氯己定质量浓度对牙本质与树脂粘接耐久性的影响

目的 探讨氯己定质量浓度对牙本质与树脂粘接耐久性的影响,为进一步选择最佳质量浓度的氯己定应用于临床粘接提供参考.方法 40颗第三磨牙通过随机数字表法分为5组,1组用1.5 μl纯水处理牙本质表面(对照组),其余4组分别用0.02%、0.2%、2%、20%氯己定处理牙本质表面(氯己定组),每组制作32个微拉伸试件,分别经24 h和6个月37℃纯水储存后测试粘接强度;并用扫描电镜观察断裂界面.结果 氯己定处理对水储存24 h牙本质与树脂粘接强度的影响较小.水储存6个月后,0.2%和2%氯己定组的粘接强度[分别为(24.68±5.26)和(23.19±5.26)MPa]与对照组[(19.10±4.67)MPa]相比,差异有统计学意义(P=0.007,0.045);0.2%、2%氯己定组的粘接强度与0.02%氯己定组[(19.01±6.87)MPa]相比,差异有统计学意义(P=0.006,0.041).水储存24 h时试件断裂多为界面破坏和混合破坏,水储存6个月后混合破坏和内聚破坏增加.水储存6个月后0.2%、2%和20%氯己定组界面断裂多发生于混合层顶部(近粘接树脂端);而对照组和0.02%氯己定组断裂多发生于混合层底部(近牙本质端).结论 氯己定处理牙本质表面可以提高牙本质与树脂的粘接耐久性;氯己定质量浓度超过0.2%后,增加质量浓度未能进一步提高粘接耐久性.     

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.     

Nd:YAG激光增加非龋性硬化牙本质全酸蚀粘接强度的实验研究

目的 通过微拉伸粘接强度实验,探讨激光对全酸蚀粘接剂处理后的非龋性硬化牙本质与复合树脂粘接强度的影响.方法 选择牙本质视觉分级为3级以上的(牙合)面磨损后牙10颗,每颗牙以低速锯垂直于牙本质表面,将硬化牙本质分为面积相等的两部分(约12 mm2),按随机数字表法将这两部分分为实验组和对照组,实验组经Nd∶YAG激光(1 W,10 Hz)处理后,使用Scotchbond (STB)酸蚀、涂布粘接剂Adper Single bond 2(ASB)联合Z350复合树脂充填,对照组使用STB酸蚀、涂布粘接剂ASB联合Z350复合树脂充填.置于37 ℃生理盐水中24 h后,制作微拉伸试件并测试微拉伸粘接强度,体视显微镜下观察断裂模式并分类.采用SPSS13.0软件对微拉伸粘接强度值做t检验.结果 实验组粘接强度[(26.11±1. 62)Mpa]显著高于对照组[(22.27±2.16)Mpa],差异有统计学意义(P=0.006).体视显微镜下可见断裂多发生于牙本质-树脂粘接面.结论 Nd∶YAG激光能够提高硬化牙本质与全酸蚀粘接系统的粘接强度.     

氯己定预处理牙本质后对自酸蚀粘接剂粘结效果的影响

目的 评价2%氯己定在不同作用时间下对自酸蚀粘接剂稳定性的影响。方法 选择50颗无龋离体牙作为研究对象,制作牙本质试件,采用Adper^TM Easy One自酸蚀粘接剂粘结,堆积复合树脂,制作粘结试件。试件分别用2%氯己定进行0、15、30、45、60 s预处理,分别在老化循环前后进行微拉伸强度和扫描电镜测试,检测氯己定对自酸蚀粘结的影响。采用SPSS 19.0软件包对数据进行统计学分析。结果 氯己定预处理45、60 s组即刻测试微拉伸强度显著高于对照组,老化循环后氯己定预处理60 s组微拉伸强度较对照组高,差异显著(P<0.05)。结论 2%氯己定能提高自酸蚀粘接剂的粘结强度,改善粘结界面的老化退变,提高粘结的持久性。     

