—Bond C＆B和Resinomer＋One—Step粘接于牛牙釉质上。24小时后置于TCML咀嚼模拟疲劳实验机上进行疲劳实验。经3000次5℃／55℃冷热循环，3×10^6次30牛顿机械负荷疲劳实验后，观察粘接面破坏及裂纹中染色剂微渗漏情况。分4级记录。数据作非参数Kruskal—Wallis和Mann—whitney统计学检验。结果 三组的破坏和微渗漏的差异无显著性，破坏和裂纹多发生在粘接剂-金属界面（14例），少数为粘接剂-金属界面和粘接剂内聚破坏的混合（2例）。结论 所选用的三种粘接系统经冷热循环机械载荷疲劳实验后均有不同程度的脱落和裂纹出现，但其差异无统计学意义。金属-粘接剂界面是整个粘接结构的薄弱环节，提示提高金属-粘接剂-牙釉质粘接耐久性的关键是提高金属与粘接剂之间的寿命。     

原花青素对树脂-牙本质粘接界面耐冷热循环老化作用的影响

目的 探讨天然交联剂原花青素预处理脱矿牙本质是否对冷热循环下树脂-牙本质粘接界面有保护作用.方法 制备10％和15％原花青素交联预处理剂、5％戊二醛用于脱矿牙本质粘接前的短暂预处理(60和120s),无预处理组为阴性对照.根据冷热循环与否分亚组,每亚组4颗牙,制备树脂-牙本质粘接试件,即刻或于冷热循环(5000次)后测试微拉伸粘接强度,观察粘接断裂模式、界面微观形貌并测量胶原降解量.结果 冷热循环后15％原花青素预处理60和120 s组粘接强度[分别为(21.88±3.49)和(23.09±3.19) MPa]显著高于阴性对照组[(15.47±3.78) MPa](P＜0.05).各组粘接断裂模式均以混合破坏和界面破坏为主.各预处理组粘接界面混合层均一致密,而阴性对照组混合层中可见狭窄的空隙或裂缝.所有预处理组冷热循环后胶原降解量均显著低于阴性对照组(P＜0.05),其中15％原花青素预处理120 s组胶原降解量最低[(0.316±0.019) mg/g].结论 应用原花青素预处理脱矿牙本质可减缓因冷热循环引起的树脂-牙本质粘接界面退变,有助于提高粘接修复体的耐久性.     

不同树脂粘接剂粘接界面微裂隙的观测与评价

目的 比较3种树脂粘接剂与牙齿粘接界面的微裂隙,以期为临床提供参考.方法 收集15颗人离体第三恒磨牙,用随机数字表随机分为3组(每组5颗),颊侧备洞后,分别用全酸蚀粘接剂(3M ESPE Adper Single Bond 2)(A组)、双组分自酸蚀粘接剂(3M ESPE Adper SE Plus)(B组)和单组分自酸蚀粘接剂(iBond Self Etch)(C组)进行粘接,树脂充填.扫描电镜下定点测量充填体侧壁、底壁与牙体间的微裂隙宽度,所有试样经3000次冷热循环后再次测量.使用秩和检验比较3组组间差异和冷热循环前后差异.结果 冷热循环后各组侧壁或底壁的微裂隙宽度均比冷热循环前显著增加(P＜0.05),冷热循环前后A、B、C组侧壁或底壁微裂隙宽度增加量[侧壁:1.33(1.14,1.74)、1.27(1.04,1.86)、1.11(0.55,1.46) μm;底壁:2.22(1.36,2.50)、1.91 (1.48,2.88)、2.38(2.08,2.47) μm]差异无统计学意义(P＞0.05).结论 3种树脂粘接剂对牙齿粘接性能的影响无差异;冷热循环可破坏粘接界面的稳定性.     