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。     

丁香油酚对全酸蚀/自酸蚀牙本质粘接系统微拉伸强度的影响

目的:评价含丁香油酚的暂封剂氧化锌丁香油糊剂(zincoxide- eugenol ,ZOE)对全酸蚀/自酸蚀牙本质粘接系统微拉伸强度的影响。方法:选择因正畸拔除的完整、无龋前磨牙;两种全酸蚀牙本质粘接系统:AllBond 2和SingleBond ,两种自酸蚀牙本质粘接系统:ClearfilSEBond和iBond。实验组使用氧化锌丁香油糊剂;对照组牙本质表面不做任何处理;分别存储于3 7℃的蒸馏水中,一周后两组分别使用4种牙本质粘接系统,用微拉伸法测试粘接强度。在体视显微镜下观察断裂界面。结果:双因素方差分析使用ZOE对粘接强度有显著影响(P <0 .0 5 ) ,粘接剂的类型对粘接强度无显著性影响(P >0 .0 5 ) ,交互作用有统计学意义(P <0 .0 5 )。多重比较提示,AllBond 2和SingleBond的实验组和对照组无显著性差异,而ClearfilSEBond和iBond实验组的微拉伸强度明显低于对照组,有显著性差异。体视显微镜下观察断裂多发生在粘接剂内。结论:含丁香油酚的暂封剂氧化锌丁香油糊剂对全酸蚀系统的AllBond 2和SingleBond的粘接强度无影响,对自酸蚀系统的ClearfilSEBond和iBond有显著不利影响。     

丹酚酸B对人牙本质自酸蚀粘结强度的影响

目的：探讨丹酚酸B对牙本质自酸蚀粘结即刻及长期粘结强度的影响。方法：将10颗新鲜拔除的人下颌第三磨牙去除面牙釉质,暴露中层牙本质,打磨后制备出标准粘结面,以硬组织切片机将每颗牙均分为近中及远中两部分,自凝塑料包埋牙根,随机选取每颗实验牙的近中或远中部分共10个牙体单位于牙本质粘结面涂布两层Adper Prompt自酸蚀粘结剂（3MESPE）,光固化10s后以Filtek Z350通用型纳米树脂（3MESPE）堆塑5mm高的树脂核;其余10个牙体单位则先以丹酚酸B处理牙本质粘结面,再以相同方法与材料制作树脂核。以硬组织切片机将各牙体单位切为1mm×1mm×8mm的微拉伸试件,每个牙体单位选出2个试件并随机分组,最终形成A1、A2、B1、B2四组（n=10）,A1设为对照组。对A1、B1组试件进行即刻微拉伸强度测试,A2、B2组试件水储6个月后进行微拉伸强度测试,评估其粘结强度。实验所得结果采用SPSS18.0软件进行ANOVA两因素方差分析和LSD多重检验。结果：丹酚酸B处理与未处理组的即刻微拉伸强度分别为（40.05±2.24）MPa、（41.58±1.98）MPa,两组即刻粘结强度无统计学差异;6个月水储后丹酚酸B处理组微拉伸强度为（18.96±2.05）MPa,高于未处理组（13.14±2.17）MPa（P〈0.05）。结论：丹酚酸B对牙本质自酸蚀粘结的即刻粘结强度没有明显影响,但能有效减缓长期（6个月）粘结强度的降。     