酪蛋白磷酸肽-无定形磷酸钙对牙本质粘接界面耐pH循环老化的影响

目的 研究局部应用酪蛋白磷酸肽-无定形磷酸钙（CPP-ACP）对牙本质粘接界面耐pH循环老化的影响。方法 常规制备牙本质粘接试件,将其随机分为3组,其中2组行pH循环,期间每日分别加用CPP-ACP、去离子蒸馏水（DDW）处理,15 d后测定微拉伸粘接强度,观察断裂模式、界面形貌及纳米渗漏,并确定混合层内元素含量。另一组试件制备完成后即刻测试。结果 无pH循环组及pH循环/CPP-ACP组微拉伸粘接强度差异无统计学意义,但二者均显著高于pH循环/DDW组（P＜0.05）。试件均以混合破坏为主。pH循环/CPP-ACP组混合层质量优于pH循环/DDW组,纳米渗漏少。无pH循环组及pH循环/CPP-ACP组混合层内Ca含量显著高于pH循环/DDW组,Ag含量显著低于pH循环/DDW组（P＜0.05）。结论 牙本质粘接界面局部应用CPP-ACP可增强界面耐pH循环老化的能力,延缓界面退变。     

五种牙本质粘接剂对乳牙牙本质边缘封闭性的比较

目的 检测5种牙本质粘接剂对乳牙牙本质的粘接性能,为牙本质粘接剂的临床使用提供依据.方法 将50颗因滞留而拔除的乳前牙按随机数表法分为5组,每组10颗.用棒状金刚砂车针EX-41在唇面中1/3处制备约直径1.5mm、深1mm的Ⅰ类洞,各组分别使用FL-BondⅡ、Clearfil Protect Bond、Clearfil SE Bond、AdperTMEasy One和AdperTM Single Bond 2,每组分别按说明进行粘接,树脂充填.冷热循环5000次,体视镜下观察充填物边缘染料渗入的深度、分级进行统计.结果 各组均发生微渗漏,各组间微渗漏程度差异无统计学意义(P＞0.05).结论 AdperTM Easy One组的边缘封闭性与其他4组相同,由于操作简便更适用于儿童乳牙的粘接.     

两种全酸蚀粘接剂对牙本质与玻璃陶瓷粘接界面封闭性能的影响

目的:研究2种全酸蚀粘接剂对正常牙本质与玻璃陶瓷粘接界面封闭性的影响。方法:选取20个牙本质块,分2组(n=10),分别采用2种全酸蚀粘接剂Variolink N和U.link,与玻璃陶瓷瓷块制备粘接试件。两组试件经氨化硝酸银染色后进行能谱分析,并于场发射扫描电镜(field emission scanning electron microscope,FESEM)下观察粘接界面纳米渗漏情况。结果:两组纳米渗漏差异无统计学意义(P>0.05)。结论:U.link全酸蚀粘接剂的界面封闭效果与Variolink N全酸蚀粘接剂相似。     

Thermal and mechanical load cycling on microleakage and shear bond strength to dentin

This study evaluated the influence of mechanical and thermal cycling on microleakage at the cervical margins of proximal slot restorations and shear bond strength on flat dentin surfaces. Microleakage Evaluation: One hundred and twenty slot cavity restorations were performed on bovine incisors. The restorations were randomly divided into four groups (n = 30): control (no thermal and mechanical load cycling), thermal cycling (2,000 cycles, 5 degrees C-55 degrees C), mechanical load cycling (50,000-80N) and thermal and load cycling (2,000 5 degrees C-55 degrees C/50,000-80N). The specimens were sealed with acid resistant varnish, leaving a 1-mm window around the cervical margin interface. To detect marginal leakage, a 2% methylene blue buffered solution was used for four hours. The specimens were sectioned longitudinally and qualitatively evaluated by stereomicroscopy (45x) following a ranked score for the dentin cervical margin. The data were analyzed by Kruskal-Wallis test (alpha = 0.05). Shear Bond Strength Evaluation (SBS): Eighty bovine incisors were embedded and polished to obtain a flat standard surface on dentin. The surfaces were restored with Single Bond adhesive system and a resin composite subsequently inserted in a bipartite Teflon matrix. The specimens were randomly divided into the four groups (n = 20) described above for microleakage. Shear bond strengths were measured in a universal testing machine with a crosshead speed of 0.5 mm/minute. The data were analyzed by one way ANOVA test (alpha = 0.05). No statistically significant influence of thermocycling, mechanical load cycling or the combination was observed for both microleakage and shear bond strength.     