4种粘接系统对龋损影响牙本质的粘接效果的比较

目的：比较4种不同的粘接系统对正常牙本质和龋损影响牙本质的粘接强度。方法：24颗近中袷面中龋的人离体磨牙，在龋损检知液监控下用慢速球钻去龋，在远中袷面健康牙本质上制备相同深度的窝洞。随机分为4组，分别用4种粘接系统（Prime＆Bond NT，Adper Single Bond2，Adper Prompt和XenoⅢ）按照使用说明进行粘接，用树脂（FiltekP60）修复后保存于37℃的水中。沿牙长轴方向将树脂和牙齿从颊舌方向片切，厚度约为1．0mm，并修整成粘接面（正常牙本质或龋损影响牙本质）面积约1mm。的试件，进行微拉伸实验，并用扫描电镜观察粘接面形态。结果：4种粘接系统在正常牙本质上获得的粘接强度均强于在龋损影响牙本质上获得的强度（P〈0．05）；2种全酸蚀粘接系统在2种牙本质上获得的粘接强度均强于2种自酸蚀粘接系统获得的强度（P〈0．05）。扫描电镜观察，混合层在龋损影响牙本质上表现得厚但更疏松；与正常牙本质相比，龋损影响牙本质上形成的树脂突少。结论：2种全酸蚀粘接系统无论在正常牙本质还是龋损影响牙本质上均能获得比2种自酸蚀粘接系统更强的粘接力。     

2种自制牙本质粘接剂的微拉伸粘接强度和耐久性能的实验研究

目的 测试自行研制的自酸蚀及全酸蚀粘接剂的微拉伸粘接强度和耐久性能,并与市售的进口同类产品进行对比.方法 选用正畸拔除前磨牙60颗,随机分成4组,每组分循环前、后各2个亚组,各15个试件,分别为自制的自酸蚀粘接剂(44组)和全酸蚀粘接剂(45组),Easy one(EO组)和Single Bond2(SB组).测试各组冷热循环前后的微拉伸粘接强度变化,并进行统计分析,体视显微镜观察断裂模式.结果 冷热循环前,各组微拉伸粘接强度从大到小分别为SB组(35.05±3.01)Mpa＞44组(27.76±1.44)Mpa＞ 45组(27.65±1.67)Mpa＞EO组(26.03±2.15)Mpa,45组和SB组之间及44组和EO组之间微拉伸粘接强度的差异有统计学意义(P＜0.05).冷热循环后,各组从大到小为SB组＞44组＞EO组＞45组,45组和SB组之间及44组和EO组之间微拉伸粘接强度的差异有统计学意义(P＜0.05).同一粘接剂冷热循环前后相比,粘接强度均呈下降趋势(P＜0.05);试件的断裂面类型以混合型断裂为主.结论 自制牙本质粘接剂和市售的进口同类产品相比,自酸蚀粘接剂粘接强度高且耐久性能好,全酸蚀粘接剂则与之相反.冷热循环后各组粘接剂的微拉伸粘接强度均有下降.     

基质金属蛋白酶8对牙本质树脂粘接的影响

目的 研究基质金属蛋白酶8(MMP-8)对牙本质树脂粘接的影响,探讨其抑制剂在粘接中的应用.方法 收集60颗口腔颌面外科拔除的人正常第三磨牙.其中20颗用于制备牙本质粉并随机平均分成4组,第一组不做处理,第二组磷酸酸蚀,第三组磷酸酸蚀后粘接剂处理,第四组磷酸酸蚀后先用基质金属蛋白酶8的特异性抑制剂(MMP-8 Inhibitor I)孵育;然后4组均粘接剂处理,提取蛋白质检测MMP-8的活性.另外40颗离体牙随机均分为对照组和MMP-8Inhibitor I处理组(实验组),制作牙本质树脂试件并储存在人工唾液中,分别在储存l天和3个月时进行微拉伸试验分析粘接强度的变化,电镜观察断面和混合层降解的情况.结果 MMP-8活性实验结果显示,第一组呈现少量酶活性:第二组活性大幅度提高;第三组活性下降;第四组未检测到MMP-8活性.微拉伸试验结果显示在相同的时间点,实验组的粘接强度高于对照组,差异有统计学意义.扫描电镜显示,3个月后实验组混合层的胶原纤维网比较完整,对照组的胶原纤维出现明显的降解.结论 MMP-8 Inhibitor I可以通过抑制牙本质中MMP-8的活性抑制混合层胶原纤维网的降解.     

10-MDP-钙盐形成对牙本质粘接成绩影响的评价

目的 分析10-MDP-钙盐形成对牙本质粘接成绩的影响.方法 采用酸蚀冲洗粘接模式,根据牙本质表面的处理方式和选择粘接剂的不同将牙齿随机分为以下4组(n=5)进行处理,制作牙本质/树脂粘接试件:①对照组,直接使用全酸蚀粘接剂Single bond 2(SB2)处理后粘接;②10-MDP组,使用SB2处理进行粘接前,牙本...     

Influence of chlorhexidine application on longitudinal adhesive bond strength in deciduous teeth

The aim of this study was to evaluate the influence of applying 2% chlorhexidine for 30 seconds after phosphoric acid conditioning of dentin on the immediate and long-term bond strengths in deciduous teeth. The occlusal enamel was removed from 40 human sound deciduous molars, which were exfoliated by natural means, and the dentin was conditioned with 37% phosphoric acid for 15 seconds and washed with running water. The specimens were divided into two groups of 20 teeth. The test group received an application of 2% chlorhexidine for 30 seconds prior to a three-step etch-and-rinse adhesive system, whereas the control group received only the adhesive system. Three cylindrical restorations were made with a composite resin for each tooth. Ten teeth in each group were submitted to a microshear bond strength test after 24 hours, while the remaining teeth were stored in distilled water at 37 °C for 6 months before testing the microshear bond strength. The test group had a higher bond strength than did the control group after 6 months of storage. No statistical differences were found when groups with the same dentin treatment were compared at different times. Short applications of chlorhexidine at low concentrations prevent hybrid layer degradation and positively affect bond strength over time.     

Chlorhexidine preserves dentin bond in vitro

Loss of hybrid layer integrity compromises resin-dentin bond stability. Matrix metalloproteinases (MMPs) may be partially responsible for hybrid layer degradation. Since chlorhexidine inhibits MMPs, we hypothesized that chlorhexidine would decelerate the loss of resin-dentin bonds. Class I preparations in extracted third molars were sectioned into two halves. One half was customarily restored (etch-and-rinse adhesive/resin composite), and the other was treated with 2% chlorhexidine after being acid-etched before restoration. Specimens were stored in artificial saliva with/without protease inhibitors. Microtensile bond strengths and failure mode distribution under SEM were analyzed immediately after specimens' preparation and 6 months later. With chlorhexidine, significantly better preservation of bond strength was observed after 6 months; protease inhibitors in the storage medium had no effect. Failure analysis showed significantly less failure in the hybrid layer with chlorhexidine, compared with controls after 6 months. In conclusion, this in vitro study suggests that chlorhexidine might be useful for the preservation of dentin bond strength.     

Effects of mechanical properties of adhesive resins on bond strength to dentin.

OBJECTIVES: The purpose of this study was to evaluate the relationship between the micro-tensile bond strength to dentin and mechanical properties of the cured adhesive resins. METHODS: Coronal dentin surfaces of extracted human teeth were treated with four commercial self-etching priming systems (Clearfil SE Bond; UniFil Bond; Tokuso Mac-Bond II; and Imperva Fluoro Bond) and bonded with a resin composite. After 24h storage in water at 37 degrees C, the bonded specimens were trimmed and subjected to micro-tensile bond strength testing at a cross-head speed of 1mm/min. Debonded surfaces were observed under a FE-SEM. For testing mechanical properties, 0.7-mm thick slabs of each adhesive resin were prepared, light-cured, and stored dry at the room temperature for 24h. After trimming, ultimate micro-tensile strength was measured. The nano-hardness and Young's modulus were also evaluated using cured adhesives that were prepared in the same manner as described above. RESULTS: The micro-tensile bond strengths to dentin and ultimate micro-tensile strengths of the resins were not significantly different among all systems (P>0.05). However, the nano-hardness and Young's modulus of Clearfil SE Bond and Imperva Fluoro Bond adhesive resins were significantly higher than those of UniFil Bond and Tokuso Mac-Bond II resins (P<0.05). The micro-tensile bond strength significantly correlated with the ultimate micro-tensile strength of the resins (r(2)=0.77; P<0.05), but was not correlated with the nano-hardness or Young's modulus (P>0.05). SEM observation of the debonded surfaces revealed a mixed type of fracture with a combination of interfacial and cohesive failure within the adhesive resin. SIGNIFICANCE: The four self-etching priming systems exhibited similar dentin bond strengths, which also correlates with the ultimate strength of the adhesive resins.     