Effect of thermal cycling on bond strengths of single-step self-etch adhesives to bovine dentin

The purpose of this study was to clarify the effect of thermal cycling on dentin bond strengths of single-step self-etch adhesives. Five commercially available single-step self-etch systems were used. The adhesives were applied to the dentin surfaces of bovine incisors, and then light-irradiated. Resin composites were condensed into a mold and light-irradiated. Bonded specimens were divided into two groups and stored in water at 37 degrees C for 24 h without thermal cycling, or in water at 37 degrees C for 24 h followed by 10,000 thermal cycles between 5 degrees C and 60 degrees C. Ten samples per group were tested for shear strength at a crosshead speed of 1.0 mm/min. The data were analyzed by Student's t test and Tukey HSD test at a probability level of 0.05. After 24 h of storage in water, the mean dentin bond strengths ranged from 9.3 MPa to 14.0 MPa. After 10,000 thermal cycles, the mean bond strengths remained unchanged. Failure after the test was commonly due to adhesive breakdown associated with partial cohesive failure of the resin. The present results suggest that the benefit of using single-step self-etch systems, in terms of simplifying the clinical procedure, might be acceptable even after thermal stresses.     

Microleakage of bonded amalgam restorations: effect of thermal cycling

This study examined the effect of thermal cycling on the microleakage of bonded amalgam restorations. Three dental amalgam alloys and a gallium alloy were tested with two adhesive resin systems and copal varnish as a control. Class V cavity preparations were prepared on 168 freshly extracted premolars or molars. The preparations were placed parallel to and 1.0 mm occlusal to the cementoenamel junction (CEJ). Four groups of 42 teeth each were treated with one of the following adhesive dentin systems: Bond-It, All-Bond 2/Resinomer or a copal varnish (Copalite). The four groups of 42 teeth each were then restored with one of three dental amalgams: Orosphere Plus, Indiloy, Oralloy or a Gallium alloy (Galloy), resulting in 12 test groups of 14 teeth each. The specimens were stored in double distilled water at 37 degrees C for 24 hours. Final contouring and polishing of the restorations were performed under water spray. Half of the restorations in each group were thermocycled for 3000 cycles (5 degrees C-37 degrees C-55 degrees C-37 degrees C) with a dwell time of 15 sec at each temperature. The other half were stored in double distilled water at 37 degrees C for 24 hours. Then all 168 restorations were stained with dye, sectioned and scored for microleakage. Results showed that the adhesive dentin systems reduced microleakage in amalgam restorations compared to copal varnish only in non-thermocycled specimens. Statistical analysis of the results showed that there was an extremely significant difference (p < 0.001) in microleakage between the non-thermocycled and the thermocycled specimens in all test groups, whereas, there was no significant difference (p > 0.05) among thermocycled specimens. The reduction of microleakage was not significantly different between Bond-It and All-Bond 2/Resinomer in non-thermocycled specimens. Oralloy showed the most microleakage in the non-thermocycled groups when compared to the other alloys using the same adhesive liner.     

Microleakage of various cementing agents for full cast crowns.

OBJECTIVES: To evaluate microleakage and marginal gaps in full cast crown restorations bonded with six different types of cementing agents. METHODS: Sixty non-carious human premolars and molars were prepared in a standardized manner for full cast crown restorations. The mesial and distal margins were located in dentin, while the vestibular and palatal/lingual margins were located in enamel. Crowns were made from a high-gold alloy using a standardized technique. The specimens were randomized to six groups of cementing agents: one zinc-phosphate cement (Harvard cement), one conventional glass-ionomer cement (Fuji I), one resin-modified glass-ionomer cement (Fuji Plus), two standard resin cements (RelyX ARC, Panavia F), and one self-adhesive universal resin cement (RelyX Unicem). After 4 weeks of storage in distilled water at 37 degrees C, the specimens were subjected to 5000 thermocycles ranging from 5 to 55 degrees C. Then, they were placed in a silver nitrate solution, embedded in resin blocks, and vertically cut in buccolingual and mesiodistal direction. Subsequently, the objects were evaluated for microleakage and marginal gap using a high-resolution digital microscope camera. RESULTS: A number of inter-group differences were statistically significant. RelyX Unicem showed the smallest degree of microleakage both in enamel and in dentin. Panavia F und RelyX Unicem were associated with significantly larger marginal gaps than all other cementing agents. No association was observed between microleakage and marginal gap other than a weak direct correlation when using Harvard cement on enamel. SIGNIFICANCE: The cementing agents investigated revealed different sealing abilities. These differences were not associated with specific types of materials.     