The incorporation of chlorhexidine in a two-step self-etching adhesive preserves dentin bond in vitro

Objectives

To investigate whether the incorporation of chlorhexidine in a two-step self-etching adhesive can preserve dentin bond strengths.

Methods

Different amounts of 20% chlorhexidine digluconate were added directly to the primer of Clearfil SE Bond to prepare mixtures of four different concentrations of chlorhexidine: 0.05%, 0.1%, 0.5% and 1.0%. Sixteen extracted third molars were randomly divided into 4 groups. Each group corresponded to one of the four chlorhexidine concentrations. Each of the 16 teeth was sectioned into two halves. One half was bonded with Clearfil SE Bond without chlorhexidine, and the other half was bonded with Clearfil SE Bond containing different concentrations of chlorhexidine. Specimens were stored in 0.9% NaCl containing 0.02% sodium azide at 37 °C. Microtensile bond strengths were tested 24 h after specimen preparation or 12 months later. The modes of fractures were examined under a stereomicroscope.

Results

Twelve-month storage resulted in significant bond strength reduction of all control groups (p < 0.05). When incorporated in SE Bond primer, chlorhexidine preserved dentin bond in the 0.1%, 0.5% and 1.0% chlorhexidine group (p < 0.05); in the 0.05% group, there is no statistical difference of bond strength between control group and experimental group tested at the 12-month period (p > 0.05).

Conclusions

When incorporated in the primer of Clearfil SE Bond, chlorhexidine can preserve dentin bond as long as the concentration of chlorhexidine in the primer is higher than or equal to 0.1%.     

Effect of remaining dentin thickness and the use of conditioner on micro-tensile bond strength of a glass-ionomer adhesive.

OBJECTIVES: The purpose of this study is to investigate the effect of remaining dentin thickness and the use of a 20% polyalkenoic acid conditioner on the micro-tensile bond strength of a glass-ionomer adhesive to dentin. METHODS: Resin composite was bonded to flat dentin surfaces from 14 extracted human teeth using Fuji BOND LC (GC) with or without a polyalkenoic acid conditioner, then sectioned to thin slabs, trimmed into an hourglass shape with the area of the interface being approximately 1mm(2), and subjected to micro-tensile testing at a cross-head speed of 1mm/min. Micro-tensile bond strengths were determined at three depth levels with a remaining dentin thickness of more than 3mm, between 2 and 3mm, and less than 2mm. Failure modes of the broken interfaces were determined using field-emission scanning electron microscopy. RESULTS: The micro-tensile bond strength to dentin significantly improved when the remaining dentin thickness increased and the conditioner was used. When the conditioner was used (irrespective of remaining dentin thickness), failures mainly occurred adhesively at the interface between the adhesive and resin composite. When no conditioner was used, no adhesive failures between the adhesive and resin composite occurred, but failures occurred mainly adhesively between dentin and the adhesive, or mixed adhesive-cohesively. SIGNIFICANCE: The bonding effectiveness of the glass-ionomer adhesive tested was affected by the area of intertubular dentin available for micro-mechanical retention through hybrid-layer formation. Removal of the smear layer improved the bond strength of the adhesive to dentin.     

The effect of chlorhexidine on dentin hybrid layers in vivo

This in vivo study evaluated by TEM the degradation of dentin hybrid layers in deep occlusal resin composite restorations. Caries-free premolars scheduled for extraction as part of orthodontic treatment were prepared, restored and evaluated after two and six months. The adhesive used was a single-bottle etch-and-rinse product (Single Bond Plus, 3M ESPE). Control group restorations were placed according to the manufacturer's instructions, while the experimental group received application of a 2% solution of chlorhexidine digluconate after etching. No degradation was observed in either group after two months. Slight degradation was found in the control group after six months, but none was observed in the experimental group. In vitro testing showed no significant difference in microtensile bond strength between the control and experimental adhesive protocols.     

The effect of hybrid layer thickness on bond strength: demineralized dentin zone of the hybrid layer

OBJECTIVES: The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using specimens acid-conditioned for varying lengths of time. METHODS: The dentin surfaces of human premolars, sectioned to remove the enamel from the labial surface, were conditioned with 35.0% phosphoric acid of an adhesive resin system (Scotchbond Multi-Purpose; 3M) for 15 (as directed by the manufacturer), 60, 120, or 180 s (experimental acid-conditioning times). The bonded specimens were then sectioned perpendicular to the adhesive interface to measure the hybrid layer thickness by SEM. The specimens for the micro-tensile test were sectioned perpendicular to the adhesive interface and trimmed to an hourglass-shape. Then, the micro-tensile test was performed at a crosshead speed of 1.0 mm/min. The bond strengths and hybrid layer thickness were statistically compared with Student's t-test (p < 0.05). All fractured surfaces were also observed by SEM. RESULTS: Significant differences between the groups exposed to acid for 15 and 60 s, and those exposed for 120 and 180 s were observed in hybrid layer thickness and bond strength (p < 0.05). SEM observation of the fractured surfaces revealed that a demineralized dentin zone without resin impregnation remained within the hybrid layer. SIGNIFICANCE: A demineralized dentin zone was formed in the bond structures after prolonged acid-conditioning, resulting in low bond strength. The shrinkage of the hybrid layer due to desiccation during the SEM examination process provided evidence of the presence of the demineralized dentin zone within the hybrid layer.     

Matrix metalloproteinase inhibitory properties of benzalkonium chloride stabilizes adhesive interfaces

This study evaluated the effects of different concentrations of benzalkonium chloride (BAC) on the preservation of adhesive interfaces created with two etch‐and‐rinse adhesives and its inhibitory properties on dentin matrix metalloproteinase (MMP) activity. The following groups were tested with the adhesive systems Optibond Solo Plus and All‐Bond 3: Group 1, adhesive without inhibitor (control); Group 2, topical 2.0% chlorhexidine (2.0% CHX); Group 3, phosphoric acid with 1.0%wt BAC (BAC‐PA); Group 4, 0.25% BAC‐adhesive (0.25% BAC); Group 5, 0.5% BAC‐adhesive (0.5% BAC); Group 6, 1.0% BAC‐adhesive (1.0% BAC); and Group 7, 2.0% BAC‐adhesive (2.0% BAC). Composite cylinders were fabricated, and shear bond strength (SBS) was evaluated after 24 h, 6 months, and 18 months of storage. Extracts from concentrated demineralized human dentin powder were subjected to SDS‐PAGE and incubated in the presence of 0.25, 0.5, 1.0, and 2.0% BAC. Overall, stable bonds were maintained for 18 months. Improved bond strengths were seen for 0.5% BAC and 1.0% BAC when bonding with Optibond Solo Plus, and for 0.25% BAC and 0.5% BAC when bonding with All‐Bond 3. Zymographic analysis revealed complete inhibition of gelatinolytic activity with BAC. Benzalkonium chloride, at all concentrations, inhibited dentin proteolytic activity, which seems to have contributed to the improved bond stability after 18 months for specific combinations of BAC concentration and adhesive.