In vitro microleakage of dentin adhesives.

This in vitro study measured the microleakage of current dentin bonding agents and glass-ionomer bases. Freshly extracted human molars were prepared to a flat surface, and dentin adhesives and composite resins were applied in a plastic matrix. Samples were stored in water at 37 degrees C, thermocycled, stained with AgNO3, embedded in epoxy resin, and sectioned for evaluation of stain penetration at the composite resin/tooth interface. The reliability index of the dentin adhesives varied significantly between materials. The enamel control had essentially no microleakage, and the aluminum oxalate dentin adhesive on dentin had significantly less microleakage than other dentin adhesives tested. Present dentin adhesives were unable to prevent, but may reduce, microleakage.     

The effect of pulse activation on microleakage of a 'packable' composite resin and two 'ormocers'

The purpose of the study was to examine the effect of pulse polymerization on microleakage of one packable composite resin and two organically modified ceramics (ormocers), within a high C-factor preparation. Class-V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on 60 freshly extracted premolars or molars. Teeth were randomly assigned to 12 experimental groups (five teeth each) representing the different restorative systems, mode of polymerization and thermal cycling test. Three groups of 20 teeth each were restored with one of the following restorative systems: Scotch bond 1/Filtek P 60, Admira bond/Admira, Etch&Prime 3.0/Definite. 10 restorations of each restorative system (two experimental groups) were conventionally polymerized, whereas the other 10 restorations were polymerized with a pulse program. The specimens were stored in double-distilled water at 37 degrees C for 24 h. Ten restorations from each restorative system (30 restorations, half of the specimens) were thermocycled, the other 30 restorations were kept in double-distilled water at 37 degrees C for 24 h. Then all 60 restorations stained with dye, sectioned and scored for microleakage. Results showed that there were no significant differences (P > 0.05) among the materials with respect to microleakage scores. The experimental groups that were conventionally polymerized revealed significantly more microleakage (P < 0.05) after thermal cycling than all the other groups. The gingival microleakage was significantly more (P < 0.05) than occlusal in conventionally polymerized, thermocycled experimental groups.     

Effect of dentin age on effectiveness of dentin bonding agents.

The purpose of this research effort was to investigate the effect of age changes in dentin on the effectiveness of two dentin adhesives in minimizing microleakage at the tooth-restoration interface. Cavities were prepared in permanent teeth extracted from patients below 20 years or over 55 years of age. Wedge-shaped cervical preparations were made with the gingival cavosurface margin on dentin. Treatment groups were randomly restored with one of two composite restorative materials, together with the appropriate dentin adhesives. The control group specimens were restored with the respective composite restorative materials without the adhesives. All specimens were thermocycled, then placed in 0.5% basic fuchsin dye solution for 24 hours and subsequently sectioned longitudinally. Microleakage at the tooth-restoration interface was assessed by dye penetration. The results showed that the use of adhesives significantly reduced microleakage along the tooth-restoration interface. The adhesive formulated with glycidyl methacrylate was significantly more effective in reducing microleakage in dentin of the over-55 age group.     

Hybridization quality in cervical cementum and superficial dentin using current adhesives.

OBJECTIVES: The aim of this research was to determine the hybridization quality of adhesives to gingival cementum and close superficial dentin using both total-etch and self-etch, one-step and two-step adhesives in vitro. METHODS: Five adhesive systems were used and evaluated in this study; three kinds of two-step adhesives (total-etch--Single Bond and self-etch--Clearfil SE Bond and Clearfil Protect Bond) and two one-step adhesives (Clearfil S3 Bond, G Bond). Fifteen extracted intact human third molars were used in this study. A diagonal cut which was approximately 45 degrees to the long axis of the roots, with the initiating point located 2 mm below the buccal enamel-cementum junction and ascending towards the pulp chamber was prepared on each tooth. Flat cervical cementum and dentin surfaces were ground with wet 600-grit silicon carbide paper, and bonded with one of the adhesives and finished by applying a flowable resin composite. After 24 h storage at 37 degrees C in water, the bonded assemblies were sectioned into approximately 1mm thick slabs. Two central slabs from each tooth were chosen. One slab was totally demineralized in 0.5 M EDTA and the other was not demineralized and immersed into 50% (w/v) solution of ammoniacal silver nitrate for 24 h, and successively exposed to photodeveloping solution for 8 h. The specimens were then processed for TEM observation. Both the stained demineralized silver unchallenged and unstained non-demineralized silver challenged resin-cervical cementum/proximal superficial dentin interface were observed and evaluated under a transmission electron microscope. RESULTS: The nanoleakage pathway and extent vary among the different adhesives used and also between the resin-cementum interface and resin-dentin interface. Two-step self-etch adhesives showed better hybridization quality both in cementum and proximal superficial dentin as compared to those of two-step total-etch adhesive and one-step self-etch adhesives. SIGNIFICANCE: Two-step self-etch adhesives may provide a better sealing in cervical cementum and the proximal superficial dentin region.     

Tensile strength and durability of bovine dentin

This study investigated the effects of thermal cycling on the tensile strength of dentin. Bovine dentin were divided into 10 groups, which were then subjected to various conditions: intact after preparation, thereby serving as a control; heating in boiling water for 45 minutes; 10,000 thermal cycles in water; 10,000 thermal cycles in PBS; storage in water at 5, 23, or 55 degrees C for two weeks; and storage in PBS at 5, 23, or 55 degrees C for two weeks. Subsequently, bovine dentin were trimmed into dumbbell-shaped specimens and the tensile test performed in distilled water at 37 degrees C. Mean tensile strengths were compared statistically by one-way ANOVA and Fisher's PLTD test (p<0.05). Fracture surfaces were observed by scanning electron microscopy, and reliability of the results was analyzed with Weibull distribution. Tensile strength did not significantly change after thermal cycling or storage in water and PBS at all temperatures tested (71.2-77.0 MPa) but decreased after treatment with boiling water (65.5 MPa).     

Effect of dentin conditioning time on nanoleakage

OBJECTIVES: To study the nanoleakage pattern in the dentin hybrid layer by using different dentin adhesives. The null hypotheses tested in this study were: 1) dentin conditioning time does not affect nanoleakage within the hybrid layer; 2) the type of dentin adhesive used does not affect nanoleakage. METHODS: Standardized Class V cavities were prepared in 30 intact human molars on the buccal and lingual surfaces. The specimens were randomly assigned to 2 total-etch dentin adhesives (OptiBond SOLO Plus [OPS, Kerr] and One-Step [ONS, BISCO Inc]) and 2 self-etch dentin adhesives (Clearfil SE Bond [CSE, Kuraray] and Adper Prompt L-Pop [APL, 3M ESPE]). The specimens were etched or conditioned for 15 seconds, 30 seconds or 60 seconds. Upon restoration of the Class V cavities with the proprietary resin composite, the specimens were isolated with nail polish except for a 2.0-mm rim around the restoration, and they were immersed in 50 wt% ammoniacal silver nitrate solution (pH=9.5) for 24 hours followed by 8 hours of immersion in photo-developing solution to reduce the silver ions to metallic silver. The specimens were fixed, dehydrated and processed for FESEM and TEM. Silver penetration was measured along the cervical wall, and data were analyzed with Kruskal-Wallis non-parametric tests at a significance level of 95%. RESULTS: There were no statistically significant differences among the experimental groups for the factor "conditioning time" (p>0.926). There were significant differences for the variable "dentin adhesive" (p<0.0001). The least amount of nanoleakage within the hybrid layer occurred with CSE, while ONS resulted in the greatest penetration of silver ions. The adhesives OPS and APL ranked in the intermediary subset. Under TEM, all adhesives resulted in some degree of nanoleakage within the hybrid layer. Both spotted/reticular and water-tree nanoleakage patterns were observed. SIGNIFICANCE: Longer conditioning times did not increase nanoleakage within the hybrid layer. Nanoleakage varied with the type of adhesive used.